Evaluation 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 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 open-air burst pressure and minimum required eversion pressure and calculate a safety factor and nominal eversion pressure for each tube size. The candidate tubes were everted into a rigid phantom of the simulated knife wound at the nominal eversion pressure and their ability to stop pulsatile blood flow near healthy human diastolic pressures was measured with a new, low-cost, load cell-based flow measurement system. Rectangular tubes with 40 and 50 mm diameters, with areas 3 and 5 times that of the wound area, respectively, were found to have a sufficient safety factor above 1.75 and resulted in minimal blood loss. In a silicone knife wound phantom, bleeding was stopped by 30, 40, and 50 mm diameter tubes in all trials. Not only has eversion been shown to be a rapid and effective means of applying internal pressure to non-compressible wounds, this work also characterizes the increased minimum eversion pressure when an everting tube size exceeds the size of a lumen.