One day this week, Andrew Smith came to my office and we talked about the fact that low-tech, low-cost simulation does not receive as much attention as the bells and whistles of computerized models. Coincidentally, preparing for an upcoming high-school science fair, one of our partner’s daughter (Dr. Mohamed Sheheta, Faculty of Engineering) presented on the topic of low-tech, low-cost solutions to the development of simulators to teach ultrasound skills. This topic is very timely considering our work with development of simulation-augmented education in Haiti and for our own remote north. In this issue of the newsletter we decided to give you 2 such recipes.
Low-cost homemade gel block for ultrasound training
Author: Dina Shehata
(High school Student)
Context: Ultrasound is a valuable tool being increasingly integrated into a multitude of different disciplines of clinical medicine. Point of Care Ultrasound (PoCUS) improves patient safety when used to guide procedures such as central line placement, paracentesis, and thoracentesis. Training residents to be proficient in ultrasound needle guidance predominantly relies on the use of commercial phantoms or gel blocks. These simulators range in cost from $100-5000 per unit and facilitate a defined number of needle-sticks. Home-made phantoms are inexpensive ($5-10 per block) and have been cited in the literature as being of good quality.
Provided are recipes and preparation instructions for 2 such models.
Homemade “thick” gel block
This recipe is based on the link on YouTube:
https://www.youtube.com/watch?v=u9_1md1f-NM&feature=youtu.be&noredirect=1
Ingredients
• Gelatin
• One mixing bowl
• Metamucil (sugar-free)
• Measuring cup
• 2 Tupperware containers of the same size (I used a 7 ½ x 4 ¾ x 2 ⅞ inch containers)
• 2 water pipes with different outer diameters (¾ inch pipe and 7/16 inch pipe)
• Spade drill bits that correspond with the water pipes
• Drill
• Cloth soaked in cooking oil
• Any preservative (I used 70% isopropyl alcohol)
• Hot water
• Hand mixer
• Spoon and sieve
Preparation
1. Take one of your Tupperware containers and drill two different sized holes on the left and right faces of the containers. Have each hole line up with the hole of the same size on the opposite sides of the containers. Note that these two holes will be made with the drill bits that are the same size as your water pipes.
2. Place the two water pipes in their corresponding holes through the container from end to end.
3. Then lubricate the pipes with your oil-soaked cloth so that they would be easier to take out later.
4. Take your mixing bowl and in it put 180 grams of gelatin powder, 1000 milliliters of water, 60 milliliters of preservative and 2 tablespoons of Metamucil.
5. Use the hand mixer for about 1-2 minutes and make sure all the powder dissolves.
6. Using the sieve remove the air bubbles and debris from the surface.
7. Pour liquid into container then place it in the refrigerator for around 3-4 hours.
8. Once the model is firm, remove the pipes but be a bit cautious as to not move them around too much so they won’t ruin the block.
9. Put the model in a new plastic container.
10. While it is in the container fill the two holes of the model with water. Remove all excess air by tilting the container then pushing down on the model and squeezing the air out and refill until the vessel is full. Make sure there are no air bubbles.
Homemade ”thin” gel block
This recipe is based on the link on YouTube: https://www.youtube.com/watch?v=ypw8vjZ2DN0
Ingredients:
• Gelatin
• Two different sized plastic tubes (I used a ¼ inch plastic tube and ¾ inch plastic tube)
• Measuring cup
• Measuring spoons
• Whisk
• Tupperware container at least 2-3 inches in height (I used a 7 ½ x 4 ¾ x 2 ⅞ inch container)
• Non-stick spray or cooking oil
• Pot
• Paperclips or staples
Preparation
NOTE: There will be two different layers two this block.
Bottom Layer:
1. Put 250cc water into a pot and boil until you see little bubbles coming out the bottom of the pot.
2. Gently stir in 21 grams of gelatin.
3. Whisk rapidly so you won’t get clumps of gelatin.
4. Once the gelatin is added and dissolved, add in one tablespoon of Metamucil all the while still whisking.
5. Pour the mixture into your container and then place in your fridge for about an hour
6. Take your plastic tubes and tie off the ends with some string or knot them. Then fill them up with water and tie off or knot the top. Make sure that they are not leaking water. If they are leaking, something I did was to set fire to each end and mold them shut while they are still hot and are able to be easily shaped.
7. Take your container out of the fridge and put the plastic tubes on top of the mold. They should be a few cm away from each other. In order to secure Penrose Drain, I used paper clips and bent them into the shape of staples and tacked down the Penrose Drain.
Top Layer:
Note: This layer will actually be thicker than the bottom layer.
1. Put 425cc of water into a pot and make it boil until once again there are little bubbles reaching the surface of the water.
2. Mix in 35 grams gelatin and whisk it. Make sure it has dissolved and there are no clumps before adding in 1.5 tablespoons of Metamucil. Mix until completely smooth.
3. To make sure there are no clumps you can use a tissue as a sift to take out all clumps.
4. Let this mixture cool for about 20-25 minutes before pouring it onto the 1st layer. Every 5 minutes go and stir it to prevent clumps and so it can cool evenly.
5. Then pour mixture onto 1st layer and then take the whole thing and place it in the refrigerator for about two hours.
6. When you take it out you’ll notice that it is not completely solidified but it is still pretty firm.
7. Take a dull knife to go around the edges and the model should easily fall out.
8. Put the mold on wax paper, wrap the model, put the whole thing in a Ziploc bag and place it in the fridge overnight.
9. After that it will be ready for use.
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