Repeated measurements of pulmonary function following spinal cord injury

Twelve subjects (11 males, 1 female) with complete spinal cord lesion (level of lesion ranging from C4 to T10), with a mean age of 23.5 years participated in pulmonary function testing (PFT). Inspiratory and expiratory flow measurements were made at 2-month intervals from 25 to 351 days post injury. The values were interpolated and extrapolated to common dates to facilitate comparison. The effect of time on pulmonary function was determined by a repeated measures ANOVA. Forced expiratory volume in 1 second (FEV1.0) significantly increased during the course of the study (40%, p < 0.05), but increases in forced vital capacity (FVC) (32.5%) and maximal voluntary ventilation (MVV) (16%) were not statistically significant. Lesion level was found to be correlated (Spearman Product Moment Correlation) with pulmonary function if a single measure was made (r = 0.55 to 0.73), but emerged as a stronger predictor if the average of several repeated PFTs was correlated with lesion level (r = 0.74 to 0.84). In addition, lesion level was not correlated with the amount of improvement attained during the time period studied. We conclude that the time course of recovery of pulmonary function is variable between individuals with spinal cord injuries and can only be weakly predicted by knowledge of the initial value and the lesion level.