How & Why To Make Your Own Ultra Low-Cost, High Fidelity Models
“She’s 26 weeks pregnant and attends with… Oh, my God. She’s just arrested!!!”
There are situations in Emergency Medicine in which seconds matter. The time it takes you to decide to perform a critical intervention, the time it takes to start and the time it takes you to complete it can mean the difference between life, life with permanent disability and death. Ask any seasoned EM doctor for examples and I guarantee you won’t be kept waiting long for an answer. They’re the Nightmare Scenarios; the ones which might get your own heart rate up just thinking about them, even more so if you could conceivably be the most senior doctor in the department when they occur. Could “the buck stop with you”?
Well, you’d better have a detailed plan. A general outline is not enough.
Picture the scene: That 24-year-old pregnant female who attended with severe breathlessness has just gone into asystole. Right now. There’s a split-second moment of recognition from the team around you; a kind of collective in-drawing of breath.
What do you do?
You’re the senior doctor. You need to Lead; Get control…
Someone lays the trolley flat then starts compressing her chest.
Start with A, B, C…You start directing people; task allocating.
You see the barely concealed fight-or-flight response in the pale faces of those around you. Shrug it off! Not now. Focus.
What’s different about this situation? She’s pregnant! How many weeks?
The adrenaline’s surging through you; your own heart rate is 140+. Congratulations, you’ve just acquired a resting tremor. There’s a torrent of thoughts and potential interventions: Left lateral position! (How do we do that when she’s lying flat and we’re compressing her chest?!). We need more help! More nurses. And call Obstetrics! Call Anaesthetics! Call the Neonatal Team – do we have one?! Intubate! Fluids! Is she bleeding? Is this a massive PE? Thrombolysis? That medical student looks like he’s going to faint. SIT ON THE FLOOR, PLEASE! Are we at 2 minutes? What’s the rhythm? 26 weeks? Perimortem C-section! That’s after the gestation cut-off, right?! Is the foetus too young to survive? Let’s do it! What do I need? Can I have the scalpel? I need to start cutting. Big breath.
Have you mentally visualised this before? If so, kudos to you! Have you physically drilled it? If so, brilliant! If I had a cap, it would be doffed. So when was the last time you drilled it?
My Perspective: Low Cost & High Fidelity Simulation
I wanted to recreate this scenario for our department. Here were the learning objectives:
Recognise and institute appropriate management for cardiac arrest during pregnancy.
Employ the use of a wedge or manual displacement of the uterus in maternal shock of any aetiology.
Understand the need to perform perimortem maternal C-section / resuscitative hysterotomy within 4 minutes of cardiac arrest and know how to perform it.
Distribute tasks efficiently between team members to facilitate effective perimortem C-section and obtain additional resources and staff members.
Many people realise that the fidelity of simulation is is not directly dependent upon the kit you use. Emotional fidelity counts for a lot. Stripping things down to what you need to meet your learning objectives is usually the way to go. If it doesn’t help you achieve your learning objectives, why complicate things?
However, for this session I wanted participants to rehearse the resuscitative hysterotomy procedure by not just describing what they’d do but also by picking up the instruments and actually making the incisions. Mental visualisation combined with physically performing the procedure.
I didn’t want to put a business case forward for spending hundreds or thousands of pounds getting a high fidelity, high cost, dedicated training model. It had to be cheap. After initial online research into the topic, I came up with a concept for making a training model and met with colleagues with simulation interests to develop it further (Dr Alistair Dewar, Deputy Charge Nurse Ian Lee, Simulation Educational Coordinator Nathan Oliver and Simulation Technician David Wright). We have since run this scenario over 3 separate training days.
What follows is a step-by-step guide on how to create a low cost, high fidelity perimortem C-section / resuscitative hysterotomy simulation model. I have included the details of our Prototype Models and why we settled on our final model to save others time working out the kinks. We attached our model to a “Sim Mom” mannequin for the scenario. Alternatively, the model could be attached to lower-fidelity mannequins if required using tape/Sleek.
For our prototype, we used a beach ball (£2), cut a small hole in it and inserted thin wire strips bought from a DIY shop (£2) to provide some structural support. We then inserted a lubricated, low-fidelity neonatal manikin (borrowed; complete with detachable umbilical cord) and placed a filled (& tied!) water balloon into the anterior aspect (between the manikin and the inner aspect of the beach ball so that this would be the 1st thing cut after the external wall of the uterus. We covered over the hole we’d made with sleek (obtained from the ED). We closed the beach ball over the model using cable ties/zip ties (£2.50 for 50 from DIY shop). We then covered the rest of the rest of the model with sleek to give the ball a more uniform pink appearance. We removed the anterior abdomen skin of Sim Mom and placed in our model “womb”. We flanked it on either side with rolled up towels for stabilisation. We obtained pig skin (with some attached subcutaneous tissue) for free from a friendly Butcher and used that for the anterior abdominal wall. We secured it with sleek.
When we used this model, we found there wasn’t enough “gush” of fluid when cutting into the simulated womb. Additionally, the metal wire mesh we created was too thin to provide much support to the beach ball shape.
Same a Prototype A but we also hooked up 2 fluid lines and inserted them through small holes on the posterior aspect of the “womb”, again securing with sleek. We attached these to 2 x 500ml pressure bags of crystalloid, closed the flow slider and inflated each to 200mmHg. We concealed the lines and bags under the bed sheets. The confederate/”stooge” had the task of opening the flows surreptitiously when the scenario participants were about to cut into the simulated womb (not difficult given the focus of the team on the procedure itself), creating a “gush” and a continued flow of fluid. This addition worked quite well but the wire mesh (reinforced with more strands) was still too weak to support the overall structure adequately. We decided we should try a new approach to the womb creation involving a simulated womb filled with liquid from the outset:
- Malleable Plastic/Rubber Water Carrier [ours was unbranded, clear rubber and bought from a Pound store. Unfortunately, I can’t find the pics of our one. A similar one found online is this “Adroit 5 Litre Expandable Collapsible Water Carrier”; £2.69 from Amazon:
- Pink Sleek to cover [Free; obtained from department]
- Neonate model (low-fidelity plastic model with detachable placenta) [Borrowed from education dept; free]
- Lubricant gel [Free from ED]
- Water for “amniotic fluid”; add colouring to this if you like! [Free]
- Towels [Free – borrowed from ED & returned]
- Pig skin [Free – obtained from friendly Butcher]
Total Cost: £1 using our Water Carrier from the pound store; £2.69 using the materials above. Clearly there are costs to the department for sleek, etc. but we were allowed to use the Emergency Department materials we needed for free.
Create the “womb”. Cut a hole out of the water carrier large enough to be able to insert neonatal model. Cover the neonatal model in lubricating gel and insert into water carrier. Cover the incised hole with layers of sleek (internally and externally if possible). Fill the carrier with water and ensure there is no leakage. Depending upon the thickness and colour of your water carrier, cover the whole carrier with pink sleek to make it look less like plastic/rubbery.
Remove the artificial skin abdomen from Sim Mom and insert the model “womb”. Make sure that any handles/protuberances are facing posteriorly. Stabilise it on either side with rolled up towels.
Use the pig skin (from the friendly Butcher) as the anterior abdominal wall and secure it at the lateral and superior margins to the towels/Sim Mom with – you guessed it – sleek.
Here’s what our eventual model looked like. A wider area of pig skin would obviously have reduced the amount of sleek coverage we needed for the abdominal wall; we used what we had.
This set-up worked extremely well; the layers were all easy to cut through, the womb structure held its rounded shape and there was a satisfying “gush” of fluid when the sim “womb” was incised. In future, I might try to obtain some yellow foam (like the stuff inside seat cushions) to use as a thicker “fat layer” since the pig skin (+ subcutaneous tissue) wasn’t particularly thick. Other than that, everything worked perfectly.
Mentally rehearse the situation. Visualise the critical interventions, their optimum order and the kit you need. Rehearse the steps. If you’re able, create your own models and go sim it with your teams.
Dr Craig Walker
Consultant in EM and Critical Care