But overall opioid use unchanged in this lap chole study
Preliminary data indicate reduced postoperative/post-discharge nausea and vomiting (PONV/PDNV) and improved patient satisfaction after a single dose of IV acetaminophen in patients undergoing laparoscopic cholecystectomy, compared with traditional opioid-based anesthetics. Despite this, the overall amount of opioid administered intraoperatively and in the postanesthesia care unit (PACU) was not reduced.
“There have been a lot of reports, both anecdotally and in the literature, about ways to help minimize PONV and pain,” commented Daniel Bosshart, MD, assistant professor of anesthesiology at Hofstra North Shore–LIJ School of Medicine, in Hempstead, N.Y. “So, we wanted to determine the effect of a single dose of IV acetaminophen on PONV, PDNV, pain and overall patient satisfaction.”
Dr. Bosshart and his colleagues enrolled 65 outpatients, American Society of Anesthesiologists (ASA) physical status 1 to 3, scheduled for laparoscopic cholecystectomy, into the trial. Each patient received a regimen of an opioid and an inhalational anesthetic, with preemptive antiemetics based on preoperative PONV risk according to ASA guidelines. The intervention group of 32 patients received 1,000 mg of IV acetaminophen (Ofirmev, Cadence Pharmaceuticals) after removal of the gallbladder but before emergence. The control group of 33 patients received opioids and other analgesics, including ketorolac, as per usual practice. Pain scores were recorded with an 11-point rating scale before surgery and at 10-minute intervals in the PACU. Both PDNV and patient satisfaction were assessed within seven days of surgery.
“We wanted to measure the effect of giving an intraoperative dose of Ofirmev versus just giving standard, opioid-based analgesics that clinicians would typically give for these cases,” Dr. Bosshart explained. “We picked this particular procedure because it’s one of the most commonly performed surgeries in the outpatient setting.”
As Dr. Bosshart reported at the 2014 annual meeting of the International Anesthesia Research Society (abstract S-29), PACU pain scores did not differ significantly between the IV acetaminophen patients and the controls at 10 minutes (1.4±3.1 vs. 2.3±3.0, respectively;P=0.12) or one hour after surgery (2.6±2.5 vs. 2.1±2.3, respectively; P=0.77). Total opioid use (intraoperative plus PACU) as measured by morphine equivalents also was comparable between groups (72±36 vs. 69±36 mg, respectively; P=0.9).
Trends toward less PONV were observed in the PACU, with 36% of controls experiencing the side effect compared with 21% of the treatment group (P=0.3). Similar results were found for PDNV, which affected 38% of controls and 14% of patients receiving IV acetaminophen (P=0.08).
“We also found that PDNV was actually more prolonged in the control group,” Dr. Bosshart said. Indeed, 24% of controls reported PDNV on the day of surgery, with 7% and 7% reporting the adverse event on postoperative days 2 and 3, respectively. “In the IV acetaminophen group,” he said, “it was only noted on the actual day of surgery [P<0.05].”
Patient satisfaction with pain control, PONV management and overall experience also trended in favor of IV acetaminophen, although this did not reach significance: 67%, 71% and 84%, respectively, for controls versus 84%, 93% and 96% for the treatment group (P=0.5, 0.1 and 0.4).
“We found the effect of the IV acetaminophen on nausea particularly interesting … not only initially, but also after discharge,” he said. “It was equally interesting that overall patient satisfaction was higher in the treatment group, despite the actual perception of the pain being similar in both groups. We expect these differences to reach statistical significance once we finish enrollment.
“These preliminary results seem to demonstrate that there’s another factor involved here with regard to PONV than just opioid sparing,” Dr. Bosshart added. “It seems there is a central effect that may have something to do with a metabolite of acetaminophen and how it affects cannabinoid receptors in the brain.” The study is ongoing.
Session moderator Raafat Hannallah, MD, professor of anesthesiology and pediatrics at Children’s National Health System, in Washington, D.C., proposed a possible confounding factor that may have influenced the results. “The problem, of course, with looking at postdischarge results is that they will be somewhat affected by what the surgeon prescribes after the surgery. These agents will be responsible for at least some of the observed response.”