Influence of the 30 degrees laterally inclined position and the 'super-soft' 3-piece mattress on skin oxygen tension on areas of maximum pressure--implications for pressure sore prevention.

The measurement of the transcutaneous PO2 (tc PO2) demonstrates that localized pressure on skin sites under bony prominences (e.g., the sacral and trochanteric areas) decreases the tc PO2 at these skin positions to zero when subjects are lying motionless on a normal hospital mattress. This explains the high risk of pressure sore formation in elderly patients, who have a greatly reduced frequency of involuntary movements. Therefore, the first principle of pressure sore prevention is the elimination of localized pressure on both the trochanteric and sacral skin areas simultaneously. This can be achieved by bedding elderly patients who are at risk on a 'super-soft' mattress and by turning them regularly to the 30 degrees laterally inclined position. With healthy adults, placed in this position, both the skin areas over the trochanteric and sacral bony prominences remain almost free from pressure and thus normally oxygenated. In addition, the tc PO2 measurement allows an immediate assessment of the efficacy of a procedure for sore prevention.