Impact of Lower Tidal Volumes During One-Lung Ventilation: A 2022 Update of the Meta-analysis of Randomized Controlled Trials.

OBJECTIVES

To clarify the influence of lower tidal volume (4-7 mL/kg) compared with higher tidal volume (8-15 mL/kg) during one-lung ventilation (OLV) on gas exchange and postoperative clinical outcome.

DESIGN

Meta-analysis of randomized trials.

SETTING

Thoracic surgery.

PARTICIPANTS

Patients receiving OLV.

INTERVENTIONS

Lower tidal volume during OLV.

MEASUREMENTS AND MAIN RESULTS

Primary outcome was PaOto-the oxygen fraction (PaO/FIO) ratio at the end of the surgery, after the reinstitution of two-lung ventilation. Secondary endpoints included perioperative changes in PaO/FIO ratio and carbon dioxide (PaCO) tension, airway pressure, the incidence of postoperative pulmonary complications, arrhythmia, and length of hospital stay. Seventeen randomized controlled trials (1,463 patients) were selected. Overall analysis showed that the use of low tidal volume during OLV was associated with a significantly higher PaO/FIO ratio 15 minutes after the start of OLV and at the end of surgery (mean difference 33.7 mmHg [p = 0.02] and mean difference 18.59 mmHg [p < 0.001], respectively). The low tidal volume also was associated with higher PaCO values 15 minutes and 60 minutes after the start of OLV and with lower airway pressure, which was maintained during two-lung ventilation after surgery. Moreover, the application of lower tidal volume was associated with fewer postoperative pulmonary complications (odds ratio 0.50; p < 0.001) and arrhythmias (odds ratio 0.58; p = 0.009), with no difference in length of hospital stay.

CONCLUSIONS

The use of lower tidal volume, a component of protective OLV, increases the PaO/FIO ratio, reduces the incidence of postoperative pulmonary complications, and should be considered strongly in daily practice.