Temperature modulation of pressure ulcer formation: Using a swine model

Developing reliable animal models as a means to study the etiology, prevention, and/or treatment of pressure ulcers is not a simple task. Numerous considerations need to be evaluated for appropriateness, such as similarity of the cutaneous layers to those of humans, reproducibility of injuries, the effects of administered anesthetic or analgesic agents, the locations of the created lesions, the typical rates of healing (controls), and/or the overall health status of the animals. The author's laboratory previously developed one such model: a porcine model to aid in investigations of pressure ulcer formation, healing, and prevention. The author and colleagues specifically studied the relationships between temperature, pressure, and time in the formation of cutaneous and/or deep tissue injuries. To do so, an apparatus and procedure were created to apply 12 metal discs (each with a diameter of 51 mm) to the dorsal aspect of the swine. At equal pressures ranging between 10-150mmHg, four discs were applied for 1 to 10 hour periods, while their temperatures were servo-controlled between 25-45°C. The severity of resultant tissue injuries correlated with increases in applied parameters. Briefly, no damage was observed in the superficial or deep tissues underlying the sites of the 25°C pressure discs even with 10 hours of applied pressure. Only deep tissue damage resulted from the application of the 35°C discs for five hours, and the application of higher temperatures for shorter durations caused both cutaneous and subdermal damage. In addition, degrees of healing could be easily monitored in such animals for months and was typically uniform relative to the degree of induced damage. This animal model of temperature-modulated pressure ulcers has the potential for significant use in all major areas of this field, i.e., wound formation, healing, and prevention. The use of this approach on transgenic individuals or those with induced disease would also be of great interest.