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Year : 2020  |  Volume : 7  |  Issue : 5  |  Page : 293-296

Acute bronchiolitis in children

1 Department of Pediatrics, Pt. B. D. Sharma, PGIMS, Rohtak, Haryana, India
2 Department of Anaesthesia and Critical Care, Pt. B. D. Sharma, PGIMS, Rohtak, Haryana, India
3 Deputy Civil Surgeon, Rohatak, Haryana, India

Date of Submission13-Aug-2020
Date of Decision20-Aug-2020
Date of Acceptance27-Aug-2020
Date of Web Publication14-Sep-2020

Correspondence Address:
Dr. Kundan Mittal
Department of Pediatrics, Pt. B. D. Sharma, PGIMS, Rohtak, Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JPCC.JPCC_131_20

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Bronchiolitis is the most common respiratory disease in children below 2 years of age. Primarily, the disease is caused by viral infection (respiratory syncytial virus), mainly in the month from November to April. Climate and environment both influence the season and severity of bronchiolitis. Forty percent infants are affected in 1st year of life. Diagnosis of the bronchiolitis is mainly clinical though various definitions have been suggested by different groups. Laboratory investigations including reverse transcription polymerase chain reaction, chest X-ray, and others do not contribute in diagnosing the disease. There is no effective treatment available and mortality is also low with bronchiolitis.

Keywords: Bronchiolitis, children, respiratory syncytial virus

How to cite this article:
Mittal K, Bansal T, Mittal A. Acute bronchiolitis in children. J Pediatr Crit Care 2020;7:293-6

How to cite this URL:
Mittal K, Bansal T, Mittal A. Acute bronchiolitis in children. J Pediatr Crit Care [serial online] 2020 [cited 2020 Dec 2];7:293-6. Available from: http://www.jpcc.org.in/text.asp?2020/7/5/293/295018

  Introduction Top

Acute bronchiolitis is most important cause of hospital admission between November and April, in children below 2 years of age [Figure 1]. Although different peaks occur in tropical countries, it is a dynamic disease and its clinical features may change rapidly. In 1850, John Eberle published the first medical description of acute bronchiolitis “(a catarrhal effect in children <1 year, which was accompanied by breathing difficulty, coughing, and wheezing, similar to an asthma crisis).” Various definitions for bronchiolitis have been proposed since then. Bronchiolitis means inflammation of the small airways, the bronchioles and usually defined by its clinical and epidemiologic manifestations. “The American Academy of Paediatrics subcommittee defines bronchiolitis as a disorder in infants <24 months of age that is most commonly caused by a viral lower respiratory tract infection characterised by wheezing.” The European guidelines define bronchiolitis “as a seasonal viral illness in infants <12 months of age characterised by nasal discharge, cough, tachypnoea, retractions, and bilateral crackles.”
Figure 1: Seasonal occurrence of bronchiolitis

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Common etiological agents causing acute bronchiolitis are; respiratory syncytial virus (RSV type A and B), rhinovirus, human bocavirus, metapneumovirus, enterovirus, adenovirus (also known to cause bronchiolitis obliterans and pneumonia), parainfluenza virus, coronavirus, mumps, picornavirus, echovirus, herpes simplex, mycoplasma pneumoniae, and  Chlamydia trachomatis Scientific Name Search  [Figure 2]. Inflammation of lower respiratory tract is characterized by edema, necrosis of epithelial cells, replacement of ciliated epithelium with cuboidal epithelial cells, peribronchiolar infiltration, luminal obstruction, increased mucous production, bronchospasm, V/Q mismatch, hypoxia, hyperventilation, air trapping, and atelectasis. Epithelial cells start regenerating in 3–4 days and functional regeneration take 2 weeks. Risk factors for bronchiolitis are preterm child, low birth weight, age <3 months, cyanotic heart disease, chronic lung disease, neuromuscular disorders, airway abnormalities, male gender (1.5 times), overcrowding, exposure to tobacco, lack of breast feeding, and low-economic status. Various factors which contribute to severity of viral bronchiolitis are decreased airway diameter, collateral ventilation, lung recoil, chest wall stability, pulmonary and respiratory muscle reserve, direct cytopathic effect, and ciliary dysfunction.
Figure 2: Viruses contribution in bronchiolitis

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  Clinical Features Top

Bronchiolitis is a clinical syndrome characterized by running nose, low-grade fever, increased respiratory rate and work of breathing, apnea (”red-flag sign”), hyperextended and hyper-resonant chest, polyphonic wheeze, crepitations on auscultation (diffuse, course, and sticky) at lung base. Liver and spleen may be palpable due to hyperinflation of chest. Extrapulmonary manifestations of RSV are seizures, encephalopathy, hypo or hyponatremia. Severity is usually assessed using following parameters: respiratory rate, work of breathing or use of accessory muscles, mental status, oxygen requirement, breath sounds, cough, apnea, and feeding. Clinical phenotype may be restrictive or obstructive type. Various scores have been developed to categorize severity [Table 1] and [Table 2] of bronchiolitis. Role of chest X-ray in diagnosis of disease is controversial and even may not be performed unless confusion in making the diagnosis is present. X-ray examination may reveal hyperinflation, atelectasis, increased interstitial marking, and peribronchial cuffing/enlargement. Clinical course of viral bronchiolitis is shown in [Figure 3].
Table 1: Respiratory distress assessment instrument

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Table 2: Modified Tal scoring system

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Figure 3: Clinical course of viral bronchiolitis

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Differential diagnosis includes infantile asthma, cystic fibrosis, pneumonia, vascular rings, congenital heart diseases, congestive heart failure, gastroesophageal reflux, aspiration, retropharyngeal abscess, enlarged adenoids, pertussis, laryngo-tracheomalacia, and congenital lung diseases.

  Complications Top

  • Otitis media
  • Apnea
  • Dehydration
  • Aspiration.

  Laboratory Testing Top

  • Pulse oximetry
  • Arterial blood gas may show decreased PaO2 and increased PCO2 values
  • RSV viral study, antigen testing of nasal washing, and viral cultures are routinely not recommended
  • Reverse transcription polymerase chain reaction and other molecular diagnostic tests
  • Biomarkers interleukin-33 (IL-33), IL-13, IL-15, cysteinyl leukotrienes, cathelicidin, caspase, lactate dehydrogenase, to assess severity of disease
  • Antibody determination is not much useful
  • Complete blood count and C-reactive protein if bacterial infection is suspected
  • X-ray chest in child with suspected complications or course is not as expected.

  Management Top

Bronchiolitis can be categorized mild (no respiratory distress, saturation normal, and feeding well), moderate (tachypnea, saturation <90%), and severe (severe tachypnea, not feeding well, increased work of breathing, signs of respiratory fatigue, hypoxia). Admission criteria include apnea, respiratory distress, tachypnea, oxygen requirement, poor feeding, underlying risk factor, and poor socioeconomic condition. Treatment is mainly supportive and careful monitoring.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16]

  • Monitor the child for apnea, respiratory distress, hypoxemia/saturation, and dehydration
  • Place the child in position of comfort to avoid laminar flow becoming turbulent (mother's lap), minimal handling, and prone position
  • Maintain airway using simple methods. Nasopharyngeal suction (avoid deep suctioning) done if needed, since infants are obligatory nose breather
  • Supplementary oxygen (used if SPO2<90% in absence of respiratory distress) targeting saturation >92%. Try to use oxygen in nonfrightening way. Oxygen support using face mask of oxygen hood is preferred
  • Maintain hydration (100% fluid) since fast respiration and less oral intake may cause dehydration in infants. Keep a watch on serum electrolytes, serum, and urine osmolality since respiratory illness are known to develop Syndrome of inappropriate antidiuretic hormone secretion (SIADH). Restrict fluids to 70%–80% of normal in a child having features of SIADH. Continue breast feeding or oral feeding in milder case, if oral intake is <50% of normal intake start nasogastric feed or intravenous fluids (normal saline or DNS 100 mL/kg up to 10 kg)
  • Inhaled β2-agonist has no role but in severe cases trial may be given (nebulized with salbutamol 2.5 mg or use metered dose inhaler (MDI) with spacer and mask). There is lack or immaturity of β2-receptors in infants
  • Racemic epinephrine 0.05 mL/kg/dose diluted in 3–5 mL of saline may have some benefits in early stage of disease, i.e., decreasing need for hospitalization. Epinephrine acts on alpha-adrenergic receptors thus decreasing the edema and relaxation of bronchial muscles due to its action on β-receptors
  • Role of 3% hypertonic saline (improves mucous viscosity and elasticity, enhancing mucus transport, and decreasing epithelial edema) is controversial and has shown to decrease hospital stay in moderate-to-severe cases. There is no role of inhaled normal saline
  • Ipratropium bromide (minor improvement in oxygenation has been reported), theophylline and caffeine (prevention of apnea), montelukast, nebulized recombinant human DNAse (helps in liquefying mucus by cleaving the released DNA) and nasal phenylephrine have no proven roles in viral bronchiolitis
  • Inhaled and systemic steroids (dexamethasone 0.15 mg/kg 6 h for 48 h showed benefit in one study) have no clinical benefit. Inhaled epinephrine combined with oral dexamethasone have shown some clinical benefits in one study but more studies are required
  • Inhaled or intravenous magnesium sulfate has some improvement in clinical severity scores but still no recommended for use in bronchiolitis
  • Nasal CPAP; 4–8 cmH2O is indicated in severe respiratory distress, higher oxygen requirement, and apnea. It improves functional residual capacity (FRC), V/Q mismatch, and decreases work of breathing
  • Noninvasive positive-pressure ventilation, usually applied in children above 1 year of age improves FRC, V/Q mismatch, recruitment of lung units, alveolar gas exchange, and lower oxygen requirement in some patients
  • Heated-humidified-high flow nasal cannula have some beneficial effect in children with moderate-to-severe respiratory distress
  • Heliox, a low-density gas has shown to play some role in decreasing resistance to gas flow thus allowing increase gas flow and decrease work of breathing. In addition, carbon dioxide diffuses four to five times more rapidly thus allowing improved ventilation. Data supporting heliox therapy are lacking. If the oxygen requirement is >40% this will not work. Heliox is delivered through simple face mask or nonrebreathing mask and also the flow should be kept higher than child peak inspiratory flow rate. Delivery of heliox by mechanical ventilator is difficult
  • Surfactant therapy only decreases hospital stay but have no effect on gas exchange
  • Inhaled nitric oxide known to enhance blood flow and ventilation-perfusion quotient but has no bronchodilator effect in bronchiolitis
  • Chest physiotherapy (vibration, percussion, assisted autogenic drainage, and intrapulmonary percussive ventilation) in acute care is inconclusive
  • Suspecting impending respiratory failure start invasive mechanical ventilation (worsening lung compliance, exhaustion, and apnea) volume or pressure controlled is choice. Variable positive end-expiratory pressure (PEEP) is used depending on lung status
  • High frequency oscillatory ventilation and extracorporeal membrane oxygenation also have some place in children not responding to conventional therapy
  • No active immunization against RSV is available. Children at risk (acyanotic congenital heart disease, immunodeficiency, chronic lung disease of prematurity, and preterm <29 weeks gestation) should receive passive immunization with palivizumab which is given monthly over five doses (15 mg/kg/dose) during winter. Motivzumab, a second-generation humanized monoclonal antibody is still not available for commercial use
  • Hyperimmune RSV immunoglobulin intravenous (RSV 15 mL/kg) and monoclonal RSV monoclonal immunoglobulin have shown to reduce hospital admission rate
  • Ribavirin used in immune-compromised children has some clinical benefit
  • Antiviral drugs are not recommended
  • Effective RSV vaccine is under research
  • Anti-RSV pharmacological agents (presatovir, MDT-637, and lumicitabine) which inhibit replication of virus are under research
  • Handwashing and contact precautions are important limiting factors in RSV transmission
  • Discharge the child if clinically stable, feeding well, fully hydrated maintain saturation >92% in room air for the past 4 h
  • Child with recurrent wheeze and persistent wheeze with clinical improvement are referred to higher center
  • Child usually recovers symptomatically in 1–2 weeks and radiological clearance of atelectasis may take several weeks
  • Bronchiolitis is associated with increased risk of bronchial asthma later in life or recurrent wheezing
  • Lung function abnormalities (expiratory flow rate) may persist beyond 10 years of life
  • Cough caused by RSV infection may last for 3 weeks
  • Future apnea outcome is good.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Domachowske J. Introduction to Clinical Infectious Diseases: A Problem Based Approach. New York: Springer; 2019.  Back to cited text no. 3
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Erikson EN, Bhakta RT, Mendez MD. Pediatric Bronchiolitis. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519506/. [Last accessed on 2020 Aug 11].  Back to cited text no. 5
Florin TA, Plint AC, Zorc JJ. Viral bronchiolitis. Lancet 2017;389:211-24.  Back to cited text no. 6
Ghazaly M, Nadel S. Overview of prevention and management of acute bronchiolitis due to respiratory syncytial virus. Expert Rev Anti Infect Ther 2018;16:913-28.  Back to cited text no. 7
Meissner HC. Viral bronchiolitis in children. N Engl J Med 2016;374:62-72.  Back to cited text no. 8
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Øymar K, Skjerven HO, Mikalsen IB. Acute bronchiolitis in infants, a review. Scand J Trauma Resusc Emerg Med 2014;22:23.  Back to cited text no. 10
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Strokes DC, Brooks LJ, Cataletto ME, Katkin JP, Stout JW, Hook KV, et al. Pediatric Pulmonology, Asthma, and Sleep Medicine. USA: American Academy of Paediatrics; 2018.  Back to cited text no. 12
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Walsh BK. Neonatal and Paediatric Respiratory Care. 4th ed. Missouri: Elsevier; 2015.  Back to cited text no. 14
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Wilmott RW, Sly P, Deterding R, Zar HJ, Li A, Bush A, et al. Kendig's Disorders of Respiratory Tract in Children. 9th ed. Philadelphia: Elsevier; 2019.  Back to cited text no. 16


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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