Physiological effects of high flow oxygen therapy: What happens in the first 24 hours after extubation?

Abstract

Rationale | | High flow nasal cannula (HFNC) is a non-invasive oxygen therapy using humidified high flow to support patients with respiratory failure. This study aimed to compare the physiological effects on respiratory effort and aeration between patients receiving high flow oxygen therapy or conventional oxygen therapy (COT) in the first twenty-four hours after extubation.

Methods | Post-extubation patients were randomized to receive either HFNC or COT. Esophageal pressure measurements and Electrical Impedance Tomography were used to evaluate the physiological effects. Measurements were taken at baseline (during mechanical ventilation just before extubation) and at 2, 4, and 24 hours post-extubation. Linear mixed model analyses were applied to assess changes over time.

Results | No statistically significant differences in respiratory effort were observed, although trends emerged in the linear mixed model analyses. In terms of aeration, the COT group showed increasing inhomogeneity over time, while the HFNC group maintained stable aeration with a progressive increase in dorsal ventilation. No changes in tidal volume were observed.

Conclusions | While statistically significant differences were limited, HFNC showed clinically relevant and important trends in stabilizing respiratory effort and lung aeration, suggesting it may provide better support for weaning and reduce re-intubation risk.