Screen Shot 2018-07-18 at 11.47.58 AMThe Article:

Doshi. P. High-Velocity Nasal Insufflation in the Treatment of Respiratory Failure: A Randomized Clinical Trial. Ann Emerg Med. 2018;72:73-83.


To be or not to be, chocolate or vanilla, Bipap or High Flow… That is the question. In respiratory failure which modality is best for the distressed patient to prevent intubation. I’ve always thought that Bipap for CHF, High flow for everything else. This week we have a study that looked at this question…

The Summary

This was a prospective multicenter RCT of high flow (HF) vs BiPAP in patients with respiratory distress. The “distress” was defined by clinician judgement at the time.  The authors concluded this trial showed HF was non-inferior to BiPAP because of a difference of less than 15% of patients were intubated at 72 hours (7% vs 13%, respectively). However, it is a little more complicated than that.  HF did have less intubations at 72 hours but it also had more patients fail that pathway and crossover to BiPAP than did in the BiPAP arm. I think a larger study that excluded CHF patients would be great. The bottom line is I still think BiPAP for CHF and high flow for all other respiratory distress.  If you want the nitty gritty it’s below

The Dirty Details

Study Method: Prospective Multicenter, parallel group RCT of high flow and BIPAP in 5 centers in the US.  A sample size of 204 patients (102 in each arm) was calculated such that a test of proportions with a .05 significance level and 90% power with a noninferiority margin for intubation of 15%.  Analyses were based on an intention-to-treat

Study Population: >18 yo with clinical judgment of the treating clinician of acute respiratory failure requiring escalation to BIPAP.

Exclusion criteria: overdose, CV instability, end stage cancer, life expectancy less than 6 months, significant respiratory depression on presentation (e.g., drug overdose), Glasgow Coma Scale score less than 9, cardiac or respiratory arrest on presentation, need for emergency intubation, known or suspected cerebrovascular accident, known or suspected ST-segment elevation myocardial infarction, and patients with increased risk of pulmonary aspiration, agitation, or uncooperativeness.

Primary Outcome: The primary outcomes were treatment failure rate, defined as the need for intubation, and arm failure rate, defined as the decision for crossover to the alternate therapy, within 72 hours of initiation of assigned therapy. Failure of the assigned noninvasive ventilatory therapy was defined as failure to tolerate therapy, failure to oxygenate, failure to ventilate, failure to alleviate respiratory distress, or deteriorating medical status.

Hypothesis Generation: Secondary outcomes included evaluation of the ability of high-velocity nasal insufflation versus BiPAP to affect the degree and timing of changes of PCO2, pH, and other signs or symptoms of respiratory distress, including vital signs and perceived exertion scores reported by the patients.


Patients Enrolled: 228 patients from October 2014 to September 2016. 204 were enrolled in the trial, 24 patients randomized but not enrolled (You can’t do that, No soup for you!)

Demographics:  APACHE II scores were similar in both (6.3 vs 6.5). Mean baseline PCO2 level was 53.4 mm Hg in the high-velocity nasal insufflation group and 58.7 mm Hg in the BiPAP group. The most common condition treated was COPD, both in terms of presenting condition (39%) and discharge diagnosis (26%). The second most common discharge diagnosis was acute decompensated heart failure (21%), followed by pneumonia (14%) and acute multifactorial hypoxic and hypercapnic respiratory failure (14%).

BIPAP Dose: High-velocity nasal insufflation was titrated to a mean flow rate of 30 L/min, BiPAP was titrated to mean settings of 13 cm H2O over 6 cm H2O

Noninferiority=15% difference High Flow BiPAP
N 104 100
Intubation at 72hr* 7 (7%) 13(13%)
Mode Success 77 (74%) 83 (83%)
Mode Failure 27 (26%) 17 (17%)
Intubated 4 (4%) 11 (11%)
Crossed Over 23 (22%) 6 (6%)
Intubated after Cross over 3 (13%) 3 (50%)

The Bottom Line

So essentially this trial would argue statistically that High Flow is non-inferior to BiPAP.  However, it is a little more confusing than that. Starting with HF there were fewer overall intubations. However, there were more “failures” in the HF also where more people crossed over to BIPAP (were those the CHF patients?). Unfortunately, these are things we don’t know. So, I don’t think this will change my practice much as of now although I already do a fair amount of High Flow but I will still keep doing BiPAP in CHF until I see otherwise. From my clinical experience BiPAP works so well for CHF.


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