Comparison of lung volume measurements in individuals with spinal cord injury by two different methods

BACKGROUND/OBJECTIVE: Few detailed studies have been performed among subjects with spinal cord injury (SCI) using whole body plethysmography for measurement of static lung volumes. Because abdominal gas volumes and respiratory patterns among subjects with varying levels of SCI may differ significantly from able-bodied individuals, methodological concerns related to this technique could conceivably lead to inaccuracies in lung volume measurements. The purpose of this study was to compare lung volume parameters obtained by whole body plethysmography with those determined by the commonly used nitrogen washout technique among individuals with SCI. PARTICIPANTS: Twenty-nine clinically stable men, 14 with chronic tetraplegia (injury C4-C7) and 15 with paraplegia (injury below T5) participated in the study. METHODS: Lung volumes were obtained using whole body plethysmography and the open-circuit nitrogen washout technique. Within both study groups, data were evaluated by the paired Student's t test and by determination of correlation coefficients. RESULTS: No statistically significant differences for any lung volume parameter were found within either group. In subjects with tetraplegia on paraplegia, respectively, strong correlation coefficients were found for measurements of total lung capacity (.86 and .97), functional residual capacity (.87 and .96), and residual volume (.77 and .85). CONCLUSION: These findings indicate that body plethysmography is a valid technique for determining lung volumes among subjects with SCI. Because airway resistance measurements can also be obtained during same study sessions for assessment of airway caliber and bronchial responsiveness, body plethysmography is a useful tool for examining multiple aspects of pulmonary physiology in this population.