Fenestrated Escharotomy Instrument

The material properties of human skin when exposed to flames or high temperatures change and lose their necessary elasticity. An area of interest is the chest and torso skin, where burnt skin can cause tightness in the chest and impede normal breathing. The current method to relieve skin contractures is to use a scalpel blade to make multiple long incisions across the burnt skin. We seek to develop an incision device to produce a mesh pattern on the surface of the skin to allow for expansion and relieve pressure from the tightening of the skin.

The sponsor for this project, Dr. Samuel Lance, is a plastic surgeon who had the idea for a fenestrated cutting device that can be used for such surgeries but will cut in a lattice pattern to increase the expansion of the skin to further reduce the issues caused by the skin tightness.

Upon discussing with our project sponsor and faculty advisor, we were able to narrow the primary objectives that this device is attempting to achieve:

• Design a rotary blade system to produce fenestrations on burned skin

• Develop a safety housing and a cut depth control system

• Ensure device is autoclavable (high temperature and pressure sterilization)

• Ergonomic design to ensure firm grip in a surgeon's hand during operation

• Detachable handle and blade system

In-depth descriptions and information on the Final Design of the device can be found in the Final Design section.

Before fabricating the blades the team conducted some testing in order to determine the optimal blade geometry to create maximum expansion in the skin tissue.

To do this the team cut 6 different cut patterns into uniform samples of 15mm polyurethane as detailed below.

The team vertically hung masses varying from 500g to 2000g from these samples and measured the amount of expansion of the polyurethane sample. The team then modeled the expansion of the different samples and found that patterns 1 & 3 had significantly more expansion as shown below.

To confirm that the force required to cut flesh wasn’t greater than what a surgeon’s hand was capable of providing, a test for an Instron load cell was programmed. A fixture was created to keep a polyurethane sheet in tension over a block of ballistics gel while one of the blade disks could be pressed down into it by the load frame.

Testing the force required to cut through the polyurethane challenge case, the experimenters determined that puncture occurred at a range of 13.3 to 24.8 N. The range of forces establishes a 3 blade design with a factor of safety of 0.792, or a 2 blade design with a factor of safety of 1.188.