Maximum Inspiratory Pressure is a Discriminator of Pneumonia in Individuals With Spinal-Cord Injury

BACKGROUND: Respiratory complications remain a major cause of mortality among individuals
with spinal-cord injury (SCI). The present study investigated whether respiratory function is a
discriminator of pneumonia in individuals with SCI and is aimed to determine the best predictive
parameter. METHODS: This was a retrospective cohort study. Individuals with traumatic SCI,
level C3 to T12, complete and incomplete lesions, were included. Data on respiratory function were
extracted from medical records. The receiver operating characteristic curve was calculated for each
parameter (forced vital capacity, FEV1, peak expiratory flow, and maximum inspiratory and
expiratory pressure [PImax and PEmax]) to determine the discriminator with the largest area under
the curve between individuals with and without pneumonia. RESULTS: Data of 307 subjects were
analyzed. PImax was identified as the best discriminator between individuals with and without
pneumonia, both in motor complete (area under the curve 0.86, 95% CI 0.78 – 0.93, P < .001) and
incomplete individuals (area under the curve 1.0, 95% CI 1.00 –1.00, P < .001). In individuals with
motor complete lesions, the threshold value for PImax was 115% of the lesion-specific reference
value (sensitivity 74.4%, specificity 83.4%). In motor incomplete individuals, the PImax threshold
value was 93.5 cm H2O (sensitivity 100%, specificity 100%). CONCLUSIONS: PImax is the best
discriminator between spinal cord-injured individuals with versus those without pneumonia. Individuals with a PImax below threshold values are at risk of pneumonia. Key words: paraplegia;
tetraplegia; respiratory complications; risk threshold; predictor; respiratory strength.