Physiological response of the heel tissue on pressure relief between three alternating pressure air mattresses.

Heels have substantially higher tissue interface pressures and are prone to ulceration compared to other bony prominences. Although many different types of alternating pressure air mattresses (APAMs) are used for the prevention and treatment of pressure ulcers, a few high-quality randomised controlled trials (RCTs) are available on which to base purchasing decisions. Faced with this situation, physiological measurements are increasingly being used as a surrogate. A time-based technique, which calculates pressure relief index (PRI), has been previously reported for analysing the ability of such systems. This technique has demonstrated that different designs produce variable results in this regard. The aim of the present study is to investigate the performance of three APAMs using PRI and blood perfusion measurements. Eleven able-bodied adult volunteers (6 males and 5 females) participated in the study. Their age, weight, height and body mass index (BMI) were (mean +/- s.d.) 23.9 +/- 2.1 years, 65.6 +/- 12.4 kg, 1.76 +/- 0.84 m and 21.0 +/- 2.4 kg/m2, respectively. There was no statistically significant difference in maximum interface pressure for the three mattresses. However, the AUTOlogic produced a statistically significant lower minimum interface pressure (Duo Care Plus, p < 0.0001 and higher pressure relief index below 30 mmHg than either the Duo Care Plus, p = 0.002 or Proficare, p < 0.0001. The AUTOlogic also gave a statistically significant enhanced perfusion per cycle when compared to other two mattresses (Duo Care Plus, p = 0.03 or Proficare, p = 0.01).