Effect of alertness level and backrest elevation on skin interface pressure

Critically ill patients may experience reduced mobility and sensation related to various pharmacologic therapies and treatments, making this patient population especially susceptible to pressure ulcers. An alert patient may be better able to reposition in response to discomfort, therefore preventing the development of pressure ulcers. However, little is known about the effect of an individual's alertness level on skin interface pressures. This study describes the effect of alertness level and backrest elevation on skin interface pressures.

Fifty healthy participants were recruited from the Virginia Commonwealth University (Richmond, VA) population. Participants simulated each of 2 alertness levels (sedated or alert) while in 3 backrest elevations (30°, 45°, or 60°). Activity level, backrest elevation, and interface pressures were recorded continuously for 30 seconds. Random effects models were used to examine the effects of alertness level and backrest elevation on average and peak pressure. Participants had a mean age of 30 and 82% were female.

There was a significant interaction between alertness level and angle as related to average pressure (P < 0.0001) and peak pressure (P < 0.0001). Increases in backrest elevation increased average pressure and peak pressure. Interface pressures were generally greater when participants were simulating the alert state.

These findings may indicate that interface pressure is a poor indicator of patient discomfort. Higher body mass index (BMI) was associated with higher average pressure (P < 0.0001), but lower peak pressure (P < 0.0001), suggesting better pressure distribution across the patient's body area. These findings are similar to previous studies in which low BMI is associated with increased pressure ulcer risk. .