Using NIV in a patient with altered mental status (AMS)?

Learn about the subset of patients with altered mental state (AMS) that are candidates for NIV in this article.
Last update26th Nov 2020

Conventional teaching states that altered mental status (AMS) is a contraindication to use of noninvasive ventilation (NIV) due to three main concerns:

  1. Patients with certain types of AMS have a risk of developing aspiration with positive-pressure ventilation, or NIV.
  2. Patients whose AMS results in agitated behavior may have reduced cooperation with a tight-fitting NIV mask.
  3. Due to the tight seal of the NIV mask, secretions cannot be cleared from their mouth if needed.

But not all altered mental status is the same! The presence of AMS is not as important as the type of AMS. For example, patients with coma are different from patients with agitated delirium or patients with confusion.

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Using NIV for patients with coma

Literature supports the use of NIV in patients with a low Glasgow Coma Scale (GCS) score. In fact, NIV can be successful in patients with a GCS score of less than 8, especially if the cause of the low GCS score is due to confusion from hypercapnia such as in acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Similarly, mental status changes such as delirium due to an infection may also be amenable to the use of NIV.

Figure 1. The literature supports the use of noninvasive ventilation (NIV) in a subset of patients with a low Glasgow Coma Scale (GCS) score. NIV can be used for patients with confusion due to hypercapnia or delirium, but it is not recommended for patients in a deep coma due to neurological injury such as seizure or stroke.
However, patients in a deep coma due to neurological injury, such as seizure, stroke, or similar diseases, would likely not be candidates since it would be atypical for the altered mental status to be rapidly reversed or controlled with medications or supportive care.

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Recommended reading

  • Gónzalez Díaz, G, Alcaraz, AC, Talavera, JCP, et al. 2005. Noninvasive positive-pressure ventilation to treat hypercapnic coma secondary to respiratory failure. Chest. 127: 952–960. PMID: 15764781
  • ​Scala, R, Naldi, M, Archinucci, I, et al. 2005. Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness. Chest. 128: 1657–1666. PMID: 16162772

About the author

Michael Allison, MD
Chief of Critical Care Medicine at the University of Maryland St. Joseph Medical Center, USA.
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