The effect of venous occlusion with tourniquets on peripheral blood pooling and ventricular function.

Rotating tourniquets were once part of the traditional treatment of acute pulmonary edema. Their effectiveness has been questioned and vasodilator therapy has replaced them, but early favorable results suggested that they may play a beneficial role. A radioisotope technique was used to evaluate blood volume increments in the leg after venous occlusion at 60 mm Hg in 26 patients with left ventricular dysfunction following myocardial infarction. Mean radionuclide counts (reflecting the blood volume distal to the occlusion) increased from the preocclusion value. Thus, satisfactory trapping of blood is achieved. However, mean left ventricular ejection fraction (EF) decreased slightly but significantly and this decrease in EF was observed in 18 of 26 patients. Left ventricular end-diastolic and end-systolic volume equivalents tended to decrease slightly but not in all patients. Mean stroke volume and cardiac output equivalents were reduced by 14 percent while peripheral resistance increased significantly. The present study thus fails to support the hypothesis that preload reduction by tourniquets improves left ventricular function; the exact opposite effect may occur because of increased afterload.