A pilot study of heated and humidified low flow oxygen therapy: An assessment in infants with mild and moderate bronchiolitis (HHOT AIR study)

Pediatr Pulmonol. 2019 May;54(5):620-627. doi: 10.1002/ppul.24267. Epub 2019 Mar 18.


Background: Heated and humidified high flow nasal cannula oxygen therapy has been used in children with severe bronchiolitis. No data exists in children with mild to moderate bronchiolitis requiring lower flows of heated and humidified oxygen therapy.

Methods: We conducted a prospective, randomized pilot study of standard dry oxygen (control) versus heated and humidified low flow nasal cannula (HHLFNC), <4 liters per minute (LPM) oxygen, (treatment) in healthy children ≤24 months old with bronchiolitis. Clinical assessments were made using Respiratory Distress Assessment Instrument (RDAI), respiratory rate (RR), and oxygen saturation.

Results: Thirty-two children were enrolled (16 participants in each group). There was no significant difference in mean RDAI over time between groups. There was a significant difference in mean RDAI over time within control group, at hour 12, and treatment group, at hour 1, compared to baseline. RDAI in the treatment group was overall lower over time compared to control group. There was no significant difference in mean RR over time between or within groups, between mean length of stay and duration of oxygen requirement. Subgroup analyses showed lower RDAI in subjects that had RSV infection, male gender, and non-black race.

Conclusions: The use of HHLFNC oxygen therapy may provide more comfort and may result in more rapid improvements in RDAI compared to standard dry oxygen therapy over time. HHFLNC is safe and well tolerated compared to standard dry oxygen. Larger studies are needed to assess the clinical efficacy of HHLFNC oxygen therapy.

Keywords: RDAI RSV; hypoxia; pediatrics; respiratory distress.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Bronchiolitis / therapy*
  • Bronchiolitis, Viral / therapy
  • Cannula
  • Female
  • Hot Temperature*
  • Humans
  • Humidity*
  • Hypoxia / therapy*
  • Infant
  • Infant, Newborn
  • Male
  • Oxygen Inhalation Therapy / methods*
  • Pilot Projects
  • Prospective Studies
  • Respiratory Rate
  • Respiratory Syncytial Virus Infections / therapy*
  • Severity of Illness Index
  • Treatment Outcome