Comparison Between M‐Mode Ultrasonography and Fluoroscopy for Diaphragm Excursion Measurement in Patients With Acquired Brain Injury

OBJECTIVES: Patients with acquired brain injury show decreased pulmonary function and diaphragm excursion (DE), which can affect functional outcomes. This study aimed to compare ultrasonography (US) and fluoroscopy for DE assessment and to determine how the relationship between pulmonary function test results and DE differs according to the paralytic condition. METHODS: From September 2017 to April 2018, we prospectively enrolled patients with acquired brain injury. The patients underwent a pulmonary function test, including the functional vital capacity, forced expiratory volume at 1 second, forced expiratory volume at 1 second-to-functional vital capacity ratio, peak cough flow, and respiratory muscle strength such as the maximal inspiratory pressure and maximal expiratory pressure. Diaphragm excursion was measured with M-mode US and fluoroscopy on admission. A partial correlation analysis was used to assess the correlation between US and fluoroscopy for DE assessment. RESULTS: During the study period, 50 patients with acquired brain injury were enrolled. After adjusting for age, sex, height, and weight, the correlation coefficients between US and fluoroscopy were 0.744 for the right side (P < .001) and 0.631 for the left side (P < .001). In a subgroup analysis for patients with hemiplegia, the correlation coefficients were 0.507 for the paretic side (P = .007) and 0.677 for the nonparetic side (P < .001). Diaphragm excursion in the nonparetic side was significantly correlated with the maximal inspiratory pressure, maximal expiratory pressure, and peak cough flow (P < .05). CONCLUSIONS: M-mode US can be an alternative method for DE measurement in patients with impaired locomotion function after acquired brain injury. Preserved function of the nonparetic side might affect pulmonary function after brain injury, which suggests the importance of prestroke respiratory function.