A Model for the Study of Wounds in Normal Elderly Adults and Patients with Peripheral Vascular Disease or Diabetes Mellitus

Abstract

The purpose of the study was to test the hypothesis that significant delays in cutaneous wound healing could be demonstrated using standard wounds and high quality histological methods in patients with severe peripheral vascular disease (PVD) and/or diabetes mellitus (DM) compared to healthy elderly controls. Additionally, we proposed that standard wounds on the arms of elderly controls would heal more rapidly than comparable wounds on the legs. In order to test these hypotheses we developed and characterized a partial thickness wound model which could be used safely in human subjects. The study population consisted of 25 elderly normal volunteers, 17 patients with PVD, and 24 patients with DM. Standard wounds were created using a Simplate II bleeding-time device. A total of 309 wounds ranging in age from 1 to 25 days were determined to be suitable for analysis. A global index of wound maturity was developed based on selected epidermal and dermal events of repair which could be scored histologically. The superficial component (within 0.1 mm of the epidermis) and deep components of dermal wounds were analyzed separately. Simultaneously created arm and leg wounds were studied in 15 of the elderly controls. Transcutaneous partial pressure of oxygen (TcPO2) measurements were used to estimate the severity of cutaneous ischemia. Data analysis revealed that the most striking differences observed were in dermal events of repair. Control wounds were more mature than dermal wounds from patients with PYD (P < 0.05). A significant reduction in the number of neutrophils and macrophages (P < 0.05) was demonstrated in 7-day-old wounds of patients with PVD compared to controls. Patients with DM showed a similar trend of reduced wound maturity but it did not reach statistical significance. Wounds created in skin with TcPO2 > 20 were more mature than wounds with TcPO2 ⩽ 20 (P < 0.05) and arm wounds were more mature than leg wounds (P < 0.01). The most significant difference noted in this wound model was that the superficial compartment of dermal wounds was significantly more mature than the deep compartment (P < 0.001). Good agreement was observed between two independent scorers of wound histology and no complications were noted in either patients or controls when using this human wound model. We conclude that the model described allows evaluation of both epidermal and dermal events of repair with relative safety even in patients with PVD and DM. Differences in wound maturity were delineated between clinical subsets of patients, between anatomical locations on the same patient, and also between different regions of the same wound.