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

Rationale: The role of inspiratory effort still has to be determined as a potential predictor of noninvasive mechanical ventilation (NIV) failure in acute hypoxic de novo respiratory failure. Objectives: To explore the hypothesis that inspiratory effort might be a major determinant of NIV failure in these patients. Methods: Thirty consecutive patients with acute hypoxic de novo 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. Measurements and Main Results: ΔPes and ΔPes/ΔPL ratio were significantly lower 2 hours after NIV start in patients who successfully completed the NIV trial (n = 18) compared with those who needed endotracheal intubation (n = 12) (median [interquartile range], 11 [8-15] cmH2O vs. 31.5 [30-36] cm H2O; P<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 cmH2Oormore 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; P = 0.001 and area under the curve, 0.97; 95% confidence interval, 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.