Definition criteria for OIRD
respiratory opioid-related adverse event [, apnea
An OIRD episode was pre-defined as: respiratory rate ≤ 5 breaths/min (bpm), oxygen saturation ≤ 85%, or end-tidal carbon dioxide ≤ 15 or ≥ 60 mm Hg for ≥ 3 min; apnea episode lasting > 30 s; or any respiratory opioid-related adverse event [