Effects of High and Low Tidal Volumes on Arterial Oxygenation and Pulmonary Shunt During One-Lung Ventilation

The ideal tidal volume (TV) during one-lung ventilation (OLV) remains controversial. High tidal volumes may increase the incidence of postoperative lung injury after thoracic surgery. The investigators thus evaluated the influence of low (5 ml/kg) and high (10 ml/kg) tidal volumes on arterial oxygenation and Intrapulmonary shunt during OLV.

One hundred patients scheduled for thoracic surgery were enrolled. During OLV, patients were randomly assigned to 30 minutes of ventilation with high TV (10 ml/kg with zero end-expiratory pressure (ZEEP)) at a rate of 10 breaths/minute or low tidal volume (5 ml/kg with 5 cm H2O positive end-expiratory pressure (PEEP)) at a rate of 20 breaths/minute. During the subsequent 30 minutes, each patient received the alternative management. Minute volume was thus kept constant during each experimental condition. Arterial blood partial pressures, hemodynamic responses, and ventilatory parameters were recorded. Results are presented as means ± SDs; P < 0.05 was considered statistically significant.

Inclusion Criteria:

• ASA I-III patients scheduled for lung resection surgery.

Exclusion Criteria:

• severe cardiovascular disease
• severe alteration of the preoperative pulmonary function, with FEV1 70-120% predicted and FEV1/FVC ≥ 70% predicted considered to be normal.