Definition• Bronchiolitis is a first time wheezing with a viral respiratory infection.• It is a common respiratory illness in children less than 24 months with its peak incidence between 3 to 6 months of age.
The common causal organisms of bronchiolitis• Respiratory syncytial virus (RSV) is responsible for >50% of cases .• Other agents include parainfluenza adenovirus, Mycoplasma, and, occasionally, other viruses.• Human metapneumovirus is an important primary cause of viral respiratory infection or it can occur as a co-infection with RSV
Epidemiology• A common respiratory illness especially in infants aged 1 to 6 months old• Cyclical periodicity with annual peaks occurs in November,December and January.
Pathophysiology1)RSV infection incites a complex immune response.Eosinophils degranulate and release eosinophil cationicprotein, which is cytotoxic to airway epithelium.2)Immunoglobulin E (IgE) antibody release may also berelated to wheezing.3)Other mediators invoked in the pathogenesis of airwayinflammation includechemokines such as interleukin 8 (IL-8), macrophageinflammatory protein (MIP) 1α..
• RSV-infected infants who wheeze express higher levels of interferon-γ in the airway as well as leukotrienes. RSV co-infection with metapneumovirus can be more severe than monoinfection
Acute bronchiolitis is characterized by bronchiolar obstruction with edema, mucus, and cellular debris. Resistance in the small air passages is increased during both inspiration and exhalation, but because the radius of an airway is smaller during expiration, the resultant respiratory obstruction leads to early air trapping and overinflation. If obstruction becomes complete, there will be resorption of trapped distal air, and the child will develop atelectasis
Clinical features• Coryzal symptoms precede a sharp,dry cough,increasing breathlessness• Wheezing is often:High pitched,expiratory>inspiratory• Feeding difficulty associated with increasing dyspnoea• Recurrent apnoea
•Subcostal and intercostal recession•Hyperinflation of the chest:sternumprominent,liver displaced downwards•Fine end-inspiratory crackles•Tachycardia•Cyanosis or pallor
Investigations A chest ray is not routinely required,but recommended for children with: 1)severe respiratory distress 2)unusual clinical features 3)an underlying cardiac or chronic respiratory disorder 4)Admission to intensive care Page 13
Chest radiography revealshyperinflation,segmental,lobarcollapse/consolidationThe white blood cell and differentialcounts are usually normal.Viral testing (usually rapidimmunofluorescence, polymerasechain reaction, or viral culture) Page 14
chest X-ray shows hyperinflation of the lungs with flattening of the diaphragm, horizontal ribs and increased hilar bronchial markings. Note: chest X- ray is rarely helpful in bronchiolitis. 15Page 15
The diagnosis is clinical,particularly in a previouslyhealthy infant presenting with afirst-time wheezing episodeduring a community outbreak. Page 16
A majority of chidren with viral bronchiolitis has mild illness andabout 1% of these children require hospital admissionGuideline for hospital admission : Home Management Hospital ManagementAge<than 3 months No YesToxic looking No YesChest recession Mild Moderate/severeCentral cynosis No YesWheeze Yes YesCrepitations on auscultation Yes YesFeeding Well DifficultApnoe No YesOxygen saturation >95% <93%High risk group No Yes
Management outline1)General measures:•careful assessment of the respiratory status andoxygenation is critical•Arterial oxygenation by pulse oximetry Sp02 should beperformed at presentation and maintain above 93%-administer supplemental humidified oxygen if necessary•Monitor for signs of impending respiratory failure-inability to maintain satisfactory Spo2 on inspiredoxygen>40% or a rising pCO2•Very young infants are at risk of apnoea require greatervigilance
2)Nutrition and Fluid therapyFeeding.Infants admitted with viral brochiolitis frequently have poorfeeding are at risk of aspiration and may be dehydrated.Small frequentfeeds as tolerated can be allowed in children with moderate respiratorydistress.Naso gastric feeding maybe useful in these children who refuseto feed and also to empty the dilated stomach.Intravenous fluids for children with severe respiratorydistress,cyanosis,apnoea.Fluid therapy should be restricted tomaintenance requirement of 100ml/kg/day for infants.3)Pharmacotherapy:•Inhaled β-2 agonists:A trial of nebulised β-2 agonists,given inoxygen,may be considered in infants with viralbronchiolitis.Vigilant and regular assessment of the child shouldbe carried out if such a traetment is provided•Inhaled steroidsRandomised controlled trials of the use of inhaledsteroids for treatment of viral brochiolitis demonstratednomeaningful benefit.
4.AntibioticRecommended for all infants with:• recurrent apnoea and circulatory impairment,• - possibility of septicaemia• - acute clinical deterioration�• - high white cell count• - progressive infiltrative changes on chest radiograph
Prevention Passive immunization with humanised RSV specific monoclonal antibodies (Palivizumab) prophylaxis is given during the expected annual RSV outbreak season and is effective in reducing the incidence of hospitalization and severe respiratory disease in infants in the hisk risk categories.
Recommended catagories of infants forpassive immunization1.Chronic lung diseaseChildren or infants<24 months of age whorequiredmedical treatment in the last 6 months beforethe anticipated RSV season.Medical treatment includessupplementary oxygen,corticosteroids,brochodilatorsand diuretic.2.Premature infants less thyan 32 weeks getationwithout chronic lung disease•Infants less than 28 weeks gestation up to 12 monthsof age at the start of the RSV season•Infants between 28-32 weeks gestation up to 6 monthsof age at the start of the RSV season
Reference1.Nelson Textbook Of Pediatrics 18th Edition2.Pediatric Protocol 2nd Edition
CASE : A CHESTY INFANT Max is a 3-month-old boy seen in the community by his GP. He developed a runny nose and bit of a cough 2 days ago but has become progressively more chesty and has now gone off his feeds and is having far fewer wet nappies. He has two older siblings who also have colds. He was born at 34 weeks’ gestation but had no significant neonatal problems and went home at 2 weeks of age. Both parents smoke but not in the house.His mother had asthma as a child.Examination: Max is miserable but alert. His airway is clear. He is febrile (37.8C) and has copious clear nasal secretions and a dry wheezy cough. His respiratory rate is 56 breaths/min with tracheal tug and intercostal and subcostal recession. On auscultation, there are widespread fine crackles and expiratory wheeze. The remainder of the examination is unremarkable.• What is the most likely diagnosis?• What is the commonest causative organism?• What are the indications for referral to hospital?• What is the management in hospital?