Mini-ventilation for improved oxygenation during lung resection surgery

Lung separation is frequently used during lung resection to facilitate surgery and hypoxaemia may occur because of increasing pulmonary shunt. In this study, we tested a method of mini-ventilation to the non-dependent lung and compared it to continuous positive airway pressure (CPAP) to improve oxygenation during lung resection. Thirty-eight adult patients participated in this randomised, single-blinded crossover study. Following lung separation, mini-ventilation and CPAP of 5 cmH2O were alternately applied every 15 minutes to the non-dependent lung. Mini-ventilation was performed by a portable time-cycled ventilator with a respiratory rate of 8 breaths/minute and a tidal volume of 0.1 to 0.15 l. Arterial blood gases, peak inspiratory pressure, the dynamic compliance in the dependent lung and the surgeon's evaluation of the surgical field exposure were recorded. The arterial oxygen partial pressure was significantly higher during mini-ventilation compared to CPAP (379 vs 228 mmHg). No difference was noted in the dependent lung peak inspiratory pressure or in the dynamic compliance. The surgical conditions were similar with both methods in 53% of the patients, while the surgeon preferred CPAP in 44% and mini-ventilation in 3%. In conclusion, mini-ventilation is a simple method which improves oxygenation during lung resection. However due to interference with surgical field exposure, it should be reserved for cases in which CPAP does not relieve hypoxaemia.