Reducing tidal volume and increasing positive end-expiratory pressure with constant plateau pressure during one-lung ventilation: Effect on oxygenation

摘要

Background. It is no longer safe to use large tidal volumes (V T) (8 ml kg -1) for one-lung ventilation (OLV), and limiting plateau pressure should be a major objective. Due to the specificity of OLV, the use of positive end-expiratory pressure (PEEP) remains controversial. This study determined whether at the same low plateau pressure, reducing VT and increasing PEEP were not inferior to larger V T and lower PEEP ventilation in terms of oxygenation. Methods. This prospective, randomized, non-inferiority, cross-over trial included 88 patients undergoing open thoracotomy who received two successive ventilatory strategies in random order: V T (8 ml kg -1 of ideal body weight) with low PEEP (5 cm H 2O), or low VT (5 ml kg -1) with a high PEEP. Respiratory rate and PEEP were, respectively, adjusted to maintain constant ventilation and plateau pressure. The primary endpoint was the PaO 2/FIO 2 ratio under each ventilatory strategy. Results. The non-inferiority of low-V T ventilation could not be established. The mean adjusted PaO 2/FIO 2 ratio was lower overall during low-V T ventilation, and differences between the two ventilatory modes varied significantly according to baseline (T0) PaO 2/FIO 2. Decreased oxygenation during low V T was smaller when baseline values were low. Systolic arterial pressure was not lower during low-V T ventilation. Conclusion. During OLV, lowering V T and increasing PEEP, with the same low plateau pressure, reduced oxygenation compared with larger VT and lower PEEP. This strategy may reduce the risk of lung injury, but needs to be investigated further.