Physiological comparison of noninvasive ventilation and high-flow nasal oxygen on inspiratory efforts and tidal volumes after extubation: a randomized crossover trial

Background Extubation failure leading to reintubation is associated with high mortality. In patients at high-risk of extubation failure, clinical practice guidelines recommend prophylactic non-invasive ventilation (NIV) over high-flow nasal oxygen (HFNO) immediately after extubation. However, the physiological effects supporting the beneficial effect of NIV have been poorly explored. We hypothesized that NIV may reduce patient inspiratory efforts to a greater extent than HFNO after extubation. Methods In a prospective physiological study, patients at high-risk of extubation failure (> 65 years old or underlying cardiac or respiratory disease) were included to receive after planned extubation prophylactic NIV and HFNO in a randomized crossover order, followed by standard oxygen. Inspiratory efforts were assessed by calculation of the simplified esophageal pressure-time-product per minute (sPTP(es) in cmH(2)O s/min). Tidal volumes, distribution and homogeneity of ventilation were estimated using electrical impedance tomography. Results Twenty patients were retained in the analysis. Inspiratory efforts were lower with NIV than with HFNO (sPTP(es) 196 cm H2O s/min [116-234] vs. 220 [178-327], p < 0.001) whereas tidal volumes were larger with NIV than with HFNO (8.4 mL/kg of predicted body weight [6.7-9.9] vs. 6.9 [5.3-8.6], p = 0.005). There was a non-significant increase in dorsal region ventilation under NIV compared to HFNO. Conclusions In patients at high-risk of extubation failure, prophylactic NIV significantly decreased inspiratory efforts with increased tidal volumes compared to HFNO. The clinical benefits of NIV to prevent reintubation in patients at high-risk may be mediated by these physiological effects.