Medsim

MEDSIM SIMULATOR

Rowena Madar rowmad@hotmail.co.uk

Satthaporn Barnes s.c.barnes@hotmail.co.uk

PROBLEM SPACE AND RATIONALE

“Poor needle insertion technique can lead to both minor and major complications”

Rowena Madar & Satthaporn Barnes

Needle insertion is a common procedure in medical care. It is used in a variety of different operations ranging from taking patients bloods, anaesthetising a patient and is also a primary stage of minimally invasive surgery. Although there are many different ways and techniques used to Insert a needle they all share similar characteristics and require an understanding of both visual and tactile response. Poor needle insertion technique can lead to both minor and major complications. For this and many other reasons, improving teaching practices for such procedures has become an increasing focus in medicine.

FRAMING THE PROBLEM

One needle insertion technique that carries considerable risk is the Veress needle procedure.

The Veress needle technique is favoured by gynecologists in the UK, and the first, most critical stage laparoscopic surgery, attributed to 50% of all complications in this procedure. The needle is blindly inserted into the abdomen to inflate it, the operator relying heavily on two distinct ‘gives’ felt as the needle transcends the fascia and the peritoneum to determine that the needle has sufficiently advanced into the peritoneal cavity. At this point, the needle should immediately stop advancing, for fear of tearing the bowel. Currently a trainee gynecologist’s first experience of using a Veress needle is during surgery when inserting it into a real patient.

The project was undertaken by a multidisciplinary team of 4 master’s students. This included two product designers, a medical engineer and a mechanical engineer with the aim to make a professional Veress and lumbar puncture needle training system by optimising the mechanical, computational and design elements, suitable for use in surgery training. In particular, the designers focused on the user’s learning experience through tutorials and anatomical diagrams in an interface and a realistic product casing.

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PROBLEM SPACE AND RATIONALE

Similarly, lumbar puncture is another common needle insertion procedure often used to collect Cerebrospinal fluid (CSF) and required preliminary to spinal anesthesia. Associated risks with incorrect technique include postoperative headaches and very occasionally, brain stem herniation. Technical skills necessary for lumbar puncture procedure involve finding the correct inter-vertebral space and passing the needle into it. While relatively straightforward with the average patient, accurate needle insertion becomes more challenging when patients are obese, pregnant, elderly or uncooperative, requiring the operator to have both skill and experience.

DISCOVERY PHASE

DISCOVERY PHASE After initial meetings with supervisors and clinicians, the aims and technical objectives were established. This involved producing a medical simulator with haptic feedback capable of allowing the system to replicate the typical feedback experienced when performing both the veress and lumbar puncture needle procedures.

PROBLEM AND CHALLENGE ANALYSIS

nurses, students and residents have made them a feasible teaching solution.

One key problem with simulators is related to their cost. Surgical simulators range from $5,000 for low fidelity laparoscopic simulators to $200,000 for highly sophisticated ones.

Although high tech simulators are considered a better choice, the cost for these simulators is disproportional to the added benefit gained from them.

Rowena Madar & Satthaporn Barnes

The focus of the project lead to research into medical simulators as an additional teaching technique for surgeons. Simulators are becoming an increasingly important education service in medical teaching. Currently used to compliment other teaching methods, they aim to accelerate and deepen learning. In 2014, the global health simulator market was worth an estimated $863.5 million.

There are many features included in medical simulators, designed to heighten the learning experience for the user. In terms of casing, the simulators typically replicate the anatomy and provide a realistic looking shape. Another aspect often incorporated in such devices is an interface that can provide the user with feedback from the simulator. More specifically, higher fidelity systems often include augmented Many medical training centers in the UK now reality. This research led to the designer’s offer medical simulators, allowing staff easy focusing on how to incorporate high fidelity access to training. Advancements in technology simulator features into a low cost simulator to have made them a practical tool for the training fill the gap in the market for cheap high fidelity process. This, and the fact they are also able to simulators, therefore making them available to cater to a wide range of medical staff including a larger market.

USER INSIGHT While the simulator can be designed to cater for a wide range of users, the primary end user for this product is trainee surgeons (residents).

Due to restrictions on medical staff, resident hours are now capped to 40 hours a week, giving them less time to access specialist training and leaving many residents feeling under prepared. There is great demand for training simulators that can enable the development of such technical skills as needle procedures. One study found using a lumbar puncture simulator could improve knowledge and skill. There is an ever increasing user demand for such training simulators.

“Including many procedures in one device expands possible training infinitely”

Dr Rory O’Connor

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USER INVOLVEMENT AND TESTING

DR RORY O’CONNOR, PROFESSOR IN REHABILITATION MEDICINE TESTING MEDSIM

Rowena Madar & Satthaporn Barnes

Throughout the project the clinicians provided invaluable information, critical to the success of the product. Specifically when designing medical training devices, it is of particular importance that the experience is realistic and that the training material is accurate. Due to restricted access to medical professionals, third and fourth year medical students were also included in the project testing stages.

One of the most significant parts of the project was testing the validity of the device with clinicians.

This was done through approaching the clinicians for testing out the simulator and scoring the haptic feedback of the device. This would then confirm that the simulator response was appropriate and similar to the sensation experienced in surgery.

DESIGN PHASE casing. Though each member had their individual responsibility, there were many sections of overlap, where the different areas The simulator is comprised of many parts of expertise particular to each student were which were developed and tested in parallel necessary. to each other, with each team member taking responsibility for certain aspects of the project.

Creating the simulator involved designing, The engineers worked together, though building and testing various subsystems that the mechanical engineer mainly focused made up the overall product. Before the work on designing and building the mechanical could be divided into the subparts the initial system ensuring the force feedback could be research and project planning was necessary. generated, while the medical engineer built The work-breakdown structure, shown on the the program that would allow the mechanical next page, gives an overview of these different system to be controlled. The designers focused systems, subsystems and their components. on two subsystems which included the interface/augmented reality and the aesthetic PLANNING

USER INSIGHT

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DESIGN PHASE Rowena Madar & Satthaporn Barnes

WORK BREAKDOWN STRUCTURE OF COMPONENTS INVOLVED IN DESIGNING THE CASING DESIGN PROCESS

INTERFACE PROCESS

&

AUGMENTED

The design process of both laparoscopic and lumbar casings followed a descriptive model to provide a framework for development. This included: Stage 1 - Exploration, this involved research and creating measurable design specifications Stage 2 - Generation, a series of different solutions were created Stage 3 - Evaluation, designs were evaluating against users and the specification before the chosen design was developed Stage 4 - Communication, once the design is evaluated manufacturing was considered

Designing successful interface (UI) typically involves continual testing with the user and prototyping. For this reason the ISO-13407 standard was applied, this included: Stages 1 & 2 - researching the user, context, and the necessary structure/navigation of the UI Stage 3 - 5 different home-pages were then designed and tested with a user focus group Stage 4 - UI designs were checked against existing theories and principles to Stage 5 - 3 stages of prototypes were created Stage 6 - usability and evaluation of design

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REALITY

SOLUTION SPACE REQUIREMENT

SCORE

WEIGHT

TEST METHOD

EVIDENCE

FINAL SCORE

LOW COST <ÂŁ1,500 The device should be competitive against other simulators on the market

3.5

Raw score of the different components calculated

Raw score is significantly lower than maximum price specified

INCORPORATES EDUCATION casing should have visual impact and there should be augmented reality

3

different checklists for each subsystems are made and used to include the features

Both these features and most items on the lists have been successfully incorporated

REALISTIC HAPTIC FEEDBACK The different needle procedure feedback should be realistic

4

Clinicians will test the device and provide a rating for how realistic the product is

Feedback from the clinicians was extremely positive

90%

PORTABLE The device should be able to be moved between departments if necessary

2.5

Tests conducted to see how easy it is to move the simulator through rooms

Results concluded the device could be moved easily

75%

OPERATES IN DRY LAB Material selection and device should be appropriate for the intended environment

2

Analysis of materials used and feedback from the clinicians

Casing materials are deemed appropriate and the clinicians thought the simulator suitable

65%

Overall the final design was considered successful as the simulator met the main design requirements, scoring best in the most important areas.

87%

SOLUTION SPACE

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90%

Rowena Madar & Satthaporn Barnes

EVALUATION

100%

SOLUTION SPACE

1

2 3

4

Rowena Madar & Satthaporn Barnes

FINAL DESIGN SOLUTION MEDSIM SIMULATOR SHOWING KEY SUBSYSTEMS The final solution is a haptic training aid capable of simulating both the veress and lumbar puncture procedures. The casing is comprised of a base with two lids, one to replicate a womans torso for the veress procedure and the other a curved back for lumbar punctures.

The needle is inserted into the mechanical system which is controlled through a LabVIEW program and can run wirelessly using a MiRIO

controller. The mechanical system sits inside the casing which has a hole to allow the user to insert the needle through. The simulator also comes with a Dell Latitude tablet that gives the user feedback on how they inserted the needle, including an augmented reality. To make the learning experience more comprehensive, interactive quizzes and tutorials are included as part of the package.

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EXTERIOR LAPAROSCOPIC CASING - The laparoscopic casing is made from Polypropylene and can house all the different elements of the simulator making it easy to transport.

MECHANICAL SYSTEM - This is where the needle is inserted into the product and through use of a motor provides the realistic feedback necessary for each of the procedures.

DELL TABLET - The tablet comes as part of the device and can be used to view the additional learning material and control the simulator INTERFACE ON TABLET IN USE wirelessly.

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SOLUTION SPACE

LAPAROSCOPIC CASING DESIGN

The models were based on existing literature and validated against a clinician who specialised in both procedures. The models were then imported into the LabVIEW program on the front panel to show the needle going through the various layers.

Rowena Madar & Satthaporn Barnes

ABDOMEN MODEL - The image on the tablet THE INTERFACE & AUGMENTED REALITY shows a still from one of the walk-through videos that details the procedure, giving supporting The interface is designed to allow the user to learn about the procedures by outlining different learning material. topics related to both Lumbar Puncture and Veress techniques. The first menu allows the THE AESTHETIC CASING user to choose which procedure they would The external casing is a visual aid that makes like to learn about, colour coding the different the training device more memorable, the cases subjects to avoid confusion. A mock up represent the parts of the body that are entered interface was created using Articulate software during surgery. Each lid includes a synthetic and has 3D models and videos to increase the silicon skin patch, placed at the appropriate potential learning experience. site of entry, allowing the user to palpate the Each procedure has 6 interactive tutorials giving area realistically. specific information on the relevant theory For the Lumbar puncture casing an additional including risks associated with the surgery and anatomically correct 3D printed spine, set in correct way to insert the needle. Information in the correct alignment, provides kinesthetic the tutorials is from existing literature, mainly feedback. This spine model enables the medical journals, though further validation with user to replicate the introductory phase of clinicians would be beneficial. lumbar puncture, where they must feel for the interspinous space between the L4 and L5. The augmented reality provides important visual feedback to contextualise the simulator vertebrae. to the user, allowing them to view the different relevant tissue layers as they insert the needle into the device. This was done by creating realistic anatomically correct 3D models of the relevant tissue layers through CAD modeling.

SOLUTIONS SPACE RAW COST OF MEDSIM SIMULATOR

Rowena Madar & Satthaporn Barnes

COSTS AND PRODUCTION The mechanical system is made from standard components easy available and costing a total of £512. Most of this cost is related to the price of the MyRIO component, which costs almost £300 by itself. However, the construction of the mechanical system is straightforward and the system simple to replicate.

The cost for the interface is fixed and includes the price of the Dell tablet that comes with the simulator and the software used to develop the app.

The casing would be made from polypropylene and for high scale production manufactured by injection moulding. The raw costs seen in the figure above show the prices for manufacturing a one off product compared to a batch of 10,000. Due to high start up costs for casing production, the simulator would not be manufactured at a batch size of less than 10,000 units.

FIGURES

CASING MANUFACTURING MOULDS

COST: £833

SALES: 10,000

REFLECTION The final design incorporates a broad range of functionality and features. This makes MedSim a complete training package. The construction and implementation give a very high fidelity simulation of needle penetration for both the Veress and Epidural procedures.

By using modern materials, computer models and manufacturing techniques the costs of the product have been minimised. The end product having broader functionality whilst being significantly cheaper to produce than existing commercial devices.

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