Effect of Intravenous Acetaminophen on Postoperative Opioid Use in Bariatric Surgery Patients

The use of opioids to achieve adequate pain relief following surgery is a common clinical practice. Opioids, however, are associated with serious adverse effects, such as respiratory depression, excessive sedation, and prolonged ileus, as well as increased mortality. The administration of intravenous (IV) acetaminophen to control postoperative pain has been effective in reducing opioid consumption in various surgical populations, but no studies have been conducted in bariatric surgery patients. This investigation was performed to determine whether IV acetaminophen reduces opioid requirements after bariatric surgery.

IV acetaminophen was added to the Winthrop-University Hospital formulary in September 2012. We conducted a retrospective chart-review analysis of bariatric surgery patients who received at least four doses of IV acetaminophen (1 g every six hours) plus opioids from October 2012 to March 2013 (after IV acetaminophen was added to the hospital formulary), compared with bariatric surgery patients who received only opioids for postoperative pain control from January 2012 to June 2012 (before IV acetaminophen was added to the hospital formulary). The study's primary endpoint was the difference between the two groups in opioid consumption, expressed in oral morphine equivalents (OMEs). Secondary endpoints included the reduction in the baseline pain score; the total amount of each opioid used; and the average hospital length of stay (LOS).

A total of 96 patients were identified for potential enrollment from January 2012 to March 2013. Eight patients, however, did not qualify for participation because they had received only one dose of IV acetaminophen. The remaining 88 patients comprised two study groups: IV acetaminophen plus opiates (n = 44) and IV opiates alone (n = 44). Paradoxically, the patients in the acetaminophen/opiates group required significantly more opiates (in OMEs) compared with the group that received opiates alone (median, 93.5 mg versus 63.0 mg, respectively; P = 0.017). There were no significant differences between the two treatment groups in terms of the median change from baseline in pain scores (-4 versus -4; P = 0.162) or the median hospital LOS (two days versus two days; P = 0.704).

IV acetaminophen did not reduce opioid use for postoperative pain management in bariatric surgery patients.