Reduction in postoperative atelectasis by continuous positive airway pressure and low oxygen concentration after endotracheal extubation
(English)Manuscript (preprint) (Other academic)
Background. Atelectasis is common during and after general anaesthesia. We hypothesized that a ventilation strategy using a combination of 1) continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and 2) a reduced end-expiratory oxygen fraction (FETO2) before commencing mask ventilation with CPAP after extubation would reduce the area of postoperative atelectasis.
Methods. Thirty patients were randomized into three groups. During induction and emergence, inspiratory oxygen fractions (FIO2) were 1.0 in the control group and 1.0 or 0.8 in the intervention groups. No CPAP/PEEP was used in the control group, whereas CPAP/PEEP of 6 cmH2O was used in the intervention groups. After extubation, FIO2 was set to 0.30 in the intervention groups and CPAP was applied via a facemask, aiming at a FETO2 < 0.30. Atelectasis was studied by computed tomography 25 min postoperatively.
Results. The median area of atelectasis was 5.2 cm2 (range 1.6–12.2 cm2) and 8.5 cm2 (3–23.1 cm2) in the groups given FIO2 1.0 with or without CPAP/PEEP, respectively. In the group given FIO2 0.8, in which 7 patients were ex- or current smokers, the median area of atelectasis was 8.2 cm2 (1.8–14.7 cm2). After correction for body mass index and age, the difference between the two groups given FIO2 1.0 was statistically significant (P = 0.016).
Conclusion. Compared with conventional ventilation, this ventilation strategy reduced the area of postoperative atelectasis in one of the intervention groups but not in the other group, which included a higher proportion of smokers.
Atelectasis, CPAP, PEEP, Oxygen fraction, Ventilation, General Anaesthesia, Smoking
Anesthesiology and Intensive Care
Research subject Anaesthesiology
IdentifiersURN: urn:nbn:se:uu:diva-209961OAI: oai:DiVA.org:uu-209961DiVA: diva2:660141