LAUSR

We thank McEvoy and Amare for bringing this Cochrane review [1], that was published 6 months following acceptance of our editorial [2], to our attention [3]. Guay et al. found moderate quality evidence that high intraoperative tidal volumes (> 10 ml.kg ) are associated with postoperative pulmonary complications. This new evidence supports contemporary clinical practice, as it is widely recognised that both high tidal volumes (volutrauma) and driving pressures (barotrauma) cause harm, even in patients with healthy lungs undergoing routine surgery [4–7]. Our conclusions nevertheless remain the same. The suggestion that postoperative pulmonary complications can be prevented through selecting one mode of mechanical ventilation over another – although it may seem neat, simple and plausible – is probably incorrect. Even with the best intentions, one cannot entirely discount the possibility of unmeasured confounders leading to a non-causal association in large retrospective database studies [8].