Weaning and extubation are critical procedures in mechanically ventilated patients, as weaning failure and reintubation occur in up to 10-30% of cases and are associated with increased mortality. Several strategies have been developed to assess patients’ readiness and the optimal timing for extubation, while different tools have been addressed to prevent and treat post-extubation respiratory failure.
While the uncontrolled use of pre-emptive noninvasive ventilation (NIV) in all extubated patients leads to delayed reintubation and increases mortality , it may be of benefit as a bridge to full spontaneous breathing in hypercapnic patients and in selected cohorts of hypoxemic subjects at high risk of weaning failure [2–5].
Heated and humidified high flow oxygen delivered through nasal cannula (HFNC) appears to be an optimal tool to administer oxygen to hypoxemic patients in the weaning phase; accordingly, pre-emptive HFNC after, when compared to low-flow oxygen extubation in low-risk patients, has been shown to reduce the need for reintubation in a paper published by Hernandez et al.. Recently, the same group reported the results of a multicentre non-inferiority randomised trial comparing the effects of NIV and HFNC after extubation in non-hypercapnic patients at high risk of weaning failure.
The authors successfully enrolled 604 patients (40% of whom had respiratory failure as admission cause), who underwent pre-emptive face-mask NIV or HFNC for 24 hours after extubation and, afterwards, low-flow oxygen.
The rate of the primary endpoint (crude reintubation within 72 hours) was not different between patients treated with NIV (19%) and HFNC (23%), nor different was the rate of reintubation due to post-extubation respiratory failure. More patients experienced respiratory failure in the NIV group (50%) than in the HFNC group (27%). Time to reintubation was the main safety issue and was not different in the two groups.
As is well acknowledged by the authors, the rate of the primary endpoint in the NIV group was slightly higher than the one observed in previous studies with similar design[4, 5]. The short-term protocol (only 24 hours) and the avoidance of sedative use to enhance comfort during the treatment may have limited NIV efficacy and contributed to the higher incidence of respiratory failure during NIV. Indeed, comfort appears crucial for NIV success and up to 10% of patients may fail the treatment due to intolerance[9, 10]. In this sense, recent data seem to suggest a higher efficacy of helmet as compared to face mask interface in patients with acute hypoxemic respiratory failure, while we cannot know if such a difference between interfaces may exist after extubation too. Finally, some authors have hypothesised that pre-emptive NIV after extubation in hypoxemic patients could exert the most beneficial effects if combined with early extubation. In this case, a conventional weaning approach was used in both groups, possibly mitigating any significant difference between treatments.
Nonetheless, the study was well conducted and results seem to be reproducible and with good external validity. High-flow oxygen may be considered as a safe alternative to face-mask NIV as pre-emptive strategy after extubation in patients with high likelihood of weaning failure. Categories of patients that may best benefit from one or the other treatment have yet to be identified, while NIV remains the optimal management in hypercapnic patients undergoing scheduled extubation.
Article review submitted by EJRC member Domenico Luca Grieco.
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