One-lung versus two-lung ventilation in the closed-chest anesthetized dog:A comparison of cardiopulmonary parameters

Objective-To evaluate cardiopulmonary effects of one-lung ventilation (OLV) versus two-lung ventilation (TLV) in closed-chest anesthetized dogs. Study Design-Controlled, randomized experiment. Animals-Fourteen, 2- to 7-year-old adult dogs, weighing 23 +/- 6 kg. Methods-The dogs were anesthetized with acepromazine, morphine, thiopental, and halothane in oxygen, ventilated, and paralyzed with vecuronium. Tidal volume was 10 mL/kg. Respiratory rate was set to maintain end-tidal CO2 (ET CO2) at 40 +/- 2 mm Hg before instrumentation then not changed. The left br onchus of 7 dogs was obstructed with a Univent bronchial blocker (Fuji Syst ems Corp, Tokyo, Japan). Blood gas analysis and hemodynamic measurements we re taken at predetermined intervals for 1 hour in the TLV group and at base line and following bronchial obstruction in the OLV group. Results-Shunt fraction was not significantly different between groups, but in OLV shunt increased from baseline at 5 minutes. Arterial oxygen (Pao(2)) decreased after baseline in OLV compared with TLV. Arterial carbon dioxide (Paco(2)) increased with OLV and decreased with TLV. In OLV, systemic vasc ular resistance was Variable and decreased compared with TLV. Cardiac index increased over time in both groups but was not affected by treatment. Hear t rate, mean arterial pressure, and diastolic arterial pressure increased w ith OLV compared with TLV but did not change over time. Conclusion-This study shows that OLV statistically decreases oxygen tension and transiently increases shunt fraction, but with 100% O-2 it appears to be a feasible procedure with minimal cardiopulmonary side effects in health y dogs. Clinical Relevance-OLV is a feasible procedure in anesthetized dogs to bett er facilitate thoracic procedures such as bronchopleural fistula repair and thoracoscopy. (C) Copyright 2000 by The American College of Veterinary Sur geons.