Bronchiolitis

Bronchiolitis is the commonest cause of lower respiratory tract illness most

commonly seen in infants and young children with most severe cases occurring
among infants.
Bronchiolitis is an important cause of acute and long term morbidity.
Bronchiolitis is a disease of small bronchioles with increased mucus production
and occasional bronchospasm, sometimes leading to airway obstruction.
Bronchiolitis is potentially life-threatening disease most commonly caused by a
viral lower respiratory tract infection.
Respiratory syncytial virus (RSV) is a primary cause of bronchiolitis, followed in
frequency by human metapneumovirus, parainfluenza viruses, influenza
viruses, adenoviruses, rhinoviruses, coronaviruses, and, infrequently,
Mycoplasma pneumoniae.
Viral bronchiolitis is extremely contagious and is spread by contact with
infected respiratory secretions.
EPIDEMIOLOGY:
• Bronchiolitis is a leading cause of hospitalization of infants.
• Bronchiolitis occurs almost exclusively during the first 2 years of life, with
a peak age at 2-6 months.
• Children acquire infection after exposure to infected family members,
who typically have symptoms of an upper respiratory tract infection, or
from infected children in day care.
• Annual peaks are usually in the late winter months from December
through March.
Clinical presentation:
• Bronchiolitis caused by RSV typically has an incubation period of 4-6 days. Bronchiolitis
classically presents as a progressive respiratory illness similar to the common cold in its
early phase, with cough and rhinorrhea.
• It progresses over 3-7 days to noisy, raspy breathing and audible wheezing.
• There is usually a low grade fever accompanied by irritability, which may reflect the
increased work of breathing.
• Young infants infected with RSV may not have a prodrome and may have apnea as the
first sign of infection.
• Physical signs of bronchiolar obstruction include prolongation of the expiratory phase of
breathing, nasal flaring, intercostal retractions, suprasternal retractions, and air
trapping with hyperexpansion of the lungs.
• During the wheezing phase, percussion of the chest usually reveals only
hyperresonance, but auscultation usually reveals diffuse wheezes and crackles
throughout the breathing cycle.
• With more severe disease, grunting and cyanosis may be present.
Laboratory and imaging studies:
Routine laboratory tests are not required to confirm the diagnosis.
It is important to assess oxygenation in severe cases of bronchiolitis.
Pulse oximetry is adequate for monitoring oxygen saturation.
Rapid viral diagnosis of nasopharyngeal secretions performed by PCR
for RSV, parainfluenza viruses, influenza viruses, and adenoviruses are
sensitive tests to confirm the infection.
Identifying the viral is not necessary to make the diagnosis of
bronchiolitis.
Chest radiographs are not always necessary but frequently show signs
of lung hyperinflation, including increased lung lucency and flattened
or depressed diaphragms. Areas of increased density may represent
either viral pneumonia or localized atelectasis
• DIFFERENTIAL DIAGNOSIS:
• The major difficulty in the diagnosis of bronchiolitis is to differentiate other
diseases associated with wheezing.
Causes of wheeze include
Indication of hospitization:
Many healthy children with bronchiolitis can be managed as
outpatients; however, hospitalization may required in the following
cases:
1. Premature infants.
2. Children with chronic lung disease of prematurity.
3. Hemodynamically significant congenital heart disease.
4. Neuromuscular weakness.
5. Immunodeficiency.
Treatment:
Current therapy is primarily supportive, involving maintenance of hydration
and oxygen status.
Oxygen saturation monitoring is necessary and oxygen should be
administered via nasal prongs or headbox if the oxygen saturation falls below
92%.
An increasing oxygen requirement indicates worsening disease with
increasing ventilation/perfusion imbalance.
Hypercapnia is a sign of exhaustion and alveolar hypoventilation and if this
develops the baby should be moved to a high-dependency area or intensive
care for ventilatory support.
Nasogastric or intravenous feeding is required if the baby is unable to suck.
• Overall, no support the use of additional therapies. Bronchodilators,
including adrenaline (epinephrine), have not been shown to be helpful.
• desaturations have been reported after salbutamol(albuterol)
nebulization.
• The majority of studies have demonstrated no benefit from inhaled or
oral corticosteroid therapy either in the acute phase or in the prevention
of post-bronchiolitic wheezing.
• Antibiotics are not indicated except in the case of secondary bacterial
infection which is rare in babies who do not need ventilatory support.
• Ribavirin inhibits viral replication and is the only available antiviral agent
active against RSV. a systematic review of 10 trials showed no reliable
evidence of efficacy
Complications:
• Acute respiratory distress syndrome (ARDS)
• Bronchiolitis obliterans
• Congestive heart failure
• Secondary infection
• Myocarditis
• Arrhythmias
• Chronic lung disease
Prevention:
There is as yet no safe and effective vaccine for use in infants.
RSV is spread by direct contact with infected secretions and contaminated
objects and this may be reduced by effective and appropriate hand-washing and
cohort nursing. The importance of these measures in the prevention of RSV
transmission should not be underestimated.
Monthly injections of palivizumab, an RSV-specific monoclonal antibody,
initiated just before the onset of the RSV season confers some protection from
severe RSV disease. Palivizumab is indicated for some infants with prematurity,
chronic lung disease of prematurity, and those with hemodynamically significant
congenital heart disease in the first year of life, and rarely in the second year of
life.
Immunization with influenza vaccine is recommended for all children older than
6 months and may prevent influenza-associated disease.