Skin blood flow in relation to external pressure and temperature in the supine position on a standard hospital mattress.

The purpose of this investigation was to study the relationship between skin blood flow, external pressure and temperature in the skin over bony prominences and muscle padded areas, when healthy individuals and patients with hemiplegia were lying in the supine position on a standard hospital mattress. The pressure values under the gluteus maximus muscle and the sacrum increased significantly in the supine position with bent knees. The heels resting on the mattress gave very high pressure values. Some patients had no observable skin blood flow in the skin over the sacrum and the gluteus maximus muscle. In many individuals there was no observable blood flow in the skin over the heel among both healthy individuals and patients, which was confirmed by very high post-ischemic reactive hyperaemia. There is also a heat accumulation when lying on the mattress which increases the requirement for skin blood flow.