Intermediate-acting neuromuscular block use ‘needs revisiting’

By Eleanor McDermid, Senior medwireNews Reporter

The use of intermediate-acting neuromuscular blocking agents during general anesthesia may increase the risk for clinically meaningful respiratory complications, researchers report in the BMJ.

In the prospective propensity-matched cohort study, involving more than 37,000 patients, neither monitoring the train-of-fours ratio nor reversing neuromuscular block with neostigmine after surgery mitigated this risk.

But in an accompanying editorial, Jennifer Hunter (University of Liverpool, UK) stresses that "it would be a mistake to conclude that current recommended clinical practice should change on the basis of the findings of this one study, however large and well executed."

She says: "It is difficult to accurately define the incidence of rare but serious complications associated with widely practised techniques." Doing so in a randomized trial would require huge numbers of patients, and it would be near impossible to treat so many patients under the same conditions.

"All the confounding factors of acute care, including the multiplicity of drugs administered perioperatively and the reasons for giving them, would preclude it." These factors probably also influenced the results of the current study, she adds.

The study involved 18,579 patients who received intermediate-acting neuromuscular blocking agents during surgery and were matched by the propensity to receive such agents to another 18,579 patients who were not given neuromuscular blockade. Only half of the patients reportedly received train-of-fours ratio monitoring, and 63.2% were given neostigmine to reverse blockade after surgery.

Respiratory complications were rare, with just 0.8% of patients needing to be reintubated, and 5.0% having a desaturation event in which their hemoglobin oxygen saturation fell below 90%. However, these complications were increased a respective 36% and 40% in patients given neuromuscular block. The risk was especially marked if neuromuscular block was given for surgery lasting less than 120 minutes, with the risk for reintubation, for example, rising 2.04-fold.

Patients who were reintubated and therefore required unplanned admission to the intensive care unit had a 91-fold increased risk for dying, note Matthias Eikermann (Massachusetts General Hospital, Boston, USA) and colleagues.

The risk for desaturation and reintubation was elevated 32% and 76%, respectively, if patients were given neostigmine, and 19% and 49% if patients received train-of-fours ratio monitoring. However, the risk appeared lower in patients given both safety interventions, relative to neostigmine alone.

Hunter concludes: "In light of currently available evidence it would seem wise to continue to use quantitative neuromuscular monitoring, intermediate acting neuromuscular blocking agents, and a reversal agent unless full recovery of neuromuscular function has been adequately demonstrated."

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