Using High-Flow Oxygen to Treat Infants With Bronchiolitis

Bronchiolitis is the number one cause of nonelective admission worldwide. Emergency medicine professionals everywhere, regardless of any specialized pediatric emergency medicine training, treat children with bronchiolitis. We see this disease process so frequently that it has its own season in most geographic locations, and staffing for departments is adjusted according to it. I felt that this study, published in the New England Journal of Medicine , is one we would all benefit from knowing about and discussing.^[1]

Study Summary

This was a multicenter, randomized trial comparing a "standard" therapy group of patients receiving supplemental oxygen via nasal cannula and a "high-flow" therapy group of patients receiving supplemental oxygen via a high-flow nasal cannula (HFNC) through an Optiflow^™ system (Fisher & Paykel Healthcare; Auckland, New Zealand). A final study population of 1472 patients enrolled between 2013 and 2016 were randomized into the two groups.

The study took place in emergency departments and inpatient pediatric wards at 17 hospitals in Australia and New Zealand. Clinicians were not blinded to the treatment groups owing to the obvious visual difference between the two therapies, but they were blinded to the outcome data until all data were fully collected.

The primary outcome for this study was treatment failure requiring escalation of care on the basis of meeting at least three of four prespecified criteria. Escalation of care was defined as a need for transfer to an intensive care unit (ICU), or the need for increased respiratory support. For patients in the standard therapy group, if their conventional supplemental oxygen therapy was failing, clinicians were able to escalate to HFNC if they felt it was clinically appropriate.

The four prespecified criteria were:

• Heart rate that remained stable or increased during admission;

• Respiratory rate that remained stable or increased during admission;

• Oxygen requirement exceeding an FiO₂ of 40% in the HFNC group or exceeding 2 L/min in the standard therapy group; and

• Triggering of the hospital's internal early warning tool, which led to immediate medical review and suggestion to escalate care.

Each of the 17 sites enrolled in the study had the early warning tool in place, which consisted of a variety of factors, such as patient vital signs, condition, and workup results; 11 sites used an identical tool, whereas the remaining 6 used comparable tools.

Bronchiolitis was defined per the American Academy of Pediatrics criteria. Inclusion criteria for patients were age 12 months or younger and presentation to an emergency department or inpatient ward with signs of bronchiolitis and need for oxygen to keep saturations at specified levels. At 11 study sites, saturation targets for supplemental oxygen were set at 94%-98% on the basis of site-specific policy. At the remaining six sites, saturation targets for supplemental oxygen were set at 92%-98%.

Exclusion criteria included patients with an immediate need for ICU admission or respiratory support with intubation; patients with a history of cyanotic heart disease, basal skull fracture, upper-airway obstruction, or craniofacial abnormalities; and patients who were already on oxygen therapy at home.

The treatments in the two study groups were as follows. In the HFNC group, patients received heated, humidified oxygen at a rate of 2 L/kg/min via an Optiflow circuit. FiO₂ was adjusted for saturations either between 92% and 98%, or 94% and 98%, depending on the site as mentioned above. Treatment with HFNC was stopped if patients randomly assigned to this group maintained saturations above 92% or 94%, on the basis of site, for more than 4 continuous hours. In the standard therapy group, patients received oxygen via nasal cannula at up to 2 L/min to maintain saturations between 92% and 98% or 94% and 98%, depending on the site. Weaning of oxygen was allowed on the basis of clinical condition, and patients were encouraged to start enteral feeding as clinically tolerated, especially if they were actively weaning off oxygen.

When the data were analyzed, researchers found that treatment failed in 12% of patients (n = 87) in the HFNC group and 23% of patients (n = 167) in the standard therapy group. This resulted in a risk difference of -11 points (95% confidence interval [CI], -15 to -7; P < .001). The number needed to treat to prevent one incident of escalation of care was 9 patients (95% CI, 7-14 patients). Multiple secondary outcomes were evaluated, but none were found to have a significant difference.

Viewpoint

I felt this was a well thought-out and executed study, the largest of its kind I am aware of, and that it provides us with useful data to suggest that utilization of HFNC earlier in the treatment of bronchiolitis when oxygen therapy is indicated may prove beneficial for our patients.

The study certainly has multiple limitations, which the authors were up front about. Clinicians were not blinded to HFNC or standard therapy. In addition, owing to the practice patterns where the study was conducted and for ethical reasons, the treating clinicians for patients randomly assigned to the standard therapy group were permitted to escalate to HFNC if needed, which may have caused some confounding. Furthermore, as with any study, widespread implementation of any treatment outside of the geographic area included in the study must be done with caution, owing to significant differences in the patient populations where you and I practice compared with where this study took place.

Although HFNC is a resource that may not be available everywhere, and the decision to use it has implications for cost and disposition in most emergency departments, no other treatment option has been shown to improve outcomes time and time again for children with bronchiolitis. Local practice patterns, clinician preferences, and the availability of pediatric intensivists and specialists for consultation and disposition decisions are just a few of the many other good reasons why implementing HFNC in more cases may be challenging.

As with any study, further research that includes more geographic locations must be conducted before widespread change can be made to clinical practice. The researchers did convince me that if supplemental oxygen is needed, it may be better for my patients to receive treatment with HFNC to avoid ultimate escalation in care at a later point in time.