Measurement of interstitial tissue compliance in skin flaps.

Investigators speculate about the role of tissue pressure in skin flap necrosis as increased tissue pressure has been demonstrated to stop capillary blood flow in other conditions, both clinically and experimentally. Unfortunately, interstitial tissue pressure is difficult to measure by conventional methods. This article describes a new practical technique that measures interstitial tissue compliance as a correlate of interstitial tissue pressure. The instrument and method are described in detail. Tissue compliance was measured in normal dorsal skin and in modified McFarlane's skin flap in Sprague-Dawley rats. The skin flaps were measured at three sites (proximal, middle, and distal) at 2, 12, and 18 hours of age. The mean difference between the normal skin and all skin flaps was statistically significant. Within the skin flaps, there was a trend toward increased pressure with increasing age of the flap and distance from the flap base. These trends are statistically significant by the analysis of variance test. The data from this study support the validity of the technique and the hypothesis that increased interstitial tissue pressure is present in skin flaps.