Role of continuous positive airway pressure to the non-ventilated lung during one-lung ventilation with low tidal volumes

INTRODUCTION In multiple study populations large tidal volumes (8 - 12 ml/kg) have deleterious effects on lung function in multiple study populations. The accepted approach to hypoxemia during one-lung ventilation is the application of continuous positive airway pressure to the non-ventilated lung first, followed by application of positive end-expiratory pressure to the ventilated lung. To our knowledge the effectiveness of positive end-expiratory pressure or continuous positive airway pressure on maintaining PaO(2) with one-lung ventilation was not studied with smaller tidal volume (6ml/kg) ventilation. Our objective was to compare continuous positive airway pressure of 5 cm H(2)O or positive end-expiratory pressure of 5 cm H(2)O during small tidal volume one-lung ventilation. METHODS Thirty patients undergoing elective, open thoracotomy with one-lung ventilation were randomized to continuous positive airway pressure or positive end-expiratory pressure and then crossed over to the other modality.  RESULTS There was a statistically significant higher PaO(2) (141±81.6 vs 112±48.7, p = 0.047) with continuous positive airway pressure than positive end-expiratory pressure while on one-lung ventilation. Two patients desaturated requiring 100% O(2) with both positive end-expiratory pressure and continuous positive airway pressure. On two occasions the surgeon requested the continuous positive airway pressure be discontinued due to lung inflation. CONCLUSION The use of continuous positive airway pressure of 5 cm H(2)O to the non-ventilated lung while using small tidal volumes for one-lung ventilation improved PaO(2) when compared with positive end-expiratory pressure of 5 cm H(2)O to the ventilated lung.