Early inspiratory effort assessment by esophageal manometry early predicts noninvasive ventilation outcome in de novo respiratory failure: a pilot study.

Rationale: The role of inspiratory effort has still to be determined as a potential predictors of non-invasive mechanical ventilation (NIV) failure in acute hypoxic de novo respiratory failure (AHRF). Objectives: We explore the hypothesis that inspiratory effort might be a major determinant of NIV failure in these patients. Methods: Thirty consecutive patients with AHRF admitted to a single center and candidates for a 24-hour NIV trial were enrolled. Clinical features, tidal changes in esophageal (ΔPes) and dynamic transpulmonary pressure (ΔPL), expiratory tidal volume, and respiratory rate were recorded on admission and 2-4-12-24 hours after NIV start, and were tested for correlation with outcomes. Measurements and Main Results: ΔPes and ΔPes/ΔPL were significantly lower 2 hours after NIV start in patients who successfully completed the NIV trial (n=18) compared to those who needed endotracheal intubation (n=12) [median=11 (IQR=8–15) cmH2O vs 31.5 (30–36) cmH2O, p<0.0001] while other variables differed later. ΔPes was not related to other predictors of NIV failure at baseline. NIV-induced reduction in ΔPes of 10 cmH2O or more after 2 hours of treatment was strongly associated to avoidance of intubation, and represented the most accurate predictor of treatment success (OR=15, 95%CI 2.8-110, p=0.001, AUC=0.97, 95%CI 0.91–1, p<0.0001). Conclusions: The magnitude of inspiratory effort relief as assessed by ΔPes variation within the first 2 hours of NIV was an early and accurate predictor of NIV outcome at 24 hours.