Pressure Injury Mitigation in Prolonged Care: A Randomized Noninferiority and Superiority Trial

Abstract

Introduction: Combat casualties are at increased risk for pressure injuries (PIs) during prolonged casualty care. There is limited research on operational PI risk mitigation strategies. The purpose of this study was to (1) compare a prototype mattress (AirSupport) designed for operational conditions versus the foldable Talon litter and Warrior Evacuation Litter Pad (WELP) on PI risk factors and (2) determine whether the Talon + AirSupport pad was noninferior and superior to the Talon + WELP on skin interface pressure.

Materials and methods: Healthy adults (N = 85; 20 men and 65 women), aged 18 to 55 years, were stratified based on body fat percentage and randomized into three groups: Talon (n = 15), Talon + AirSupport (n = 35), and Talon + WELP (n = 35). The participants were asked to lie in a supine position for 1 hour. The outcomes included skin interface pressure (body surface areas: Sacrum, buttocks, occiput, and heels), sacral and buttock skin temperature and moisture, and discomfort and pressure. The study was approved by the University of Washington Institutional Review Board.

Results: Aim 1: The Talon had significantly higher peak skin interface pressure versus the AirSupport and WELP on the sacrum, buttocks, occiput, and heels. Skin temperature increase over the 1-hour loaded period was significantly lower on Talon versus AirSupport or WELP, reflecting a lower temperature-induced ischemic load. There was no significant difference in skin moisture changes or discomfort between the surfaces. Aim 2: The upper confidence limits for the difference in skin interface pressure (all body surface areas) for AirSupport versus WELP were below 25 mm Hg, establishing noninferiority of the AirSupport to the WELP. AirSupport was also superior to WELP for the peak interface pressure on the sacrum, occiput, and heels but not on the buttocks. Skin temperature changes (sacrum or buttocks) were not significantly different between the AirSupport and WELP.

Conclusions: The Talon litter presents a PI risk because of increased skin interface pressure, and hence, immediate action is warranted. The decreased PI risk associated with the lower skin interface pressures on the AirSupport and WELP was offset by the higher skin temperature, which may add the equivalent of 20 to 30 mm Hg pressure to the ischemic burden. Thus, any pressure redistribution intervention must be evaluated with a consideration for skin interface pressure, temperature, and moisture. Data from this study were applied to a predictive model for skin damage. Under operational conditions where resources and the environment may limit patient repositioning, it would be expected that casualties would suffer skin damage within 2 to 5 hours, with the occiput as the highest risk area. The severity of predicted skin damage is lowest on the AirSupport, which is consistent with the noninferiority and superiority of the AirSupport mattress compared to the WELP and Talon. Operational utility: The AirSupport and WELP, which were both superior to the Talon, are operationally feasible solutions to mitigate PI risk. The smaller size of the Talon (2.7 kgs compressible) versus the WELP (5 kgs noncompressible) may make them appropriate for different levels of the operational setting.