Muscle relaxants that are used during general anesthesia increase the risk of pulmonary complications after surgery, according to the European multicenter study POPULAR, in which Karolinska Institutet researchers are involved. The study is published in the journal Lancet Respiratory Medicine.

Increasing numbers of people around the world undergo anesthesia and surgery, and in Sweden over 10% of the population are exposed to anesthesia every year. In the case of general anesthesia, in order to reduce the dose of the anesthetic and morphine-like drugs, so-called neuromuscular blockers are often also administered, thus mitigating the risk of complications.

Even if this group of anesthetic drugs has contributed to safer and more effective anesthesia, several patient studies and smaller studies on healthy participants indicate that the addition of neuromuscular blockers to anesthesia increase the risk of respiratory complications.

In the current study, the researchers sought to ascertain if the use of these muscle relaxants in combination with anesthesia and surgery increases the risk of developing post-surgical pulmonary complications, such as infections, respiratory insufficiency, or lung collapse.

Large European study

Data from over 22,800 patients in 28 European countries who had received general anesthetic, including some 1,200 patients from ten Swedish hospitals, were gathered from between July 2014 to April 2015.

“The study shows that the use of neuromuscular blockers significantly increases the risk of pulmonary complications after anesthesia and surgery,” says Malin Jonsson Fagerlund, consultant and docent at the Department of Physiology and Pharmacology, Karolinska Institutet. “More targeted studies need to be made to find out the underlying mechanisms behind this finding.”

The study also shows that neither neuromuscular monitoring nor the use of drugs that reverse the neuromuscular blockade reduce the risk of post-surgical pulmonary complications.