Spirometry--acceptability and reproducibility in spinal cord injured subjects

The American Thoracic Society (ATS) has formulated guidelines for spirometry. We hypothesized that individuals with SCI (SCI), as a result of weak respiratory muscles, would exhibit poor test acceptability and reproducibility. Seventy-eight SCI subjects (39 with complete SCI) answered a respiratory questionnaire and performed spirometry. Of those with complete SCI, the proportion of subjects which met ATS criteria decreased with higher levels of injury. Poor test performance was not associated with age, respiratory symptoms or muscle fatigue. The most common reason for failing to meet ATS criteria for acceptability was excessive back extrapolated volumes (EBEV). Individuals with efforts that were acceptable except for EBEV and/or for exhalation of less than six seconds had values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) that were reproducible. If ATS criteria for acceptable spirometry were used in studying subjects with SCI, individuals producing otherwise reproducible values for FVC and FEV1 would be excluded. We found reproducibility similar to what has been reported in other cohorts and conclude that longitudinal study of respiratory function in SCI is feasible.