Muscle Relaxants During Anesthesia May Increase Risk of Postoperative Pulmonary Complications

Neuromuscular blocking agents, or muscle relaxants, are often used in surgery to prevent muscles from moving when a patient is unconscious. A recent study found that the use of neuromuscular blockers during general anesthesia is associated with an increased risk of postoperative pulmonary complications.

The study, also referred to as POPULAR, involved the recruitment of patients from 211 hospitals in 28 European countries, who received general anesthesia for any in-hospital procedure except cardiac surgery. The researchers also collected patient characteristics, surgical and anesthetic details, and the chart review at discharge. Within 3 days of surgery, each patient included in the study underwent postoperative physical examination to assess for adverse pulmonary events.

“These drugs are particularly needed when operating on a patient’s chest or abdomen. They are also used to protect the vocal cords from injury when a tube is placed in the airway to allow artificial ventilation,” Manfred Blobner, MD, chair of the POPULAR steering committee, anesthesiologist at the Technical University of Munich’s Clinic for Anesthesiology and Intensive Care, said in a statement.

The primary study outcome was the incidence of postoperative pulmonary complications from the end of surgery up to postoperative day 28, according to the study. Logistic regression analyses were conducted and adjusted for surgical factors and patients’ preoperative physical status.

“It's important to note that neuromuscular blocking agents have made surgery considerably safer and more effective since their introduction several decades ago,” explained Blobner. “We have constantly refined both the drugs and the techniques used. Many operations would not be possible without them. Still, the results from POPULAR raise important questions.”

Data from a total of 22,803 patients were collected between June 16, 2014 and April 29, 2015. The results revealed that the use of neuromuscular blocking agents was associated with an increased incidence of postoperative pulmonary complications in patients who had undergone general anesthesia. Furthermore, the use of neuromuscular monitoring and the administration of reversal agents were not associated with a decreased risk of postoperative pulmonary complications, according to the results.

The study emphasized that anesthetists must balance the potential benefits and risks of postoperative pulmonary complications before using neuromuscular blocking agents.

“Based on our results, we believe that patients undergoing minor surgical procedures that do not necessarily require neuromuscular blocking drugs might benefit from avoiding them,” concluded Blobner. “Using devices like laryngeal masks for anesthesia instead of tracheal tubes that go past the vocal cords could prove helpful, as well.”

Reference

Kirmeier E, Eriksson LI, Lewald H, et al. Post-anaesthesia pulmonary complications after use of muscle relaxants (POPULAR): a multicentre, prospective observational study. [published online September 14, 2018]. Lancet Respir Med. doi: 10.1016/S2213-2600(18)30294-7.