Salbutamol Improves Respiratory Muscle Strength of Children With SMA, Study Reports

A year’s worth of salbutamol improved the breathing function and respiratory muscle strength of children with spinal muscular atrophy, according to a small-sample study.

The research, “Effect of Salbutamol on Respiratory Muscle Strength in Spinal Muscular Atrophy,” was published in Pediatric Neurology.

Previous studies had shown that oral salbutamol improved respiratory and movement function. But researchers didn’t know if it would increase patients’ respiratory muscle strength, which is also known as inspiratory muscle strength.

To find out, researchers followed seven children aged 4 to 1o. One had SMA I, five SMA II, and one SMA III. The smaller the numerical category of the disease, the more pronounced, with SMA I being the most severe.

The team gave the children oral salbutamol for at least a year. They assessed the treatment’s effectiveness by comparing the children’s respiratory data with that of age-matched SMA II patients who had not received salbutamol.

Researchers discovered that the salbutamol-treated SMA II children had significantly better respiratory function than the controls. One of the yardsticks they used was maximal static inspiratory pressure, which is the most common measure of respiratory muscle strength. Another was sniff nasal inspiratory pressure, or SNIP. And a third was slow vital capacity, which measures the maximum volume of air that can be exhaled slowly after a slow deep breath.

The children’s SNIP readings tended to improve as the length of treatment increased, but there was no connection between the length of treatment and the values of the other respiratory-function measures.

One SMA I patient who could not sit without help before receiving salbutamol and one SMA II patient who could not walk before taking it acquired those abilities after the treatment.

“This preliminary study confirms the clinical interest of oral salbutamol in children with SMA, and strongly suggests a selective improvement in the strength of the inspiratory [respiratory] muscles in SMA II patients,” the researchers wrote.