Shivering is a frequent, distressing side effect for women undergoing neuraxial anesthesia for cesarean delivery, but a recent study may have come up with a safe and effective way to deal with it. Researchers concluded that a single bolus of dexmedetomidine after delivery dramatically reduced the incidence and duration of shivering, with no major hemodynamic drawbacks.
“Although neuraxial anesthesia is the preferred technique for cesarean delivery, it is unfortunately associated with intense shivering in more than 55% of patients,” said Christina Lamontagne, MD, a resident at the University of Montreal. “The shivering can be so intense that it leads to patient distress and even interferes with the monitoring of vital signs.
“We’ve long had an interest in dexmedetomidine, which is a highly selective alpha-2 adrenergic receptor agonist,” Dr. Lamontagne said. “And while it has been proven to improve shivering in the nonobstetric patient population, there are no prospective studies in the obstetric population.”
Shivering Duration Greatly Reduced
The investigators enrolled 80 healthy parturients into the prospective randomized, double-blind trial, all of whom were 18 years of age or older and undergoing cesarean delivery under neuraxial anesthesia. A total of 155 patients met the inclusion criteria and were recruited, of whom 80 presented with significant shivering and were randomized. Immediately after childbirth, the study group (n=40) received a single 30-mcg bolus of IV dexmedetomidine, while controls (n=40) received normal saline.
The trial’s primary outcome was the duration of shivering. “The shivering scale ranges from 0 to 4,” Dr. Lamontagne explained. “It has to be a 3 or 4 to be considered significant, which is shivering involving multiple muscle groups, interfering with monitoring of vital signs or causing patient distress.” Measured adverse effects included hypotension, significant bradycardia and excessive sedation.
As Dr. Lamontagne reported at the 2017 annual meeting of the Canadian Anesthesiologists’ Society (abstract 277156), women who received dexmedetomidine had their duration of intense shivering reduced to 2.6 minutes (95% CI, 1.94-3.26) compared with 17.0 minutes (95% CI, 13.9-21.9) for those who received normal saline (P<0.0001). The beneficial effects of dexmedetomidine persisted for at least 15 minutes after its administration, when chills had completely stopped in 90% of these patients versus 23% of controls.
The potential for hemodynamic effects caught the attention of Gregory M. Hare, MD, PhD, a professor of anesthesia at the University of Toronto. “We use dexmedetomidine in sedation in those doses and find that two and three hours later, we often will see bradycardia and hypotension in the recovery room. I was a bit surprised that you didn’t seem to find that. Is there more work to be done to establish that there isn’t indeed an issue with bradycardia and hypotension?”
“When we give the bolus of dexmedetomidine at five minutes after childbirth, all of our patients are essentially tachycardic, with heart rates of approximately 100 bpm,” Dr. Lamontagne said. “There was a lowering of the heart rate, but nothing that had clinical impact or required clinical intervention. Perhaps if we gave the dose to an 80-year-old man, we would have seen different results.”
Indu Singh, MD, offered other methods for reducing shivering in this patient population. “We recently did a survey in our [obstetrics] unit and found that 40% of women who were having elective C-section were severely bothered by the shivering,” said Dr. Singh, an associate professor of anesthesia and perioperative medicine, and the director of obstetric anesthesia at Western University, in London, Ontario. “But what we’ve found is that we were able to decrease that to 15% by actively warming them. We use fluid warming and we have an underbody warming mattress. Do you use any of these methods?”
“In our hospital, we offer a warmed blanket, though we don’t warm the fluids on a regular basis,” Dr. Lamontagne said. “I don’t find those methods particularly effective. They reduce the shivering a little, but they don’t put an end to it like dexmedetomidine did.”