Adding dexmedetomidine to fentanyl-based intravenous patient-controlled analgesia reduces the frequency and severity of postoperative nausea in highly susceptible patients, according to a study presented here at ANESTHESIOLOGY 2015, the Annual Meeting of the American Society of Anesthesiologists (ASA).

In the prospective, randomised, double-blind study, Young ran Kang, MD, Yonsei University College of Medicine, Seoul, South Korea, and colleagues investigated whether dexmedetomidine added to fentanyl-based intravenous patient-controlled analgesia can reduce postoperative nausea and vomiting in highly susceptible patients undergoing lumbar spinal surgery.

The study included 105 patients undergoing posterior lumbar spinal fusion and having at least 3 risk factors of postoperative nausea and vomiting (female gender, non-smoking status, and use of postoperative opioids).

Patients were randomised to intravenous dexmedetomidine 0.5 µg/kg or normal saline 30 minutes before the completion of surgery followed by intravenous fentanyl-based patient-controlled analgesia with or without a dexmedetomidine mixture (0.2 µg/kg/hr and a bolus dose of 0.1 µg/kg with a 15-minute lockout time).

The use of dexmedetomidine was associated with a significantly reduced risk of nausea within 3 hours postoperatively compared with the control group (odds ratio [OR], 0.59; P = .009).

Nausea intensity within 48 hours after surgery was comparable between the groups, but the dexmedetomidine group showed a significantly reduced risk of experiencing moderate to severe nausea (OR, 0.28; P < .003).

Pain scores were not significantly different between the groups, but patients in the dexmedetomidine group required less patient-controlled analgesia fentanyl up to 12 hours after surgery and less rescue analgesics. Almost twice as many patients in the dexmedetomidine group experienced significant hypotension and bradycardia, but this was not statistically significant.

“I was surprised to see in our study that the incidence of nausea was significantly lower 1 to 3 hours postop, and even more than 50% lower at 3 hours postop, plus a decreasing trend during 24 hours postop in the dexmedetomidine group,” said Dr. Kang.

“Another thing that surprised me is that the time period during which dexmedetomidine exerted beneficial influence on nausea closely coincided with the time period when cumulative fentanyl consumption was significantly lower, and when the antiemetic efficacy of dexmedetomidine was no longer evident after 24 hours postop, the difference in fentanyl consumption became less significant,” he said. “So the observed beneficial influence on nausea seems also to be attributable to the opioid-sparing effect of dexmedetomidine.”

[Presentation title: Dexmedetomidine Added to an Opioid-Based Analgesic Regimen for the Prevention of Postoperative Nausea and Vomiting in Highly Susceptible Patients: A Prospective Randomized Controlled Trial. Abstract A1062]