Skin oxygen tension as a function of imposed skin pressure: implication for decubitus ulcer formation.

Pressure is a crucial factor in the formation of decubitus ulcers. To elucidate the effect of imposed skin pressure, a new cutaneous oxygen sensor was used to measure the skin oxygen tension under increasing pressure upon skin tissue at "hard sites" (bony prominences) and at "soft sites" (muscle-padded areas). At hard sites the skin oxygen tension fell rapidly under increasing pressure (y = 90.9--0.39. X; r = 0.98) from an initial value of 86.4 +/- 10.6 to 20.2 +/- 12.1 mm Hg under an imposed skin pressure load of 175 gm/cm 2. At soft sites a pressure load of 175 gm/cm 2 decreased the skin oxygen tension only from 82.9 +/- 5.8 to 71.4 +/- 10.0 mm Hg. These results may explain why hard sites (bony prominences) are preferential areas for decubitus ulcer formation.