We evaluated the effects of halothane (0.4-0.6%), isoflurane (0.5-1.0%) and propofol (10-8-6 mgÐ1hÐ1) anesthesia on the venous admixture during one-lung ventilation (OLV) in 47 patients. Measurements were performed during the following stages: I: 10 min after induction, in the supine position; II: 10 min following a shift to the left lateral position; III: 10 minutes of left-lung ventilation; IV: 20 minutes of left-lung ventilation; V: 10 min of both lungs ventilation in the lateral position. The venous admixture increased significantly during OLV in the III and IV stages to 27-47% and decreased during the V stage to values observed during stages, I and II (17-21%). The venous admixture increase during OLV reflected the magnitude of hypoxic pulmonary vasoconstriction (HPV) in the non-ventilated lung. HPV during OLV and halothane anesthesia was less attenuated and the venous admixture was significantly lower than during OLV and isoflurane or propofol anesthesia.

Keywords: Anesthetics, hypoxic pulmonary vasoconstriction, venous admixture, one-lung ventilation