Association between diaphragm thickening fraction and noninvasive ventilation failure in patients with acute respiratory failure in the emergency department

BACKGROUND AND IMPORTANCE: Noninvasive ventilation (NIV) is commonly used for acute respiratory distress in the emergency department (ED); however, early identification of patients at risk of NIV failure remains challenging. The association between diaphragmatic thickening fraction (DTF) and NIV failure was evaluated in patients with undifferentiated dyspnoea. DESIGN, SETTINGS, AND PARTICIPANTS: This prospective observational study included adult patients with dyspnoea requiring NIV in the ED of a tertiary care hospital. INTERVENTION: DTF was assessed using point-of-care ultrasound for patients requiring NIV at two time points, first at initiation and second after 1 h of NIV. OUTCOMES MEASURE AND ANALYSIS: The primary outcome was NIV failure within 24 h, defined as the need for endotracheal intubation. Secondary outcomes included in-hospital mortality, duration of invasive ventilation, and ICU/hospital stay. MAIN RESULTS: Of 126 patients, 36 (28.6%) experienced NIV failure. DTF less than or equal to 32.35% at 1 h was significantly associated with NIV failure (area under the curve: 0.802, sensitivity: 75%, specificity: 74.4%, negative predictive value: 88.2%; P < 0.001), with better discrimination than baseline DTF. Multivariate analysis showed DTF at 1 h was independently associated with NIV failure (odds ratio: 8.19, P < 0.001). It also correlated with in-hospital mortality, invasive ventilation days, and ICU stay (P = 0.007, P < 0.001, P = 0.002, respectively). CONCLUSION: In this prospective study, DTF measured 1 h after NIV initiation was independently associated with NIV failure in patients with acute respiratory distress in the ED.