Abstract
A better understanding of how pressure ulcers develop in the buttocks will improve prophylactic measures. Our aim was to investigate signs of reduced perfusion and ischaemia in the subcutaneous fat in the buttocks during sitting. A microelectrode was used to quantify oxygen (pO2). Metabolites that indicate aerobic or anaerobic metabolism (glucose, lactate, pyruvate, and glycerol) were quantified using microdialysis. Sixteen healthy people were studied while they sat on a wheel chair cushion, and a hard surface. Sitting pressures were mapped, and the thickness of the subcutaneous fatty layer was measured. The results showed that pO2 and glucose were significantly reduced during sitting, and for pO2 the effect is significantly more profound during sitting on a hard surface. After loading, both glucose and pO2 increased significantly. We conclude that the subcutaneous adipose tissue covering the ischial tuberosities becomes ischaemic during sitting. This finding supports the theory that not only is the skin involved in early development of pressure ulcers, but also the deeper tissues.