Effects of hypercarbia on arterial oxygenation during one-lung ventilation: prospective randomized crossover study.

Lee, Junho; Kim, Yesull; Mun, Juhan; Lee, Joseph; Ko, Seonghoon

Background The present study was designed 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 1 patients (n = 25) were first maintained in normocarbia (PaCO2: 38 - 42 mmHg) for 30 min and then in hypercarbia (45 - 50 mmHg). In group 2 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 O2 content and O2 delivery were calculated. Results PaO2 values during normocarbia and hypercarbia were 66.5 ± 10.6 mmHg 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). SaO2 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/cmH2O, P < 0.001), arterial O2 content (15.4 ± 1.4 vs. 14.9 ± 1.5 mL/dL, P < 0.001) and O2 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 O2 carrying capacity and improves pulmonary mechanics during OLV, suggesting that it may be helpful to manage oxygenation during OLV. Therefore, permissive hypercarbia may be a simple and valuable modality to manage arterial oxygenation during OLV.