Probably thanks to heterogeneous patient populations and inter-institutional differences, non-invasive ventilation (NIV) has had variable reported success rates in weaning from mechanical ventilation and prevention of reintubation. A BMJ 2009 meta-analysis concluded NIV had “net positive” effects as a weaning mode, acknowledged the variable benefits in included studies, and noted possible greater benefits in COPD patients.
In the VENISE clinical trial protocol, which can only be described as “qui a du cran” (English translation), Girault et al randomized 208 mechanically ventilated patients (70% with respiratory failure due to COPD) in French and Tunisian ICUs who failed a spontaneous breathing trial to either be:
- Tried again the next day on either T-piece or pressure support (n=69);
- Extubated 30 minutes later to non-invasive ventilation (n=69);
- Extubated 30 minutes later to oxygen therapy only (n=70).
There was no difference in reintubation rates at 7 days (which were 30%, 32%, and 37% in groups 1, 2, 3 respectively), nor in the time to reintubation. Use of NIV resulted in fewer days of invasive ventilator support (of course), but also a longer overall period of ventilator support.
However, they also confusingly report that only 6 of 69 (9%) in the NIV group had postextubation acute respiratory failure — defined by a broad set of reasonable criteria (that any patient requiring reintubation would almost universally meet). Authors’ conclusion: NIV may help prevent postextubation acute respiratory failure (but not prevent reintubation?!).
These two statements to me are completely incongruous — if 91% in the NIV group did not have postextubation respiratory failure, why were 32% reintubated? I read (okay, aggressively scanned) this article three times for a plain English (or even French) explication of this finding, to no avail. If you can interpret this better than I, please comment. Regardless, authors caution against concluding that NIV is definitively beneficial without a larger prospective randomized trial powered for this endpoint.
Girault C et al. Noninvasive Ventilation and Weaning in Patients with Chronic Hypercapnic Respiratory Failure. Am J Resp Crit Care Med 2011;184: 672-679.