In Summary, for those who received the non-invasive ventilation:

Benefits in NNT

  • 70-80% saw no benefit
  • 12% were helped by avoiding death
  • 20% were helped by avoiding intubation
  • 1 in 8 were helped (preventing death)
  • 1 in 5 were helped (avoiding intubation)

Harms in NNT

  • 0% were harmed by non-invasive technique side effects
  • None were harmed (non-invasive technique side effects)

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Source: Ram FSF, Picot J, Lightowler J, Wedzicha JA. Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease. Cochrane Database of Systematic Reviews 2004, Issue 3. Art. No.: CD004104. DOI: 10.1002/14651858.CD004104.pub3.

Efficacy Endpoints: Reduction of mortality, Need for intubation, likelihood of treatment failure and complications, duration of stay in the hospital

Harm Endpoints: None

Narrative: Chronic obstructive pulmonary disease (COPD) is a progressive lung disease, often caused by smoking, which includes patients with a diagnosis of chronic bronchitis and emphysema. Acute exacerbations are characterized by worsened dyspnea, increased volume and/or purulence of phlegm, and consequent hypoxemia and worsened hypercapnia. Hospitalization and mortality rates are on the rise, with COPD now being the fourth leading cause of death in Canada1.

The eight studies included subjects with elevated pC02 and acute exacerbation of COPD randomized to either noninvasive positive pressure ventilation (NPPV) through a nasal or facemask in addition to usual medical care, or usual care without NPPV. Results showed a clear benefit across a variety of outcomes for NPPV. Seven studies found that the use of NPPV significantly reduced the risk of treatment failure (aggregate relative risk 0.48) as compared to usual medical care. Hospital length of stay was reduced by more than three days; furthermore, the risk of complications secondary to endotracheal intubation was reduced by 62%, primarily by eliminating the need for mechanical ventilation in many cases. Early correction of pH, PaCO2 and respiratory rate within the first hour of NPPV treatment also appeared to be critical in reducing the work of respiratory muscles and preventing respiratory failure.

Caveats: The studies included in the review lacked blinded treatment protocols because of the impracticality of constructing a sham NPPV arm. Furthermore, the data at one hour did not necessarily include all patients who started treatment, as some may have already required intubation or died before the one-hour data measurement. Thus, the reported improvement in physiologic metrics may have been overestimated.

In addition the cohort is small. A total of 758 subjects are included in relevant trials, and for a number of calculated outcomes not all of these are included. The lack of blinding and small numbers reduce statistical precision, and they raise some concern about the possibility of type I errors (interpreting the data as showing a benefit when no true benefit exists). The less invasive nature of NIPPV, the established difficulty in weaning COPD patients from ventilator dependence following endotracheal intubation, and the broad experience of clinicians, however, all seem to support NIPPV as a reasonable and often advantageous alternative to intubation whenever possible in these patients.

Author: Brittany Beingessner, MD

Published/Updated: February 20, 2013

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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