The Effect of Pressure and its Duration on Microcirculation and Healing of Skin Flaps¹: An Experimental Study in Rabbits

Abstract

An experimental model to study the effects of temperature, ischemia and pressure on microcirculation and wound healing in rabbit skin flaps is described. An island skin flap is inserted into a plexiglass chamber and a transverse segment at the middle of the flap is compressed with a plastic cuff. When the cuff is inflated the flap is divided into three segments, one used as a control, one being subjected to pressure and ischemia and one being ischemic only. The method has been tested on two groups of rabbits; in one group a pressure of 200 mmHg was applied for 2 hours while in the other the same pressure was applied for 4 hours. The temperature was kept constant at 36°C in both groups. The microcirculation was observed with a vital microscope in all segments during and after release of the pressure. After the acute experiments the flaps were resutured. Eight days later the influence of the pressure/ischemia was assessed using microangiography and by checking wound healing of the different flap segments. Two hours of compression resulted only in minor microvascular disturbances while after 4 hours the microcirculation of the compressed segment was clearly disturbed with capillary hypoperfusion. In the latter group of animals wound healing was impaired in the compressed segments, although microangiography in no case seemed abnormal. It is concluded that pressure as such aggravates an ischemic insult. 4 hours of pressure plus ischemia results in impaired wound healing despite an apparent restitution of an initially gravely affected microcirculation.