The enrolled RSV-bronchiolitis patients will be randomized into two arms , the early HHHFNC group and the standard therapy group with rescue HHHFNC to study the efficacy of this treatment.

Setting:

The study will be conducted between June 2017 and June 2020 in the short stay unit of the Pediatric Emergency Center (PEC) of Hamad General Hospital, the only pediatric emergency facility in the State of Qatar. Infants aged ≤3 months presenting to the unit for treatment of viral bronchiolitis with positive RSV test will be eligible for the study.

Procedure:

Eligible patients will be enrolled after obtaining written consent. For patients who consent, plain chest radiography, and nasopharyngeal swabs will be taken for RSV detection. If the patient has a positive RSV rapid antigen test, patients will be randomized in one of the study arms. Adverse effects in each group will be carefully monitored and documented.

Study Intervention:

Patients will be randomized into two treatment arms

Group 1: Early HHHFNC Group Patients in this group will be treated by using heated humidified high flow oxygen /air via nasal cannula; investigators will keep the patient on HHHFNC until he/she becomes clinically ready for discharge.

Group 2: Standard Therapy and Rescue HHHFNC Group:

patients in this group will be treated by usual therapy,investigators will use low flow nasal cannula oxygen therapy only if oxygenation needed to maintain Oxygen saturation (SpO2) ≥ 92% , if the patient deteriorate and require ICU, rescue HHHFNC will be started before admission to the ICU.

Inclusion Criteria:

• Previously healthy infants with age 0-3 months and gestational age ≥30 weeks admitted to the short stay unit with RSV positive bronchiolitis and clinical severity score ≥4 on Wang clinical severity scale.

Exclusion Criteria:

1. Gestational age less than 30 weeks.
2. Previous history of wheezing.
3. Use of steroid within 48 hours of presentation.
4. History of chronic lung disease.
5. Infants admitted directly to ICU.
6. Prior invasive or non-invasive ventilatory support.
7. Tracheostomy.
8. Nasogastric tubes in situ on admission.
9. Upper airway abnormality (like choanal atresia and midfacial anomalies).
10. Immunodeficient children.
11. History of cardiac disease, renal disease or liver disease.
12. History of neuromuscular disorder.