Early Inspiratory Effort Assessment by Esophageal Manometry Predicts Noninvasive Ventilation Outcome in <i>De Novo</i> Respiratory Failure. A Pilot Study

<b>Rationale:</b> The role of inspiratory effort still has to be determined as a potential predictor of noninvasive mechanical ventilation (NIV) failure in acute hypoxic <i>de novo</i> respiratory failure.<b>Objectives:</b> To explore the hypothesis that inspiratory effort might be a major determinant of NIV failure in these patients.<b>Methods:</b> Thirty consecutive patients with acute hypoxic <i>de novo</i> respiratory failure admitted to a single center and candidates for a 24-hour NIV trial were enrolled. Clinical features, tidal change in esophageal pressure (ΔPes), tidal change in dynamic transpulmonary pressure (ΔPl), expiratory Vt, and respiratory rate were recorded on admission and 2-4 to 12-24 hours after NIV start and were tested for correlation with outcomes.<b>Measurements and Main Results:</b> ΔPes and ΔPes/ΔPl ratio were significantly lower 2 hours after NIV start in patients who successfully completed the NIV trial (<i>n</i> = 18) compared with those who needed endotracheal intubation (<i>n</i> = 12) (median [interquartile range], 11 [8-15] cm H₂O vs. 31.5 [30-36] cm H₂O; <i>P</i> < 0.0001), whereas other variables differed later. ΔPes was not related to other predictors of NIV failure at baseline. NIV-induced reduction in ΔPes of 10 cm H₂O or more after 2 hours of treatment was strongly associated with avoidance of intubation and represented the most accurate predictor of treatment success (odds ratio, 15; 95% confidence interval, 2.8-110; <i>P</i> = 0.001 and area under the curve, 0.97; 95% confidence interval, 0.91-1; <i>P</i> < 0.0001).<b>Conclusions:</b> 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.Clinical trial registered with www.clinicaltrials.gov (NCT03826797).