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Bronchiolitis

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January 2013

PAKISTAN
PEDIATRICS
REVIEW

A Journal for Pediatricians and Post-Graduate Pediatric Students for

Continuing Medical Education

Respiratory and Infectious Diseases

www.pakpedsreview.org.pk
BRONCHIOLITIS
GHULAM MUSTAFA
12-A, Gilani Colony, Court road, Multan. E-Mail: falahchild@hotmail.com
------------------------------------------------------------------------------------
Pak Peds Rev 2013; (1): 5-10

DEFINITION limited benefit of bronchodilators observed in

The term "bronchiolitis" refers to the inflammation various clinical studies 2 .
of the bronchioles but the inflammation of the
bronchioles is usually not observed directly. The
American Association of Pediatrics (AAP) ETIOLOGY
guidelines have defined bronchiolitis as “a
constellation of clinical symptoms and signs RSV usually accounts for 50% to 80% of cases.
including a viral upper respiratory prodrome Other causal viruses include the para-influenza
followed by increased respiratory effort and viruses (primarily para-influenza virus type 3),
wheezing in children less than 2 years of age” 1 . influenza, and human metapneumovirus (HMPV).
HMPV is considered to account for 3% to 19% of
bronchiolitis cases. The clinical course of RSV
and HMPV seems to be similar. Most of the
PATHOPHYSIOLOGY
children are infected during annual widespread
Bronchiolitis begins with acute infection of the winter epidemics and a subset develops
epithelial cells lining the upper respiratory tract by bronchiolitis.
the viruses, which then travels down to the lower
The new data reveals that young children with
within a few days. This results in the
bronchiolitis are often infected with more than 1
inflammation of the bronchiolar epithelium, with
virus. Rates of co-infection range from 10% to
peribronchial infiltration of white blood cell types,
30% in samples of hospitalized children, usually
mostly mononuclear cells, and edema of the
with RSV and either HMPV or rhinovirus. There
submucosa and adventitia. The edema,
are controversies over the question whether the
increased mucus production, fibrin and plugs of
concomitant infections are associated with
sloughed, necrosis and regeneration of the
increased severity of the bronchiolitis or not. The
epithelium in the airways cause partial or total
published data has shown a 10 fold increase in
obstruction to the airflow. The airways keep
the risk of mechanical ventilation associated with
clearing at one site and getting blocked at others
dual RSV and HMPV infection while others have
so the site and degree of obstruction varies. This
revealed no increase in severity with dual
explains the rapidly changing clinical signs and
infections with viruses 3 .
the difficulty in accurately assessing the severity
of the illness over the time. A “ball-valve” A number of genes, including those involved in
mechanism can lead to air trapping distal to innate immunity are associated with risk for more
obstructed areas with subsequent absorption severe bronchiolitis. There are other genes like
resulting in atelectasis. Obviously hypoxemia vitamin D receptor genes that are associated with
results because of these atelectatic areas that bronchiolitis and may provide evidence to link
are not ventilated any more. The hypoxemia is neonatal vitamin D level with wheezing in young
further compounded by the lack of collateral children. Also parental and household smoking
channels in young children and iatrogenically by has been demonstrated to increase the risk of
the administration of high concentrations of bronchiolitis.
supplemental oxygen, which is absorbed more
rapidly than the room air. Smooth muscle
constriction does not seem to have much role in
the pathologic process and that may explain the

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 Mustafa G 6

EPIDEMIOLOGY respiratory prodrome. There is nasal congestion,

rhinorrhea, cough, tachypnea, and increased
Bronchiolitis is an acute, highly contagious
respiratory effort that is evident by nasal flaring;
disease of the lower respiratory tract of infants grunting; and intercostal, supra-costal and
with the highest incidence is in the winter in subcostal retractions. The work of breathing
temperate climates, and in the rainy season in
falsely increases significantly with nasal
warmer countries. It is the leading cause of
obstruction so nasal suctioning and repositioning
the infants' visit to the doctors. Under 2 years of
may allow a better assessment of lower
age, this is the most common lower respiratory
respiratory tract involvement that may be
tract disorder. There is high degree of morbidity revealed by a variety of auscultatory findings like
in bronchiolitis but mortality is low. Usually crackles, wheeze, or referred upper airway noise.
around one third of children do develop
The most sensitive and earliest sign is the fast
bronchiolitis in their first 2 years. The
respiratory rate. Apnea alone may be the
hospitalization rates vary from 3% to over 7%,
presenting sign in premature young infants or a
depending upon the type of infant population complication of bronchiolitis. A child can present
being studied. Most deaths in bronchiolitis occur with mild tachypnea to impending respiratory
in infants younger than 6 months of age. In
failure. A significant variability between serial
previously well children, bronchiolitis is usually a
examinations is common owing to dynamic
self-limiting disease that responds well to
nature of the disease. Tachycardia may develop
supportive care within the home. However, young due to dehydration and variable degrees of
infants and those having pre-existing medical hypoxemia. The minimum assessment includes
conditions form a vulnerable group that may
respiratory rate, work of breathing and hypoxia 5 .
need inpatient admission. The premature, infants
with underlying cardiopulmonary diseases or with
immunodeficiency disorders are more at risk.
DIAGNOSTIC WORK-UP
The commonest risk factor for hospitalization is
The diagnosis in most cases of bronchiolitis is
age less than 1 year (infants below 3 months are
clinically evident and does not require diagnostic
at increased risk of apnea and severe respiratory
testing. But the clinician has to be vigilant
distress), prematurity and cesarean section,
because of broad range of differential diagnosis
chronic lung disease, children born with airway
especially in the presence of atypical features
abnormalities such as laryngomalacia,
such as absence of viral symptoms, severe
tracheomalacia or cleft lip/palate and children
respiratory distress, and frequent recurrences.
with neurologic abnormalities associated
Such children may require diagnostic evaluation
dystonia may need additional support for
to rule out other causes. There is no consensus
managing secretions 4 .
among clinicians for the work up of bronchiolitis.
There is always a danger of apnea in young The practice varies widely especially for viral
infants with bronchiolitis, especially those with detection and radiography. The evidence to date
RSV. The incidence may vary depending upon does not suggest any role for diagnostic testing
the various factors but is usually around 3%. The in the management of routine cases of
risk factors included a previous history of apneic bronchiolitis. The studies have shown that if the
episode and age less than one month for full care of bronchiolitis be standardized, there can
term infants or 48 weeks post-conceptional age be substantial reduction in diagnostic testing
for premature infants. rates saving lot of cost without jeopardizing
outcome. The evidence does support only a
limited role for diagnostic testing in the diagnosis
CLINICAL MANIFESTATION of bronchiolitis 6 .
Patients usually report a history of recent upper The antiviral agents are not recommended for the
respiratory tract symptoms. Lower respiratory management of bronchiolitis so isolation of
tract symptoms such as cough, tachypnea, and specific causative virus is not required. There are
increased work of breathing follow the upper tests available for the rapid viral antigen

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 Mustafa G 7

detection but they have variable sensitivities and distal bronchioles. For most authors, pulse
specificity depending on the test used and when oximetry saturations higher than 90% are
they are used, during the respiratory season. For acceptable, as these saturations are associated
most of the cases of bronchiolitis the clinical with appropriate oxygen delivery on the oxy-
diagnosis is sufficient and viral testing adds little hemoglobin dissociation curve. A complete
to the routine management. assessment of the baby is required to decide for
the need and duration of the supplemental
Chest radiographs in children with bronchiolitis
oxygen. Oxygen may be discontinued once pulse
often show hyperinflation, areas of atelectasis,
oximetry saturations remains above 90% for
and infiltrates. The lung ultrasound is now being
most of the time and there is overall clinical
reported as a better and easy choice for the
improvement evidenced by the improved feeding
diagnosis of the bronchiolitis.
and work of breathing. A clinically improving
patient may experience intermittent decreases in
pulse oximetry saturation on day 3 or 4 of illness
THERAPEUTIC OPTIONS but that should not prompt automatic continuation
There are multiple therapeutic options like or re-initiation of oxygen supplementation as that
bronchodilators, corticosteroids, antiviral agents, practice is associated with prolonged
antibacterial agents, chest physiotherapy, nasal hospitalization and without significant benefits.
suction, and decongestant drops. But all these There are no clear guidelines for cardiac
interventions have not demonstrated any monitoring or use of pulse oximetry in children
significant impact on duration of illness, severity with bronchiolitis. The cardiac monitoring can be
of clinical course, or subsequent clinical considered for infants with underlying cardiac
outcomes, such as post-bronchiolitis wheezing. disease or those having episodes of apnea that
is associated with bradycardia. The pulse
oximetry is non-invasive tool providing rapid
SUPPORTIVE CARE 7 assessment of oxygenation but having a wide
Newer recommendations emphasize supportive variability in its use and interpretation. Though
care with hydration and oxygenation as a primary pulse oximetry helps to decide about the need for
intervention. admission, the extensive monitoring is
associated with prolonged hospital stay and
a) Hydration: Dehydration is consequent to parents are not comfortable with this. Other
faster breathing, copious secretions, fever and disadvantages of pulse oximetry are motion
poor feeding and may require intravenous fluids artifacts, variation in product accuracy and falsely
or nasogastric feedings until feeding improves. low readings in children with poor perfusion. The
The hydration may be corrected with isotonic appropriate strategy is to monitor the oxygen
fluids. saturation at regular intervals but children with
b) Feeding: The infant whose nutrition is cardiopulmonary problems, or having risk factors
compromised with severe disease may be given for apnea or who required continuous oxygen
nasogastric feeding until feeding improves. It has previously may be offered continuous oxygen
been shown that increasing protein intake of saturation monitoring.
infants increases the anabolism in critically ill
infants with bronchiolitis.
BRONCHODILATORS 8
c) Oxygen: Oxygen administration is a key
therapeutic intervention. The goal is to maintain Bronchodilators are abundantly used in the
oxygen saturation to prevent hypoxia or management of bronchiolitis at outpatient and
insufficient delivery of oxygen to metabolically inpatient facilities in our country and worldwide
active tissue. A variable hypoxemia does occur in so no surprise that their role in the treatment of
bronchiolitis from impaired diffusion across the bronchiolitis has been the subject of many
blood-gas membrane and ventilation-perfusion studies and systematic evidence based reviews
mismatch caused by heterogeneous plugging of of literature. Overall the current evidence does

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 Mustafa G 8

not support the routine use of bronchodilators. A two doses for 7 to 10 days. Patients older than 6
monitored trial of bronchodilators can be offered months and younger than 2 years should receive
as an option but should only be continued after a treatment if diagnostic certainty is strong but may
documented beneficial response such as be kept under observation if severity of infection
improvement in general condition, diminished is low.
work of breathing, low respiratory/pulse rate,
improved hypoxemia as assessed with pulse
oximetry. CHEST PHYSIOTHERAPY
As the pathophysiology of bronchiolitis involves
diffuse infection of the epithelial cells lining the
CORTICOSTEROIDS
small airways that leads to heterogeneous areas
Another area of controversy is the use of steroids of perfusion-ventilation mismatch so regional
for the treatment of bronchiolitis. Steroids are no chest physiotherapy does not provide any benefit
more recommended for routine treatment of though for RSV bronchiolitis a short term relief
bronchiolitis 9 . may be expected with special maneuvers 11 .

ANTI-VIRAL AGENTS 5 NASAL SUCTIONING AND NASAL

Trials with ribavirin have demonstrated variable DECONGESTANTS
outcomes. The high cost, difficult administration The infants are comforted when nasal suctioning
and lack of robust evidence of benefit have is performed to relieve nasal obstruction due to
limited the role of this therapy. Ribavirin may be copious secretions and it improves their feeding
considered for children with pre-existing diseases too. But the "deep" or excessive suctioning of the
like organ transplantation, malignancy, congenital lower pharynx has to be avoided because that is
immune-deficiencies or patients who remain associated with nasal edema, which can lead to
critically ill despite maximized support. additional obstruction 12 .
Bronchiolitis by RSV represents a unique
No evidence supports the use of nasal
population that may be associated with influenza
decongestant drops to relieve upper airway
and its treatment with anti-influenza medications
obstruction. Because of the lack of efficacy and
may lessen the severity and complications,
potentially harmful adverse effects nasal
especially if started within 48 hours of start of
decongestants should not be used to treat
symptoms but its initiation should only be
bronchiolitis.
considered if clinical picture surveillance data of
community is highly suggestive of influenza
infection. The best option remains the annual
influenza vaccination. LEUKOTRIENE ANTAGONISTS
The leukotriene receptor antagonist,
montelukast, has been evaluated as a potential
ANTIBACTERIAL AGENTS 10 candidate to treat bronchiolitis but does not seem
beneficial in resolution of symptoms 13 .
There is no role for antibacterial agents in viral
bronchiolitis and these should only be used in
patients with a concurrent bacterial infection. The HYPERTONIC NORMAL SALINE
most common concurrent bacterial infection is
acute otitis media (AOM). Nebulized hypertonic saline has been
associated, in recent randomized trials and in a
The antibiotic therapy should be based on patient Cochrane meta-analysis, with improvement in
age, severity of illness and diagnostic certainty. clinical score and duration of hospitalization 14 .
Patients younger than 6 months of age may
receive amoxicillin 80 mg/kg per day divided into

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 Mustafa G 9

OTHER THERAPIES Bronchiolitis. Pediatrics. 2006;118(4):1774-

93.
Other therapies like helium/oxygen, nasal
continuous positive airway pressure 15 or use of 2. Schuh S. Update on management of
surfactant for treating bronchiolitis are being bronchiolitis. Curr Opin Pediatr. 2011;
assessed for use in critically ill patients, though 23(1):110-4.
their role as of now is not established. 3. Brand HK, de Groot R, Galama JMD, et al.
Infection with multiple viruses is not
associated with increased disease severity
PROGNOSIS in children with bronchiolitis. Pediatr
Mostly the children with bronchiolitis recover Pulmonol. 2011; 47(4):393-400.
uneventfully and but a subgroup of around 40% 4. Marlais M, Evans J, Abrahamson E.
develops subsequent recurrent wheezing Clinical predictors of admission in infants
episodes through 5 years of age while only 10% with acute bronchiolitis. Arch Dis Child.
experience subsequent wheezing after 5 years. 2011; 96(7): 648-52.
Newer theories based on the immune system
development, genetic predisposition, ecology of 5. Zentz SE. Care of infants and children with
infectious agents propose that post-bronchiolitis bronchiolitis: a systematic review. J Pediatr
wheezing has an underlying predisposition to the Nurs 2011; 26(6): 519-29.
original RSV infection 16. 6. Bordley WC, Viswanathan M, King VJ, et
al. Diagnosis and testing in bronchiolitis: a
systematic review. Arch Pediatr Adolesc
CONCLUSIONS Med 2004;158(2): 119-26.
Bronchiolitis is an active area of research across 7. Ducharme FM. Management of acute
the spectrum from genetic mechanisms to bronchiolitis. BMJ 2011; 342: d1658.
population-based research. Surveillance studies
are identifying new causes of bronchiolitis and 8. Seehusen DA, Yancey JR. Effectiveness
exploring the role of viral co-infections. The of bronchodilators for bronchiolitis
studies have revealed that comorbidities are an treatment. Am Fam Physician 2011;
important determinant to predict the course of the 83(9):1045-7.
illness. Also the specific physical findings and 9. Hartling L, Fernandes RM, Bialy L, et al.
diagnostic tests used to predict the outcomes in Steroids and bronchodilators for acute
bronchiolitis do not have high predictive value. bronchiolitis in the first two years of life:
Pulse oximetry, probably, is a double edge systematic review and meta-analysis. BMJ
sword. It has contributed to better childcare but is 2011; 342: d1714.
also likely contributing to longer hospitalizations
and greater use of health care resources. The 10. Spurling G, Doust J, Del M, et al.
available data is yet largely against the routine Antibiotics for bronchiolitis in children.
use of bronchodilators or corticosteroids, though Cochrane Database Syst Rev. 2011;
a combination of these two looks promising ;(6):CD005189.
future trend. The role of nebulized hypertonic 11. Postiaux G, Louis J, Labasse H, et al.
saline in bronchiolitis is getting a wider Evaluation of an alternative chest
acceptance and is likely to establish as a part of physiotherapy method in infants with
routine care respiratory syncytial virus bronchiolitis.
Respir Care 2011; 56(7): 989-94.
12. Wagner T. Bronchiolitis. Pediatr Rev 2009;
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 Mustafa G 11

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