Recipe of the Week

A Simulator for Ultrasound Guided Regional Anaesthetic Blocks

Dr Duncan Farquhar-Thomson 

Consultant Anaesthetist Dorset County Foundation Trust Hospital

Preparation Time 24hrs of which cooking time 60minutes

Ingredients                                                        

Gelatine Granules         
Food Colouring
Penne Pasta
Spaghetti
Bone from leg of lamb or chicken thigh

Recipe

The simulator is designed to demonstrate ultrasound anatomy in a realistic way. The principle is simulated anatomical structures suspended in layers of gelatine Time is needed for Gelatine to set in the refrigerator before each new layer is added. The process may take 24hrs in total. 

Take plastic container approximate dimensions 20cm long by 10cm wide by 8cm deep approximately.

Make up the Gelatine solution.  Dissolve one sachet of Gelatine in 250mls of very hot water. Do not use boiling water or dissolve in a pan over the stove as this will denature the protein and the gel will not set.  Add some food colouring to disguise contents of simulator.  You can speed up the process by adding some ice to the solution to cool it rapidly to about 20 Celsius. Pour about 2cm deep layer of the liquid into the bottom of the plastic container. Place in the refrigerator till set.

The next layer will contain the important structures of the simulator-bone, vessels and nerves.    Use a clean cooked bone to simulate human bone, cooked penne pasta or 7mm silicone tubing to simulate the vessel and cooked spaghetti to simulate nerves. The penne pasta can be formed into a tube by gluing together with ‘Superglue’.

I would suggest arranging the anatomical elements to simulate actual anatomy for example the axillary block.   Arrange the different elements onto your first layer of now set gelatine.  Secure the different elements to the bone with ‘superglue’ so they do not float away when the next layer gelatine is added.

Mix up some more Gelatine Solution and add some food colouring.It is essential that this solution be allowed to cool to 20 degrees Celsius before it is added to the container.  If not the first layer will melt and all elements of you simulator will sink to the bottomAdd sufficient Gelatine solution to just cover your simulator materials.  Allow setting in the refrigerator.

Finally make up you final layer with further gelatine solution and food colouring to disguise contents.  Fill the plastic container so it is flush with the edged of the container.  Remember to cool solution to 20 degrees Celsius. Refrigerate.  Once set simulator can be protected with a layer of cling film but be sure to exclude any air.

Simulator will keep in the fridge for several days but will only last one day of heavy use and may deteriorate rapidly in hot atmospheric conditions.

Have fun with your simulator-a variety of other materials can be added to give interest to your simulator for example ‘Alphabet spaghetti’ spelling out different words!

Figure 2