Impact of Low Tidal Volumes During One-Lung Ventilation. A Meta-Analysis of Randomized Controlled Trials

Objectives: The link between ventilation strategies and perioperative outcomes remains one of the fundamental paradigms of thoracic anaesthesia. During one-lung ventilation (OLV), one lung is excluded from gas exchange and ventilation is directed at the dependent lung. The authors hypothesised that the use of low tidal volumes (V_T) during OLV provides adequate gas exchange and improves postoperative outcome.

Design: Meta-analysis of randomized clinical trials.

Setting: Thoracic surgery.

Participants: Patients undergoing OLV.

Interventions: None.

Measurements and main results: The authors performed a meta-analysis of all randomized trials on low versus high V_T during OLV in patients undergoing thoracic surgery. Outcomes of the study were gas exchange and airway pressures during and after OLV, postoperative pulmonary complications (PPCs), and hospital stay (HLOS). Fourteen randomized trials were selected, but only a few of them contained one outcome of interest. Low V_T was associated with lower arterial oxygen tension, lower airway pressures, and higher arterial carbon dioxide tension at specific time points during OLV. Low V_T was associated with preserved gas exchange after OLV, lower incidence of pulmonary infiltrations, and acute respiratory distress syndrome. Incidences of PPCs and HLOS were similar.

Conclusions: The use of low V_T reduces airway pressure but worsens gas exchange during OLV. Preservation of postoperative oxygenation and reduction in infiltrates suggest a lung-protective modality with no demonstrable impact on PPCs and HLOS.