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.

Invasive mechanical ventilation is the cornerstone of respiratory failure treatment. Setting ventilator parameters is a balancing act between providing adequate oxygenation and ventilation on the one hand, and minimizing lung damage and adverse cardiovascular effects on the other hand. This thesis aims to find the differences between two methods for the titration of positive end-expiratory pressure: electrical impedance tomography and esophageal pressure monitoring. Moreover, methods are proposed to suppress cardiac activity from electrical impedance tomography and esophageal pressure recordings.