Noninvasive Ventilation Intolerance: Characteristics, Predictors, and Outcomes

Abstract

BACKGROUND: Noninvasive ventilation (NIV) intolerance is one reason for NIV failure. However, the characteristics, predictors, and outcomes of NIV intolerance are unclear. METHODS: A prospective observational study was performed in the respiratory intensive care unit of a teaching hospital. Subjects with acute respiratory failure who used NIV were enrolled. Initially, continuous use of NIV was encouraged. However, if the subject could not tolerate NIV, it was used intermittently. NIV intolerance was defined as termination of NIV due to subject refusal to receive it because of discomfort, even after intermittent use was attempted. RESULTS: A total of 961 subjects were enrolled in the study. Of these, 50 subjects (5.2%) experienced NIV intolerance after a median 2.4 h of NIV support. Age (OR ‫؍‬ 0.98, 95% CI 0.963-0.996) and heart rate (OR ‫؍‬ 1.02, 95% CI 1.006 -1.030) measured before NIV were 2 independent risk factors of NIV intolerance. After 1-2 h of NIV, independent risk factors of NIV intolerance were heart rate (OR ‫؍‬ 1.03, 95% CI 1.016 -1.044) and breathing frequency (OR ‫؍‬ 1.06, 95% CI 1.027-1.099). Intolerant subjects had no improvement in mean arterial pressure, heart rate, or breathing frequency after the NIV intervention. Moreover, intolerant subjects had a higher intubation rate (44.0% vs 25.8%, P ‫؍‬ .008) and higher mortality (34.0% vs 22.4%, P ‫؍‬ .08). The three most common complaints were that NIV worsened subjects' distress (46%), that NIV resulted in dyspnea (26%), and that the flow or pressure of NIV was too strong to bear (16%). CONCLUSIONS: NIV intolerance worsened subjects' outcomes. Younger subjects with a high heart rate and breathing frequency may be more likely to experience NIV intolerance.

Noninvasive ventilation with helmet versus control strategy in patients with acute respiratory failure: a systematic review and meta-analysis of controlled studies

“…The patient tolerance scale in the helmet group was remarkably higher than in the facial mask control group [14, 17, 29, 39]. Better tolerance allowed a longer continuous application [14, 31] and increased the success rate of NIV [40]. In fact, no patients failed NIV as a result of claustrophobia, discomfort, or pain related to a helmet while 38 % patients might have a failed NIV owing to a mask [14], which would increase hospital mortality.…”

Noninvasive Ventilation: Do Not Tolerate Intolerance

“…9,11 The main explanation for this finding may be the mild severity in these subjects compared with subjects in previous studies. Because decreased severity is associated with better tolerance, the low severity of symptoms in the subjects included by Liu et al 13 could explain the low prevalence of poor tolerance in their study. As expected, the authors reported a poorer outcome in subjects with intolerance, since subjects experiencing NIV intolerance were more frequently intubated (44% vs 26%, P ϭ .008) and presented a trend toward higher mortality (34% vs 22%, P ϭ .08).…”

“…The study by Liu et al 13 has a number of limitations. First of all, the authors did not look for the presence of patient-ventilator asynchrony.…”

“…As expected, the authors reported a poorer outcome in subjects with intolerance, since subjects experiencing NIV intolerance were more frequently intubated (44% vs 26%, P ϭ .008) and presented a trend toward higher mortality (34% vs 22%, P ϭ .08). It is noteworthy that Liu et al 13 asked subjects to describe any complaints in relation to NIV. Although many types of complaints were observed, three complaints were most frequently reported: (1) NIV worsened subjects' distress (46%), (2) NIV resulted in dyspnea (26%), and (3) the flow or pressure of NIV was too strong to bear (16%).…”

“…From a practical point of view, NIV intolerance could be defined as the need to discontinue NIV because the patient is no longer able to tolerate NIV. This definition was used in this original study from Liu et al, 13 who prospectively enrolled 961 subjects receiving NIV as first-line treatment of acute respiratory failure, mostly related to an exacerbation of COPD or pneumonia. The main finding of their study was the low level of NIV intolerance (5.2%).…”