Effects of low-dose intraoperative fentanyl on postoperative respiratory complication rate: a pre-specified, retrospective analysis.

BACKGROUND: Fentanyl is one of the most frequently administered intraoperative drugs and may increase the risk of postoperative respiratory complications (PRCs). METHODS: We performed a pre-specified analysis of 145 735 adult non-cardiac surgical cases under general anaesthesia. Using multivariable logistic regression, we evaluated the association of intraoperative fentanyl dose and PRCs within 3 days after surgery (defined as reintubation, respiratory failure, pneumonia, pulmonary oedema, or atelectasis). We examined effect modification by patient characteristics, surgical site, and anaesthetics used. RESULTS: PRCs within 3 days after surgery occurred in 18 839 (12.9%) patients. In comparison with high intraoperative fentanyl doses [median: 3.85; inter-quartile range (IQR): 3.42-4.50 µg kg-1, quartile 4 (Q4)], low intraoperative fentanyl dose [median: 0.80, IQR: 0.00-1.14 µg kg-1, quartile 1 (Q1)] was significantly associated with lower odds of PRCs [Q1 vs Q4: 10.9% vs 16.2%; adjusted odds ratio (aOR) 0.79; 95% confidence intervals (CI) 0.75-0.84; P<0.001; adjusted absolute risk difference (aARD) -1.7%]. This effect was augmented by thoracic surgery (P for interaction <0.001; aARD -6.2%), high doses of inhalation anaesthetics (P for interaction=0.016; aARD -2.2%) and neuromuscular blocking agents (NMBAs) (P for interaction=0.001; aARD -3.4%). Exploratory analysis demonstrated that compared with no fentanyl, low-dose fentanyl was associated with lower rates of PRCs (decile 2 vs decile 1: aOR 0.82, CI 0.75-0.89, P<0.001). CONCLUSIONS: Intraoperative low-dose fentanyl (about 60-120 µg for a 70 kg patient) was associated with lower risk of postoperative respiratory complications compared with both no fentanyl and high-dose fentanyl. Beneficial effects of low-dose fentanyl were magnified in specific patient subgroups. CLINICAL TRIAL REGISTRATION: NCT03198208.

The association of early postoperative desaturation in the operating theatre with hospital discharge to a skilled nursing or long-term care facility.

It is unclear which criteria should be used to define readiness for tracheal extubation in the operating theatre. We studied the effects of desaturation in the operating theatre immediately after tracheal extubation on long-term outcomes. Performing a pre-specified, retrospective analysis of 71,025 cases involving previously independent adults undergoing non-cardiac surgery, we evaluated the association between desaturation events (oxygen saturation < 90%) within 10 min of tracheal extubation and adverse discharge (to a skilled nursing facility or long-term care facility). A total of 404 (12.3%) cases with, and 5035 (7.4%) cases without, early postoperative desaturation had an adverse discharge. Early postoperative desaturation was associated with higher odds of being discharged to a nursing facility (adjusted odds ratio 1.36 (95%CI 1.20-1.54); p < 0.001). Increased duration of desaturation augmented the effect (p for trend < 0.001). Desaturation was associated with a higher risk of respiratory, renal and cardiovascular complications as well as increased duration of hospital stay, postoperative intensive care unit admission frequency and cost. Several modifiable factors were associated with desaturation including: high intra-operative long-acting opioid administration; high neostigmine dose; high intra-operative inspired oxygen concentration; and low oxygen delivery immediately before tracheal extubation. There was substantial provider variability between anaesthetists in the incidence of postoperative desaturation unexplained by patient- and procedure-related factors. Early postoperative desaturation is a potentially preventable complication associated with a higher risk of adverse discharge disposition. Anaesthetists may consider developing guidelines to define tracheal extubation readiness that contain postoperative desaturation as an adverse outcome after tracheal extubation.