Interstitial Fluid Pressure in Free Vascularized Skin Flaps of the Rat Epigastrium

ABSTRACT The purpose of this study was to observe the magnitude and time course of changes in tissue edema in experimental free flaps. Thirty female Sprague Dawley rats underwent elevation and orthoptic transplantation of free epigastric skin flaps. Using a modified “wick in needle” technique, interstitial fluid pressure (IFP) was measured in the flaps at various times up to 2 weeks postoperatively. Increases in IFP to positive values were seen by 12 hours. IFP remained elevated for 3 to 5 days, after which they gradually returned to control values by 2 weeks. This is the first study to follow the time course and magnitude of changes in IFP and edema in free flaps. It is a useful animal model by which the hemodynamic effects of physical and pharmacological manipulation of flaps can be studied.