Evaluation of pulmonary function in neuromuscular disease.

Pulmonary function tests were performed on 40 patients with neuromuscular disease. The maximum expiratory pressure was the most sensitive indicator of weakness and was decreased in 87% of adult patients. A comparison of Stead-Wells, electronic (Vanguard), and bellows spirometry (Vitalor) indicated an excellent correlation between the Stead-Wells and electronic devices. The bellows spirometer consistently underestimated volumes, particularly in severely weak patients.