High flow O2 in ARDS?

High flow O2 vs standard O2 vs NIV in reducing intubation rates and mortality in ARDS

This is a prospective, multicenter, randomized, controlled trial


Exclusion criteria: Paco2 of more than 45 mm Hg, exacerbation of asthma or chronic respiratory failure, cardiogenic pulmonary edema, severe neutropenia, hemodynamic instability, use of vasopressors, a Glasgow Coma Scale score of 12 points or less (on a scale from 3 to 15, with lower scores indicating reduced levels of consciousness), contraindications to noninvasive ventilation, urgent need for endotracheal intubation, a do-not-intubate order, and a decision not to participate.


  1. Physicians could not be blinded, so there is a potential for bias here. However, the commitee members analyzing the data were blinded to the patients’ allocation.
  2. Only patients with stable ARDS (no resp.acidosis and mean BP was 130/90) were included. The trial excluded patients with co-morbid conditions and PaCO2>45 mmHg.
  3. High flow O2 could be stopped and patients could switch to standard O2 therapy after 2 days. Similarly, in between NIV, high flow O2 was given to patients.
  4. This study is underpowered to detect between group difference in rate of intubation, although post-hoc study in patients with hypoxemia (FiO2:PaO2 <200), there was significant difference between the rate of intubation (High flow O2 35%, Standard O2 53%, NIV 58%, p=0.009)
  5. In my opinion, mortality should be the primary outcome. This study is not powered to detect mortality difference. However, the study showed significant mortality reduction in ICU and in day 90 in high flow O2 group.


High flow O2 is possibly better than standard O2 therapy and NIV in ARDS, especially in hypoxaemic group of patients. Caveat being this is a study of patients with NO CO2 retention.

Reference: Jean-Pierre Frat et al. High-Flow Oxygen through Nasal Cannula in Acute Hypoxemic Respiratory Failure. N Engl J Med 2015; 372:2185-2196.


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