Intraoperative recording of tissue gas tensions in calf muscles of patients with peripheral arterial disease

Abstract

O 2 and CO 2 tensions were determined in the gastrocnemius muscles of patients undergoing reconstructive arterial surgery due to obstructive arteriosclerosis (32 patients) or abdominal aortic aneurysm (5 patients). Four patients undergoing some other major operation in the abdominal region and showing no signs of arterial ischemia served as controls. Measurements of tissue gas tensions were carried out by means of implanted Silastic tonometers. Immediately after the beginning of operation basal tissue gas tensions showed no essential differences between the various groups of patients: those with (a) intermittent claudication, (b) rest pain, (c) ischemic gangrene, (d) abdominal aortic aneurysm, and (e) controls. Closure of the aorta resulted in a profound fall of muscle PO 2 and elevation of muscle PCO 2. During reactive hyperemia after the release of circulation the tissue PO 2 levels increased sharply and the tissue PCO 2 declined. These changes were clearest in aneurysm patients and smallest in patients with ischemic gangrene. Before closure of wounds local intra-arterial injection of papaverin increased the tissue PO 2 and decreased the PCO 2 for a few minutes. The largest changes were observed in control and aneurysm patients and the smallest in patients with ischemic gangrene. At the end of operations the muscle tissue gas tensions varied according to the severity of the disease, the lowest O 2 tensions and the highest CO 2 levels being observed in the most ischemic extremities. In advanced ischemia the occlusive lesions were frequently multi-segmental in nature and therefore, arterial bypass at one level was not sufficient to normalize tissue oxygenation completely.