Association of preoperative nocturnal hypoxaemia nadir and fentanyl ventilatory sensitivity in children with obstructive sleep apnoea undergoing general anaesthesia: multicentre clinical cohort study.

Background: Obstructive sleep apnoea (OSA) has been thought to increase the risk of respiratory depression from opioids. The primary aim of this study was to assess whether preoperative hypoxaemia by sleep study pulse oximetry imparts greater opioid sensitivity.

Methods: A multicentre observational cohort study with in-cohort dose randomisation was performed in children 2-8 yr of age with OSA undergoing adenotonsillectomy. Ninety patients were assigned to one of two Spo cohorts by preoperative sleep study Spo nadir of < or ≥85% to receive fentanyl 1.0 or 1.5 μg kg (maximum 25 μg) after sevoflurane induction. The primary outcome was the extent of opioid-induced central ventilatory depression over time by Spo status as defined by the differences in tidal volume, respiratory rate, end-tidal CO, and minute ventilation for 10 min after fentanyl administration when compared with pre-fentanyl baseline values. Secondary outcomes included assessment of body mass index, fentanyl dose, sex, age, and race on opioid-induced central ventilatory depression. Intention-to-treat and per protocol analysis were performed.

Results: Ninety patients underwent in-cohort randomisation (Spo <85%; n=47 and Spo ≥85%; n=43). Final per protocol analysis included 73 subjects, fentanyl 1.0 μg kg (Spo <85%; n=36 and Spo ≥85%; n=37) and 15 subjects, fentanyl 1.5 μg kg (Spo <85%; n=9 and Spo ≥85%; n=6). Multivariable mixed effect model for the primary outcomes (tidal volume, respiratory rate, end-tidal CO, and minute ventilation) from baseline to 10 min (as % change per minute) were not different between groups by Spo nadir (< or ≥85%) and fentanyl dose for the intention-to-treat and per protocol analyses.

Conclusions: Single-dose fentanyl ventilatory effects in paediatric OSA patients during sevoflurane anaesthesia were not associated with preoperative nocturnal hypoxaemia nadir. Fentanyl dosing in children with OSA should not be determined by sleep study Spo nadir.

Clinical Trial Registration: NCT05051189.