Diver Medic Magazine Issue 7 Feb 2016 by Diver Medic and Aquatic Safety

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Issue 7

ICE DIVING OPERATIONS

BY ANDREA ZAFERES & BUTCH HENDRICK

FEATURING OUR NEW International Board of Undersea Medicine Journal

THE BIG FIVE MISTAKES IN DIVING BY DAN ORR

www.ibum.org Our BOD and staff Richard Sadler, M.D. , F.A.C.S. - Medical Director Harry Whelan, M.D., CAPT U.S. Navy (ret) - Director of Research Carla Renaldo, D.O. Dick Rutkowski, Founder Jeffrey Bertsch, CHT Jon Dembo, CHT Morgan Wells Ph.D. Joseph Dituri, M.S., CDR U.S. Navy (ret) The International Board of Undersea Medicine (IBUM) exists to train hyperbaric chamber operators, diving medical technicians, clinical hyperbaric technicians, and hyperbaric physicians as well as educate and increase safety for those who work in the hyperbaric field including certifications to the highest international standard for hyperbaric facilities. We are - Hyperbarics, Chamber Certification and Diving Research...Simplified! Our research department has first rate research fellows in hyperbarics who are pushing the technical frontier and publishing our results. Aside for our internal research, we seed hyperbaric medicine and diving research throughout the world to help improve our community. We tackle research problems that organizations historically shy away from.

Editor-in-Chief Chantelle Newman Editor Betty Orr Technical EditorS Andrea Zaferes, Gareth Lock Designers Allie Crawford, Sarah Crawford Medical and Diving Specialist Consultants Dr Anke Fabian Dr Adel Taher and Dr A Sakr Diving Consultants Dan and Betty Orr Jill Heinerth Advertising and Subscriptions Chrissie Taylor Newman Contributors Thank you to the following contributors: Betty Orr, Butch Hendrick, Andrea Zaferes, Team Lgs, Andy Davis, Dan Orr, Dr Anke Fabian, Gareth Lock, Jill Heinerth, Yannis Papastomatiou, Rod Hancock, Ruth Mort, Becky Kagan Schott, Code Blue Nurses, WDHOF, Dan Consulting, Aquamed, Human in the System, Dr Christian Oest, Richard Sadler, Harry Whelan, Carla Renaldo, Joseph Dituri, Jim Standing PHOTOGRAPHERS Cover Image by Becky Kagan Schott, Ethan Daniels, Little Sam, Dudarev Mikhail, DJ Mattaar, Think4photop, Dray van Beek, Andrea Izzotti, Beckyloveslobsters, bikeriderlondon, Aleshyn Andrei, PhotoSky, CyberEak, Cecile Riviere, Nonwarit, spfotocs, Gareth Lock, Jill Heinerth, Brian Artjeh, Mark Powell, Pete Bullen, Mercy Hospital, Chantelle Newman. James A Dawson

Magazine address The Diver Medic Ltd Great West House, Great West Road, Brentford, TW8 9DF Telephone +44 020 8326 5685 EMAIL info@thedivermedic.com www.dmaasm.com www.thedivermedic.com

Contents 4 Public Safety Ice Diving Operations 6 The Icarus Effect - Part 2 14 The 'Big Five' Mistakes in Diving 24 CASE STUDY: cerebral arterial gas embolism 34 Skills in Recreational & Technical Diving 44 Emergency Gas Management on Rebreathers 50 Time Pressure and the Impact on Accidents 56 Shark Bite 64 Letter from Editor By Betty Orr

By Walt "Butch" Hendrick & Andrea Zaferes

By Andy Davis

By Dan Orr

By Dr Anke Fabian By Gareth Lock By Jill Heinerth

By Mark Powell

By Yannis Papastamatiou

IBUM JOURNAL Heliox Versus Air for the Treatment of Air or Nitrox Induced Decompression Illness Selected Readings in Human Factors Science Part 1: Accident Theory and Neuropsychology

71 74 We are conducting diving research at IBUM in conjunction with the Medical College of Wisconsin! 78

Issue 7 | February 2016

A Letter from the Editor... You are reading this edition of Diver Medic, which means you take your dive safety and your knowledge base about diving seriously. The articles that this issue contains cover topics such as leadership, followship, “Groupthink”, time pressure, the impact of diet on oxygen toxicity, Heliox treatment for decompression illness, gas management, cautionary tales of diving choices made and a few others for you to discover. With the time pressure we all have in our everyday lives away from diving, it might be tempting to pick one or two articles to read and skim through a few more, thinking that you don’t do that style of diving or you have already read “something sort of like” that somewhere else. But if you are truly wanting to broaden your command of diving you should take the opportunity to delve into each and every article. Consider doing what you do best and dive in. Don’t limit yourself to the words on the electronic page, but read between the lines. Determine how every facet of a topic could be used to your advantage to become a better diver below, as well as above, the surface of the water. When I read Jill Heinerth’s article on “Emergency Gas Management on Rebreathers”, I picked up the broader importance of knowing your limitations and the limitations of your equipment. And in Dr. Anke Fabian’s “Case Report CAGE (cerebral arterial gas embolism)” I saw that health choices I made decades ago could affect my diving life today. Each and every article has the ability to give you more insight into your dive life than you may first guess.

Photo by Becky Kagan Schott

We would like to announce that from this issue forward we have teamed up with International Board of Undersea Medicine to include a scientific journal in our magazine. Remember, like diving, the best articles offer more under the surface. Enjoy. Dive safe. Dive smart.

Betty Orr Editor 5

PUBLIC SAFETY

CE DIVING

OPERATIONS

By Walt "Butch" Hendrick and Andrea Zaferes

The techniques described in this article were taught to approximately 1,000 students worldwide.

Photo by TeamLGS

ome divers ice dive for fun, others do it as a job. Those that ice dive professionally may do so as ice diving instructors, as scientific divers, or as public safety divers.

Unfortunately many of the standards, practices, and guidelines used today are relatively arbitrary. Except for the polar diving scientists who meet in polar diving AAUS (American Academy of Underwater Scientists) conferences to discuss standards, the other ice diving communities use standards presented by their instructor, their certification agency or their particular public safety department. These standards are typically created by sport diving instructors who are ice divers or ice diving instructors, or by public safety divers who learned how to ice dive from a sport instructor. This has progressed in the last few years to public safety dive training agencies teaching “public safety ice diving” that too often lack even the safety standards taught by recreational ice instructors. These standards are generally not tested and are not discussed in conferences with panels of experts. Especially for public safety divers (PSD), these standards often do not meet the needs of the job. One of the main concerns with today’s PSD ice diving training is that it does

not provide procedures or techniques for thin ice operations. PSD ice classes often allow divers to walk, crawl, stand, and sit on the ice, which does not prepare students for real world ice operations. If you are deployed on an ice call it is almost always because the ice was too thin to support a dog, child or adult who then fell through the ice into the frigid water. If the ice cannot support these victims, then it certainly cannot support a single, fully dressed diver, let alone the mandatory minimum five personnel (primary diver, backup diver, 90%-ready diver, primary tender, backup tender). Only calls that involve a car or truck puncturing through the ice might have strong enough ice to support standing, walking, or crawling dive team members. The Ontario Underwater Council, which regulates all diving conducted in Canada, pronounced in 1986, “Perhaps the only definite statement which can be made at this time is to recognize the need for a study of ice diving procedures by the various training agencies; with the intention of developing agreed upon procedures which will only add to the safety of divers participating in ice diving.” It is 2016 and after a continuance of needless ice diving deaths we are not much closer to achieving this goal and well past the time to take such action.

Photo by TeamLGS One of this articleâ&#x20AC;&#x2122;s main missions is to demonstrate the need for universally accepted, proven, hands-on tested ice diving safety standards and procedures for all types of ice divers both recreational and working. This article will provide readers with proven life-saving standards and practices that can readily be implemented in sport diving practices, training program standards, and in public safety diving standard operating procedures and guidelines. Ice diving is technical diving. It is not recreational technical diving, which is associated with mixed gas and untethered deep diving, rather it is technical in that it requires advanced and specialized training, procedures, equipment, and it requires well-trained surface support. Public safety ice diving operations require even more highly advanced training and equipment. In certain areas, for four or more months a year, divers descend below the ice roof. Ice diving is without a doubt severe, overhead diving. For the most part there is only one way in and one way out. Divers in 10 feet of water cannot push through a one and a half to two inch thick piece of ice and they cannot dig their way out without special training and a special ice pick-type tool. At depth, the darkness can be euphoric and incredibly unexpected.

Ice diving is incredibly equipment and personnel dependent, with environmental difficulties that supersede almost any other type of diving. The simplest things can become major difficulties when ice diving. Ice changes in density and characteristics as continuously and as often as the weather. Unexpected temperature changes are not infrequent in the ice diving environment nor is mild hypothermia. Cold hands can keep divers from functioning and unable to perform the most basic skills. Cold stress can cause irrational thinking, inability to make a decision, and inability for self-rescue. Cold stress is compounded with the cold and abnormal function of equipment and with unexpected weak ice. Without sufficient contingency plan training and continued practice, these variables can rapidly increase the severity of small problems into an escalating chain of events leading to injury or death.

When performed correctly, recreational ice diving allows divers to fully enjoy diving all year, creating new experiences in a unique dimension full of exciting and advanced underwater dynamics. Ice diving is exhilarating as fresh powder is for advanced snow skiers. Ice divers can explore a familiar summer dive site by experiencing it in a new way. Ice diving brings a new beauty to the underwater world while fostering improved personal dive skills and knowledge. In the public safety realm, ice diving operations possibly have the highest chances of victim survival due to the cold water and, in most cases, exact knowledge of where the victim is located. There are three major differences between recreational and public safety ice diving: • Recreational divers pick their dive days and sites while in public safety diving, the situation picks the site and time. • In recreational ice diving, two divers diving as a buddy team are normally in the water at any given time while the public safety diver is usually a solo diver. • Recreational divers have the mission of “have fun”, while public safety divers are there to search for a drowning victim or evidence. In the world of public safety diving no ice is safe ice. If the ice was safe then chances are the public safety divers would not have been called to the scene. There is no walking, standing, kneeling and, sometimes, not even crawling on the ice. There are no support personnel standing around watching as in sport diving. Rescuers often start falling through the ice before reaching the “Victim’s Point-Of-Entry”. Therefore, due to a lack of sufficient training and equipment, the average ice dive operation begins to fall apart before it even gets started.

Photo by TeamLGS

Often drills and training do not effectively prepare public safety divers for the reality of thin ice. Consider the majority of ice training dives you have observed or participated in. Divers and tenders probably walked out to a pre-cut hole. Tenders stood on the ice to tend. A bucket of warm water was ready at hand to manage freeflow problems.

Next consider actual ice diving calls where divers and tenders wore themselves out to a state of exhaustion just trying to reach the victim’s hole because the ice was too thin to support them. When they finally reached the victim’s hole, the ice was so broken up, that the exact location of the victim’s hole was lost. Tenders and divers, now in the water, are then working on self-survival. Every year there are actual ice diving incidents that seriously risk the lives of public safety personnel because they

Photo by TeamLGS

Issue 7 | February 2016

were not trained for realistic conditions â&#x20AC;&#x201C; thin, nonsupportive ice. Training needs to prepare students for the type of situations that they may face. Public safety divers will sometimes respond to winter and ice emergencies without proper training, preparation or equipment. This is especially true when a team is in a rescue mode, which is the most dangerous time to break safety standards. True, the benefits may be higher during an ice situation than during warm weather calls, but the risks are far greater. Always remember, two dead are never better than one. Public safety divers are not alone in being unprepared. It is not uncommon for sport ice diving classes to give students ice diving certification cards without ever teaching them how to cut holes safely (or at all), how to tend, that a true redundant air source such as a pony bottle is mandatory, how to manage an accidental disconnect, entanglement hazard management, how to transport an injured diver to shore, and how to manage other ice related problems. In rescue modes public safety divers must be capable of rapid deployment professional motion. That means dressing in under three minutes, performing the mandatory three equipment checks, rapidly securing the scene, setting up an incident command system, creating a plan of action, rapidly and safely carrying out the plan, rapidly and gently transporting the victim from the bottom to the shore, and preparing proper incident documentation.

If a diver needs assistance or actual rescuing during recreational dives, then they too need to be capable of rapid deployment professional motion. Recovery teams should also be capable of moving in rescue modes. Even strict recovery-only teams will respond in a rescue mode, when the chiefâ&#x20AC;&#x2122;s little girl falls through the ice a few blocks from where the team is conducing a drill. It is crucial to have strict and stringent safety standards during rescue modes because that is when adrenaline is high, and greater risks are more likely to be taken for a perceived greater potential benefit. Recovery-only teams are at greater risk than rescue-recovery teams in such operations because they are not trained or used to moving rapidly. In both rescue and recovery modes, public safety divers need to constantly be aware of the technical preparation and instantaneous planning needed to obtain a safe and fulfilled operation. To conduct a safe dive operation anytime requires a commitment to training, planning, and coordination. The same is true for any and all ice diving operations whether they be recreational or work-related. With all the controversy and discussion created around the concepts of recreational technical diving, ice diving is often

missed. Divers, diving instructors, and dive teams need to better understand all the parameters of safe ice diving. Recreational and, specifically, public safety ice diving is extreme technical diving. The lack of proper training is unfortunately demonstrated every year. Cave diving is another form of overhead diving. An important difference is that there are strict, universally accepted, tested, and well thought out standards. Divers know they need training. They begin with cavern and then work their way up through a series of ever advancing cave certification classes before dreaming of setting fin in a cave. A basic cave diver in Florida will use very similar procedures and standards as a cave diver in Mexico. However a certified ice diver may use very different procedures, equipment, and standards than a diver on the same lake. Two ice instructors on that same lake may be conducting classes in a completely different manner. One instructor may cut a single, round hole prior to the class, exert himself to pull the circle of ice out of the hole and stack it on the ice roof, use octopuses, put divers down on separate lines, and put the lines in the hands of tenders with no training. The other instructor may teach students how to use chainsaws to safely cut three triangular holes with an ice piton, a strap and a carabineer screwed into each triangle, after which the triangles are pushed under the ice roof where highly trained tenders will be standing, divers all have pony bottles and multiple cutting tools, and divers are tethered on a yoked line with harnesses. The cave deaths that have occurred are almost always divers who have entered caves without cave certification. Even a trained and very experienced cave diver can die with a natural disaster such as a cave collapse, but that is not the fault of the safety standards or training. Trained cave divers and instructors rarely are in the cave fatality statistics. And in many ways cave diving has fewer risks than ice diving. Cave diving does not have dangerous free-flow problems that can empty a diver’s tanks in seconds; it does not have the same risks of cold stress and hypothermia, and does not rely on surface support to the same degree as ice diving.

Does ice diving belong in the technical realm? Yes. Can ice diving be dangerous? Yes. Should any of these deaths have happened? No. In each case, the deaths were clearly a result of improper procedures and equipment. Our plan is not to die today. Our plan is not to go under the ice thinking “we're just going to take a look” or “I know this bottom like I know the palm of my hand.” If you believe you know any body of water the way you know the palm of your hand, put your hand in your pocket and describe exactly what it looks like. Disorganization, lack of planning, lack of air and sudden fear of not being able to get out, create instantaneous chaos. Compound it with the fact that “I must save my friend, my instructor,” and another inevitable multiple death is only seconds away.

Photo by Stephen Kerkhofs Photo by TeamLGS

Very sadly, the lack of proven and tested, universally accepted ice diving standards is demonstrated by the fact that the majority of divers who die under the ice had previous ice training or were in the process of being trained by a certified ice instructor. There are far too many headlines of “instructor and student die under the ice.” That is completely unacceptable.

This is a modified article taken out of Ice Diving Operations by Hendrick & Zaferes, (Pennwell Publishing, 430 pages, 2003) available from Amazon. com and Amazon.co.uk.

The

ICARUS EFFECT

Harmful Psychological Factors Influencing Diving Teams by Andy Davis, consultant technical diving instructor at scubatechphilippines.com

Part Two In the last article I covered negative individual and team dynamics that can lead to diving accidents. I will now outline a number of formally identified psychological phenomena that can influence teams to make flawed decisions, especially in regards to

These phenomena can occur in isolation, or combination, and they are known to have cost lives through their influence of team behaviors in the past. Understanding them can help identify them if they occur. 14

Photo byk Ethan Daniels

continuing flawed and dangerous diving projects.

'The Normalization of Deviance describes a dangerous facet of human nature.'

Issue 7 | February 2016

Normalization of Deviance Normalization of Deviance is a term that arose from NASA's inquest into the 1986 Space Shuttle Challenger disaster. The term was first published in Diane Vaughan’s book, 'The

Challenger Launch Decision'. It is a concept now being adopted as a causal factor in accident analysis in other fields, including diving.

Normalization of Deviance is well described by Steve Lewis (Doppler) in his technical diving blog: "The Normalization of Deviance describes a dangerous facet of human nature. It goes something like this: We do something that does not follow the accepted (and acceptable) rules or guidelines – for example, we skip certain steps in a “standard” procedure because it saves time. The trouble stems from the unfortunate fact that we get away with taking the shortcut. Then, believing it’s safe to make the same safety shortcut next time around, we do the same thing… we ignore safe practice, established safe practice. In the absence of things going totally pear-shaped, our deviation from normal practice and safe procedure becomes a new acceptable norm".

Photo by Little Sam

What we might identify this factor in individuals or teams who make rapid escalations in diving risk or challenge; rarely spending any time consolidating at a given level before progression to the next. At the same time, we might also see even the most basic 'standard diving guidelines', in respect of prudence, conservatism, experience acquisition and diving mindset being over-ruled or ignored again and again. A team or individual might conduct ever more risky and challenging dives. They might be successful. They "get away with it". The dives aren’t repeated sufficiently enough to make sure it wasn't just ‘survival by luck’. Each single, successful dive establishes an instant and unquestioned precedence that the team is 'competent and safe' to progress further.

We can see a distinct deviation from best, or accepted, practices for technical, overhead environment or recreational diving. The increment of deviation gets larger with each dive that doesn’t go wrong. Ultimately it will go wrong and if the dive parameters are sufficiently unforgiving, it can cost lives. In her book, Diane Vaughn describes how this deviation from best practice resulted in "Predictable Surprise". NASA succumbed to ‘normalization of deviance’ and, eventually, their luck ran out and it killed five astronauts, two payload specialists; and grounded the space shuttle program for almost three years. With hindsight, the accident was foreseeable and avoidable, but the team had become complacent to believe they were justified to take the short-cuts they had decided upon.

Photo by Gareth Lock

As Steve Lewis notes in his blog article: "....if the dive community, ... could put greater emphasis on the pratfalls and consequences associated with the normalization of deviance, it might help to lessen the unfortunate tendency of some divers to depart from established best practices… We would in essence, be removing a link that shows itself in many chains of error. And we might see diving fatalities shrink: perhaps not to nothing, but at least shrink a little. We will never change human nature, and never eliminate human error; but we can help to create a culture of responsibility based on a realistic review of what kills divers". The answer to preventing Normalization of Deviance is quite simply for the team to adhere to a disciplined and unequivocal commitment to applying best practices, proper procedures and standards.

No amount of evidence to the contrary should deter the team from what they initially agree is the right way of doing things.

Groupthink and Flawed Consensus The term 'Groupthink' was first used by social psychologist Irving Janis in his 1972 book "Victims of Groupthink". It is a damaging psychological process that can easily effect diving teams.

Collective rationalization

Groupthink occurs when the team makes faulty decisions and ignore alternatives, due to pressures that lead to a deterioration of “mental efficiency, reality testing, and moral judgment”. A team is especially susceptible to groupthink when its members are similar in background, insulated from outside opinions, when there are no clear rules set for decision making, when the team is highly cohesive and under significant pressure to achieve a result.

• The team believes in the appropriateness of their project, leading them to ignore the ethical or moral consequences of their decisions.

Illusion of invulnerability

• The team develops an excessive optimism which, in turn, encourages them to take extreme risks.

Belief in inherent morality

Stereotyped views of out-groups

• The team shields itself from critical feedback by viewing outside commentators as the “enemy”.

Direct pressure on dissenters

• Individual team members are put under pressure not to express views contrary to the team opinion.

Photo by Dudarev Mikhail

Janis described 8 symptoms to identify groupthink:

• The team ignores or over-rules warnings and fails to reconsider assumptions they have made.

''enabling' can be used negatively in psychology to describe dysfunctional behaviour that is intended to help resolve a problem; but in fact may prolong or worsen the issue'

Issue 7 | February 2016

Self-censorship

irrational thinking, all in an effort to preserve team cohesion. Ultimately, the probability of achieving a successful, or safe, outcome deteriorates.

Illusion of unanimity

To counter-act the issue of ‘Groupthink’ diving project teams can install safeguard processes to help protect against groupthink occurring. These might include;

Self-appointed ‘mindguards’

1. Empowering team members to speak out critically within the team 2. Inviting external experts to observe the team project and challenge team view 3. Encouraging team members to discuss the project with experts outside of the team 4. Nominating a 'Devil's Advocate' within the team (also known as the ‘Tenth Man’ Rule) 5. Taking time to observe and consider external (peers/rivals/community) reactions to the project variables.

• Team members feel obliged to not express doubts or deviations from the perceived group consensus.

• Team members assume that the majority view and judgments are unanimous and representative of all involved.

• Team members act to protect the team and the leader from information that is problematic or contradictory to the group’s cohesiveness, view, and/or decisions. When there is pressure for team unanimity and common-purpose, individual team members become less motivated to realistically assess the alternatives; especially those that may be deemed negative to achieving the team goal. The result is increased carelessness and

Photo by DJ Mattaar

Enabling Behavior The term ‘enabling’ can be used negatively in psychology to describe dysfunctional behavior that is intended to help resolve a problem; but in fact may prolong or worsen the issue. It is often used in conjunction with those people who support, or fail to discourage, addictive behavior in others.

esteem might be dependent on their ability to assist. Providing, rather than withholding, this assistance allows the enabler to retain a sense of control in an otherwise uncontrollable situation. The reality, though, is that enabling doesn’t help, it actually makes the situation worse.

In respect of diving teams, this can exhibit as willingness to support another person's flawed (and potentially harmful) actions. Enabling is often carried out with the best of intentions; often with the desire to help another achieve an important goal. In that sense, it has the same meaning as ‘empowering’; helping others achieve what they could not achieve by themselves. However, if that achievement is dangerous, it can mean the enabler is actively assisting someone put themselves at risk; where they couldn’t otherwise do it alone.

Where one, or more diving team members is consciously aware of dangerous flaws in the team project, the decision to assist or abstain from the team can be agonizing. The ultimate decision is often whether continued involvement with the team will contribute to their improved safety or empower them to progress to an anticipated disaster.

Enabling may also stem from a fear or insecurity, which prevents a decision to stop actions that the person identifies as unsafe and/or unsound diving conduct. When this is the case, the enabler might be called ‘codependent’, because the enabler’s own self-

This may occur when a team member, or members, have voiced concerns about the project but have been over-ruled or ignored. Their last remaining influence may be to remove themselves from the team and the project. In making this decision, the individual will have to consider which is the ‘lesser of two evils’.

Avoiding Dangerous Team Psychological Phenomena Be aware that these psychological phenomena are known to have affected high profile and professional teams in numerous fields and have, previously, resulted in loss of life. Don't be insular and isolated as a team. Reach out externally to the community, to peers and experts, for a second opinion. Heed that opinion, especially if it disagrees with the team consensus. The team leader must empower individual team members to think for themselves: to

question, critique and, if necessary, veto team assumptions. Never assume team consensus and challenge it whenever it occurs. As a supporting member of a team, your role isn't to be a cheerleader or provide unquestioning positive motivation. The team needs members who remain “grounded”, safety orientated, willing to speak out and cognizant of the big picture. Be prepared to veto or condone any course of action that you feel is unreasonable.

About the Author Andy Davis is a PADI TecRec, ANDI, BSAC and SSI qualified, independent instructor who specializes in teaching advanced Sidemount, Technical and Advanced Wreck courses across South East Asia. Currently based in ‘wreck diving heaven’ at Subic Bay, Philippines, he has amassed more than 8000 scuba dives over 25 years of diving across the globe. Andy writes for a popular blog (www.scubatechphilippines. com) on sidemount-technical-wreck diving and is currently writing a series of ebooks to be published on advanced diving topics. He works as a product consultant and evaluator for several sidemount equipment manufacturers. Prior to becoming a professional technical diving educator in 2006, Andy was an officer in the Royal Air Force and served in Iraq and Afghanistan performing a variety of planning and civil affairs team roles. 22

Photo by Think4photop

Issue 7 | February 2016

THE

'BIG FIVE'

MISTAKES IN DIVING

Dan Orr, President Dan Orr Consulting, LLC. As every diver knows, recreational scuba diving is an inherently safe sport. Nothing, however, especially when they take place in the outdoors, is completely without risk. Divers Alert Network (DAN), the world’s largest diving safety organization, has been collecting and publishing data on diving accidents for over 25 years in order to help the recreational diving community and individual divers identify and mitigate risks. Recently, DAN researchers analyzed nearly 1,000 diving fatalities collected between 1992 and 2003 in order to determine what factors contributed to a diving fatality. DAN researchers identified the following ‘triggering events’, which were the earliest identifiable root causes that initiated a cascade of events that turned a relatively unremarkable dive into a tragedy: Out of breathing gas Entrapment Equipment problems Rough water Trauma Buoyancy Inappropriate gas

= = = = = = =

41% 21% 15% 10% 6% 4% 3%

When you look at these numbers, virtually every one of these is either directly or indirectly caused by human error. While we make the assumption that human beings do make mistakes, with the appropriate amount of forethought and preparation, we should be able to reduce the likelihood that when something does happen, an incorrect choice will plunge the diver into a cascade of events leading towards truly unwanted circumstances. Now, let’s address the mistakes divers make and see what we can do to reduce our risks in diving.

Photo by Dray van Beeck

Mistake #1: Not taking care of your health When you look at the DAN injury and fatality data, one thing that stands out clearly is that nearly 1/3 of all fatalities are cardiac related. Of those, at least 50% are from the 40-59 age group. What is particularly disturbing is that 60% of those who ultimately died as a result of a cardiac-related incident had signs and symptoms that they or the people they were diving with recognized as cardiac-related before or during the dive. They still chose to continue diving anyway. Since cardiovascular disease is a serious problem in today’s society, all of us should be aware of the signs and symptoms of heart problems and know when to call the dive because of a medical issue. All of us who dive should understand that we have an obligation to ourselves and those we dive with to be in good health. Diving medical authorities suggest that an annual physical performed by a physician familiar with diving medicine is recommended for everyone over the age of 35 or any time there is a noticeable change in your health. If you don’t know the location of a physician familiar with diving, you can contact the DAN Medical Department in your region of the world for the name of a qualified physician near you.

Mistake #2: Not communicating effectively with your buddy Considering the triggering events identified above, it is essential that you and the people you dive with communicate clearly throughout the entire diving evolution from pre-planning through completion of the dive activity. Prior to beginning your dive, those who dive together should develop a working dive plan and discuss potential contingencies should the conditions during the dive change. Prior to beginning any dive, you should all agree that any member of the dive group has the right, actually the obligation, to “call” the dive if they feel they should not continue to dive regardless of the reason. This includes before the dive actually begins and should be a precondition for any dive you make. All you have to do is raise your thumb and the dive is over, no discussion and certainly no recriminations. The only way a dive can be done safely is if every diver understands and agrees to that basic safety procedure. Along with the “thumbs up” signal indicating the dive is over, it is a good idea for all divers to review other essential hand signals so that they can be clearly understood when trying to communicate information to each other. One important signal would indicate when to begin your return to the exit point based upon minimum breathing gas supply. When any one of the divers reaches the pre-determined breathing gas turn around point, all divers in the dive team will begin their return to the exit point. In that way, they will exit the water with the minimum required amount of breathing gas. Remember, the data from above, indicates that the primary triggering event (41%) in diving fatalities, is running out of breathing gas while still underwater.

Photo by Dudarev Mikhail

Mistake #3: Not practicing critical skills One of the other primary triggering events in diving fatalities (21%) is what is identified as “equipment problems”. In my opinion, the term should actually be “problems with equipment”. When reviewing the DAN fatality and injury data, it is clear that one of the significant issues in diving equipment use is “user error”. This is especially true in a diving emergency when divers attempt to use complex psychomotor skills such as the exchange of air in an out-of-air emergency without recent practice. Another would be removal and jettisoning a diver’s weights in an emergency. Regardless of the number of years you have been diving or the number of dives recorded in your logbook, without recent practice of critical emergency skills, you cannot hope to use them successfully without recent practice and reinforcement.

Mistake #4: Not using a checklist or pre-dive ritual Since many diving accidents could be prevented by divers working together to prepare for a dive, it is essential for all divers to develop a consistent pre-dive ritual so that their steps towards complete predive preparation is something that is repeated each and every time you dive. Along with that, a pre-dive checklist will keep you and your diving partners from missing or skipping crucial steps in preparing for any dive. As part of the 2012 Rebreather Forum 3.0, the use of checklists was identified as an important safety procedure to reduce the likelihood of diving fatalities.

Photo by Andrea Izzotti

Mistake #5: Not accepting personal responsibility for the dive Each member of a diving group should have equal responsibility for the conduct of the dive. When all divers in a group understand and agree with that precept, then, as a whole, the dive group has a number of ways to protect itself from individual or collective harm. With each diver being situationally aware and monitoring their individual breathing gas supply, depth, dive time, or any changes that could negatively impact safety, divers can individually and collectively improve the likelihood that each and every dive will be high on enjoyment and low on risk. When all divers monitor the dive and share information, you can make choices during the dive that could improve your safety. If, for example, you were to experience stronger currents or waves than expected or, due to some other condition, are working harder than anticipated, you and your diving partners can reduce the bottom time or dive shallower than planned to compensate or increase your safety stops. All of this requires being aware of all that’s happening during a dive, communicating collectively and, basically, knowing when to say “when”. Be prepared in every way so that you and your diving companions that maximize your enjoyment of our wonderful sport and minimize the risk! To quote the Diving Equipment and Marketing Association (DEMA), “Diving is, after all, like nothing else on earth!” When you look at the diving fatality data above, it is clear that the majority (63%) were likely triggered by “diver error”. That initial error was compounded by the diver’s inability to prevent or stop a cascade of events that, ultimately, led to a fatality. We can prevent this catastrophic chain of events from claiming more lives by being prepared to manage all manner of diving emergencies not by physical strength but by thorough preparation and the effective application of knowledge and skill.

(Bonus) Mistake #6: Not being insured against loss in diving Although diving accidents are rare, any pressure-related injury does require specific treatment protocols from a physician and treatment facility familiar with diving medicine. In order to protect yourself from potential catastrophic financial losses resulting from treatment not covered by your health insurance, diving safety experts suggest that you verify, in writing, that your personal health plan will cover both the required hyperbaric treatment and possible evacuation coverage necessary to get you from the possibly remote site of your injury to the nearest available appropriate treatment facility. If your present insurance coverage can’t or won’t verify that you have the appropriate coverage, it is suggested that all divers consider becoming a member of Divers Alert Network (DAN) and consider getting the appropriate insurance coverage. Being a knowledgeable diver is one key element in becoming a safer diver. Safety, after all, can never be taken for granted and requires the active participation of everyone who dives.

Photo by Andrea Izzotti

Photos by BeckyLovesLobsters, Photo by Ellen Cuylaerts

bikeriderlondon, Aleshyn Andrei, PhotoSky, CyberEak, Cecile Riviere, Nonwarit, spfotocz

Issue 7 | February 2016

A CASE REPORT

CAGE (cerebral arterial gas embolism)

By Dr Anke Fabian Matthias is a healthy male diver, 47 years old, who spent a dive vacation at the Red Sea. He is an experienced diver with more than 700 dives without any incidents. Physically, he is healthy without any chronic diseases and has no history of cardio-pulmonary problems. Since he had quit smoking a couple of years ago he felt better than ever.

Dive History: Day One: First dive 19 metres/ 60 minutes, second dive 28.4metres / 60 minutes. Surface interval 2 hours 23minutes. Both dives went without difficulties or other incidents. (Figure 1; Figure 2)

Photos by Dudarev Mikhail

Issue 7 | February 2016

Day Two: First dive 20.5 metres / 48 minutes. The dive proceeded without any anomalies. A five minute safety stop at five metres had been correctly accomplished. (Figure 3)

Photos by Andrea Izzotti

Issue 7 | February 2016

s a responsible dive instructor, Matthias waited until everyone else was back on board. He tried to take his fins off but he had great difficulties doing so due to a lack of motor strength in his right arm. Climbing up the ladder proved to be even more difficult but he managed. By then, the paresthesia in the form of a tingling sensation had occurred first in his left arm and then in both legs. His condition deteriorated with an increasing weakness in all four extremities. Only with the help of the boat crew could he manage to take off his tank, buoyancy compensator device and wetsuit. At this point, Matthias was unable to move his arms and legs and he had lost any superficial sensation. He immediately thought of decompression sickness (DCS) but did not understand how that could have been possible. It was only the second day of his diving vacation without a large amount of residual nitrogen in his body. The dive profiles were within the accepted limits, even taking into consideration that the second dive on day one was deeper than the first dive. He had respected all safety stops and it was easy diving. He had even used Enriched Air Nitrox during the accident dive providing an extra margin of safety. From the moment Matthias developed signs of paralysis, 100% oxygen was applied. A fellow diver gave him two aspirin and encouraged him to drink one litre of water during the one-hour boat trip back the harbor. The rescue chain was activated: Medical Helpline Worldwide’s aqua med™ hotline doctor was called and the nearest recompression chamber was informed about the incident. Due to the prompt oxygen application and replacement of fluids, Matthias’ clinical condition had improved when the vessel entered the harbor: the sensation in his limbs was slowly recovering and he could walk with assistance to the waiting car to take him to the hyperbaric chamber. The initial clinical examination at the hyperbaric center showed: blood pressure 100/70, pulse 75/minute, temperature 37.2 centigrade, respiratory rate 18/minute; chest showed equal air entry on all sides, no crepitation, no rhonchi; abdomen, ears, nose and throat free of pathological findings. The neurological examination revealed a partial loss of superficial sensation in the right arm and both legs. His

muscle strength and reflexes were normal. The patient was diagnosed with a DCS type II and recompression treatment was started immediately with a US Navy Table 6, an intravenous line with Ringer solution and one vial Solu-Cortef®. By the end of the third oxygen cycle Matthias was completely free of symptoms with no need for any modulation or extensions of the treatment. One follow up US Navy Table V session was implemented the next day. After the second recompression Matthias was stable and free of symptoms with no need for further sessions in the decompression chamber. He received clearance as fit-to-fly and travelled home to Germany 72 hours after the last recompression treatment. To search for the real reason of his DCS, he requested help and advice from the Center for Diving and Hyperbaric Medicine in Heidelberg. Doctor Chris Oest, medical superintendent and aqua med™ hotline doctor, examined Matthias thoroughly. At this point Matthias reported residual tingling in both hands and in the face, increased sweating and general malaise. Being clinically stable after the second treatment in Egypt, those symptoms had re-occurred during the flight home. The rebound of symptoms is not unusual considering the decreased ambient pressure in an airplane thus causing an overcritical desaturation of the slow tissues. Matthias received more recompression treatments (problem wound table TS 140/90). Meantime, the dive doctor initiated more tests. Initially, the case appeared to be straightforward: severe DCS Type II, most likely due to dehydration. But Matthias was convinced he had a sufficient fluid uptake, even considering the warm temperatures in Egypt.

He is a healthy diver, exercising in the gym several times a week. He does not drink any alcohol and quit smoking three years ago. First, a PFO (patent foramen ovale) had to be excluded. Matthias was sent to have an ultrasound investigation of the heart (bubble

Photo by Cecile Riviere

Issue 7 | February 2016

test). Later on a brain magnetic resonance imaging (MRI) and neurological examinations by a specialist were done. All tests showed inconclusive findings: no signs of a PFO, brain infarct or other cerebral malperfusion nor cerebral bleeding. Doctor Oest was still not content. Why had Matthias suffered from such a severe DCS with a cerebral or spinal gas embolism? Considering that there was no cardiac shunt or other intracerebral causes which could have explained the disorder, the dive doctor decided to investigate further, keeping in mind that the real cause might be crucial for Matthiasâ&#x20AC;&#x2122; future fitness to dive. The high-resolution computed tomography (HRCT) of the lungs in both in- and expiration revealed the real cause of the unexpected DCS, a cerebral arterial gas embolism, CAGE, caused by a bullous lung emphysema (Figure 4; Figure 5). Pulmonary emphysema is defined as the "abnormal permanent enlargement of the airspaces (bullae) distal to the terminal bronchioles accompanied by destruction of the alveolar wall and without obvious fibrosis".

Emphysema is one of the lung diseases grouped together as chronic obstructive pulmonary disease.

The enlargement of the airspaces looks like a small bubble or sack. This bubble is often not properly connected to the ventilation forming a one-way valve, that is, air enters under pressure, cannot exit and is trapped. The enlargement of the airspaces looks like a small bubble or sack. This bubble is often not properly connected to the ventilation forming a one-way valve, that is, air enters under pressure, cannot exit and is trapped. In diving, while ascending, the trapped air increases in volume and leads to an over-inflation of the corresponding lung parts and, in some cases, to a rupture. This can cause a pneumothorax, subcutaneous air emphysema or, as in the case of Matthias, an arterial gas embolism with nitrogen microbubbles.

A Pulmonary Bullae cannot be picked up by an ordinary X-ray but only by doing a High Resolution CT Scan

Issue 7 | February 2016

Photo by Pavel L Photo and Video

Chest X-ray

Photo by Ellen Cuylaerts

Issue 7 | February 2016

Nitrogen microbubbles occur in the venous system after every dive that is deeper than 10 metres according to Henry’s Law. When ascending slowly and executing the decompression stops properly, the lungs usually breathe out the nitrogen microbubbles.

If a bulla ruptures, the nitrogen bubbles can shunt from the venous system to the arterial system thus causing an arterial gas embolism. Once in the arterial vessel system, the microbubbles block the arteries like a clot in a stroke causing the same symptoms. Without fast treatment, this can lead to permanent hypoxic damage such as paralysis or even death. What caused the bullous lung emphysema? The most common cause is smoking. The less frequently occurring causes such as alphaantitrypsin deficiency, an inherited disorder, or a side effect after intravenous injection of methylphenidate (Ritalin lung) could also cause this problem. Matthias had been a heavy smoker with a history of 20 pack years until three years ago. During his smoker’s years, he had silently developed a bullous lung emphysema without realising it. There are unfortunately no early clinical symptoms. The changes progress

Matthias

Photo by Yiorgos GR

slowly and are compensated for over a long period. The normal lung function (spirometry) stays within the normal range for a long time. While diving, pressure changes may occur in the thorax and abdomen due to immersion or increased efforts such as finning against a current, pulling your self up on board or climbing up a ladder. This increased pressure can lead to a rupture of the bullae. Matthias was lucky. He recovered completely after his severe dive accident but he will never be able to dive again. There is no cure for a bullous emphysema. The damage is permanent and the chances of another incident are simply too high. A smoker’s life is more endangered and probably shorter than the life of a nonsmoking person. That is nothing new. Each smoker sacrifices approximately seven to ten years to the cigarette industry and pays not only with a lot of money, but also with his health.

If the smoking person is participating in a sport in which the lung and the airways are holding a key role, such as in diving, that person has to question himself if it makes sense to stick to the smoking habit. Every smoking diver is fond of his “decocigarette”. It is even tastier along with the “deco-beer” while commonly recalling the adventures of the dive with the buddies, maybe while still in his wetsuit. This case report points out the slow changes to the lungs, which creep along undramatically and insidiously as the cigarette pack years are passing by, but are definitely leading to pathological findings, risky malfunctions and are very likely to cause a serious problem underwater. Dr. Christian Oest and Dr. Anke Fabian aqua med Medical Helpline Worldwide

Photo by Gareth Lock

Issue 7 | February 2016

The Application of Non-Technical Skills to Recreational and Technical Diving

By Gareth Lock

Two perfectly serviceable Boeing 747s crashed into each other on the runway killing 583 people...the pilots shutdown the wrong engine and 74 people were killed when the aircraft crashed. But what has that got to do with diving?

In 1977, two Boeing 747s were on the runway at Los Rodeos airport, Tenerife, Spain. The first from Koninklijke Luchtvaart Maatschappij N.V., KLM (the Royal Dutch Airline), was lined up ready to take off, the other from Pan-Am was taxiing down the runway towards them to exit and turn around to await the former’s departure. However, there was thick fog and neither crew could see each other. At 17:06 the captain of the KLM aircraft, the most senior captain in KLM at the time, decided that they had clearance to take-off in the thick fog, despite the the first officer and engineer not being sure and felt unable to speak up because of social pressures. As they accelerated down the runway, they collided with the Pan-Am jet and 583 people were killed: there were 61 survivors, all from the Pan-Am aircraft. There was nothing technically wrong with either aircraft.

they started another 180 degree turn, the captain noticed that something wasn’t right and questioned the co-pilot in a non-committal manner. Less than 10 seconds later they impacted the ground: less than half the time it took you to read read this paragraph. 97 of 163 passengers died. There was nothing technically wrong with the aircraft other than a blown bulb in the cockpit.

In 1972, Flight 401 was making a late night approach to Miami International Airport, United States, and as the crew were completing their pre-landing checks, they noticed the gear light didn’t indicate “down and locked”. They entered a holding pattern and engaged the autopilot while they attempted to resolve the issue. Both pilots and the flight engineer were then task fixated into trying to determine if the fault was a blown bulb or a landing gear problem. None of the crewmembers noticed the slow descent that had commenced due to an incorrect autopilot selection. As

These crashes in the aviation world were seminal events, highlighting that the engineering teams and aircraft manufacturers were making very high quality products and the failure points were primarily down to the human interaction with the system. Furthermore, providing more technical training (pure flying skills) was unlikely to make a difference. As such, the evolution of crew resource management (CRM) started. It initially focused on the pilots as they were “the last to touch the controls, therefore it must be their fault” as cockpit resource management.

In 1989, a British Airways 737 crashed into an embankment on the M1 just short of East Midlands airport, United Kingdom. This was because the pilots had shut down the right engine due to task loading, cognitive biases, and poor training on the new 737 they were flying. The failure in the left engine was manageable as it was certified to fly on one engine at the heaviest weights. 47 died, 74 injured.

46 Photo by Gareth Lock

Photo by Gareth Lock

Issue 7 | February 2016

However, it was soon realised that the whole crew including cabin staff needed to be involved so it was renamed crew resource management. CRM is now in its 5th generation having been in place for four decades and anyone who is involved in air operations must undertake some form of CRM training to remain certified inline with the regulatory bodies. Training is not just a single course, but is part of every simulator exercise and flight they operate, with ground-based staff and maintenance engineers all having to undertake refresher courses. The world of healthcare recognised, along with other industries such as oil and gas, that they were suffering from adverse events despite highly skilled and qualified professionals being involved. This lead to the development of Non-Technical Skills (NTS or NOTECHS) research programmes which produced behavioural markers covering areas of decision making, situational awareness, communications, leadership and followership, teamwork and the effects of stress and fatigue. All are the same areas that CRM covers. If we now consider recreational and technical diving, how many accidents or incidents are actually down to the equipment technically failing in an undetected or uncontrollable manner? From my own research and that contained within the literature, very few considering

the hundreds of thousands or millions of dives that take place every year. The common factor is the “human”. However, it is easy to use the phrases “diver error”, the “diver should have”, “why didn’t the diver” or makes use of the well trodden “75-80% of all accidents are down to human error” but there are issues with this frame of reference. It is natural to jump to the conclusion that the diver made an error, they had a choice, why did they choose “that bad thing to do” which cost them their life or got them injured? However, divers, like most people, don’t normally get up in the morning and decide that today is a good day to die. The choices we make are not normally active choices, but rooted in some of the cognitive biases we have and influenced by the lack of effective non-technical skills. The diagram below is one that I use in my CRM and NTS training and coaching classes. It highlights the key information flows and shows why non-technical skills are so important for anyone involved in high-risk operations. While some will argue that not all diving is high-risk as it depends on the type of diving, ultimately divers are in an environment that cannot sustain life without external technical support and failure of that, for whatever reason, may end in death.

Photo by Gareth Lock

Issue 7 | February 2016

"When we are tired, we are more likely to make bad decisions, be curt with our communications or not necessarily

Photo by Gareth Lock

act as a good team member"

We all want to make good decisions, but we can’t do that if we don’t have good situational awareness. Situational awareness is noticing what is going on around you, thinking about what it means and anticipating what might happen in the future so you can actively plan your actions accordingly. While good situational awareness requires experience to be able to project into the future, it can really be helped by good communications with the rest of the dive team (skipper, instructor, dive master, buddy or others). This means that everyone is clear on what needs to be done when, by whom and what limitations or constraints the dive has to be conducted within. It also provides the assertion skills to speak up when something isn’t right. Good communications are assisted by good leadership (who is the “dive leader”) and good followership (being a good buddy, supporting the “leader” and questioning when things aren’t right or need clarification). When everyone is working together with a coherent understanding of the common, achievable goal, we have effective teamwork which helps support the communications process and ultimately good decision making. We must recognise that these factors are all shaped or influenced by stress and fatigue. When we are tired, we are more likely to make bad decisions, be curt with our communications or not necessarily act as a good team member. So why is an ex-military aviator talking about something which doesn’t appear to have a place in a recreational activity? We don’t have the social or organisational structures present to need such skills, but consider all of the accidents and incidents that you know of and look through what the contributory factors were. How many of them could have been prevented by having effective non-technical skills? How many agencies teach effective teamwork, effective decision-making, effective communications skills, both topside and underwater, effective situational awareness or what a good leader or follower means? Is it any wonder that “human factors” and “human error” rank so high when it comes to diving incidents or accidents if they aren’t taught?

Emergency Gas Management on Rebreathers By Jill Heinerth My partner was speeding up; swimming quickly through the cave while causing uncharacteristic silting. What was the hurry? I signaled with my light and as he turned I hardly recognized his face. There was no hiding the overwhelming panic apparent in his bulging, bugged-out eyes. Fumbling for his open circuit regulator, he dropped the loop and began a sprint for the exit of the cave. What ensued was a terrifying race. My dive partner could no longer control the rate of his breathing and he was consuming gas faster and faster. All I could do was hang on and try to get him to switch to the next tank before he sucked the last fumes out of his bailout. Although we had practiced tank swapping, that was not going to happen. In the heat of the moment, even getting him to accept a long hose was nearly impossible. It was like a wrestling match with him practically drowning at each mandatory regulator swap but somehow he survived a massive carbon dioxide hit. Agitated, he was able to go home with a massive headache and new respect for his titanic lung capacity.

Catastrophic failures on open circuit scuba are usually manifested in events such as high-pressure seat failure in a first stage, hose rupture or possibly manifold and valve issues. In other words, major open circuit failures are accompanied by a big â&#x20AC;&#x153;boom and hiss!â&#x20AC;? Technical divers spend lots of time rehearsing valve drills and abort scenarios, since gas loss equates to time pressure. They manage their emergency and get out and up quickly.

On a rebreather, the worst failures frequently creep on slowly. A hose rupture or first stage failure is actually one of the easiest issues to manage. In many cases, a diver simply reaches back, turns off a valve and feathers it on and off through his/her exit from an overhead environment or he/she simply aborts, utilizing open circuit gas.

Photo by Jill Heinerth

'If a diver is in doubt about the accuracy of sensor readings, a vigorous flush with diluent gas will help determine if any of the sensors are reliable and accurate.'

In the early days of rebreather training, we used to put a considerable emphasis on keeping a diver on the loop. These days, we teach technical divers the multitude of options available to them in emergency scenarios, but encourage divers to bailout to open circuit if there is any doubt about the safety of breathing mix or if the task load is too large. If in doubt, bail out. Examining the type of failures that could lead to the necessity of an open circuit abort will help a diver settle on how much bailout gas should be carried and whether tank swapping is really a viable option in the event of catastrophe. Confusing Data If a diver is in doubt about the accuracy of sensor readings, a vigorous flush with diluent gas will help determine if any of the sensors are reliable and accurate. After determining which, if any sensors, are accurate, the diver may allow the systemâ&#x20AC;&#x2122;s voting logic to get them home, or they can run the unit manually with the single accurate sensor during their aborted dive. Extreme caution is advised during manual aborts. If a diver is not able to disable the feedback from bad sensors, voting logic can highjack control of errant sensors as readings drift around. In the case of any uncertainty about the accuracy of sensors, from flooding, poor calibration or other electronic failures, then an open circuit bailout may be the best choice. Semi-closed operation or metabolic oxygen replacement, in a very conservative manner, can extend gas supplies, and makes sense if exiting a long overhead penetration at stable depth. But if you have enough open circuit gas, then there is no shame in bailing off the loop.

Catastrophic Loop Failure Mechanical problems can cause catastrophic loop failures that demand open circuit bailout. Ripping or tearing a breathing hose inside a wreck, counter lung tears, dry-rotted rubber hoses, lost or torn mouthpieces, and breakage of the Diver Surface Valve (DSV) lever itself are all examples of failures that render the loop unrecoverable, leaving the diver with the only option of open circuit abort. Carbon Dioxide Breakthrough Carbon dioxide breakthrough is the most insidious problem leading to unrecoverable loop failure. Partial flooding or improper packing may lead to channeling of scrubber material. Using carbon dioxide absorbent beyond its specification may also lead to rapid breakthrough. Damaged non-return valves or improper assembly of canister sealing agents could also lead to carbon dioxide build-up. Many rebreather divers have adopted a standard practice of sharing team bailout gas, mandating that a dive team of three carry 1.5 times enough gas to get a single diver home safely. Arguably, this results in greater team conservatism than is offered to open circuit divers having a bad day out. However, it also leaves a team of three with the need to stay together and swap tanks or share long hoses throughout the abort so that a diver is never left without open circuit or suit inflation gas. Other divers have taken drastically different approaches, preferring a true Alpine approach that puts their trust completely in the functionality of their rebreather.

Photo by Brian Artjeh

'I find that carrying two tanks with long hoses in a sidemount style is very easy and comfortable and will get me out of most emergencies while offering redundancy over a single bailout tank'

Given the scenarios above, I have personally chosen to carry ample open circuit to get myself out of a cave with measured conservatism, for almost all of my dives. In limited cases of extreme exploration, my team and I have chosen to share bailout beyond a certain point of penetration, arguing that the further we are into a cave the less likely we are to have a two-person catastrophic loop failure. I find that carrying two tanks with long hoses in a sidemount style is very easy and comfortable and will get me out of most emergencies while offering redundancy over a single bailout tank. I use smaller tanks for lighter penetration and bigger ones for longer dives.

Beyond that, staged gas is preferred when cave diving. Understanding that carbon dioxide issues will significantly elevate my Respiratory Minute Volume (RMV), I am very conservative with gas planning. My best advice to rebreather divers is to make a careful risk assessment prior to your dive and visualize the worstcase possible scenario. Only then, can you make the right risk assessment decision for yourself and your team about the amount of gas to carry in reserve. Be conservative. Youâ&#x20AC;&#x2122;re worth it.

Photo by Jill Heinerth

Time Pressure and the Impact on Accidents

By Mark Powell

There are many factors that can contribute to the build up to an accident: equipment failure, peer pressure, over confidence, diving beyond your limits, poor planning and poor judgement are just some of the more commonly mentioned factors. However, one of the most common, but often overlooked, factors is time pressure. Working to a deadline can be productive at times, and indeed, the only thing that finally gets me to complete an article such as this. But when preparing for a dive it can be counterproductive. I believe that this time pressure causes many accidents. Of course that means that by being more aware of time pressure we may well be able to reduce the stresses that lead to these accidents. 56

Photo by Gareth Lock

Issue 7 | February 2016

Time pressure can be caused by a number of factors. Poor planning is one of these factors. We have all seen the diver running around to get a fill just before the dive boat is due to depart or who is still putting together bits of their kit just minutes before they are due to jump in. Time pressure can also be introduced by external factors. Traffic on the way to the dive site can introduce unplanned delays or an equipment problem may require the diver to make a last minute adjustment to their kit. Our buddies may also introduce a delay by taking longer to kit up then we do and so leaving the buddy check until the very last minute. The very fact that we follow a dive plan based on a specific

bottom time, or only have enough back gas or bailout gas for a limited period of time means that all dive plans have an inherent time pressure built in. This means that we can never completely get rid of time pressure but we can try to identify the type of problems caused by this stress, identify the symptoms of it in ourselves and try to avoid some of the situations that will increase time stress. In my technical diving courses I will regularly put some time pressure on my students. This is often realistic time pressure. If, for example, the course is being run on the South Coast of the United Kingdom then there will be a

Photo by

Photo by Pete Bullen

Photo by Mark Powell

Issue 7 | February 2016

slack water time at which point we are aiming to dive. This is a fixed time and if the divers are not ready then they will miss the slack water time and rather than having little or no water movement, they will have a gradually increasing current to work against. Even if I am not teaching in the sea or if there are no tidal constraints, I will still set a fixed time, a simulated slack water time, at which point we are aiming to jump in the water. Further to this I will also make sure that the timing of the preparation is shorter than would be ideal, either by extending my briefing or bringing up a point that I know will generate an extended discussion. I donâ&#x20AC;&#x2122;t do this just to make the students rush

or just to make them feel uncomfortable but to illustrate the point that things will go wrong when you rush. When I do this I donâ&#x20AC;&#x2122;t know exactly what is going to go wrong but I can be sure that there will definitely be some impact. Sometimes the divers are rushing and forget to attach a dry suit hose or they do not have enough time to write out their plans. Other times they misunderstand the dive plan or react in a counterproductive way to the situation they face. Each and every time it is a different problem but the one thing that remains the same is that there is usually a problem that would not have occurred if they had allowed more time.

Photo by Pete Bullen The problems usually fall into one of three categories. The first is where rushing has a direct impact on the dive. This could be because in the rush the diver has forgotten something or has not prepared for the dive correctly. For example, I have often seen divers leave a dry suit hose disconnected, forget to put their back up regulator around their neck, forget to open their cylinder valves, mark up their stage cylinder incorrectly, write out their plan incorrectly or unintelligibly, forget to put on their mask or fins or one of a hundred other minor problems. Each of these over looked details can be directly traced back to the diver rushing to get ready and should have been caught by a pre-dive check. However, the fact that they are rushing also

means that the pre-dive check is often missed or carried out in a very hurried fashion and fails to spot these problems. In addition to these equipment problems, rushing also introduces problems into teamwork and communication. By rushing, the divers may skip the buddy check and may also skip the team briefing. As a result there may be no agreement as to who is leading the dive, what positions the rest of the divers should adopt, whether the team is returning to the shot or deploying a Delayed Surface Marker Buoy (DSMB), who will be deploying the DSMB and when. That may lead to confusion on the dive that can lead to further problems that are exacerbated

Photo by Mark Powell

Issue 7 | February 2016

by any other problems that occur. This combination of a lack of team planning combined with another, potentially unrelated problem, can mean the difference between an issue that is quickly resolved and one that escalates into a more serious situation. The last class of problems are those that, on first glance, do not seem to be directly related to the rushing at the start of the dive. They may occur at any time into the dive and take the form of one or more divers making a mistake in the execution of a skill or making a poor decision. In some cases it may be possible to trace the problem back to the lack of team

planning, but in many cases there are often problems that seem completely unrelated to the initial problems. However, after having used this training technique for many years, I have observed that the level of problems and mistakes is consistently higher on the dives where the students are rushed when compared to the dives when they are not rushed. From this, the only conclusion I can reach is that rushing during the preparation and kitting up phase of a dive will increase the chance of a mistake or poor judgement in later phases of the dive. There may be a number of reasons for this situation. The time pressure and rushing may have produced a flight or flight reflex in the body and this is known to affect peopleâ&#x20AC;&#x2122;s

decision-making ability. Alternatively, after all the hassle and effort of rushing to get ready, the divers may be less inclined to call the dive if the conditions are less than ideal. In addition, the stress of working hard during the preparation and potentially still being out of breath during the descent may result in increased carbon dioxide that has been linked to narcosis. During the debrief I will often ask my students when they thought that the problems started to occur. Usually they will focus only on the very end of the incident and will not link the problems with the rushing during the preparation for the dive. It is only when it is pointed out to them that they were rushing and under considerable

time pressure that they start to see how the whole series of events leading to the failure were linked. From the above descriptions it is clear that time pressure in itself does not directly cause the accident but is a factor when combined with other problems. As such it fits very well into the Swiss Cheese model of accident analysis. In this model, an individual or organisations defence against failure is represented as a series of barriers depicted as slices of Swiss cheese. The holes in the slices represent weaknesses in various parts of the system and are continually varying in size and position across the slices. The system produces failures when

Issue 7 | February 2016

Photo by Pete Bullen

Some instructors may be nervous about using a teaching technique that appears to increase the risk of incidents and problems occurring during a training dive or any technique that seems to be increasing the risk of a potential problem. It is certainly true that the instructor needs to be monitoring the situation closely during all phases of the dive and to step in before anything gets out of control or dangerous. In addition the instructor is likely to have simulated some aspects of the dive to reduce the risk, for example performing a simulated decompression dive rather than a real decompression dive. However, I believe that introducing realistic problems into training scenarios better prepares the students for this type of situation. The ability to deal with stress and time pressure is not something that can be learned from a book or taught in a classroom. The student needs to experience relevant situations and be able to identify when they are feeling under time pressure. They also need to see the impact that time pressure can have on them, their teammates and the progression of the dive. Without a realistic example to base this on the student will never learn the lesson until the situation occurs for real.

a hole in each slice momentarily aligns, permitting â&#x20AC;&#x153;a trajectory of accident opportunityâ&#x20AC;?, so that a hazard passes through holes in all of the slices, leading to a failure. Time pressure has the effect of opening up more holes in the cheese or increasing the size of some of these holes. For example, rushing to kit up and forgetting to turn on your valves opens up a hole in one layer of cheese. Normally this would be detected by the buddy check but skipping the buddy check opens a hole in another layer of cheese and allows this hazard to progress further. In the same way, the lack of a team briefing widens one of the holes in one layer but this is not a problem unless some other hazard occurs which would have been prevented by the team briefing.

This is why I think it is useful for instructors to introduce some sort of time stress experience into diver training. Without this experience the diver will not fully appreciate the implications of time stress and just how insidious the effects can be. It is also important for divers to be aware of the impact of time pressure on themselves and to be aware of the symptoms they may feel when they come under this pressure. Finally, it is critical that divers accept the danger of time pressure and try to avoid creating this type of stress in themselves, as well as, in their buddies. The simplest way to achieve this is by allowing enough time to prepare your kit, yourself, your team and your dive plan. Good planning can ensure that you are very rarely left with insufficient time to achieve all of these goals. This results in a calm and relaxed period of getting everything ready before the dive. However, we must always realise that there are external factors beyond our control that may introduce time pressures. In these cases it is essential that divers do not allow time pressure to force them to skimp on pre-dive checks or team briefing. Finally, one of the most important lessons that divers can learn is that if you are working to a fixed timescale but there is not enough time to do everything properly before jumping in the water then, rather than rushing or skipping an essential safety step, it is always an option to call the dive rather than blindly rushing on. Mark Powell Mark Powell is a TDI/SDI Instructor Trainer and a member of the TDI Training Advisory panel. He represents TDI/SDI on the British Diving Safety Group and lectures regularly at dive shows throughout the world on accidents, diving safety and decompression. Mark is also the author of Deco For Divers.

Photo by James A Dawson

Issue 7 | February 2016

Shark Bite by Yannis Papastamatiou As a marine biologist who has been studying sharks for over 15 years, I have been fortunate to work, dive and tag sharks all over the world, with species that include white, tiger, hammerheads, oceanic whitetips and many more. We really have one golden rule when it comes to working with and tagging sharks, and that is to never take your eyes off the mouth. Our procedure typically includes catching the shark, restraining it along side the boat, doing the tagging, and releasing the animal. It is a te chnique that has served me well and I have used it to tag everything from small reef sharks to five metre tiger sharks. The person who controls the sharkâ&#x20AC;&#x2122;s pectoral fins has the most critical job in the whole process, as they essentially control the shark during the tagging.

Photo by Mercy Hospital Photo by Mercy Hospital While tagging a large shark at a remote tropical island, I broke the golden rule. As we were releasing an animal, a line got snagged around the tag we had just attached and I turned my head for a second to untie it. The next thing I know, the shark had my hand in her mouth and had clamped down. First, I remember thinking that I was going to lose my hand and wondering what would that be like. Then I realized that she wasn’t letting go of my hand and if she started to thrash I would certainly lose my hand. I relaxed, and she let go after what seemed like ages, but probably was just a few seconds. I had been wearing a glove so I removed it expecting my hand to fall off. Instead I was greeted with an arterial spurt of blood, which caused me to just freeze. Luckily for me, my colleague who was standing next to me leaped into action. She quickly applied QuikClot®, a hemostatic device that accelerates the clotting process of the wound,

and then applied a pressure bandage. Due to her very quick action, and the QuikClot®, the bleeding was quickly under control. I knew I needed to get to a hospital but unfortunately we were on an island with no doctors, and being late afternoon, the airport was not useable as there were no lights for a nighttime landing. We immediately contacted DAN Europe (Divers Alert Network Europe), and sent them pictures of my hand. I was actually in very little pain, but was just starting to get tired from all the events. DAN Europe quickly got back to us. After consulting with specialists they decided I needed to see a plastic surgeon and would need to be evacuated to a medical facility on the mainland of the United States. Because the air ambulance could not land at night, they would come and get me first thing the next morning.

Photo by Chantelle Newman

Issue 7 | February 2016

The plastic surgeon ended up using nearly 50 stitches to close the wounds, and I spent two days in hospital on IV antibiotics. The shark had managed to nearly bite clean through the hand in a few sections, but somehow missed all major nerves and tendons. After two days, I was given a heavy supply of oral antibiotics and hopped on a plane to get back to work. I had one day of severe exhaustion but after that was fine and diving just over a week later. I made a full recovery and other than a faint scar and some permanent swelling, I have no lasting effects. I have learned several lessons from this incident: 1. If while tagging, a shark does bite and hold on, try to relax. I believe fighting at that point will just make the shark thrash around and cause more damage. 2. If you are working with sharks, it’s a good idea to keep Quick Clot® in the first aid kit. 3. In the case of an injury to a hand, remember cloth items such as gloves may actually help control the bleeding. I only started to bleed heavily when the glove was removed. 4. Never take your eyes off the shark while handling, especially if you are the one closest to the mouth. 5. In remote locations while you are waiting for medical treatment, the wound should be well flushed, cleaned, and then covered with a sterile dressing (obviously this is after bleeding has been controlled). Because of this incident, I have since taken a Diving Medical Technician course so that I will be better prepared for situations like this that may require skills that are not taught in a basic first aid course.

Finally, it’s important to state that the whole incident was my fault and not the shark’s. I am pretty sure if someone tried to tag me I would want to bite them too.

Photo by Chantelle Newman

Morning arrived and the air ambulance came to fly me to the United States. The excellent paramedics wanted to put in a precautionary IV, but I hate flying and needles and I would have had to be in a really bad way before I allowed both at the same time. Other than a heavily bandaged hand, I didn’t have any other symptoms.

Yannis P. Papastamatiou, PhD Yannis is now an Assistant Professor at Florida International University. He is a PADI Instructor and certified in mixed gas decompression diving, closedcircuit rebreathers and cave diving. He has published nearly 50 scientific paper on sharks and other fishes.

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The International Board of Undersea Medicine (IBUM) offers hyperbaric chamber operators, diving medical technicians, clinical hyperbaric technicians, and hyperbaric physicians training as well as educates and increases safety for those who work in the hyperbaric field including certifications to the highest international standard for hyperbaric facilities. We are - Hyperbarics, Chamber Certification and Diving Research...Simplified! This is the IBUM Journal. It consists of peer reviewed scientific papers which are referenced and note studies and research performed. www.ibum.org

Heliox Versus Air for the Treatment of Air or Nitrox Induced Decompression Illness by Joseph Dituri, M.S. CDR, USN (ret)

Helium oxygen treatment tables should be used for better resolution of neurologic and spinal cord decompression illnesses. As a growing trend, decompression illnesses (DCI) with neurological symptoms as well as delayed treatments of symptoms are being treated on tables that start deeper than 60 feet. These treatments allow restoration of circulation prior to initiation of therapeutic oxygen. The increased depth precludes the use of 100% oxygen leaving two major inert gasses to choose from in order to reduce the partial pressure of oxygen (PPO2): nitrogen and helium. Nitrogen, the â&#x20AC;&#x153;old standbyâ&#x20AC;?, is well tested and has been used frequently for many years. Problems with oxygen air treatment tables (TT) include (but are not limited to): 1. High rates of incomplete neurological insults. 2. Unexpected deterioration of neurological decompression sickness (DCS) during and after use of TT. 3. Increased narcosis, which can mask symptoms at 165 feet saltwater (fsw). 4. Some TTs wait too long at depth allowing the nitrogen absorbed at depth to become a liability upon making a hasty ascent to the 60-foot stop. 5. Long exposure at 165 fsw puts inside tenders at a greater risk for DCI. Juxtaposed to the autoimmune system, the theoretical cause of DCI is the inert gas bubble. In many of these cases the bubbles are nitrogen. It is understood that insults can result from carbon dioxide, oxygen, or water vapor. This paper is primarily based upon the bubbles caused from inert gasses.

Increasing external hydrostatic pressure causes shrinkage of bubbles. Bubbles will also grow or shrink, depending on whether the surrounding tissue tension is greater or less than the bubbleâ&#x20AC;&#x2122;s internal pressure. Bubble pressure increases with external pressure by compression. If the partial pressure of the gas inside the bubble exceeds the dissolved gas tension of that gas in the surrounding blood and tissue, the gas will diffuse from the bubble to the surrounding blood and tissue causing the bubble to shrink. At the same time the surface tension of the bubble will increase which also decreases bubble size. This cycle will continue until the bubble has dissipated. Upon surfacing, a bubble will grow until it reaches a state of equilibrium with the dissolved nitrogen tension. As the nitrogen tension in the tissue surrounding the bubble decreases due to respiration and circulation, the nitrogen gradient is increased and the bubble will begin to shrink even if nothing is done. A major factor that affects nitrogen off-gassing is the nitrogen gradient between the blood and tissue and the bubble. While recompressing, if nitrogen is contained within the breathing medium, the off-gassing of the insult must take longer due to the lower nitrogen gradient. An increase in the nitrogen gradient would increase the speed of off-gassing. The only way to maximize the gradient deeper than 60 fsw without exceeding the oxygen threshold of 2.81 PPO2 is with the incorporation of an alternate inert gas. The use of the inert gas helium to replace nitrogen during treatment allows an increase in the nitrogen gradient to maximum amount when not using 100% oxygen. The increase in depth without a corresponding increase in PPO2 promotes the safer execution of initial deep spikes. An added benefit to the use of helium is the elimination of nitrogen narcosis. Symptoms of DCI are sometimes masked due to narcosis of the patient and tender while at 165 fsw. In conjunction with increasing the nitrogen gradient, helium also helps physically reduce nitrogen bubble size when used as a recompression gas. When nitrogen bubbles are present in the blood (following all dives where nitrogen is one of the inert gasses breathed) and a gas switch is made for recompression, the transfer of gas in certain tissues through convection and the growth of the bubble is due to the relative solubility of the gasses present in the blood. Under these circumstances, a switch to helium will cause a reduction in the size of the bubbles because helium is less soluble than nitrogen in blood. Qualified personnel administering recompression treatment should note the danger of gas switches in the opposite direction. Recompression of a helium oxygen or Trimix (HE O2 N2) diver using air will expand the bubbles. Therefore, Trimix and Heliox divers should NOT be recompressed using a Heliox TT. It should also be noted that the solubility and diffusion coefficients in water are greater for helium than it is for nitrogen, therefore, helium oxygen TTs may not be a good alternative to air oxygen TTs when inner ear or pulmonary involvement are noted.

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With equal partial pressure differences, the flux of oxygen is twice that of nitrogen and four times that of helium. This may be responsible for a temporary increase in the volume of nitrogen bubbles, especially in tissues with low oxygen consumption rate, and hence the deterioration seen in the patient’s condition. In cases of air bubble observation in the fatty tissues of rats, recompression with air resulted in a bubble size increase. During recompression with oxygen most bubbles grew initially and then shrank and disappeared. During recompression with helium oxygen the bubbles shrank and disappeared. Notice the difference in the initial pattern. When DCIs occur, the off-gassing process is disrupted. It is likely due to the insult that the off-gassing rate will decrease.iii For this reason, all reasonable steps should be taken to improve off-gassing and shrink the bubble. Given the initial increase in size of the gas bubble with respect to the oxygen decompression, the benefit of helium is easily seen. In non-clinical trials with personal DCIs, I have found the breathing media to be of less consequence than the depth. Tables 1, 2, and 3 consist of results found by Kol, Adir, Gordon and Meamed in the treatment of seven spinal cord DCIs from October 1989 to October 1991 using Comex-30. Each case in each table correlates to previous table numbers with amplifying information. None of these patients experienced deterioration of symptoms during recompression on Heliox.v Table 3 discusses delays in treatment for each case as well as the number of treatments that required hyperbaric oxygen (HBO) that leads to the all too important final outcomes. Additionally, numerous animal studies have been accomplished lending similar positive findings. Helium treatment gas as an alternative to air was introduced six years before oxygen in 1959. No evidence exists that helium based TTs have harmed air nitrox divers. The increased thermal conductivity of helium is offset by the initial increase in pressure and consequently temperature, which may increase the patient’s comfort level. The possible positive outcome achieved by helium oxygen TTs seriously outweighs the cost of helium and the communication "Mickey Mouse" voice problems associated with helium. In the new U.S. Navy dive manual, a Diving Medical Officer has been given the option to recommend modifications to current tables for the inclusion of Heliox for depths deeper than 60 fsw. In the referenced study, five of seven victims had full recovery and only two (who had significant delay in treatment) had only minor sensory and weakness issues. It is important to note that none of the victims worsened indicating no negative aspects using helium. While the negative aspects are small, the prognosis for the use of helium is significant. Provided these protocols are neither used for pulmonary and inner ear DCIs nor treatment for a diver using Heliox or Trimix, helium oxygen TTs show promise for more rapid and more permanent the resolution of neurologic and spinal cord DCIs.

(i) Maiken, Eric, “Background, theory and introduction to the VPM”, 1995, Bubble Decompression Strategies Part I (ii) Hills BA, “Scientific considerations in re-compression therapy”. In: James PB, McCallum RI, Rawlins JSP, eds. Proceedings of the VIIth Annual meeting of the EUBS, symposium on decompression sickness. Cambridge, 1981:143-153 (iii) Shupak, Melanmed, Ramon, Bentur, Abramovich, Kol. “ Helium and oxygen treatment of severe air-diving-induced neuralgic decompression sickness”, ARCH NEUROL/VOL 54, MAR 1997 (iv) James, PB. “Problem areas in the therapy of neurological decompression sickness. Cambridge, 1981:143-153 (v) Kol, Adir, Gordon, Melamed. “Oxy-helium treatment of severe spinal decompression sickness after air diving.” Undersea and hyperbaric medicine, Vol 20 No. 2, 1993

Richard Sadler M.D. FACS Selected Readings in Human Factors Science Part 1: Accident Theory and Neuropsychology

There is special challenge those who care for divers. It combines diving and medicine, endeavors that have a higher rate of near misses and mishaps (aka “accidents”) compared to other fields. Yet there are some inherently dangerous fields, such as nuclear power plant operation and carrier aviation, which minimize these events. They transform themselves into High Reliability Organizations (HRO). The identification and minimizing of human failure, managing Human Factors, is essential to creating a HRO. A thorough understanding of Human Factors can allow us to reconstruct accidents, gain insight to behavior, and recommend countermeasures. “What were you thinking?” is the inevitable question. It is actually an inquiry into how does one think, what factors influenced your thinking, what were the limitations to your thinking and so on. There are also multiple models or constructs of human behavior that are relevant to this discussion. Example: A trained diver with “advanced” certification fails to open the valve on his cylinder, resulting in a near miss drowning. In this case, it is not enough to state that an action or inaction occurred. Solutions or countermeasures can only be formulated when the context and mechanism of the error can be identified. Critical questions include: was the operator tired, distracted, bored, untrained, overtasked or culturally predisposed to the accident? Was more than one factor involved? This will be a three part series. Designed to act as a reference or primer in Human Factors science, it will not make specific recommendations. Instead, it will summarize and reference key concepts to enable the Diver Medic to seek solutions based on their needs. Indeed, it will become obvious that the massive scope of human errors cannot lend itself to any one solution. Part 1 is focused on the modern theories of Human Factors science. It reviews various models so the reader may understand how accidents are described and failure points identified. It will also include a focused review of neuropsychology. Part 2, Accidents and Cognitive Processes, will focus on the cognitive processes associated with accidents, such as loss of situational awareness and biases. Part 3, Solutions and Countermeasures, will review the best practices of HROs. The word “accidents” in this paper is meant to include near misses, fatal and non-fatal events, or in general incidents and decisions that had a specific or generally negative outcome. The logical place to start is the formalized techniques for identifying accident causation. Accident Analysis Methodologies: Importance: The Diver Medic provider must first understand “what happened”, to both aid in diagnosis and prevent recurrence. Thus, familiarity with the basic methodologies should be understood.

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Wilson, Paul F.; Dell, Larry D.; Anderson, Gaylord F. (1993). Root Cause Analysis: A Tool for Total Quality Management. Milwaukee, Wisconsin: ASQ Quality Press. pp. 8–17. Root Cause Analysis: Typically a process driven, detailed analysis looking at what behaviors, actions, inactions, or conditions that led to the event. It requires gathering of documentation, requires a team, and is always a post hoc analysis. Its strength lies in uncovering multiple causes. It is time consuming, subject to personal biases of the investigators, and emphasises structural and organizational issues at the expense of behavioral factors. The “Five Whys”: attributed to Sakichi Toyoda of Toyota fame, it is an iterative technique used to identify cause and effect. In contrast to Root Cause Analysis, it is immediately applicable. When an event is identified, the investigator then asks “why” did this occur, generally repeating the questions five (or six or seven or more) times until the causation is established. Its advantage is that a knowledgeable user can do this on the fly, rapidly gaining insight. However, an incorrect response may then lead to erroneous conclusions. True to its manufacturing roots, it focuses on process rather than behavior. The Development of Human Factors Modeling: Importance: The evolution of Human Factors science has developed with input from engineering, physiologic, behavioral and social sciences. Familiarity will assist in understanding why solutions and countermeasures need to be specific. Skills, Rules and Knowledge: Rasmussen, Jens (1983). Skills, rules, and knowledge: signals, signs and symbols and other distinctions in human performance models. IEEE Transactions: Systems, Man & Cybernetics, 1983, SMC-13, pp.257-267. The SRK (skills, rules, knowledge) model proposes that humans have three levels of cognitive processing, with skills being the lowest level (automated) and knowledge the highest level (creative). Importance: It is the basis for all subsequent advances in HF modeling. Latent Factors: Reason, James (1990-04-12)."The Contribution of Latent Human Failures to the Breakdown of Complex Systems". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences Reason, J, Understanding adverse events: human factors; Quality in Health Care 1995;4:80-89 Building on Rasmussen’s work, Reason refined the Skills - Rules - Knowledge (SRK) model. Reason hypothesized that most accidents can be traced to one or more of four failure domains: organizational influences, supervision, preconditions and specific acts. This has been widely known as the “Swiss Cheese” model, where the slices of cheese are barriers to failure and the “holes” are defects. When the “holes” line up, failure occurs. It has been become the dominant model for Human Factors science. Although volumes have been dedicated explaining this model, no better summation exists than Reason 1995. This is perhaps the single most important resource.

Crew Resource Management (CRM) and Non Technical Skills: Flin R, Martin L Development of the NOTECHS (non-technical skills) System for Assessing Pilots' CRM Skills Human Factors in Aerospace Safety 01/2003; 3(2003): 97-119. In 1977, two Boeing 747s collided on the island of Tenerife, resulting in 583 deaths, the worst aviation accident in history. Although there were multiple causative factors, major contributors were poor communication and teamwork. CRM concerns itself with knowledge, skills, and attitudes including communications, situational awareness, problem solving, decisionmaking and teamwork. The ability to integrate these skills is now called NOTECHS, or Non technical skills. Optimization of NOTECHS as it pertains to diving and surgery will be discussed in Part 3, Solutions and Countermeasures. uman Factors and Organizations Wiegmann, D. A., & Shappell, S. A. (2003). A human error approach to aviation accident analysis: The human factors analysis and classification system. Burlington, VT: Ashgate Publishing, Ltd.: HFACS is based on the "Swiss Cheese" model of human error (discussed above), which looks at four levels of active errors and latent failures, including unsafe acts, preconditions for unsafe acts, unsafe supervision, and organizational influences. It is a comprehensive human error framework that combined Reason's ideas into the applied setting, defining 19 causal categories within four levels of human failure. It has become the de facto methodology for the U.S. DOD, civilian aviation, USN diving and American surgery. Organizational Factors J T Reason, J Carthey, M R de Leval Diagnosing “vulnerable system syndrome”: an essential prerequisite to effective risk management; Quality in Health Care 2001;10 (Suppl II):ii21–ii25 Finally, Reason and de Leval (see below) discuss “Vulnerable System Syndrome”. Complex systems like medicine and commercial diving operations have many components that are tightly coupled. Typically accident review includes blame, denial and the pursuit of misguided excellence. Meaningful change creates double loop learning, looking beyond the immediate actions to the basic assumptions and conditions that gave rise to them. HROs make themselves capable of systemic change. Neuropsychology: Importance: For all its astounding capacity, the human brain has limitations. Analyzing error and developing solutions must accept these limitations and leverage its strengths. LEACH J. Why people ‘freeze’ in an emergency: temporal and cognitive constraints on survival responses. Aviat Space Environ Med 2004; 75:539–42. The “freeze” response threat is well documented. This paper explores the obligatory processing delay when unrehearsed or novel threats present themselves. It emphasizes the value of embedded behavioral schemata (training) in avoiding these “freezing” phenomena.

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Croskerry P, MD, PHD, The Cognitive Imperative: Thinking about How We Think Academic Emergency Medicine • November 2000, Volume 7, Number 11 1223-31 Emergency Medicine provides a mix of inconstancy, uncertainty, variety, and complexity with an overlay of time constraints. This paper will introduce you to the concept of “heuristics”, the cognitive practice of learned “shortcuts” that has remarkable efficacy, is commonly used, but also has failure points to be avoided. This will be discussed later as it relates to Recognition Primed Decision Making. Cowan, Nelson What are the differences between long term, short term, and working memory? 2008 Prog Brain Res. 169 (169): 323–338. Any accident analysis inevitably looks at human failure, often when the operator appears to have forgotten an action. A basic understanding of memory, especially “working memory” is essential to formulating countermeasures. K. Anders Ericsson, Ralf Th. Krampe, and Clemens Tesch-Romer, The Role of Deliberate Practice in the Acquisition of Expert Performance Psychological Review 1993, vol. 100, no.3 363-406 Any discussion of human deficiencies raises the logical question of what is expertise and how does one obtain it. This landmark paper received some notoriety for quantifying the number of time needed for achieving world-class expertise at 10,000 hours. But a deeper reading of this makes clear that expertise is intimately linked with deliberate practice, sometimes known as mindfulness. This has profound implications in the way training is conducted. Summary: Part 1 has reviewed three fundamentals. First, accidents are analysed in a systematic way, with the goal of looking at all components, from systemic and organizational to human behavior. These typically include Root Cause Analysis, Five Whys methodology, Fishbone diagrams or any variation. The crucial point is to find out what happened before asking why it happened. The goal is to avoid “blamestorming”, which is the reaction to assign responsibility (blame) without meaningful change. Second, the evolution of behavioral models, looking first at cognitive processing (Rasmussen) then progressing to Reason’s Swiss Cheese model and finishing with the Human Factors Analysis Classification System (HFACS). HFACS helps identify systemic and organizational levels of failure as well as individual behaviors. Finally, human limitations of cognitive processing (Leach and Croskerry), different kinds of memory (Cowan, et.al.), and a model for obtaining expertise (Ericsson) are reviewed. Specifically identifying areas of human limitation will aid the Diver Medic in formulating and executing countermeasures that will be successful. Part 2, Accidents and Cognitive Processes, will focus on actual failures in order to understand both what and how operators were thinking. Examples from aviation, surgery, diving and military accidents will be examined. The crucial points are understanding that Human Factors failures and potential solutions tend to be universal.

CALL TO DIVERS We are conducting diving research at IBUM in conjunction with the Medical College of Wisconsin!

Our research team requests assistance in finding volunteers for an IRB-approved research project throughout our membership. The study asks: â&#x20AC;&#x153;Does diving while in ketosis decrease the likelihood of oxygen toxicity events in divers using closed-circuit rebreathers?â&#x20AC;? The purpose of this study is to assess whether diving in ketosis decreases the incidence of oxygen toxicity in divers using closed-circuit rebreathers, thereby decreasing the incidence of oxygen-induced seizures and the risk of sustaining decompression illness during a rapid ascent rescue. This has further implications for patients in recompression chambers who need oxygen but cannot tolerate it. By monitoring divers who have experienced symptoms of oxygen toxicity in the past, as well as those who have not, we will be able to detect a decrease in number of events in the divers on a ketogenic diet if such a decrease exists. A ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that forces the body to burn fats rather than carbohydrates, forming ketone bodies which pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, i.e., ketosis, is known to reduce the frequency of epileptic seizures and have a neuroprotective effect. On a ketogenic diet you would consume foods like eggs and bacon with cheese, salad greens with high-fat dressing, green vegetables with buttery sauce, and meat or fish with creamy sauces. Here is our FaceBook page: https://www.facebook.com/CCRDivingResearch/info#!/CCRDivingResearch/info?tab=page_info Harry T. Whelan, M.D. CAPT U.S. Navy (Ret) Undersea Medical Officer Bleser Professor of Neurology Director of Hyperbaric Medicine Medical College of Wisconsin Email: hwhelan@mcw.edu

Joseph Dituri, M.S. CDR, U.S. Navy (Ret) Saturation Diving Officer International Board of Undersea Medicine Director Tampa, FL Email; joe@gallantaquatic.com

Additional information and literature review Background This review of the literature assesses the assumption that diving on a ketogenic diet will be beneficial to divers diving very deep on high partial pressure oxygen using closed circuit rebreather (CCR) apparatuses. The review uses a plethora of resources to analyse the results that have been found in the existing literature, with the results informing this current proposed study. To begin this review, it is important to assess the problem of oxygen toxicity within the practice of diving and the potential measures that can be used to help assess the level of oxidative stress that occurs within an individual while diving.

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The author begins with an assessment of the belief that ketosis can reduce, or delay, central nervous system (CNS) oxygen toxicity. There has been ample research into the effects of a ketogenic diet (KD) on refractory epilepsy, and the utilization of this diet is now mainstream. (Freeman & Kossoff 2010) However, research into the particular area of ketogenic diet and oxygen toxicity, as related to humans and diving, is sparse hence the importance of this proposed current work. One key study by D’Agostino et al. (2013) found that “ketones may prevent synaptic dysfunction by preserving brain metabolism during metabolic stress or oxidative stress from excess reactive oxygen species (ROS) production”. This supports the belief that ketosis or ketogenic diet provides positive effects on certain neurological disorders (Freeman & Kossoff, 2010). This research is further supported by Gasior, Rogawaski and Hartman (2006). They argued that the “the ketogenic diet can provide symptomatic and disease-modifying activity in a broad range of neurodegenerative disorders including Alzheimer’s disease and Parkinson’s disease, and may also be protective in traumatic brain injury and stroke” (p.431). This reflects that, while under-researched, the impact of a ketogenic diet on the individual’s ability to prevent or delay illness is apparent. In a study of rats to assess the neuroprotective effect of ketosis on animals subjected to a partial pressure of oxygen (PO2) of five atmospheres (ATA), there was a five fold increase in oxygen (O2) tolerance, and seizure onset was delayed from 11 minutes to 50 minutes. (Arieli et al 2008) Because of the limit of the research on ketogenic diets and the impact on the protection of individuals from the effects of oxygen toxicity, it is therefore important to consider this wider literature on oxygen toxicity, its symptoms and forms of measurement. It is also important to assess the impact of oxygen toxicity on divers using CCRs when diving. In order to effectively assess oxygen toxicity in the diver it is crucial to gain an assessment of the potential symptoms and measures of the onset of oxygen toxicity in individuals when diving. The proposed study needs to incorporate potential measures that could conceivably be used. Signs such as facial pallor, inspiratory predominance, sweating, hiccups, (diaphragmatic spasms), bradycardia, nausea, palpitations, spasmodic vomiting, depression, fibrillation of lips, apprehension, lip twitching, visual field constriction, twitching of cheek, nose, eyelids , tinnitus, syncope, auditory hallucinations, convulsions, vertigo, headaches, faintness, retching, anxiety, and seizures are underlined as common symptoms (Kindwall, & Whelan, 2008; Farmery & Sykes, 2012; Smerz, 2004; Arieli, Shochat & Adir, 2006) and could conceivably be used as a measure, with the study aiming to find less positive signs among those on the ketogenic diet. There is of course the limitation of the use of some of these signs in the underwater environment; however, some signs demonstrated a specific relationship to seizures underwater such as tinnitus, hyperventilation, hearing disturbances, disorientation, amnesia, and facial twitching. In dives where the event led to unconsciousness, divers reported between three and nine precipitating events (Arieli et al. 2006) suggesting that the documented signs can be used as predictors of oxygen toxicity. The linking of oxygen toxicity to illness and incidents including death underwater is supported by Alcaraz-García et al., (2008). The work highlighted that using closed-circuit breathing apparatus with high PO2 increased the chances of suffering oxidative hyperoxia-induced stress. The divers recovered from an impacted total antioxidant status during the process, suggesting that they are able to adapt to the experience of hyperoxia. Arieli et al. (2008) and Kindwall & Whelan (2008) have also found no residual effects of oxygen toxicity and seizure to date. This suggests that by decreasing the incidence of O2 toxicity events, we are unlikely to be negatively impacting neurologic outcomes.

The literature also underlines that to date, there has been limited study of central nervous system (CNS) oxygen toxicity accidents and it is important to assess the possible risk of seizure, death, and other complications when diving at deep depths using CCRs. A study by Arieli, Yalov and Goldenshluger (2002) aimed to assess the impact of diving at different depths and for different amounts of time. They found symptoms of oxygen toxicity increased when diving at deeper depths and for longer periods of time (p.254 also Arieli et al 2006). Therefore, their work underlined that there is an increased risk of toxicity at deeper depths and the increased risk of death after a seizure because of the length of time it takes to get the diver to the surface. A diver rendered incapacitated at depth can only be resuscitated at the surface, necessitating a rapid ascent. (Unless a submarine or underwater facility/ platform is available and this is not likely with the vast majority of dives.) Underwater events at depth increase the risk of decompression illness (DCI) in the affected diver as well as the rescue diver during assent. (Verdier et al 2008) The incidence of oxygen toxicity related events at high pressure have been evaluated in two studies of note. Arieli et al (2006) researched the occurrence of CNS oxygen toxicity in Israeli navy divers. They found an incidence of 2.5% CNS events at oxygen pressures of 1.1 ATA â&#x20AC;&#x201C; 1.4 ATA among actively diving subjects. Smertz (2004) found an incidence of 2% CNS events at PO2 2.6 â&#x20AC;&#x201C; 2.9 ATA in sedentary divers within a hyperbaric dive chamber. All of the above data allow us to estimate that there is a 2.5% incidence at 1.2 ATA with a potentially increasing incidence with increases in pressure and depth. Both of these studies found incidence of actual seizures at <1%. In all, from all causes, CCR diving has a mortality rate ten times that of open circuit diving. (Fock, 2013) This review has exposed that oxygen toxicity can cause seizures at partial pressures of oxygen in CCR divers and that divers who seize underwater are at extreme risk of drowning, placing them and the rescuers at risk for DCI through rapid ascent rescue attempts; DCI, unlike oxygen toxicity CNS events, can cause permanent CNS damage; short periods of oxygen toxicity do not cause apparent permanent deficits; a ketogenic diet reduces seizures from oxygen toxicity by increasing latency; and ketogenic diets are neuroprotective. From this we can hypothesize that diving on a ketogenic diet should decrease incidence of oxygen toxicity induced seizures, thereby decreasing risk of DCI, while also protecting the CNS from potential damage from increased high PO2 exposure and other neurological insults related to DCI. The results of the literature highlighted that there is ample evidence to suggest that specific symptoms can be used as measures of oxygen toxicity in CCR divers. These include inspiratory predominance (feeling of choking), hiccups (diaphragmatic spasms), bradycardia, nausea, retching, spasmodic vomiting, palpitations, depression, fibrillation of lips, apprehension, lip twitching, visual field constriction, twitching of cheek, nose, eyelids, tinnitus, syncope, auditory hallucinations, convulsions, headaches, faintness, retching, anxiety, and seizures. It is with this premise that we propose our study.

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Hypothesis • Diving while in ketosis decreases incidence of oxygen toxicity underwater. Goal • The goal of the study is to assess whether diving in ketosis decreases the incidence of oxygen toxicity thereby potentially decreasing the incidence of oxygen induced seizures and the risk of sustaining decompression illness during a rapid ascent rescue. • In addition, by comparing divers who have experienced symptoms of oxygen toxicity in the past (documented as specifically related to a CCR dive undertaken at >0.6 atmospheres of oxygen), to those who have not, we should also be able to assess whether the KD improves O2 sensitivity. • By monitoring the many dive variables, this study may reveal variables that affect oxygen toxicity. Study Design & Procedures This is a non-randomized, non-blinded interventional trial to evaluate the efficacy of the ketogenic diet in reducing oxygen toxicity in CCR divers, utilizing a web-based survey. There will be two main groups of divers, and two sub groups, participating in the study. Those using a KD diet and those eating a regular diet and further sub-divided by; • Those who have shown evidence of oxygen sensitivity in the past, KD and control and • Those who have not had evidence of oxygen toxicity, KD and control.

Research Location The research will be conducted centrally by the research team of the Medical College of Wisconsin. However, the location of each dive will be discrete locations determined by the study participant’s requirements. The dives will not be conducted solely for this study. The dives will be the routine dives that each participant would be undertaking in the course of work or recreation. Whether or not the participant is in ketosis for each individual dive will be a matter of convenience as determined by the other factors related to each individual dive.

References / Literature Review Alcaraz-García MJ, Albaladejo MD, Acevedo C, Olea A, Zamora S, Martínez P, Parra S. (2008). ‘Effects of hyperoxia on biomarkers of oxidative stress in closed-circuit oxygen military divers.’ Journal of Physiological Biochemistry 64(2), pp.135-41. Arieli, R., Yalov, A. & Goldenschluger, A. (2002). ‘Modeling pulmonary and CNS 02 toxicity and estimation of parameters for humans.’ Journal of Applied Physiology 92, pp.248-256. Arieli R, Shochat, T & Adir, Y. (2006). ‘CNS toxicity in closed-circuit oxygen diving: symptoms reported from 2527 dives.’ Aviation Space Environmental Medicine 77(5), pp.526-32. Arieli, R., Truman, M., Abramovich, (2008) A. ‘Recovery from central nervous system oxygen toxicity. in the rat at oxygen pressures between 100 and 300 kPa.’ Eur J Appl Physiol 104:867–871 Arieli R, Arieli Y, Daskalovic Y, Eynan M, Abramovich A. (2006). ‘CNS oxygen toxicity in closed-circuit diving: signs and symptoms before loss of consciousness.’ Aviation Space Environmental Medicine 77(11):pp.1153-7. D’Agostino DP, Pilla R, Held HE, Landon CS, Puchowicz M, Brunengraber H, Ari C, Arnold P, Dean JB. (2013). ‘Therapeutic ketosis with ketone ester delays central nervous system oxygen toxicity seizures in rats.’ American Journal of Physiol Regul Integr Comp Physiology 304, pp.829–836. Farmery, S. & Sykes, O. (2012). ‘Neurological oxygen toxicity.’ Emergency Medicine 29, pp.851-852. Fock AW. (2013) Analysis of recreational closed-circuit rebreather deaths 1998-2010. Diving Hyperb Med. Jun;43(2):78-85. Fock A, Harris R, Slade M. (2013). ‘Oxygen exposure and toxicity in recreational technical divers.’ Diving Hyperbaric Medicine 43(2), pp.67-71. Fock A, Millar I. (2008) ‘Oxygen toxicity in recreational and technical diving.’ Diving and Hyperbaric Medicine 38(2), pp.86-90. Freeman JM, Kossoff EH. (2010). ‘Ketosis and the ketogenic diet: advances in treating epilepsy and other disorders.’ Advanced Pediatrics 57, pp.315–329. Freeman J, Veggiotti P, Lanzi G, Tagliabue A, Perucca E. (2006) The ketogenic diet: from molecular mechanisms to clinical effects. Epilepsy Res. Feb;68(2):145 Grant, R.W. and Sugarman. J. (2004) Ethics in Human Subjects Research: Do Incentives Matter? Journal of Medicine and Philosophy, 29(6): 717–738, Gasior, M., Rogawski, M. & Hartman, A. (2006). ‘Neuroprotective and disease-modifying effects of the ketogenic diet.’ Behavioral Pharmacology 17(5-6), pp.431-439. Harabin, A.L., Survanshi, S.S., Homer, L.D. A Model for Predicting Central Nervous System Oxygen Toxicity from Hyperbaric Oxygen Exposures in Humans, Toxicology and Applied Pharmacology, Volume 132, Issue 1, May 1995, Pages 19-26, Kindwall, E.P., Whelan, H.T. (2008) Hyperbaric Medicine Practice Best Publishing Company p. 75 Kot J, Sićko Z, Wozniak M. (2003).Oxidative stress during oxygen tolerance test. Gdynia, Poland: National Center for Hyperbaric Medicine, Institute of Maritime and Tropical Medicine, Medical University of Gdańsk Mackenzie C. Cervenka, Bobbie Henry, Janak Nathan, Susan Wood, and Jeff S. Volek (2013) Worldwide Dietary Therapies for Adults With Epilepsy and Other Disorders J Child Neurol August 2013 28: 1034-1040 Shreeves, K. & Richardson, D. (2006). Mixed-gas closed-circuit rebreathers: an overview of use in sport diving and application to deep scientific diving. California: PADI Worldwide. Smerz RW. (2004). ‘Incidence of oxygen toxicity during the treatment of dysbarism.’ Undersea Hyperbaric Medicine 31(2), pp.199202. Verdier, C. Lee, D.R., Schoff, H. (2008) Unconscious Recreational Rebreather Diver and Rescue Techniques. Last accessed at the Rubicon Foundation 11/22/2013 http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/7826/DIRrebreather_ Rescue_Procedures.pdf?sequence=1 http://www.waisman.wisc.edu/events/ethics/spring06-sem2-incentives-compensation.pdf last accessed 11/23/2013 Part of the template was drawn from http://e-articles.info/e/a/title/how-to-prepare-a-research-proposal-~-the-content-of-a-proposal/