(979) Impact of Preoperative Oral Acetaminophen on Postoperative Opioid Requirements After Cardiac Surgery

Introduction: Acetaminophen (APAP) is a preferred adjunct analgesic after cardiac surgery with evidence supporting reduced postoperative pain, nausea and vomiting, and mixed evidence in reducing postoperative opioid requirements. The impact of preoperative APAP on postoperative opioid requirements is not described in the cardiac surgery literature. This study tested the hypothesis that preoperative oral APAP reduces postoperative opioid requirements in patients undergoing cardiac surgery.

Methods: This single-center, retrospective review at an academic, tertiary medical center included adult patients who underwent cardiac surgery during index admission. Patients with an allergy to APAP, on extracorporeal membrane oxygenation, underwent heart or lung transplant, indication for deep sedation, preoperative chronic opioid therapy, or liver disease were excluded. Univariate analysis compared patients who did and did not receive preoperative APAP. The primary outcome was cumulative postoperative opioid requirements in morphine milligram equivalents (MME) at 24 hours after surgery. Secondary outcomes included pain intensity scores, incidence of severe pain, mechanical ventilation duration, ICU length of stay, and opioid-related adverse effects. Data are presented as descriptive statistics and compared with Mann-Whitney U, Pearson Chi-square, or Fisher’s exact test as appropriate.

Results: A total of 506 patients were included, 100 (20%) of which received preoperative APAP at a median dose of 1000 mg administered 2 hours prior to surgery. The most common surgery type involved valve repair/replacement (68%) and most underwent full sternotomy (80%). In the first 24 hours postoperatively, the APAP group had higher cumulative MME, though not significantly higher than the no APAP group (88.2 vs 70.3, p=0.19). Intra- and postoperative pain management was similar between groups. Postoperatively, greater than 95% of all patients received scheduled oral and rectal APAP, 27% received ketorolac, and 18% received lidocaine patches. There was no difference in secondary outcomes between groups.

Conclusions: Oral APAP prior to cardiac surgery was not associated with a difference in postoperative opioid requirements within 24 hours after cardiac surgery compared to patients who did not receive preoperative APAP.