Does prophylactic noninvasive ventilation prevent reintubation in obese patients?

And should NIV be provided more often?

After liberation from mechanical ventilation, obese patients may be at increased risk for recurrent respiratory failure and reintubation.

Obesity reduces lung volumes, especially functional residual capacity, producing atelectasis and propensity to hypoxemia and hypoventilation.

Noninvasive ventilation (NIV) may help recruit posterior alveoli and improve ventilation and oxygenation. NIV is commonly used in obese patients who show signs of respiratory difficulty after extubation.

Should noninvasive ventilation be applied to all obese patients after extubation, as a standard measure to prevent reintubation?

At least three randomized trials have examined this question in recent years.

In all three trials, obese patients with respiratory failure were randomized to receive noninvasive ventilation or oxygen immediately or as soon as possible after extubation.

1. HIGH-WEAN

At multiple ICUs in France, 648 patients considered to be at high risk for failing extubation (due to age, cardiac, or respiratory disease) were randomized to NIV plus high-flow oxygen or high-flow oxygen alone, applied immediately after extubation.

About one-third (n=203) were obese and another third (n=213) were overweight.

In the overall group, those receiving NIV had a reintubation rate of 11.8% vs. 18.2% (statistically significant) at 7 days. There was a non-significant mortality reduction with the use of NIV (6% with NIV+O2 vs. 9% with O2 alone).

In a post hoc analysis of the obese patients (not pre-specified), there was a strong correlation between NIV’s effects and obesity or overweight:

• At 7 days, 7% of obese or overweight patients treated with NIV were reintubated, vs. 20% receiving oxygen alone (p=0.0002).

• Among obese patients only, reintubation rates were 6% with NIV vs. 18% with high-flow oxygen alone.

• Normal-weight patients had no significant difference in reintubation rates according to whether NIV or oxygen alone was delivered.

Trials testing reintubation decisions have a large and unavoidable potential for bias due to their unblinding. Two signals suggested the higher intubation rates with oxygen alone were not primarily due to clinician bias in decision-making based on treatment assignment:

• More patients in the oxygen group overall had post-extubation respiratory failure according to prespecified criteria at 7 days (29% vs 21%).

• Over a longer period (through ICU discharge), more patients were reintubated in the oxygen group (20% vs. 12%), arguing against the existence of “gaming” around the 7-day mark.

ICU mortality was also significantly lower in obese or overweight patients treated with prophylactic NIV (2% vs. 9%, p=0.006).

The French Ministry of Health funded the study. The authors reported prior financial support from Fisher & Paykel, marketers of noninvasive ventilation equipment.

Thille et al JAMA 2019

Thille et al AJRCCM 2022