Bronchiolitis
Bronchiolitis, most commonly due
to respiratory syncytial virus (RSV), affects everyone by the age of 2yrs.
Whether you meet this infection in your first winter, or your second,
determines how ill you will be. RSV invades the nasopharyngeal epithelium and
spreads to the lower airways where it causes increased mucus production,
desquamation, and then bronchiolar obstruction. The net effect is pulmonary
hyperinflation and atelectasis. The other causes of bronchiolitis include
infection with para-influenza, influenza, adenovirus, rhinovirus,
metapneumovirus, chlamydia, and Mycoplasma
pneumoniae.
There is an increased risk of
severe infection in infants with CHD, CLD of prematurity, immunodeficiency, and
other lung disease.
In winter months infants with a
typical history will have had coryza, fol-lowed by a dry cough, followed by
worsening breathlessness. Other fea-tures in the history include:
·
wheeze;
·
feeding
difficulty;
·
episodes
of apnoea.
Rarely, other presenting histories
in babies include:
·
encephalopathy
with seizures due to hyponatraemia;
·
apnoea
and near miss sudden infant death.
A thorough examination is needed
in order to assess the degree of res-piratory distress:
·
cyanosis
or pallor;
·
dry
cough;
·
tachypnoea;
·
subcostal
and intercostal recession;
·
chest
hyperinflation;
·
prolonged
expiration;
·
pauses
in breathing or apnoea;
·
wheeze
and crackles.
Key investigations include:
·
Pulse oximetry: to assess oxygenation.
·
CXR: to assess hyperinflation,
atelectasis, and consolidation.
·
Nasopharyngeal swab: immunofluorescent antibody testing
for RSV binding.
The treatment of RSV bronchiolitis
is mainly supportive and includes:
·Oxygen to achieve pulse oximetry
saturation >92%.
·If tachypnoea, limit oral feeds
and use a NGT.
·Bronchodilators
for wheeze: nebulized
salbutamol, ipratropium, and adrenaline
have all been used in studies. The best evidence is for nebulized adrenaline.
·Mechanical ventilation for severe
respiratory distress or apnoea.
Antiviral therapy with ribavirin
should be reserved for immunodeficient patients and those with underlying heart
or lung disease, although its ben-efit is uncertain.
Palivizumab is a monoclonal
antibody to RSV and can be used as prophy-laxis. Preterm babies and
oxygen-dependent infants at risk of RSV infec-tion can receive a monthly IM
injection (for 5mths starting in October) to reduce risk of hospitalization and
the need for mechanical ventilation.
Recurrent cough, wheeze, and
tachypnoea may occur after RSV infection. These may require treatment and are
best assessed in outpatients. Daily oral montelukast granules can sometimes
help reduce the symptoms. A proportion of patients may develop asthma—they may
have been predis-posed to develop this problem irrespective of RSV in early
infancy.
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