Abstract
Hemodynamic variables, heart rate and mixed venous oximetry, end-tidal CO2 and nitrogen tensions, and transesophageal echocardiograms were recorded after induction of anesthesia (baseline), after tourniquet inflation, after cementing, and for 15 min after tourniquet deflation. Echocardiograms revealed either showers of miliary echogenic material (Group S, 9 patients), or large echogenic masses superimposed on the showers (Group MS, 26 patients). In Group MS only, pulmonary vascular resistance index increased above baseline (205±6 [sem] dyne·s·cm−2) beginning 5 min after tourniquet deflation (maximum 328±29, P < 0.05). Mean pulmonary arterial pressure increased above baseline (20±1.0 mm Hg) for both Groups S and MS beginning 3 min after tourniquet deflation (27±1.0, P < 0.05). Cardiac index did not change. Five of 10 patients demonstrated fresh thrombus from the catheter in the operative limb. Echogenic emboli occurred in all patients upon tourniquet deflation during knee arthroplasty. Pulmonary vascular resistance index increased only in patients with large echogenic material. Our data suggest that these emboli represent fresh thrombus formation during tourniquet inflation. Heparin administration prior to tourniquet inflation may diminish embolic showers. Presented in part at the Annual Meetings of the Association of University Anesthesiologists, Winston-Salem, NC, April 1993, and the American Society of Anesthesiologists, Washington, DC, October 1993. Address correspondence and reprint requests to Jonathan L Parmet, MD, Hahnemann University, Broad and Vine, Philadelphia, PA 19102–1192. Accepted for publication July 6, 1994. © 1994 International Anesthesia Research Society...