Assessing the Performance of Alternating Pressure Air Mattresses (APAMs)

Abstract

Pressure ulcers cause great pain and suffering to patients and their treatment is both costly and time consuming, therefore every effort should be directed towards their prevention and treatment. Patients with impaired blood circulation in the lower extremity are at particularly high risk and global demographic trends might suggest that this factor will become increasingly problematic over time. The heel is most prone to tissue damage due to substantially higher interface pressures (IPs) plus the increased likelihood of peripheral vascular disease associated with a more aged population. There are many products on the market that attempt to provide pressure redistribution (PR) to this problematic area and alternating pressure air mattresses (APAMs) are widely used both in the institution and in homecare settings. However, some devices may be based on dated technology and may no longer be aligned to the rapidly evolving needs of the patient. Strategy depends on the ability of hyperaemia after PR to adequately compensate for intervals of flow deficits. We investigated the effect of pressure-relief on heel blood flow, in diabetic patients and healthy adult volunteers, using interface pressure and laser Doppler (LD) blood flow measurements, when the subjects were lying supine on four different APAMs. They included the Duo™ and the Duo 2™ (Hill-Rom Inc), as well as the Nimbus™ 3, the Nimbus Logic™ (Huntleigh Healthcare Ltd). The measurements elicited significant differences in the performance of the APAMs and indicated how new technology had influenced performance. An interesting finding was that low air cell pressures do not necessarily produce lower IPs, under the heel, contrary to the intuitive classical notion.