The relation between changes in capillary morphology induced by ischemia and the postischemic transcutaneous pO2...

The postischemic transcutaneous pO2 response following release of tourniquet cuff occlusion is expressed as oxygen reappearance time (ORT) and oxygen recovery index (ORI). ORT and ORI have been assessed in patients with peripheral arterial insufficiency. The purpose of the present investigation was to study the relationship between capillary structure of the skin and ORT and ORI in patients with critical ischemia. ORT and ORI were measured when breathing ambient air and supplemental oxygen. The capillary morphology was studied and classified according to severity (capillary stage A, B or C) in the same ischemic area of the skin using vital capillary microscopy (VCM). ORT and ORI were assessed against the capillary morphology stages. Based on both VCM and transcutaneous pO2 (TCpO2) findings, patients could be separated into two groups. Group I had normal or minor changes of capillary morphology and significantly better ORT and ORI values than group II. Group II had poor ORT and ORI values, impaired response to breathing of supplemental oxygen and pathological capillary morphology. The results from this study indicate that major changes in capillary structure observed in critical ischemic skin may hamper O2 diffusion and modify both ORT and ORI. The influence of structural capillary changes on the TCpO2 parameters probably increases with the extent of morphological deterioration.