PACU Deep Sedation Associated With Respiratory Depression

Patients with deep sedation had higher rates of PACU to ICU admissions, spent more time in the PACU, and had a longer hospitalization.

Deep sedation during anesthesia recovery is associated with increased risk for opioid-induced respiratory depression (ORID) and naloxone rescue, according to results of a study published in Anesthesia & Analgesia.

Investigators examined the incidence and risk factors for postanesthesia deep sedation and the association between deep sedation during anesthesia recovery and increased risk for subsequent severe ORID. The retrospective analysis involved data from adult patients who underwent general anesthesia procedures at the Mayo Clinic in Rochester, Minnesota, between 2018 and 2020 (n=56,275, including 30,013 women; median age, 60.3; median procedure duration, 3.2 hours; median BMI, 28.5 kg/m2).

The investigators identified patients having deep level of sedation in the postanesthesia care unit (PACU) as those with a score of -4 or less on the Richmond Agitation-Sedation Scale (RASS) instrument. Overall, 2003 patients had deep sedation. The patients with deep sedation were younger, they had lower BMI, and had longer surgical procedures than patients without deep sedation (all P <.001).

Patients who experience deep sedation during anesthesia recovery have an increased risk of opioid-induced respiratory complications on general care wards.

Preliminary analyses indicated that the likelihood of deep sedation was higher in patients exposed to more soluble halogenated anesthetics. To estimate the odds of deep sedation, the investigators compared various anesthetic regimens to desflurane without propofol; anesthetic regimens thus associated with deep sedation included isoflurane with propofol (odds ratio [OR], 6.39), isoflurane without propofol OR, 4.21), sevoflurane with propofol (OR, 4.20), total intravenous anesthesia with propofol-remifentanil (OR, 2.98), desflurane with propofol (OR, 2.61), and sevoflurane without propofol (OR, 1.85).

Deep sedation was also associated with use of dexmedetomidine (OR, 2.47; P <.001), gabapentinoid (OR, 2.17; P <.001), and midazolam (OR, 1.34; P <.001) and an opioid dose of 30.1 mg intravenous morphine equivalents compared with 15.1-20.0 mg (OR, 1.28; P =.02).

In general, risk for deep sedation increased with the dose of propofol as well as with the dose of dexmedetomidine.

Compared with patients who did not have deep sedation, those with deep sedation had a higher rate of OIRD (0.6% vs 0.2%; P =.001), were more likely to receive naloxone (0.5% vs 0.1%; P =.001), had higher rates of PACU to ICU admissions (10.9% vs 6.3%; P <.001), spent more time in the PACU (median, 99 vs 61 min; P <.001), and had a longer hospitalization (median, 2 vs 1 day; P <.001).

In the final model, deep sedation was associated with risk for requiring naloxone (adjusted OR [aOR], 2.93; 95% CI, 1.42-6.03; P =.004) and for OIRD complications (aOR, 2.59; 95% CI, 1.32-5.10; P =.006).

This study is limited by its retrospective design and the inability to precisely determine equianesthetic concentrations, which hampered researchers’ ability to directly compare sedation effects.

The study authors concluded that “Likelihood of deep sedation after recovery increased with intraoperative use of halogenated agents with higher solubility and increased further when propofol was concomitantly used. Patients who experience deep sedation during anesthesia recovery have an increased risk of opioid-induced respiratory complications on general care wards.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Deljou A, Soleimani J, Martin DP, et al. Anesthetic management and deep sedation after emergence from general anesthesia: a retrospective cohort study. Anesth Analg. Published online April 3, 2023. doi:10.1213/ANE.0000000000006470