Noninvasive Ventilation vs High-Flow Nasal Oxygen After Extubation

• In ICU
• Mon, 12 May 2025

In ICUs, extubation decisions are challenging, as 20-30% of patients experience post-extubation respiratory failure, with 10-15% requiring reintubation. Reintubation has high mortality rates and is a key patient outcome in the post-extubation period. 

Noninvasive ventilation (NIV) and high-flow nasal oxygen (HFNO) therapies, when applied immediately after extubation, reduce the risk of reintubation compared to standard oxygen. Studies show that both NIV and HFNO reduce inspiratory efforts, though NIV may be more effective in patients at high risk of extubation failure. The most recent guidelines recommend NIV over HFNO for these patients. However, no study has compared the effects of NIV and HFNO on inspiratory efforts after extubation. Understanding these effects is crucial, as NIV may lower inspiratory efforts more than HFNO, which could benefit patients experiencing respiratory muscle weakness, alveolar derecruitment, or impaired ventilation post-extubation. Additionally, NIV may improve tidal volumes and lung recruitment, which could further reduce the risk of reintubation.

In a prospective physiological study, high-risk extubation failure patients (over 65 years old or with underlying cardiac or respiratory disease) were randomly assigned to receive prophylactic NIV and HFNO after planned extubation, followed by standard oxygen. The study assessed inspiratory efforts using the simplified esophageal pressure-time product (sPTPes) and measured tidal volumes, ventilation distribution, and homogeneity with electrical impedance tomography.

The analysis included 20 patients. Inspiratory efforts were lower with NIV than with HFNO (sPTPes 196 cm H2O s/min vs. 220), and tidal volumes were larger with NIV (8.4 mL/kg vs. 6.9 mL/kg). There was a non-significant increase in ventilation in the dorsal region with NIV compared to HFNO.

In this study, NIV significantly reduced inspiratory efforts compared to HFNO and standard oxygen while also increasing tidal volumes and minute ventilation. NIV promoted more posterior ventilation with a non-significant increase in end-expiratory lung inflation (EELI). These findings suggest that NIV effectively relieves inspiratory workload and may aid in re-aerating lung regions. However, there was no difference in dynamic compliance, and NIV led to a modest but significant increase in transpulmonary swings.

A recent physiological study showed that HFNO significantly reduced inspiratory efforts compared to standard oxygen after extubation, which may explain its reduced risk of reintubation in patients with mild hypoxemia. However, in the current study, while a trend towards reduced inspiratory efforts with HFNO was observed, it did not reach statistical significance. The study included low-risk patients, and larger inspiratory efforts may have underestimated HFNO's benefits. Despite this, other clinical trials also found no significant difference in reintubation risk between HFNO and standard oxygen after extubation. Although HFNO is recommended by clinical guidelines, this recommendation remains conditional with low certainty.

In contrast, older physiological studies showed that NIV significantly reduced inspiratory efforts compared to standard oxygen in high-risk patients after extubation. NIV has even been found to reduce diaphragm energy expenditure in patients with chronic respiratory disease. Studies also suggest that NIV reduces the risk of post-extubation respiratory failure and reintubation compared to standard oxygen. Several trials have shown that NIV is more effective than HFNO in reducing reintubation risk in high-risk patients. As a result, NIV is recommended for these patients by clinical guidelines with moderate certainty of evidence. The lower inspiratory efforts under NIV observed in this study may play a major role in its clinical benefits.

NIV resulted in significantly larger tidal volumes than HFNO, leading to increased minute ventilation. This was likely due to re-aeration of lung regions, particularly the dorsal areas, which may help reverse atelectasis in patients with respiratory muscle weakness. Despite low levels of pressure support (4 cm H2O), NIV still had this effect, and higher levels of pressure support may further enhance these benefits. However, while large tidal volumes under NIV can be associated with increased mortality in acute hypoxemic respiratory failure, the tidal volumes in this study were modest and below the threshold seen as harmful in acute respiratory failure. Thus, in the post-extubation setting, the risk of ventilation-induced lung injury may be negligible, and larger tidal volumes may even be beneficial.

NIV also improved the homogeneity of ventilation by reducing the pendelluft phenomenon compared to standard oxygen, though the difference between NIV and HFNO was not significant. The modest reduction in pendelluft may not have a clinically significant impact, and the inhomogeneity index showed no differences. Surprisingly, tidal volumes were lower under invasive ventilation compared to NIV despite lower pressure support and PEEP under NIV. This counterintuitive result likely reflects critical differences in experimental conditions, such as the effects of the endotracheal tube and reduced mobility in invasive ventilation.

In high-risk patients for extubation failure, prophylactic NIV reduced inspiratory efforts and increased tidal volumes, with stable dynamic compliance and potential re-aeration of lung regions, compared to HFNO and standard oxygen. These results offer valuable insights into the clinical effects of NIV in the post-extubation setting.

Source: Critical Care

Image Credit: iStock 

References:

Arrive F, Le Pape S, Bruhn A et al. (2025) Physiological comparison of noninvasive ventilation and high-flow nasal oxygen on inspiratory efforts and tidal volumes after extubation: a randomized crossover trial. Crit Care. 29, 185.