Contributor: Alec Coston, MD

Educational Pearls:

BiPAP is often effective in severe asthma, but many patients struggle with mask tolerance due to intense air hunger–driven anxiety, often compounded by hypoxia.
Benzodiazepines are commonly used for anxiety, but they can depress respiratory drive, making clinical improvement difficult to interpret (a lower RR may reflect sedation rather than true physiologic improvement).
Low-dose fentanyl is a useful alternative when patients cannot tolerate BiPAP despite coaching.

Opioids blunt the perception of dyspnea and are well established for treating air hunger.
When carefully titrated, fentanyl provides anxiolysis without significant respiratory suppression.
It is rapidly titratable (e.g., 25 mcg IV every 5 minutes).

Evidence primarily comes from palliative and oncology literature, but growing clinical experience supports its use in severe asthma to improve BiPAP tolerance.
Failure of fentanyl should prompt escalation to ketamine, often signaling impending need for intubation.

References

Pang GS, Qu LM, Tan YY, Yee AC. Intravenous Fentanyl for Dyspnea at the End of Life: Lessons for Future Research in Dyspnea. Am J Hosp Palliat Care. 2016 Apr;33(3):222-7. doi: 10.1177/1049909114559769. Epub 2014 Nov 25. PMID: 25425740.

Summarized and edited by Meg Joyce, MS2