Effects Of Hypercarbia On Arterial Oxygenation During One-Lung Ventilation: Prospective Randomized Crossover Study

Background: This study aimed to evaluate the effects of hypercarbia on arterial oxygenation during one-lung ventilation (OLV).Methods: Fifty adult patients undergoing elective video-assisted thoracoscopic lobectomy or pneumonectomy were enrolled. Group I patients (n = 25) were first maintained at normocarbia (PaCO2: 38.42 mmHg) for 30 min and then at hypercarbia (45.50 mmHg). In Group II patients (n = 25), PaCO2 was maintained in the reverse order. Arterial oxygen partial pressure (PaO2), respiratory variables, hemodynamic variables, and hemoglobin concentration were compared during normocarbia and hypercarbia. Arterial O-2 content and O-2 delivery were calculated.Results: PaO2 values during normocarbia and hypercarbia were 66.5 +/- 10.6 and 79.7 +/- 17.3 mmHg, respectively (mean difference: 13.2 mmHg, 95% CI for difference of means: 17.0 to 9.3, P < 0.001). SaO(2) values during normocarbia and hypercarbia were 92.5 +/- 4.8% and 94.3 +/- 3.1% (P = 0.009), respectively. Static compliance of the lung (33.0 +/- 5.4 vs. 30.4 +/- 5.3 ml/cmH(2)O, P < 0.001), arterial O-2 content (15.4 +/- 1.4 vs. 14.9 +/- 1.5 ml/dl, P < 0.001) and O-2 delivery (69.9 +/- 18.4 vs. 65.1 +/- 18.1 ml/min, P < 0.001) were significantly higher during hypercarbia than during normocarbia.Conclusions: Hypercarbia increases PaO2 and O-2 carrying capacity and improves pulmonary mechanics during OLV, suggesting that it may help manage oxygenation during OLV. Therefore, permissive hypercarbia may be a simple and valuable modality to manage arterial oxygenation during OLV.