Correlation of diaphragmatic ultrasound with pulmonary function testing in patients with chronic cervical spinal cord injury: A single center pilot study

Pulmonary function tests are the gold standard of evaluating pulmonary function in individuals with a spinal cord injury (SCI). However, there are limitations to its accessibility thereby reducing its clinical utility. Diaphragmatic ultrasound is used to evaluate pulmonary function in non-neurologic individuals but there is limited evidence demonstrating its benefit in individuals with SCI. The objective is to determine if diaphragmatic ultrasound measurements are correlated with forced vital capacity (FVC), peak cough flow (PCF), neurological level of injury (NLI), and/or motor level. A pilot study at a single rehabilitation hospital. Individuals ≥18yo with traumatic and non-traumatic SCI for ≥6 months with NLI from C1-C6, and ASIA Impairment Scale scores A, B, or C. N/A. Associations between FVC, PCF, and diaphragmatic ultrasound measurements (thickness at total lung capacity, thickness at functional residual capacity, and right diaphragm excursion). Also, associations between diaphragmatic ultrasound measurements with NLI and motor level. Significant associations were detected between the thickening ratio and FVC (<i>r</i> = 0.5384, P = 0.047), diaphragm excursion with FVC (<i>r</i> = 0.5757, P = 0.0395), and diaphragm excursion with PCF (<i>r</i> = 0.8061, P = 0.009). Thickness at functional residual capacity and thickness at total lung capacity were not significantly associated with FVC nor PCF. No significant association was found between NLI or motor level with any of the recorded pulmonary or diaphragmatic measures. Diaphragmatic ultrasound is a promising tool in the evaluation of two parameters of pulmonary function in those with cervical SCI. A larger, longitudinal study to confirm these findings and evaluate for normative values would be beneficial.