Effect of positive-pressure ventilation before extubation on respiratory function: physiological evaluation under simulated extubation

Abstract

Background: Positive-pressure ventilation (PPV) before extubation may improve oxygenation and reduce complications after extubation. However, no study has quantitatively evaluated the effects of extubation on breathing and lung volume. Methods: A crossover randomized study was performed on 16 patients who received mechanical ventilation and planned to undergo extubation in the intensive-care unit. We used the automatic tube compensation (ATC) mode to simulate extubation. We used electrical impedance tomography and an esophageal balloon catheter to evaluate the work of breathing and lung volume after simulated extubation. We compared the work of breathing and lung volume with and without PPV before simulated extubation. Result: There were no differences in the changes in end-expiratory lung impedance (-7.4 [-18.2–2.3] vs. -11.2 [-16.6–1.1] arbitrary units, p=0.53), anterior-to-posterior ventilation ratio (0.60 [0.49–0.74] vs. 0.60 [0.52–0.79], p=0.75), esophageal pressure swing (4.9 [2.1–8.7] vs. 5.4 [1.9–6.6] cmH2O, p=0.61), dynamic transpulmonary pressure (7.2 [6.7–9.9] vs. 7.6 [6.6–9.7] cmH2O, p=0.93), and pressure time product (2.4 [1.4–4.2] vs. 3.1 [1.0–4.3] cmH2O*s, p=0.84) with and without PPV before simulated extubation. Conclusion: PPV before extubation did not affect breathing work or lung volume after extubation. Therefore, it may delay extubation and increase patient stress.