Not all children who wheeze have asthma. Most children younger than 3 years who wheeze are not predisposed to asthma. Only 30% of infants who wheeze go on to develop asthma.
To establish the diagnosis of asthma, certain criteria should be met:
1.Episodic symptoms of airflow obstruction or airway hyperresponsiveness
2.Reversible airflow obstruction of at least 10% of predicted forced expiratory volume in one second (FEV1) after use of short-acting beta2-agonist ( CONSULT YOUR PAEDIATRICIAN).
PATHOPHYSIOLOGY
Numerous environmental stimuli induce an allergen-antibody interaction, causing a release of mediators that create airway inflammation. Airway inflammation is the primary factor responsible for smooth muscle hyperresponsiveness, edema, and increased mucous production.
A complex interaction occurs between inflammatory cells and airway epithelium. Mast cells, eosinophils and lymphocytes secrete mediators include histamine, tryptase, heparin, leukotrienes, platelet-activating factor, cytokines, interleukins, and tumor necrosis factor and create an environment toxic to respiratory epithelial cells by causing edema, mucous secretion, bronchospasm and increased work of breathing.
Speculation exists that all infants are born with highly responsive airways. Increased immunoglobulin E (IgE) levels have been found in those younger than 2 years
Rhinovirus infections are an important contributor to asthma exacerbations in children. Hence, therapies against rhinovirus might reduce the risk of severe exacerbations. Fever and bronchospasm are not associated with a more severe clinical course. In fact, fever as a response to infection may have a beneficial effect and can be seen as a good prognostic indicator. Recently, it has been hypothesized that severe infection with Respiratory Syncytial Virus (RSV) may be a marker of a predisposing factor for asthma.
Breastfeeding might protect children younger than 24 months of age against recurrent wheezing. Exposure tobacco smoke the first year appears to predispose children to reactive airway disease.
Current research on the genetic basis for the pathogenesis of asthma may lead to new diagnostic and preventive treatments. The ADAM33 gene on the short arm of chromosome 20 is hypothesized as being important in the development and pathogenesis of asthma.
Laboratory findings
A complete blood count (CBC) may be indicated for a suspected viral infection (lymphocytosis, leukopenia), parasitic infection (eosinophilia), or hemosiderosis.
An arterial blood gas (ABG) determination should be performed for any patient in status asthmaticus to check for hypoxia, hypercarbia, or acidosis; alternatively, a venous blood gas measurement can be used to assess for hypercarbia and acidosis and combined with pulse oximetry monitoring.
An assessment of electrolyte levels may reveal hypokalemia in patients who are using recurrent/ continuous salbutamol usage . Routine radiography does not need to be part of the initial routine evaluation of asthma.
Consider chest radiography if increased temperature, absence of family history of asthma, and the presence of localized wheezes or rales.
Hyperinflation
Peribronchial thickening
Atelectasis
Radiographs may provide evidence of foreign body, associated vascular anomalies, cardiac enlargement, pulmonary hypertension, infiltrates, or masses.
All chronically wheezing infants and children with chronic asthma should have a sweat chloride test for cystic fibrosis at a subsequent primary care provider (PCP) visit or during inpatient evaluation.
A tuberculosis skin test may be indicated if significant risk factors exist.
Allergy testing
Exercise tolerance testing
Procedures for diagnosis
Spirometry (decreased forced expiratory volume in one second [FEV1])
Bedside spirometry is the primary procedure for children with RAD who are older than 5 years.
Patients with decreased FEV1 require further evaluation and treatment.
A barium swallow may be indicated to determine any esophageal, pulmonary, or vascular pathology, particularly a tracheoesophageal fistula.
Bronchoscopy (rarely indicated) (see Table 1 below)
Peak expiratory flow (PEF) is the most common form of pulmonary function test monitoring. Record the best of 3 attempts. Possible life-threatening asthma exacerbation with PEF predicted of less than 30%; severe exacerbation, with less than 50%; and moderate exacerbation, with less than 80%.
Prehospital Care
Provide oxygen during transport, cardiorespiratory monitoring and pulse oximetry, beta-agonist nebulization, and intravenous access if the patient is in moderate-to-severe respiratory distress. Subcutaneous terbutaline or epinephrine may be considered if severe distress and very poor air movement are present.
Emergency Department Care
Mild-to-moderate exacerbations (PEF >50% and/or oxygen saturation >92% on room air)
Levosalbutamol is recommended for the initial treatment of mild-to-moderate acute exacerbations of asthma, administered either by a metered-dose inhaler with spacer (with or without mask) or by a hand-held nebulizer.
Two to six puffs of levosalbutmol via metered-dose inhaler with spacer or 0.15 mg/kg (2.5 mg minimum dose, 5 mg maximum dose) via hand-held nebulizer every 20 minutes for up to 3 doses is recommended.
Oral dexamethasone 0.6 mg/kg/dose (first-line treatment) or oral prednisolone 2 mg/kg/dose (second-line treatment).
Severe exacerbations (PEF < 50% and/or oxygen saturation < 92% on room air) or exacerbations refractory to first-line treatment
Nebulized ipratropium bromide and short-acting beta-agonists, every 20 minutes for up to 3 treatments, are recommended for the treatment of children (250 mcg/dose) and adolescents (500 mcg/dose) with severe exacerbations.
Supplemental oxygen (by nasal cannula or mask, whichever is better tolerated) to maintain an oxygen saturation >92% is recommended during the delivery of short-acting beta-agonists and anticholinergics in patients with severe exacerbations.
Oral dexamethasone 0.6 mg/kg/dose (first-line treatment) or oral prednisolone 2 mg/kg/dose (second-line treatment) may be administered if early response to bronchodilators, otherwise parenteral steroids (dexamethasone or methylprednisolone) should be given.
