Basics
Description
Acute infection of the lower respiratory tract in infants and young children leading to mononuclear infiltration of the bronchiolar epithelium, causing edema and mucus plugging of the small airways á
Epidemiology
- Peak season is November through April, with some variation by state in the United States (begins earlier in the Southeast).
- Most common cause of infant hospitalization
- ~150,000 hospitalizations/year in the United States
- Hospitalization rates tripled from 1980 to 1997 but have decreased over the last decade.
- Most recent estimate ~15 hospitalizations/1,000 person-years for children <2 years of age
- Approximately, 1/3 of all children will get bronchiolitis in the first 2 years of life.
Etiology
- Respiratory syncytial virus (RSV) is the most common causative organism, but other organisms include the following:
- Human rhinovirus
- Adenovirus
- Human metapneumovirus
- Enterovirus
- Coronaviruses
- Influenza viruses
- Parainfluenza viruses
- Mycoplasma pneumoniae
- Majority of bronchiolitis cases are caused by one virus, but viral coinfections (2 or more viruses) may occur in ~1/4 of cases.
Commonly Associated Conditions
- Patients at high risk of severe bronchiolitis:
- Premature infants (<36 weeks' gestation)
- Young infants (<2-3 months of age)
- Congenital heart disease
- Chronic lung disease (including bronchopulmonary dysplasia [BPD])
- Low birth weight
- Cystic fibrosis
- Immunodeficiency
- Neuromuscular diseases
- Trisomy 21
- Exposure to cigarette smoke is a risk factor for more severe disease.
Diagnosis
History
- Generally begins as an upper respiratory infection with rhinorrhea but spreads to lower respiratory tract within 2-3 days
- Often multiple sick contacts in household
- Variable timing of symptoms. The unpredictability of the time course of the disease may be partly explained by viral coinfections.
- Poor feeding and increased insensible water loss may lead to dehydration and decreased urine output.
- Fever in approximately 50% of patients
- Restlessness or lethargy may indicate impending respiratory failure (hypoxemia and/or CO2 retention).
- Apnea can be sole presenting sign in younger infants.
Physical Exam
- General appearance
- Interactive versus ill-appearing
- Paroxysmal cough common
- HEENT exam
- Nasal congestion with copious secretions
- Otitis media is common.
- Pulmonary exam
- Pattern of breathing: apnea or periodic breathing
- Tachypnea: >70/min is associated with severe illness.
- Grunting, nasal flaring, and accessory muscle use (supracostal, intercostal, subcostal retractions) are signs of more severe disease.
- Thoracoabdominal asynchrony ("abdominal breathing"Ł)
- Hyperresonance to percussion
- On auscultation: diffuse, high-pitched heterophonic wheezing; prolonged expiratory phase; inspiratory crackles; diffuse rhonchi
- Lung exam can change rapidly.
- Other findings:
- Signs of dehydration
- Poor peripheral perfusion (delayed capillary refill time, cool extremities, weak peripheral pulses, mottling of skin) is a concerning sign.
- Liver and spleen often caudally displaced by hyperinflated lungs.
Diagnostic Tests & Interpretation
Lab
- The majority of bronchiolitis cases do not warrant any laboratory investigation.
- Blood gas
- In severe cases, can help determine acid-base status and effectiveness of ventilation; however, decisions to escalate support can generally be based on clinical assessment.
- Arterial PO2 generally does not add much information beyond that provided by a pulse oximeter.
- CBC +/- differential: low yield; a bandemia common with RSV
- Serum electrolytes: On occasion, may assist with assessment of hydration (BUN, creatinine), and hyponatremia rarely occurs due to antidiuretic hormone release.
- Viral testing
- Rarely changes management
- Some hospitals require it for cohorting, but can be misleading given the broad number of potentially causative viruses and the high frequency of viral coinfections.
- Best obtained by nasopharyngeal aspirate; can also be obtained by nasal swab
- Viral cultures are accurate, but may take up to 14 days for results.
Imaging
- Chest radiography is of little value in the majority of bronchiolitis cases, and multiple recent efforts have attempted to limit unnecessary radiographic testing.
- When obtained, findings may include the following:
- Hyperinflation, flattened diaphragms
- Peribronchial thickening
- Patchy or more extensive atelectasis
- Possible collapse of a segment or a lobe
- Diffusely increased interstitial markings are common.
Differential Diagnosis
- Pneumonia (viral or bacterial)
- Foreign body aspiration
- Asthma
- Gastroesophageal reflux (GER)
- Pulmonary edema (e.g., congestive heart failure)
- Cystic fibrosis
- Airway abnormalities (tracheomalacia or bronchomalacia)
Treatment
General Measures
- There is substantial variation in the use of diagnostic testing, hospitalization, and treatments, but bronchiolitis is a self-limited condition that generally improves without intervention.
- Most cases are mild and may be managed at home.
- Ensure adequate fluid intake.
- Antipyretics may be used for comfort-given concerns of association between acetaminophen use and asthma, consider ibuprofen as first line in infants >6 months of age.
- For rhinorrhea, nasal suction with bulb syringe may be of use.
- Supplemental oxygen
- Can be given humidified via nasal cannula, high-flow nasal cannula, face mask cannula, noninvasive positive pressure ventilation, or via endotracheal tube
- Should be titrated to respiratory distress and/or oxygen saturation
- Home oxygen use is an alternative and has been shown to successfully and safely reduce hospital admission rates from the emergency department.
- Pulse oximetry
- Continuous pulse oximetry can be useful as a monitoring device in order to titrate oxygen therapy, but it may also prolong length of stay by contributing to the overdiagnosis of hypoxemia (i.e., transient desaturations in otherwise comfortable infants).
- Consider intermittent pulse oximetry use in infants who are not requiring oxygen.
- The following medications/therapies are of no proven benefit in bronchiolitis and should be avoided:
- Corticosteroids (systemic or inhaled)
- Ipratropium bromide
- Leukotriene modifiers
Inpatient Considerations
- Common indications for hospitalization include the following:
- Need for IV hydration
- Need for frequent suctioning
- Moderate to severe distress (respiratory rate >60-70 breaths/minute, accessory muscle use, agitation, cyanosis, poor perfusion)
- Apnea
- Although hypoxemia is often used as an indication for hospitalization, exact oxygen saturation thresholds are uncertain. The American Academy of Pediatrics (AAP) suggests using supplemental oxygen for saturations <90%.
- Hydration
- Intravenous crystalloid boluses of 10-20 mL/kg should be given to infants with signs of poor perfusion.
- For infants who are unable to maintain adequate PO intake, hydration can be maintained with nasogastric feeds or maintenance IV fluids. Because of the risk of hyponatremia, hypotonic fluids should be avoided.
- Suctioning
- Nasal suctioning may improve work of breathing and facilitate feeding. Noninvasive suctioning (i.e., a nasal aspirator placed over the naris) is preferable to deep suctioning, which may cause trauma to the nasopharynx and worsen edema.
- Aerosols
- β-Adrenergic agonists have no clear benefit in bronchiolitis. While some trials have suggested transient improvements in respiratory scores, none has demonstrated any impact on clinically meaningful outcomes such as hospitalization rates or hospital length of stay.
- Racemic epinephrine, with its ╬▒-adrenergic properties, holds more promise than albuterol given that bronchiolitis is characterized more by airway edema than bronchospasm. Racemic epinephrine has been demonstrated in some studies to reduce hospital admission rates compared to placebo and to shorten length of stay when compared to albuterol.
- Neither β- or ╬▒-adrenergic agonists are recommended by the AAP for routine use.
- Preliminary studies on nebulized hypertonic saline (HTS) suggest that it might reduce length of stay. Although most studies use HTS in combination with albuterol or racemic epinephrine, at least one large study has suggested that these adjuvants are not necessary.
- If aerosols are to be used in bronchiolitis, careful attention should be paid to the clinical exam before and after administration (preferably with the use of a respiratory score) in order to support their ongoing use.
- Antimicrobials
- Antibiotics are overused in bronchiolitis and should be avoided in most cases.
- Special considerations include the following:
- Respiratory failure requiring intubation, in which case a substantial portion of patients have bacteria isolated from respiratory cultures
- Urinary tract infection
- Otitis media
- See RSV chapter for discussion of ribavirin and RSV immunoprophylaxis.
- The following inpatient medications/therapies are of no proven benefit in bronchiolitis and should be avoided:
- Corticosteroids (systemic or inhaled)
- Ipratropium bromide
- Leukotriene modifiers
- Methylxanthines (theophylline, aminophylline)
- Recombinant human DNAse
- N-Acetylcysteine
- Chest physiotherapy
Ongoing Care
Follow-up Recommendations
Patient Monitoring
- Most infants with no underlying disease improve within 1 week.
- A fraction of infants (~20%) will have symptoms for 3 weeks or more.
- Clinical course is prolonged in younger infants (<6 months) and those with comorbid conditions.
Prognosis
- For most previously healthy infants, the prognosis is good.
- A small fraction of infants, especially young or chronically ill ones, need support in the ICU with positive pressure ventilation.
- Mortality rates are very low (<0.1%).
- Infants with chronic underlying disease may have a protracted course and are at risk for repeated hospitalizations.
- Although up to 50% of infants with bronchiolitis develop subsequent episodes of wheezing, the direction of causality between bronchiolitis and asthma is unclear.
Complications
Alert
Almost all infants with bronchiolitis get better and do not need testing or therapies. á
Be aware of viral coinfections-1/4 of hospitalized patients with bronchiolitis have evidence of infection with at least 2 viruses. á
Additional Reading
- Mansbach áJM, Piedra áPA, Teach áSJ, et al. Prospective multicenter study of viral etiology and hospital length-of-stay in children with severe bronchiolitis. Pediatrics. 2012;130(3):e492-e500. á[View Abstract]
- Ralston áS, Garber áM, Narang áS, et al. Decreasing unnecessary utilization in acute bronchiolitis care: results from the value in inpatient pediatrics network. J Hosp Med. 2013;8(1):25-30. á[View Abstract]
- Ralston áSL, Lieberthal áAS, Meissner áHC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. Pediatrics. 2014;134(5):e1474-e1502. doi:10.1542/peds.2014-2742.
- Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics. 2006;118(4):1774-1793. á[View Abstract]
- Zorc áJJ, Hall áCB. Bronchiolitis: recent evidence on diagnosis and management. Pediatrics. 2010;125(2):342-349. á[View Abstract]
Codes
ICD09
- 466.11 Acute bronchiolitis due to respiratory syncytial virus (RSV)
- 466.19 Acute bronchiolitis due to other infectious organisms
ICD10
- J21.9 Acute bronchiolitis, unspecified
- J21.0 Acute bronchiolitis due to respiratory syncytial virus
- J21.8 Acute bronchiolitis due to other specified organisms
SNOMED
- 4120002 Bronchiolitis (disorder)
- 57089007 respiratory syncytial virus bronchiolitis (disorder)
- 13089009 adenoviral bronchiolitis (disorder)
FAQ
- Q: How did my child get bronchiolitis?
- A: Viral bronchiolitis is a common, seasonal, respiratory tract infection that is easily transmissible. It is acquired in much the same way as the common cold.
- Q: Can my child become reinfected?
- A: Children can become reinfected with RSV bronchiolitis, and infection can occur more than once during the same respiratory season. Furthermore, some patients can get two viral infections at the same time.
- Q: Do patients with bronchiolitis need to be isolated?
- A: Ideally, all patients with bronchiolitis are kept in isolation from other patients with and without bronchiolitis. If cohorting is necessary, patients with the same virus can be roomed together, although contact precautions should still be taken.
- Q: Will my child develop asthma?
- A: There is an ~50% chance that a patient with bronchiolitis will wheeze again. However, it is not clear whether the virus causes asthma or if infants who are predisposed to asthma are more likely to get bronchiolitis.