PREVENTION OF PRESSURE ULCERS BY FOCAL COOLING - HISTOLOGICAL ASSESSMENT IN A PORCINE MODEL

Using an established porcine model for the formation of pressure ulcer s, the present study was performed to determine: 1) the effects of the duration of applied pressure and applied temperature on wound formati on and 2) the threshold temperature below which focalized cooling woul d minimize the potential for wound formation. In the first set of expe riments, twelve metal disks (57 mm in diameter) were applied on the do rsal aspect of the swine at an equal pressure of 100 mm Hg for a 2-, 5 -, or 10-hour period while servo-controlling the disk temperatures at either 25, 35, 40, or 45 degrees C (three disks at each temperature). In the second set of experiments, twelve metal disks were applied at 1 00 mm Hg for ten hours at temperatures 25, 27.5, 30, and 32.5 degrees C. The severity of resultant tissue injuries, determined histologicall y, correlated with increases in applied temperature and duration. Mini mal damage was observed in both the superficial and deep tissues under lying the sites of the 25 degrees C applicator disks even after the te n-hour application period. It was concluded that cutaneous and subderm al tissue damage can be reduced by focal cooling with temperatures of 30 degrees C or less.