CPAP with air and oxygen to non-ventilated lung improves oxygenation during one lung anaesthesia.

Ten adult patients undergoing one lung ventilation for elective thoracotomy were selected. All these patients failed to maintain oxygen saturation (SaO2) > 90% despite administration of 100% oxygen to the non-ventilated lung (NVL). These patients were studied for the efficacy of continuous positive airway pressure (CPAP) of the NVL using air and oxygen combination (FiO20.5) employing a variable FiO2CPAP system. It was observed that application of CPAP (5-10 cm H2O) with a mixture of air and oxygen to the NVL increased the SaO2 > 90% in all these patients. This could be attributed to nitrogen in air which prevented absorption atelectasis in the NVL. This produced a better ventilation/perfusion ratio and hence the increased oxygen saturation.