THE ROLE OF BLOOD PERFUSION AND TISSUE OXYGENATION IN THE POSTISCHEMIC TRANSCUTANEOUS PO2 RESPONSE

The transcutaneous pO2 (TCpO2) response following release of tournique t cuff occlusion is expressed as oxygen reappearance time (ORT) and ox ygen recovery index (ORI). In the present study the effects of blood p erfusion and tissue oxygenation on ORT and ORI in healthy control subj ects and two patient groups with peripheral arterial insufficiency wer e assessed. In control subjects, ORT reflects diffusion time for O2 mo lecules from capillaries to the TCpO2 sensor. In patients with claudic ation, ORT was prolonged probably because of delayed postischemic repe rfusion and reduced tissue oxygenation. In patients with critical isch emia, prolonged ORT seems to be attributed more to reduced tissue oxyg enation than to delayed postischemic reperfusion. ORI in control subje cts and patients with claudication apparently depends more on capillar y PO2 than on magnitude and duration of the postischemic reperfusion. In patients with critical ischemia, ORI is more related to decreased 0 2 delivery subsequent to reduced or absent reactive hyperemia response . In addition, increased O2 extraction (''O2 steal'') and extensive co untercurrent O2 exchange during low flow states may reduce ORT and ORI in severely ischemic skin.