Post-operative atelectasis : a randomised trial investigating a ventilatory strategy and low oxygen fraction during recovery

• BACKGROUND: Atelectasis is common during and after general anaesthesia. We hypothesized that a ventilation strategy with a combination of 1) continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and 2) a reduced end-expiratory oxygen concentration during recovery would reduce post-operative atelectasis.METHODS: Sixty patients were randomized into two groups. During anaesthesia induction, inspiratory oxygen fraction (FI O2 ) was 1.0, and depending on weight, CPAP 6, 7 or 8 cmH2 O was applied in both groups via facemask. During maintenance of anaesthesia, a laryngeal mask airway (LMA) was used, and PEEP was 6-8 cmH2 O in both groups. Before removal of the LMA, FI O2 was set to 0.3 in the intervention group and 1.0 in the control group. Atelectasis was studied by computed tomography (CT) approximately 14 min post-operatively.RESULTS: In one patient in the group given an FI O2 of 0.3 before removal of the LMA a CT scan could not be performed so the patient was excluded. The area of atelectasis was 5.5, 0-16.9 cm(2) (median and range), and 6.8, 0-27.5 cm(2) in the groups given FI O2 0.3 or FI O2 1.0 before removal of the LMA, a difference that was not statistically significant (P = 0.48). Post-hoc analysis showed dependence of atelectasis on smoking (despite all were clinically lung healthy) and American Society of Anesthesiologists class (P = 0.038 and 0.015, respectively).CONCLUSION: Inducing anaesthesia with CPAP/PEEP and FI O2 1.0 and deliberately reducing FI O2 during recovery before removal of the LMA did not reduce post-operative atelectasis compared with FI O2 1.0 before removal of the LMA.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Anestesi och intensivvård (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Anesthesiology and Intensive Care (hsv//eng)

Keyword

Clinical Physiology

Klinisk fysiologi

Publication and Content Type

ref (subject category)

art (subject category)