Does High Flow Oxygen therapy play a roll inside as well as outside "the ICUs box" in Bronchiolitis?

Bronchiolitis is the most common reason worldwide for nonelective hospital admission in infants. In the USA, it’s responsible for $1.7 billion in hospitalization costs annually. In Australia and New Zealand, there has been a population-based increase in admissions to the ICU for bronchiolitis, with associated increases in hospital costs.

High-flow nasal cannula oxygen therapy (HFO) has been increasingly used in infants with this diagnosis, despite limited high-quality evidence of its efficacy. Its efficacy in settings other than ICUs is nuclear, but evidence is growing.

This was a multicenter, randomized, controlled trial, including emergency departments and general pediatric inpatient units in 17 tertiary and regional hospitals in Australia and New Zealand. It assigned infants under than 12 months of age wiht bronchiolitis and a need for supplemental oxygen therapy (to keep oxygen saturation level in the range of 92 (94) to 98%) to receive either HFO (HFO group – 2L/kg/min delivered by Optiflow system with the use of age-appropriate Optiflow Junior cannula and the Airvo 2 HFO system) or standard oxygen therapy (standard-therapy group – up to a maximum of 2L/min). Those in the standard-therapy group could receive rescue HFO if their condition met criteria for treatment failure. Infants were recruited between October 2013 and August 2016.

The primary outcome was escalation of care due to failure, defined as meeting at least 3 of 4 clinical criteria: persistent tachycardia, tachypnea, hypoxemia, and medical review signaled by a hospital early-warning tool. Secondary outcomes included duration of hospital stay, of oxygen therapy, and rates of transfer to a tertiary hospital, ICU admission, intubation, and adverse events.

1472 patients were recruited. 12% received escalation of care (87/739) in the HFO group, as compared to 23% (167/733) in the standard-therapy group (risk difference, -11%; 95% confidence interval, -15 to -77; P<0,001). In hospitals without an on-site ICU, escalation of care occurred in 20/270 infants (7%) in the HFO group, as compared with 69/247 (28%) in the standard-therapy group (risk difference -21%; 95% CI -27 to -14). However, in hospitals with an on-site ICU, escalation of care occurred in 67/469 (14%) in the HFO-group and in 98/486 (20%) in the standard-therapy group (risk difference -6%; 95% CI-11 to -1).

No significant diferences were observed in the duration of hospital stay or the duration of oxygen therapy.

In each group, one case of pneumothorax (<1% of infants) occurred. Among the 167 failures of treatment in the standard-therapy group, 102 (61%) had a response to HFO rescue therapy. A total of 12 infants (1%) underwent intubation, including 8 infants in the HFO group and 4 in the standard-therapy group.

Significantly fewer infants in the HFO group than in the standard-therapy group received escalation of care. There was no significant between-group difference in the incidence of adverse events. Among infants who were treated outside na ICU, those who received HFO had significantly lower rates of escalation of care due to treatment failure than those in the group that received standard-therapy.

This was one of the most awaited “big studies” regarding the use of HFO in Pediatrics, the PARIS study. Clever design! On the one hand, it clearly shows that we can and should consider HFO early on during admission, without having to wait for the standard therapy to do its work, when criteria are met. On the other hand, it reassures the community in terms of its safety and level of pressure generated, with less than 1% of adverse events using flows of 2L/kg/min, considering of course that the method is well used, (cannula /nostril diameter relation being < 50% oclusion p. ex.). Last but not least, the use of HFO outside ICUs as finally been proven efective, safe, and a first line indication when facing an infant with bronchiolitis, early on admission, regarding mostly clinical criteria, as shown by the authors. More studies are needed to determine not only predictors of success, but mostly of failure of the technic, in order not to postpone escalation of care when needed.

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