BACKGROUND: The use of noninvasive ventilation (NIV) in the emergency setting to reverse hypercapnic coma in frail patients with end-stage chronic respiratory failure and do-not-intubate orders remains a questionable issue given the poor outcome of this vulnerable population. We aimed to answer this issue by assessing not only subjects' outcome with NIV but also subjects' point of view regarding NIV for this indication. METHODS: A prospective observational case-control study was conducted in 3 French tertiary care hospitals during a 2-y period. Forty-three individuals who were comatose (with pH < 7.25 and P aCO 2 > 100 mm Hg at admission) were compared with 43 subjects who were not comatose and who were treated with NIV for acute hypercapnic respiratory failure. NIV was applied by using the same protocol in both groups. They all had a do-notintubate order and were considered vulnerable individuals with end-stage chronic respiratory failure according to well-validated scores. RESULTS: NIV yielded similar outcomes in the 2 groups regarding in-hospital mortality (n ‫؍‬ 12 [28%] vs n ‫؍‬ 12 [28%] in the noncomatose controls, P > .99) and 6-month survival (n ‫؍‬ 28 [65%] vs n ‫؍‬ 22 [51%] in the noncomatose controls, P ‫؍‬ .31). Despite poor quality of life scores (21.5 ؎ 10 vs 31 ؎ 6 in the awakened controls, P ‫؍‬ .056) as assessed by using the VQ11 questionnaire 6 months to 1 y after hospital discharge, a large majority of the survivors (n ‫؍‬ 23 [85%]) would be willing to receive NIV again if a new episode of acute hypercapnic respiratory failure occurs. CONCLUSIONS: In the frailest subjects with supposed end-stage chronic respiratory failure that justifies treatment limitation decisions, it is worth trying NIV when acute hypercapnic respiratory failure occurs, even in the case of extreme respiratory acidosis with hypercapnic coma at admission.