Tissue Gas Tensions in the Calf Muscles of Patients with Lower Limb Arterial Ischaemia

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Abstract
O2 and CO2 tensions were measured in the gastrocnemius muscles of patients submitted for reconstructive arterial surgery due to obstructive arteriosclerosis (37) or abdominal aortic aneurysm (5). Four patients without signs of arterial ischaemia served as controls. Measurements were carried out by means of implanted silastic tonometers during breathing of air and 100% O2 and immediately after walking on a treadmill. Peripheral blood pressures in the ankles were recorded with a Doppler apparatus. Baseline tissue gas tensions showed no essential differences between the various groups of patients: intermittent claudication, pain at rest, praegangrene, abdominal aortic aneurysm and controls. In contrast, baseline ankle pressures correlated well with the severity of the disease. During breathing of oxygen, the smallest increases of muscle PO2 were observed in extremities with pain at rest or praegangrene and the highest responses were recorded in controls and aneurysm patients. Muscle PCO2 values showed no alterations during oxygen breathing. In physical exercise, muscle PO2 and PCO2 levels as well as ankle blood pressures remained unchanged in controls and patients with aneurysm but no claudication. However, in all groups with arterial ischaemia, the exercise test resulted in a profound fall of muscle PO2 and ankle blood pressure and an increase of muscle PCO2.