Development of an Everting Soft Robot for Rapid Wound Packing

Bleeding from noncompressible penetrating deep wounds is a significant healthcare challenge. Failure to control bleeding in these wounds is primarily due to inability to tamponade bleeding by applying even pressure to inaccessible bleeding blood vessels. We have designed a device intended for the rapid treatment of complex non-compressible wounds: the Rapid Everting Tamponade (RET) is designed to apply internal pressure to affected vessels through the everting growth of a flexible, inflated tube so that the tube quickly grows into any wound shape and applies even pressure to the wound cavity. We investigate the optimal sizing of an inelastic tube for a simulated knife wound as a design trade-off between openair burst pressure and minimum required eversion pressure and calculate a safety factor and nominal eversion pressure for each tube size. The candidate tubes and an elastic latex condom were everted into a rigid phantom of the simulated knife wound at the nominal eversion pressure and their ability to stop blood flow was scored. A 50 mm rectangular tube shape with an area 5 times that of the wound area was found to have a sufficient safety factor of 1.75 and stopped bleeding during all trials while demonstrations of the elastic tube were also able to fully stop bleeding. In a silicone knife wound phantom, bleeding was stopped by the 50 mm tube in all three demonstrations. Not only has eversion been shown to be a rapid and effective means of applying internal pressure to non-compressible wounds, this is also the first characterization of increased minimum eversion pressure when an everting tube size exceeds the size of a lumen.