Effects of elevating the head of bed on interface pressure in volunteers

Objective: Intensive care unit patients are at particular risk for pressure ulcers and ventilator-associated pneumonia. Current guidelines recommend that mechanically ventilated patients be kept in a semirecumbent position with the head of bed elevated 30 degrees-45 degrees to pievent aspiration and ventilator-associated pneumonia. We tested the effects of elevating the head of bed on the interface pressure between the skin of the sacral area and the bed with healthy volunteers. Interventions. Interface pressure profiles of the sacral area were obtained for the 0 degrees, 10 degrees, 20 degrees, 30 degrees, 45 degrees, 60 degrees, and 75 degrees head of bed elevated positions from 15 subjects (14 men, one woman). Measurements and Main Results: Peak sacral interface pressures increased with large increases in head of bed elevation. The 30 degrees, 45 degrees, 60 degrees, and 75 degrees head of bed positions all had peak interface pressures that were significantly (p < 0.02) greater than the supine measurement and also were different from all other head of bed positions. Affected areas, defined as areas over which an interface pressure 32 mm Hg was obtained, increased with large elevation of the head of bed. The affected areas of the 45 degrees, 60 degrees, and 75 degrees head of bed positions were significantly greater than the supine position and were also significantly different from all other head of bed positions. Conclusions: Raising the head of bed to 30 degrees or higher on a intensive care unit bed increases the peak interface pressure between the skin at the sacral area and support surface in healthy volunteers. At 45 degrees head of bed elevation or higher, the affected area attributed to a skin-intensive care unit bed interface pressure 32 mm Hg increased as well. Further study is needed to determine whether the increased peak interface pressures and affected areas that result from raising the head of bed actually increase the incidence of pressure ulcer formation. (Crit Care Med 2008; 36:3038-3042)