Bonfils intubating fibrescope in normal paediatric airways.

a wide variation in the observed (A–a)DO2. However, these factors were not significantly different between the two groups and our primary outcome measure was the change in (A–a)DO2 between 1 h before extubation and 1 h after, so each patient acted as their own control such that only events occurring between the two measurements of (A–a)DO2 will have affected our results. All patients received a neuromuscular blocking agent, although we did not standardize which one as we are unaware of any evidence that specific drugs have different effects on postoperative lung function. Similarly, we did not document the use of reversal agents as their use was at the discretion of the anaesthetist with clinical responsibility for the patient, with whom responsibility for safe clinical care of the patient rested, including adequate breathing and airway reflexes at extubation. We do not agree that ventilation with 7–10 ml kg represents significant variance—the range provided allows account to be taken of the patient’s BMI as lean body mass was not formally calculated. Once again, we know of no evidence that tidal volume within this range has been shown to influence atelectasis formation. The decision to allow an FIO2 of 100% before extubation was taken as this represented the current safe practice in our institution. The use of 100% oxygen at critical periods for airway problems is regarded as mandatory by some commentators, and rather than being a confounding factor, our inclusion of 100% oxygen before extubation was quite deliberate as we hoped to demonstrate that this safety measure could be used without detriment. Sadly, we failed to demonstrate this was so, and therefore clinicians must continue to balance the benefit of 100% oxygen in prolonging the time to desaturation if post-extubation airway problems occur vs the risks of it exacerbating postoperative atelectasis. Despite Dr Cattano’s reservation about our methods, we cannot agree with his conclusion. Our interpretation is that each patient acted as his/her own control, we used a single standardized recruitment manoeuvre which is proven to work, followed by a level of positive airway pressure before extubation which is known to be effective at preventing atelectasis on induction and safe in clinical use, allowed the anaesthetists to use enough oxygen to maximize the safety of their patient, and studied a group of patients whose management involved appropriate clinical use of neuromuscular blocking agents. This strategy was indeed ineffective.