2. BRONCHIOLITIS
• Bronchiolitis is a seasonal acute viral illness in
infants < 12 months of age characterized by nasal
discharge and a dry wheezy cough, tachypnoea,
retractions and reveals crepitations and/ or wheeze
as defined by European guidelines.
• Another definition is: a disorder in infants < 24
months of age, most commonly caused in infants by
viral LRTI; it is a very common lower respiratory
infection in this age group and is characterized by
acute inflammation, oedema and necrosis of
epithelial cells lining the small airways, increased
mucus production and bronchospasm. (AAP).
3. AETIOLOGY
• Respiratory syncytial virus, (RSV), is a primary cause,
(60-85%) of cases.
• Others are human metapneumovirus, parainfluenza
viruses, influenza viruses, adenoviruses, rhinoviruses,
coronaviruses, and infrequently, Mycoplasma
pneumoniae.
• Viral bronchiolitis is mostly spread by contact with
infected respiratory droplets, by coughing, sneezing or
talking, and touching infected items and contaminating
eyes, nose, mouth, handshakes, hugs.
• It is the most frequent infectious disease in children< 1
year of age with a peak at 3-6months.
• Each year 150 million new cases are reported
worldwide, >100 thousand per annum in Nigeria.
• 11-13% need admission, 1-3% require intensive care.
4. EPIDEMIOLOGY
• Two to three percent of children in first twelve
months of life admitted to hospital are due to
bronchiolitis with a peak age at 2-6mo. Children 2
to five years are occasionally affected.
• Risk factors: age < 3mo, male sex, smoking, RSV
infection, overcrowding, low socio-economy.
• Babies with co- morbidities including premature
birth, chronic lung disease of prematurity,
immunodeficiency, left to right shunt congenital
heart diseases, neuromuscular weakness, have
more severe diseases.
• Peaks are in late winter and rainy season.
• Protective factor is maternal breastfeeding.
5. CLINICAL MANIFESTATIONS
• Incubation period: 2-6 days, initially like common
cold with nasal congestion, rhinorrhoea, cough,
progresses to noisy breathing and audible wheezing
• There is a low-grade fever, hypothermia in infants <
1 month, and some irritability.
• In very young infants infected with bronchiolitis,
apnoea may be the first sign.
• Nasal flaring, prolonged expiration phase,
intercostal and suprasternal recessions, air trapping
and hyper-expansion of the lungs, hyper-resonance
crepitations and wheezes (rhonchi), are present.
• Grunting and cyanosis in severe cases.
6. PATHOPHYSIOLOGY
• The virus infects the respiratory epithelial cells of the small
airways, bronchioles, leading to necrosis, inflammation,
oedema, increased mucous secretion. The combination of
cellular destruction and inflammation leads to obstruction
and constriction of the small airways. There is dynamic
collapse of the airway during expiration leading to air
trapping. Decreased ventilation in affected areas with
increased lung resistance results in ventilation/perfusion
mismatch, with hypoxia and increased work of breathing. The
physiological and clinical results consist of hyperinflation,
atelectasis, and wheezing. In severe cases, interstitial
inflammation and alveolar infiltrates also develop. Cytokines
and chemokines, released by infected respiratory epithelial
cells amplify the cellular immune response. Re-growth of the
epithelial cell layer does not occur until approximately 2
weeks after infection, with compete recovery requiring 4 to 8
weeks.
7. PATHOPHYSIOLOGY
• Early studies reported that respiratory syncytial
virus (RSV) infection was associated with
mediators typically produced by type-2 helper T
cells (TH2 cells). However, subsequent clinical
studies have suggested that the severity of RSV
infection and the likelihood of wheezing with any
respiratory viral infection probably reflects a less
robust adaptive immune response to infection.
Additionally, RSV may inhibit the lung antioxidant
system and promote the development of reactive
oxygen species, resulting in increased lung
oxidative damage.
8. DIAGNOSIS
• Diagnosis is commonly clinical, with or without routine laboratory
investigations.
• Diagnostic criteria include exposure to other children or adults
with respiratory viral infections, age < 12 mos, preceding upper
respiratory illness, and signs of acute lower respiratory illness
evidenced as respiratory distress, low oxygen saturation as
measured by pulse oximetry, rales and sometimes wheezing.
• antigen tests by immunofluorescence or enzume-linked
immunosorbent assay (ELISA) of nasopharyngeal secretions for
RSV, parainfluenza viruses, influenza viruses and adenoviruses
are sensitive. Polymerase chain reaction can be done.
• Chest x-ray shows features of lung hyperinflation: increased lung
lucency, flattened or depressed diaphragm.
• Areas of increased density may represent viral pneumonia or
atelectasis.
9. DIFFERENTIAL DIAGNOSIS
• Differentiate from other causes of wheezing.
• From asthma by younger age of presentation,
presence of fever (unless the trigger for asthma
exacerbation is by a respiratory infection),
absence of personal or family history of asthma.
• Foreign body aspiration, congenital airway
obstruction, pneumonia, exacerbation of chronic
lung disease, cystic fibrosis, cardiogenic asthma
which is wheezing associated with pulmonary
congestion secondary to left-sided heart failure.
10. MANAGEMENT
• Bronchiolitis treatment is supportive therapy,
including respiratory monitoring, hydration,
upper airway suctioning, assisted feeding, fever
control, minimal handling, nursing prone, and
oxygen.
• Hospitalization is indicated in moderate or
marked respiratory distress, hypoxaemia,
apnoea, poor feeding, lack of appropriate care at
home, and high risk babies.
• A small group infants especially those with co-
morbidities who are in impending respiratory
failure should be recognized early and given
mechanical ventilation.
11. MANAGEMENT
• Minimal handling is required.
• Milder cases are given small frequent feeds, and
breastfeeding is supported.
• Infants with more severe resp. distress are given
small feeds by nasogastric tube, and if too
distressed, intravenous feeding is given. RSV
infection can cause inappropriate antidiuretic
hormone secretion and fluid given should be
two thirds of maintainance.
12. MANAGEMNTE: Respiratory support
• Oxygen is the main stay of treatment for resp distress.
• Administered via nasal cannula or headbox, to minimize
handling. A facemask can also be used. Nursing the infant in a
prone position can improve oxygenation through improved
diaphragmatic function.
• Airway support can be through continuous positive airway
pressure (CPAP), or heated humidified high flow nasal
cannulae (HHHFNC) therapy to prevent dynamic airway
collapse and thus improve gas exchange.
• Heliox is a mixture of helium and oxygen, ratio 2:1, and has a
low density compared to air, and so has a improved gas flow
through high-resistance airways, thus reducing the work of
breathing. Can be combined with CPAP.
• For a minority intubation and mechanical ventilation to reduce
mortality. A small group may need exogenous surfactant, thus
reducing duration of mechanical ventilation and ICU care.
13. MANAGEMENT
• Bronchodilators. Nebulised beta 2 agonists,
(salbutamol), Anticholinergic agent ( ipratropium
bromide), and adrenergic agents (epinephrine)
have been tried with epinephrine giving the best
result due to its alpha and beta adrenergic effects.
• Corticosteroids are used but studies say both
inhaled or systemic showed no significant effect.
• Combination of nebulized bronchodilator, racemic
adrenalin and oral dexamethasone is said to
improve outcome.
• Aminophylline can improve apnoea. Caffeine too.
• Antibiotics are used, and antiviral agent, ribavarin,
but are said to not to make much improvement.
14. management
• Hypertonic saline (3%), nebulised, gives
some improvement, secretions are diluted
and reduced.
• Use of nebulised normal saline has been
found to be helpful and easily available.
• Use of antibiotics is controversial and is used
to prevent secondary bacterial infection.
15. PROGNOSIS
• Bronchiolitis is usually self limiting.
• Hospitalized children show improve with
supportive treatment alone. Impending respiratory
failure should be given assisted ventilation.
• Apnoea is troublesome in very small infants.
• Most cases resolve completely, but minor
abnormalities of pulmonary function and bronchial
hyper-reactivity may persist for years.
• Recurrence is common. Hospitalized children have
a higher incidence of asthma.
• Mortality is 1-3% especially in the high risk group.
16. PREVENTION
Counseling .
Palivizumab (Synagis) for immunoprophylaxis is
given. RSV- specific protein monoclonal antibody
(IgG) from recombinant DNA. Given to high risk
children intramuscularly, once a month just before
the bronchiolitis season (rainy season, late winter.
• Influenza vaccine for children above 6mo.
• Good hygiene with good handwashing habits.
• Avoid ill people.
• Avoidance of crowding and smoking.
17. REFERENCES
• Nelson Essentials of Paediatrics, seventh
edition. 357-358. Karen J. Marcdonte and
Robert M. Kliegman. Elsevier Saunders.
• ERS Handbook. Paediatric Respiratory
Medicine. Editors Ernst Eber and Fabio
Midulla.305-310.
• McKiernan c et al.(2010). High flow nasal
cannulae therapy in infants with bronchiolitis. J
Pediatr; 156:634-538.
• American Academy of Pediatrics Subcommittee
on Diagnosis and Management of Bronchiolitis.
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