Why We Use Non-invasive Ventilation for COPD

On the Shoulders of Giants

Spoon Feed
Non-invasive ventilation (NIV) in patients with acute exacerbation of COPD decreased the need for intubation and reduced in-hospital mortality.  Since this trial in 1995, many more studies have shown the same thing.  This treatment really works to keep patients off the ventilator and to reduce mortality.

Why does this matter?
Prior to this, it was not clear whether NIV (pushing air in with each breath), would benefit patients who already had an obstructive ventilatory defect (i.e. can't get air out).  This study, and others, showed this practice was beneficial, even life saving.

Pink-puff and Blue-bloat
This was a small, early, European RCT of 85 patients with acute COPD exacerbation.  Each group was given standard treatment, which included, "subcutaneous heparin, antibiotic agents, and bronchodilators (subcutaneous terbutaline, aerosolized and intravenous albuterol, and corticosteroids or intravenous aminophylline or both)."  Obviously, some of the treatments have changed over the past 22 years.  One group was given NIV versus nasal cannula in the control group.  Specifically, NIV consisted of a sealed mask that delivered pressure support at 20cm with no PEEP.  So this was iPAP, not BiPAP.  They found that the NIV group had an intubation rate of 26% vs. the control group, which had an intubation rate of 74%; NNT = 2.  The decision to intubate was based on objective criteria, established a priori.  Also a secondary outcome, in-hospital mortality, was lower in the NIV group: 9% vs 29% in the control group; NNT = 5.  The study was limited by the fact that the treating doctors could not be blinded, so this could have led to more in the control group getting intubated.  But the objective, a priori criteria for intubation likely mitigated this limitation.

Source
Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease.  N Engl J Med. 1995 Sep 28;333(13):817-22.

Another Spoonful

  • A Cochrane review from July 2017 pooled 17 clinical trials of NIV for COPD and found that it is a very good thing for patients, reducing need for intubation by 65% and decreasing mortality by 46% and also found it decreased length of hospital stay by about 3.5 days.
  • The NNT found that the pooled NNT for intubation was 5 and for mortality was 8.  This means that for every 5 patients with an acute COPD exacerbation started on NIV, one would not progress to needing mechanical ventilation; and for every 8 patients on NIV, one would not die.  That's kind of a big deal...
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