Study Questions IV Acetaminophen After Abdominal Surgery
Many anesthesiologists and pain services embraced the use of IV acetaminophen when it became available. The IV form plays a role in multimodal analgesia to reduce opioid consumption, despite some initial concern about the cost. However, a group of researchers primarily from Cleveland Clinic report that their trial found IV acetaminophen not to show any difference compared with placebo in the primary outcome measure.
The team set out to study the effect of postoperative administration of IV acetaminophen, which is hypothesized to reduce opioid consumption, on postoperative hypoxemia after abdominal surgery.
Among patients who underwent abdominal surgery, use of postoperative IV acetaminophen, compared with a saline placebo, did not significantly reduce the duration of postoperative hypoxemia over 48 hours.
"The study findings do not support the use of intravenous acetaminophen for this purpose," the authors wrote.
The randomized clinical trial included 570 patients. Participants were randomized to receive either IV acetaminophen, 1 g (n = 289), or normal saline placebo (n = 291) starting at the beginning of surgery and repeated every 6 hours until 48 postoperative hours or hospital discharge, whichever occurred first.
The primary outcome was the total duration of hypoxemia [hemoglobin oxygen saturation (Spo2) <90%] per hour, with oxygen saturation measured continuously for 48 postoperative hours. Secondary outcomes were postoperative opioid consumption, pain (0- to 10-point scale; 0: no pain; 10: the most pain imaginable), nausea and vomiting, sedation, minimal alveolar concentration of volatile anesthetic, fatigue, active time, and respiratory function.
The median duration of postoperative hypoxemia (defined as hemoglobin oxygen saturation <90%) was 0.7 minutes per hour in the acetaminophen group and 1.1 minutes per hour in the control group, a difference that was not statistically significant.
None of the 8 secondary end points differed significantly between the acetaminophen and placebo groups. Mean pain scores within initial 48 postoperative hours were 4.2 [standard deviation (SD), 1.8] in the acetaminophen group and 4.4 (SD, 1.8) in the placebo group [difference, -0.28; 95% confidence interval (CI), -0.71 to 0.15]; median opioid use in morphine equivalents was 50 mg [interquartile range (IQR), 18-122 mg] and 58 mg (IQR, 24-151 mg), respectively, with a ratio of geometric means of 0.86 (95% CI, 0.61-1.21). (See Turan A, Essber H, Saasouh W. Effect of intravenous acetaminophen on postoperative hypoxemia after abdominal surgery. the FACTOR randomized clinical trial. JAMA. 2020;24(4):350-358. https://jamanetwork.com/journals/jama/fullarticle/2768808.)