1-INTRODUCTION
Acute bronchiolitis is a common disease characterized by inflammation,
edema, and necrosis in the lower respiratory airways. It continues a
substantial health burden for infants and young children
worldwide.1 In the United States of America (USA),
approximately 2-3% of children younger than 12 months of age (accounts
for 57.000-120.000 hospitalizations annually) are hospitalized with
respiratory syncytial virus-related bronchiolitis.2–5The total estimated inpatient charges exceed $1.7 billion annually in
the USA.6 Similarly, from 2002 through 2014 in
Australia and New Zealand, increasing the admission to the intensive
care unit (ICU) due to bronchiolitis has raised health care
costs.7 The treatment of this frequent and costly
condition is mainly supportive, including hydration, oxygen
supplementation, and respiratory support.8 On the
other hand, high-flow nasal cannula oxygen (HFNCO) becomes an essential
and promising treatment modality for bronchiolitis.1,8
Initial observational and physiological studies using HFNCO determined
improved gas exchange, decreased respiratory effort, and reduced
mechanical ventilation (MV) rates.9,10 Milani et
al.11 showed that HFNCO was efficacious not only in
improving respiratory rate (RR) and respiratory effort but also in
reducing the duration of oxygen therapy and length of hospital stay
(LOS). In contrast, two recent randomized, controlled
trials12,13 comparing the effects of HFNCO and LFO in
infants with bronchiolitis found no statistically changes in heart rate
(HR), RR, duration of oxygen therapy, and LOS. Similar to these results,
there have been controversial reports regarding bronchiolitis severity
scores. While Ballestero et al.14 found that pulmonary
score decreased in more patients with HFNCO (53%) compared to those
with conventional oxygen therapy (28%), Chen et al.15did not show a significant decrease in respiratory distress assessment
instrument over time between HFNCO and standard dry oxygen. A 2014
Cochrane review16 proposed that there has been
insufficient evidence to identify the effectiveness of HFNCO. Similarly,
the American Academy of Pediatrics (AAP) Bronchiolitis
Guideline17 concluded that not enough randomized
clinical trials have been present to recommend its routine use despite
the promising. We aimed to examine whether HFNCO provided enhanced
respiratory support, evidenced by a notable improvement in HR, RR, and
clinical respiratory score (CRS), in infants with bronchiolitis and
hypoxemia admitted to the general pediatric ward.