4 minute read
Medline Q&A
Medical queries
& answers
BY THE DAN MEDICAL STAFF
The DAN-SA medical information line is here to answer all your divingrelated medical questions. You can reach the medical staff by calling 0800 020 111. You can also send an email to danmedic@dansa.org
QWhen I wear a hood, I always experience great difficulty when trying to equalise my ears, yet when I am not wearing a hood I do not struggle to equalise my ears at all. Why is this? A When the middle ear space is pressurised using the Valsalva manoeuvre or other equalisation techniques, the eardrum bulges slightly outward. If the ear canal is uncovered and can transmit that pressure, the water in the ear canal moves easily in response. A hood that fits snugly against the outer ear can greatly restrict the movement of this water, thereby hampering a diver’s ability to equalise.
One of the easiest remedies is to insert a finger under the hood near the ear, which will allow the water to move more easily. Another solution is to cut a hole from the inside of the hood (near the ear canal, through the inner lining and the neoprene), but to leave the outer fabric or covering intact. The hole allows the water to move with little restriction and helps to prevent equalisation difficulties.
DR MARTY MCCAFFERTY
QMy doctor recently put me on Coumadin. Could diving while taking this medicine cause any problems? A There is a well-recognised risk for uncontrolled bleeding in people who are being treated with anticoagulant medications such as Coumadin. However, many people who take anticoagulants, including divers, have carefully adjusted their prothrombin times and, with appropriate behaviours, may not be at undue risk. Some physicians believe that diving is an unnecessary risk for patients who are taking anticoagulants and will advise against partaking in the activity, but DAN-SA is unaware of any data indicating that sport divers face an increased risk of complications.
Some physicians trained in dive medicine may be willing to endorse recreational diving for these patients provided that: - The underlying disorder or need for anticoagulants does not put the patient at an increased risk of an accident, illness or injury while diving. - The patient understands the risks and modifies his or her dive practices to reduce the risk of ear,
sinus and lung barotrauma as well as physical injury. This includes avoiding forceful equalisation (equalisation must come easily for people who are taking anticoagulant medications). - The patient dives conservatively by planning short, shallow profiles to reduce the risk of decompression illness, which can involve bleeding in the inner ear or spinal cord. - The patient avoids diving in circumstances in which the access to appropriate medical care is limited.
DANIEL NORD
QWhen trying to provide rescue breaths in the water to an injured diver, is it an option to use my spare regulator’s purge button? That seems easier to me than trying to manage a pocket mask. A Using the purge button of a second-stage regulator has been proposed many times, but any advantage it may seem to offer does not outweigh the potential risks and complications.
If the regulator mouthpiece is not already in the unconscious diver’s mouth, trying to replace it can be difficult and time-consuming. Without a good seal and a means to occlude the diver’s nostrils, any attempt at ventilation will be unsuccessful. Even if the mouthpiece can be successfully placed in the diver’s mouth, there is a risk of it pushing the relaxed tongue to the back of the throat and blocking the airway.
If the regulator mouthpiece remained or was placed in the diver’s mouth without blocking the airway, the next challenge would be administering air. Purge buttons do not have any true regulatory capabilities. They effectively override the second stage’s function of stepping down gas from intermediate pressure to ambient pressure and thereby deliver intermediate-pressure gas directly from the first stage. Delivering breathing gas to the lungs at too high a pressure may overinflate them, potentially leading to serious injury. If the diver’s airway is not maintained in an open position, the breathing gas delivered by the purge button could be forced into the stomach, causing gastric distention. This places the diver at risk for regurgitation, which can further compromise the airway and lead to aspiration.
Delivering rescue breaths using a pocket mask or similar method provides tactile feedback via changes in the pressure required to ventilate the lungs. Alternatively, supplying rescue breaths with the purge valve eliminates this important feedback. Using a regulator’s purge valve also precludes the option of supplementing the gas with 100% oxygen.
Rescue methods that are currently taught by dive training agencies are the result of years of practical experience. Purge valves were never designed to function as rescue equipment. When ventilating an injured diver, it is best to rely on established methods.
