Diaphragm thickening fraction to predict weaning—a prospective exploratory study

BACKGROUND: Diaphragm ultrasound (DUS) is a well-established point of care modality for assessment of dimensional and functional aspects of the diaphragm. Amongst various measures, diaphragmatic thickening fraction (DTf) is more comprehensive. However, there is still uncertainty about its capability to predict weaning from mechanical ventilation (MV). The present prospective observational exploratory study assessed the diaphragm at variable negative pressure triggers (NPTs) with US to predict weaning in ICU patients. METHODS: Adult ICU patients about to receive their first T-piece were included in the study. Linear and curvilinear US probes were used to measure right side diaphragm characteristics first at pressure support ventilation (PSV) of 8 cmH2O with positive end expiratory pressure (PEEP) of 5 cmH2O against NPTs of 2, 4, and 6 cmH2O and then later during their first T-piece. The measured variables were then categorized into simple weaning (SW) and complicated weaning (CW) groups and their outcomes analyzed. RESULTS: Sixty-four (M:F, 40:24) medical (55/64, 86%) patients were included in the study. Sepsis of lung origin (65.5%) was the dominant reason for MV. There were 33 and 31 patients in the SW and CW groups, respectively. DTf predicts SW with a cutoff ≥ 25.5, 26.5, 25.5, and 24.5 for 2, 4, and 6 NPTs and T-piece, respectively, with ≥ 0.90 ROC AUC. At NPT of 2, DTf had the highest sensitivity of 97% and specificity of 81% [ROC AUC (CI), 0.91 (0.84–0.99); p < 0.001]. CONCLUSIONS: DTf may successfully predict SW and also help identify patients ready to wean prior to a T-piece trial.