Predictors of Postoperative Morphine Milligram Equivalents in Cardiac Surgery

Given both the short- and long-term deleterious effects of opioids, there has been an increased focused on reducing the use of postoperative opioid analgesia. As patients undergoing cardiac surgery often require high levels opioids postoperatively, understanding risk factors for increased postoperative opioid use may be helpful for the development of patient-specific opioid-sparing pain regimens for this patient population.

A retrospective analysis of data from our electronic medical records and the Society of Thoracic Surgeon's database.

A single-institution study at an academic medical center.

All patients undergoing open adult cardiac surgery were included. Exclusion criteria were patients with continuous intravenous narcotic drips and operative mortality.

As this was a retrospective study, no interventions were conducted on the participants.

Data for patient postoperative opioid requirements were extracted from the electronic medical record. Total opioid use on postoperative days 0 to 3 was converted to morphine milligram equivalent (MME) via standard conversion factors. The study cohort comprised 1604 patients, including 456 females and 1066 coronary artery bypass grafting (CABG) recipients. MME was 31.0% greater in patients undergoing CABG (p < 0.001), 76.3% greater in patients with liver disease (p = 0.005), and 48.8% greater in patients with patient-controlled analgesia (p <0.001) during postoperative days 0 to 3. Younger age (p < 0.001) and higher body mass index (BMI) (p < 0.001) also were associated with increased MME prescription.

CABG, liver disease, patient-controlled analgesia, younger age, and higher BMI are associated with increased narcotic use after cardiac surgery. Implementation of more aggressive perioperative multimodal opioid-sparing regimens should be considered for these patient groups.