CRITICAL THRESHOLDS FOR PRESSURE ULCER FORMATION IN A PORCINE MODEL

The objective of the present study was to define critical thresholds o f applied pressure, applied temperature and duration of application ne cessary for the formation of pressure ulcers or cutaneous burns. A por cine wound model previously developed by the authors was used. Briefly , twelve metal discs (57 mm diameter) were simultaneously applied on t he dorsal aspect of each swine while modulating applied pressure, temp erature and duration of application at each site. In all, 70 different experiments were conducted using different magnitudes of the aforemen tioned parameters. Histological assessment provided the basis for the determination of damage at different tissue levels. The severity of re sultant tissue injuries correlated well with increases in applied temp erature, applied pressure and/or duration of application. Three-dimens ional plots of the pressure, temperature and duration data were used t o visualize the critical thresholds for damage within each tissue laye r. An algebraic fit to the experimental data provided equations which may be used to predict wound formation for any combination of these pa rameters. With the knowledge that porcine models have historically cor related well with humans due to physiological similarities(1,2) and ca reful consideration of any confounding variables encountered in clinic al practice (pear nutrition, impaired circulation, etc.), these critic al thresholds and the resultant models should have widespread utility for healthcare providers (e.g., in the formulation of patient turning schedules), engineers concerned with new product design and developmen t (e.g., for support surfaces that could reduce the incidence of press ure ulcer formation) and basic scientists.