Effects of malnutrition on development of experimental pressure sores

Using food-deprived rabbits we investigated the effects of nutritional deficiency on the development of pressure sores. The body weight of these animals was decreased significantly from normal. Organ weights of liver, heart, spleen, kidney, and testis were significantly decreased from normal as well. Protein deficiency in these animals was indicated by serum tests, as well as by histologic features of liver and testis and ultrastructural findings on fibroblasts. We produced lesions in malnourished as well as normal rabbits by exposing their skin to a balloon-produced compressive force of 120 +/- 10 mmHg for 4 hours. Biopsies were taken 1, 2, and 3 days after the pressure application. Histologic findings at each time were as follows: At day one, the degree of ischemic skin destruction in the malnourished animals was more severe than that in the normal ones, and thrombi were occasionally seen in the malnourished cases. At day two, proliferation of fibroblasts and macrophage infiltration were evidenced in the normal animals, whereas signs of collagen fiber degeneration as well as microthrombi were seen in the malnourished ones. At three days, epidermal cells covered the lesions in the case of normal animals; however, massive necrosis of the epidermis was still recognized in the malnourished rabbits. Thus, the healing process of pressure sores was strongly suppressed in the malnourished animals. This suppression was attributed to the reduction in fibroblast proliferation, capillary formation, macrophage infiltration, and also to the low level of epidermal cell proliferation.