Effect of thoracic epidural anesthesia with different concentrations of ropivacaine on arterial oxygenation during one-lung ventilation

Abstract

BACKGROUND: Thoracic epidural anesthesia can contribute to facilitate the fast-track approach in lung surgery. However, data regarding the effects of thoracic epidural anesthesia on oxygenation during one-lung ventilation (OLV) are scarce and contradictory. Therefore, the authors conducted a prospective, randomized, double-blinded trial in patients undergoing lung surgery under spectral entropy-guided intravenous anesthesia to evaluate the effects of thoracic epidural anesthesia with different concentrations of ropivacaine on oxygenation, shunt fraction (Qs/Qt) during OLV, and maintenance doses of propofol. METHODS: One hundred twenty patients scheduled for lung surgery were randomly divided into four groups to epidurally receive saline (Group S), 0.25% (Group R0.25), 0.50% (Group R0.50), and 0.75% (Group R0.75) ropivacaine. Ropivacaine was administered intraoperatively (6-8 ml of first bolus + 5 ml/h infusion). Arterial oxygen tension (Pao2) and Qs/Qt were measured before, during, and after OLV. RESULTS: Pao2 was significantly lower in Group R0.75 compared with that in Group S and Group R0.25 10 min (170 ± 61 vs. 229 ± 68 mmHg, P = 0.01; 170 ± 61 vs. 223 ± 70 mmHg, P = 0.03) and 20 min after OLV (146 ± 52 vs. 199 ± 68 mmHg, P = 0.009; 146 ± 52 vs. 192 ± 67 mmHg, P = 0.03). During OLV, Qs/Qt was significantly higher in Group R0.75 compared with that in Group S and Group R0.25 (P < 0.05). Maintenance doses of propofol were significantly lower in Group R0.75. Vasopressor requirements were higher in Group R0.75. CONCLUSION: A decrease in oxygenation during OLV occurred only at the highest dose of epidural local anesthetic and not at lower doses. Higher doses of epidural medication required less propofol and more vasopressors. Copyright © 2010, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins.