What are limitations to noninvasive ventilation (NIV) in patients with chronic obstructive pulmonary disease (COPD)?

Updated: Jun 18, 2020
  • Author: Guy W Soo Hoo, MD, MPH; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Additional experience with noninvasive ventilation in hypercapnic COPD has helped to identify possible thresholds for its application. Severely hypercapnic patients with severe respiratory acidosis and lethargy or even frank coma related to the hypercapnia were often excluded from trials of noninvasive ventilation because of concerns for progressive respiratory failure and an inability to cooperate with noninvasive ventilation as a result of their carbon dioxide narcosis.

In some centers, patients with an initial pH of less than 7.25 and a Glasgow Coma Scale score of less than 11 had noninvasive ventilation failure rates of 70% or greater. [15] Some report successful application of noninvasive ventilation in patients with a Glasgow Coma Scale score less than 8 and an average pH of 7.13 ± 0.06 (mean ± standard deviation), with 76 (80%) of 95 patients responding to treatment with noninvasive ventilation. [16] Others have had less success, grading sensorium using a Kelly score of 4 or more defined as a stuporous patient, only intermittently able to follow commands, and an average pH of 7.22, where the success rate was 55% in a group of 20 patients. [17] However, in all of these series, improvement after 1-2 hours noninvasive ventilation was predictive of success.

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