Comparison of the effectiveness of two pressure-relieving surfaces: low-air-loss versus static fluid.

Limited research has been done to determine the effectiveness of the multitude of pressure reduction devices currently available for patient care. The purpose of this investigation was to examine the relative effectiveness of a dynamic low-air-loss (LAL) mattress and a static fluid mattress in reducing the risk of pressure ulcer development. The investigation consisted of two components: a comparative laboratory study and a retrospective clinical study. In the laboratory study, tissue interface pressures were measured on the two surfaces at three interface sites in a sample of six healthy adult volunteers. In the clinical study, a retrospective chart review was conducted to compare the actual incidence of pressure ulcer formation in a sample of 73 postoperative transplant patients who were placed on either the static fluid or LAL product. The instruments used were the Xsensor Pressure Mapping System (laboratory) and chart review tool (clinical). The main outcome measures included tissue interface pressures and incidence of pressure ulcer formation. The results were as follows: the laboratory study revealed significantly lower sacral pressures (t = -5.30, P = .003) on the low-air-loss mattress than on the static fluid mattress. Pressures did not differ significantly at the heel or trochanter sites. In the clinical study, the overall incidence of skin breakdown was 8.2%, with 5 occurrences (13.8%) in the LAL group and 1 occurrence (2.7%) in the static fluid group. However, this difference was not significant (Fisher's exact test = 0.107, P = .09). When considered jointly, the results of the two studies suggest that the static fluid and LAL products may be comparable in efficacy. Although the relatively small sample sizes used in the investigation limit generalizability, the results provide some initial direction for further clinical research in this area.