Morphological characteristics of the human skin over posterior aspect of heel in the context of pressure ulcer development.

The posterior aspect of heel is known as a particularly vulnerable site for pressure ulcer development, however, it is not well understood why this is so. This study was undertaken to identify the morphological characteristics of the skin over posterior aspect of heel in the context of pressure ulcer development. Human skin tissues were obtained from four different sites of the body of 4 aged subjects postmortem: posterior aspect of heel, plantar aspect of heel, sacrum and centre of gluteus maximus. The skin samples were processed for the examination using light microscopy and scanning electron microscopy. The posterior aspect of heel was characterized by a thicker epidermis, denser distribution and larger diameter of capillaries in the papillary layer, 3-dimensional architecture of collagen fibre meshwork in the reticular layer and elliptic adipose tissues situated perpendicularly to the skin surface being surrounded by thick collagen and elastic fibre septa compared to the sacrum. Given our observations in the papillary layer of the posterior aspect of heel, we assume that the tissue of this area may be less tolerant to ischaemia since the tissue has high metabolic demand to provide oxygen and nutrients to the epidermis which protects underlying tissue from external force. In addition, elliptic configuration of adipose tissues in the posterior aspect of heel situated perpendicularly to the skin surface may result in deep lesion if the forces applied exceed the tolerable level since the forces will be concentrated within the elliptic compartments.

The effect of 10-degree leg elevation and 30-degree head elevation on body displacement and sacral interface pressures over a 2-hour period.

OBJECTIVE: This pilot study was undertaken to determine the effects of a 10-degree leg elevation for 30-degree head-up position on body displacement and sacral interface pressure for 2 hours. DESIGN: The study used a comparative, quasi-experimental design with repeated measures. SETTINGS AND SUBJECTS: A convenience sample of 10 healthy Japanese women was used. INSTRUMENTS: Body displacement was defined as the difference over time between the top edge of the mattress and subject's acromion and was measured every 10 minutes by tape measure (in centimeters). Sacral interface pressure was measured every 10 minutes using a pneumatic pressure sensor. METHODS: The subject was placed supine on a standard hospital bed. The head of the bed was then elevated to 30 degrees according to 2 protocols: (1) supine for 10 minutes without leg elevation alternating with 10 minutes of side-lying, or (2) supine for 10 minutes with leg elevation at 10 degrees alternating with side-lying every 10 minutes. Body displacement and mean sacral interface pressures in both protocols were compared by using repeated measures analysis of variance. RESULTS: The 30-degree head-up position with 10-degree leg elevation significantly reduced the amount of body displacement at the acromion compared with no elevation of the legs. There were no significant differences in mean sacral interface pressure in either position. CONCLUSION: Leg elevation at 10 degrees in the 30-degree head-up position was effective for reducing body displacement at the acromion; it was not effective for reducing sacral interface pressures.