The Effect of Respiratory Muscle Dysfunction on Pulmonary Function. Studies in Patients With Spinal Cord Injuries.

The contributions of the skeleton and the .respira tory muscles to over-all lung function have been studied in various ways. Abnormal lung function has been observed in patients with abnormal chest cage and respiratory muscle function caused by kyphoscoliosis, spondylitis, :poliomyelitis, obesity, and spinal cord injury (1-9). Investigations of thoracic mechanics have been undertaken in normal subjects and in subjects who have been anesthetized and/or paralyzed by drugs (10-13). While both types of studies are informative, they fail to distinguish the effects of abnormal function of the individual respiratory muscle groups. The electromyographic studies reported by Campbell demonstrate that, in normal subjects, differential function of intercostal, abdominal, and diaphragmatic musculature exists (14, 15). It would, therefore, be of value to attempt to isolate, when possible, the independent contributions of these various muscle groups to respiration. Although documented studies of aspects of lung function have been reported in patients with spinal cord injury, there has been no overall assessment of the lung function in these subjects. Neither has the relationship between altered lung mechanics and abnormalities of gas exchange been reported. In order to further study the effects of respiratory muscle dysfunction on lung function, subjects with spinal cord injury and documented loss of respiratory muscle function were selected for study in this laboratory. It is the purpose of this communication to report complete lung function studies in such subjects, and to attempt to explain the