Bronchiolitis is a clinical syndrome of infection and associated inflammation of the lower respiratory tract that generally occurs in children less than 2 years of age. It is usually associated with a viral pathogen and can be associated with wheezing and/or rales.
Viral infection of terminal bronchiolar epithelial cells
Edema, mucus formation, sloughing of epithelial cells with subsequent obstruction of small airways and atelectasis
Most common cause is RSV (late fall/winter), followed by rhinovirus (spring/fall). Other causes include human metapneumovirus, influenza, adenovirus, and coronavirus. Approximately 1/3 of patients have infection with 2 or more viruses.1
Risk factors for Severe Disease
Age <12 weeks
Chronic pulmonary disease
Congenital/anatomic defects of the airways
Congenital heart disease
URI symptoms with presentation typically at day 3-6
Peak symptoms thought to occur ~day 4-7
Tachypnea, retractions, wheezing, rales, mild hypoxemia
Hyperexpanded on chest x-ray
Comorbid serious infections low (1-2% for bacteremia/meningitis, 5% for UTI) although in intubated infants, frequency of bacterial superinfection is as high as 40%)2,3
Apnea ~5% incidence (younger age, prematurity, increased risk of respiratory failure)
Respiratory failure in about 15%
Figure 1. Peribronchial Cuffing Typical of Bronchiolitis (occlusion of small airways via mucus plugging leads to atelectasis and prominent appearance of bronchioles).
Another common finding is shifting atelectasis.
Fluid hydration (ADH levels may be elevated so consider isotonic fluids)
Supplemental O2 to maintain SpO2 >90-92% (AAP guidelines of >90% although no specific data).
In a multicenter randomized trial of infants <12 months of age with bronchiolitis treated outside of an ICU, those who received high flow nasal cannula at 2 L/kg/min (avg weight ~ 7.3-7.6 kg) had significant less treatment failure than those who were started on regular nasal cannula at 2L/min. 61% of those that failed nasal cannula responded to HFNC (Franklin et al, NEJM 2018)
CPAP (4-8) or HFNC of 4-8LPM to reduce work of breathing (flow rates of 2L/kg/min seem to be associated with delivered PEEP).
Antibiotics potentially warranted in intubated patients given the 40% risk of bacterial coinfection.3 Antibiotics in the first 48 hours after intubation in patients with RSV was associated with a shortened duration of mechanical ventilation and a shorter hospital stay (with all the caveats of a retrospective study). In patients on the general care ward, antibiotics would not generally be recommended.
Chest PT did not improve respiratory parameters, O2 requirement, or length of stay in non-intubated patients4
Trial of inhaled bronchodilators (albuterol), if no response, stop
Hypertonic saline: Some evidence to suggest decreased risk of hospitalization and length of stay in hospitalized patients (newer RCT evidence-Angoulvant, JAMA PEDS 2017- did not show such an improvement in admission rates)5
Steroids generally not recommended unless clear history of previous reactive airway disease
Ribavarin generally not recommended unless immunocompromised or severe disease
RSV-IVIG and RSV-monoclonal Ab not recommended as no effect on outcomes
Possible reduced duration of mechanical ventilation with surfactant although not routinely used6
No significant evidence to support the use of heliox
The Bottom Line:
Supportive care with HFNC/CPAP/Mechanical ventilation as needed
Antibiotics, guided by tracheal aspirate in the intubated population (in general, given ~40% risk of coinfection)
Suctioning and PT not particularly helpful in the general inpatient population but may be necessary in the PICU population
Trial of albuterol
Hypertonic saline frequently utilized (ie q6hrs with albuterol given propensity of HTS to produce bronchospasm)
Tincture of time- length of mechanical ventilation and PICU stay can be quite variable
Possible association with the development of asthma but unclear
Mortality <2% in developed world
1) Richard N, Komurian-Pradel F, Javouhey E, et al. The impact of dual viral infection in infants admitted to a pediatric intensive care unit associated with severe bronchiolitis. Pediatr Infect Dis J 2008; 27:213.
2) Hall CB, Powell KR, Schnabel KC, et al. Risk of secondary bacterial infection in infants hospitalized with respiratory syncytial viral infection. J Pediatr 1988; 113:266.
3) Thorburn K, Harigopal S, Reddy V, et al. High incidence of pulmonary bacterial co-infection in children with severe respiratory syncytial virus (RSV) bronchiolitis. Thorax 2006; 61:611.
4) Roqué i Figuls M, Giné-Garriga M, Granados Rugeles C, Perrotta C. Chest physiotherapy for acute bronchiolitis in paediatric patients between 0 and 24months old. Cochrane Database Syst Rev. 2012 Feb 15;2:CD004873. doi:10.1002/14651858.CD004873.pub4. Review. PubMed PMID: 22336805.
5).Zhang L, Mendoza-Sassi RA, Wainwright C, Klassen TP. Nebulised hypertonic saline solution for acute bronchiolitis in infants. Cochrane Database Syst Rev 2013; 7:CD006458.
6) Jat KR, Chawla D. Surfactant therapy for bronchiolitis in critically ill infants. Cochrane Database Syst Rev 2012; 9:CD009194.
7) Shein SL, Kong M, McKee B, O'Riordan M, Toltzis P, Randolph AG. Antibiotic Prescription in Young Children With Respiratory Syncytial Virus-Associated Respiratory Failure and Associated Outcomes. Pediatr Crit Care Med. 2019 Feb;20(2):101-109.PMID: 30720644.