Lung recruitment and positive airway pressure before extubation does not improve oxygenation in the post-anaesthesia care unit: a randomized clinical trial

Abstract

Background: Atelectasis is known to develop during anaesthesia and after operation atelectasis leads to impaired oxygenation. Lung recruitment manoeuvres, positive end-expiratory pressure (PEEP), and continuous positive airway pressure (CPAP) have been proposed for reduction of atelectasis but their benefits have not been shown to persist after operation. We proposed that a combination of these techniques before extubation would improve oxygenation after operation.

Methods: Adult patients undergoing elective surgery requiring tracheal intubation and an arterial catheter were randomized to receive either: a lung recruitment manoeuvre of 40 cm H(2)O for 15 s, 30 min before the end of anaesthesia, followed by 10 cm H(2)O of PEEP and then 10 cm H(2)O of CPAP from return of spontaneous breathing until extubation; or no lung recruitment manoeuvre, <or=5 cm H(2)O PEEP, and no CPAP. Arterial blood gases were taken at randomization and 1 h after extubation. The primary endpoint of the study was the change in (a-a)DO(2) between these times. Statistical analysis of the two groups was done by chi(2) or unpaired t-test as appropriate.

Results: Twenty-two patients were recruited to each group. There were no significant differences between the groups before randomization. There was no significant difference in the change in (a-a)DO(2) between the groups (P=0.82).

Conclusions: Postoperative oxygenation is not improved by a combination of a lung recruitment manoeuvre and maintenance of a positive airway pressure until extubation. Further research is needed to elucidate the mechanism of atelectasis on emergence from anaesthesia and to evaluate more invasive clinical strategies such as post-extubation CPAP. Trial registered at URL http://www.controlled-trials.com Identification number: ISRCTN32464251 (http://www.controlled-trials.com/ISRCTN32464251).