Assessment of Respiratory Muscle Weakness in Subjects With Neuromuscular Disease

Neuromuscular diseases (NMD) are a group of rare heterogeneous disorders that may be accompanied by respiratory muscle weakness. The simplest measurements of respiratory muscle strength are maximum inspiratory pressure (P_Imax) and maximum expiratory pressure (P_Emax) of the mouth. Inspiratory muscle weakness can also be evaluated by the sniff test (sniff nasal inspiratory pressure method). This study tested the agreements in P_Imax and P_Emax (measured by using a plethysmograph and portable equipment) as well as the correlations of P_Imax and P_Emax by using the sniff nasal inspiratory pressure method, lung function, and arterial blood gas parameters in subjects with NMD.

This prospective, noninterventional study measured respiratory parameters in all the subjects with NMD who underwent measurement of maximum respiratory pressures.

A total of 55 subjects with NMD were included. There were no statistically significant differences in P_Imax and P_Emax measured by using a plethysmograph and portable equipment. Moreover, P_Imax showed a good correlation with the sniff nasal inspiratory pressure method.

Measurements of P_Imax and P_Emax by using portable equipment were equivalent to those performed by using the accepted standard, plethysmography, in the subjects with NMD. Noninvasive evaluation of the sniff test with the portable equipment correlates with P_Imax, which makes this approach a good method for measuring the maximum strength of inspiratory muscles in patients with NMD.