Maximal respiratory pressures: normal values and relationship to age and sex.

A method for determining maximal respiratory pressures is described. The test was easy to perform; reproducible results were obtained, and no complications were encountered in the 120 subjects studied. The normal range of values for the maximal inspiratory (Pi max) and expiratory (Pe max) pressures in males and females from 20 to 74 years of age was determined. There was no significant regression of Pi max or Pe max with age in subjects younger than 55 years. In subjects older than 55, Pe max in males and females and Pi max in females decreased with age. The application of the method is illustrated by the results obtained in 2 patients with neuromuscular disease.