Interface pressure at different degrees of backrest elevation with various types of pressure-redistribution surfaces

Increased elevation of the head of the bed is linked to a higher risk for sacral pressure ulcers. A semirecumbent position of at least 30° is recommended for the prevention of ventilator-associated pneumonia in patients treated with mechanical ventilation. Therefore, prevention of pressure ulcers and prevention of pneumonia seem to demand contradictory, possibly incompatible, positioning.

To measure pressure at the interface between sacral skin and the supporting surface in healthy volunteers at different degrees of upright position with different types of mattresses.

An open, prospective, randomized crossover trial was conducted with 20 healthy volunteers. Interface pressure was measured by using a pressure mapping device with the participant in a supine position at 0, 10°, 30°, and 45° elevation and in the reverse Trendelenburg position at 10° and 30°. Four types of mattresses were examined: 2 different foam mattresses and 2 air suspension beds, 1 of the latter with low-air-loss technology.

Peak sacral interface pressures increased significantly only at 45° of backrest elevation (P < .001). A mattress system with low-air-loss technology significantly reduced peak interface pressures at all angles (P < .001). The reverse Trendelenburg position led to lower peak pressures for all positions (P = .01).

Backrest elevation up to 30° might be a compromise between the seemingly incompatible demands of skin integrity and the prevention of ventilator-associated pneumonia. The reverse Trendelenburg position and a mattress system with low-air-loss technology could be additional useful tools to help prevent skin breakdown at the sacrum.