Study design

Design: Randomised controlled trial.

Allocation: Randomised manually with stratification for gestational age.

Blinding: Unblinded.

Study question

Setting: A tertiary paediatric centre in New South Wales, Australia.

Patients: Infants presenting to the emergency department or paediatric ward with a diagnosis of moderately severe bronchiolitis who required oxygen therapy.

Intervention: Initial treatment with standard low flow or high flow (1 L/kg/min up to a maximum of 20 L/min), warm humidified oxygen.

Outcomes: Primary outcome was time to weaning off oxygen. Secondary outcomes were 24 hours event-free survival (ie, without treatment failure), proportion of serious events, transfer to ICU, length of stay and acceptability of treatment.

Follow-up period: 30 days post discharge.

Main results

The results are summarised in table 1.

Commentary

Bronchiolitis is a common reason for hospital admission in both well infants and those with existing co-morbidity; additionally, it is the most common cause of non-elective admission to paediatric intensive care units (PICU).1 The search for improved therapies, therefore, is understandable.

In recent years, treatment with high-flow oxygen therapy has become increasingly prevalent.2 Despite this, there is still a perceived lack of evidence of benefit and no mention of it is made in the most recent National Institute for Health and Care Excellence (NICE) guidelines.3

The study by Kepreotes et al is a well-conducted randomised controlled trial which was adequately powered and had a comparable population to many British hospitals. Their choice of primary outcome, however, is unusual, in that high-flow oxygen is rarely used as initial therapy, aside from in infants presenting with significant respiratory distress. Therefore, the finding that it does not decrease time to weaning off oxygen or length of hospital stay is largely unsurprising—many infants randomised to receive high-flow oxygen might not have been offered it in routine practice outside of the study protocol.

Interestingly, however, their secondary outcome of time to treatment failure notes significant difference between groups. Furthermore, switch to high-flow therapy prevented the need for PICU admission in a significant number of patients who were initially randomised to receive low-flow therapy. This study’s flow rate of 1 L/kg/min is lower than that used in many other studies4 (and presumably most hospitals), where 2 L/kg/min is more common. One therefore wonders whether PICU admissions would be even lower should higher flow rates have been used.

This study provides evidence to support the use of high-flow oxygen in infants with bronchiolitis who have persisting respiratory distress on conventional, low-flow therapy. Further studies, with time to treatment failure or PICU admission rates as primary outcomes, would further strengthen this evidence base. In addition, studies looking at flow rates reflecting those used in common practice would be valuable.