The effect of exposure to intra-operative nasal positive airway pressure in high-risk obstructive sleep apnoea patients after elective total knee arthroplasty: a single-centre retrospective cohort study.

Patients with obstructive sleep apnoea face increased risk of peri-operative pulmonary complications and prolonged hospital stay. While post-operative continuous positive airway pressure use has proven to be beneficial, less is known about its peri-operative benefits, particularly in procedural settings where deep sedation without an advanced airway is used, including total knee arthroplasty. This retrospective cohort study compared postoperative respiratory outcomes of patients with diagnosed or suspected obstructive sleep apnoea who received intra-operative nasal continuous positive airway pressure vs. standard oxygen mask during total knee arthroplasty under spinal anaesthesia with deep sedation between January 2020 and December 2023. The primary outcome comprised the incidence of oxygen desaturation in the post-anaesthesia care unit. Exploratory outcomes included failure rate of breathing air trial, time to care completion and respiratory support at post-anaesthesia care unit discharge, postoperative pulmonary complication and 2-week unanticipated hospital re-admission rates. Post hoc multivariate regression and 1:1 propensity score matching analyses were performed; p < 0.05 was considered statistically significant. Among 1516 patients, 386 (25%) patients received nasal continuous positive airway pressure, while 1130 (75%) patients received simple oxygen mask intra-operatively. The nasal continuous positive airway pressure group had a higher body mass index (36.8 versus 36.1, p = 0.04) and a higher rate of pre-existing obstructive sleep apnoea diagnosis (66.8% versus 39.7%, p < 0.001). After propensity score matching, post-anaesthesia care unit oxygen desaturation (4.5% nasal continuous positive airway pressure, 4.2% simple oxygen mask, p = 0.86) and breathing air trial failure rates remained similar. Median (IQR) time to care completion was shorter in the nasal continuous positive airway pressure group [59 (48, 60) versus 60 (47, 66) min, p = 0.005]. Two-week unanticipated hospital re-admission rate was less in the nasal continuous positive airway pressure group (1.3% versus 4.0%, p = 0.023). Intra-operative nasal continuous positive airway pressure was not associated with improved postoperative pulmonary outcomes compared to simple oxygen mask use among a cohort of high-risk patients with obstructive sleep apnoea who underwent total knee arthroplasty under spinal anaesthesia and deep sedation. Randomised trials are needed to comprehensively understand the peri-operative benefits of intra-operative nasal continuous positive airway pressure in the setting of spinal anaesthesia with deep sedation.