Effect of tourniquet occlusion on peripheral blood pooling and ventricular function

: Rotating tourniquets are traditionally part of the treatment of acute pulmonary edema. However, their effectiveness has been questioned. A radioisotope technique was therefore used to evaluate directly the increments in the blood volume of the leg after venous occlusion using a pressure of 60 mmHg in 26 patients with left ventricular (LV) dysfunction following myocardial infarction. The increment in mean radionuclide count at serial 15-second intervals (reflecting the blood volume in the leg distal to the occlusion) increased significantly from the pre-occlusion value by 46 +/- 26% (p less than 0.0005). Thus satisfactory trapping of blood is achieved even in LV failure. However, mean ejection fraction decreased slightly but significantly from 0.23 +/- 0.10 to 0.21 +/- 0.10 (p less than 0.05), a decrease observed in 18 of the 26 patients. LV 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% (p less than 0.0005), while calculated peripheral resistance increased significantly. The present study fails to support the hypothesis that preload reduction by tourniquets improves LV function.