Opioid Dose Variation in Cardiac Surgery: A Multicenter Study of Practice.

Background: Although high-opioid anesthesia was long the standard for cardiac surgery, some anesthesiologists now favor multimodal analgesia and low-opioid anesthetic techniques. The typical cardiac surgery opioid dose is unclear, and the degree to which patients, anesthesiologists, and institutions influence this opioid dose is unknown.

Methods: We reviewed data from nonemergency adult cardiac surgeries requiring cardiopulmonary bypass performed at 30 academic and community hospitals within the Multicenter Perioperative Outcomes Group registry from 2014 through 2021. Intraoperative opioid administration was measured in fentanyl equivalents. We used hierarchical linear modeling to attribute opioid dose variation to the institution where each surgery took place, the primary attending anesthesiologist, and the specifics of the surgical patient and case.

Results: Across 30 hospitals, 794 anesthesiologists, and 59,463 cardiac cases, patients received a mean of 1139 (95% confidence interval [CI], 1132-1146) fentanyl mcg equivalents of opioid, and doses varied widely (standard deviation [SD], 872 µg). The most frequently used opioids were fentanyl (86% of cases), sufentanil (16% of cases), hydromorphone (12% of cases), and morphine (3% of cases). 0.6% of cases were opioid-free. 60% of dose variation was explainable by institution and anesthesiologist. The median difference in opioid dose between 2 randomly selected anesthesiologists across all institutions was 600 µg of fentanyl (interquartile range [IQR], 283-1023 µg). An anesthesiologist's intraoperative opioid dose was strongly correlated with their frequency of using a sufentanil infusion (r = 0.81), but largely uncorrelated with their use of nonopioid analgesic techniques (|r| < 0.3).

Conclusions: High-dose opioids predominate in cardiac surgery, with substantial dose variation from case to case. Much of this variation is attributable to practice variability rather than patient or surgical differences. This suggests an opportunity to optimize opioid use in cardiac surgery.