Pediatric asthma Adel Ahadi, MD

Asthma is a chronic inflammatory condition of the lung airways resulting in episodic airflow obstruction ETIOLOGY. Although the cause of childhood asthma has not been determined, contemporary research implicates a combination of environmental exposures inherent biological genetic vulnerabilities →More than 22 loci on 15 autosomal chromosomes Respiratory exposures in this causal environment include inhaled allergens respiratory viral infections chemical biological air pollutants such as environmental tobacco smoke

EPIDEMIOLOGY. Asthma is a common chronic disease, causing considerable morbidity→in 2002, 8.9 million children (12.2%) had been diagnosed with asthma in their lifetime 4.2 million children (5.8%) had an asthma attack in the preceding 12 mo, indicative of current disease Boys (14% vs 10% girls) children in poor families (16% vs 10% not poor) childhood asthma is the most common cause of childhood emergency department visits Hospitalizations missed school days A disparity in asthma outcomes links high rates of asthma hospitalization and death with poverty, ethnic minorities, and urban living

Approximately 80% of all asthmatics report disease onset prior to 6 yr of age. Of all young children who experience recurrent wheezing→only a minority will go on to have persistent asthma in later childhood.

Early Childhood Risk Factors for Persistent Asthma Parental asthma Allergy Atopic dermatitis Allergic rhinitis Food allergy Inhalant allergen sensitization Food allergen sensitization Severe lower respiratory tract infection Pneumonia Bronchiolitis requiring hospitalization Wheezing apart from colds Male gender Low birthweight

Asthma Predictive Index for Children MAJOR CRITERIA Parent asthma Inhalant allergen sensitization Eczema MINOR CRITERIA Allergic rhinitis Wheezing apart from colds Eosinophils ≥ 4% Food allergen sensitization

 Types of Childhood Asthma.  Asthma is considered to be a common clinical presentation of intermittent, recurrent wheezing and/or coughing  There are 2 main types of childhood asthma:  (1) recurrent wheezing in early childhood, primarily triggered by common viral infections of the respiratory tract  (2) chronic asthma associated with allergy that persists into later childhood and often adulthood.  A 3rd type of childhood asthma typically emerges in females who develop obesity and early-onset puberty (by 11 yr of age)  Triad asthma, characteristically associated with  hyperplastic sinusitis  nasal polyposis  hypersensitivity to aspirin and non-steroidal anti- inflammatory medications (ibuprofen  The most common persistent form of childhood asthma is that associated with allergy

PATHOGENESIS as well as airways edema basement membrane thickening subepithelial collagen deposition smooth muscle mucous gland hypertrophy, and mucus hypersecretion —all processes that contribute to airflow obstruction

Asthma Triggers Common viral infections of the respiratory tract Aeroallergens in sensitized asthmatics Animal dander Indoor allergens Dust mites Cockroaches Molds Seasonal aeroallergens Pollens (trees, grasses, weeds) Seasonal molds Environmental tobacco smoke Air pollutants Ozone Sulfur dioxide Particulate matter Dust Strong or noxious odors or fumes hairsprays Cleaning agents Occupational exposures Farm and barn exposures Formaldehydes, cedar, paint fumes Cold air, dry air Exercise Crying, laughter, hyperventilation Co-morbid conditions Rhinitis Sinusitis Gastroesophageal reflux

CLINICAL MANIFESTATIONS AND DIAGNOSIS. the most common chronic symptoms are of asthma expiratory wheezing Intermittent dry coughing nonfocal chest “pain Older children and adults will report associated shortness of breath chest tightness Respiratory symptoms can be worse at night Daytime symptoms→physical activities or play asthma symptoms in children can be subtle and nonspecific, including self-imposed limitation of physical activities general fatigue (possibly due to sleep disturbance) difficulty keeping up with peers in physical activities

The presence of risk factors, such as a history of other allergic conditions allergic rhinitis allergic conjunctivitis atopic dermatitis food allergies parental asthma symptoms apart from colds, supports the diagnosis of asthma. The chest examination is often normal. Deeper breaths In clinic, quick resolution (within 10 min) Decreased breath sounds in some of the lung fields, commonly the right lower posterior lobe→regional hypoventilation Crackles (or rales) and rhonchi The combination of segmental crackles and poor breath→ atelectasis

Differential Diagnosis of Childhood Asthma UPPER RESPIRATORY TRACT CONDITIONS Allergic rhinitis Chronic rhinitis Sinusitis Adenoidal or tonsillar hypertrophy Nasal foreign body MIDDLE RESPIRATORY TRACT CONDITIONS Laryngotracheobronchitis (e.g., pertussis) Laryngeal web, cyst, or stenosis Vocal cord dysfunction Tracheoesophageal fistula Vascular ring Foreign body aspiration LOWER RESPIRATORY TRACT CONDITIONS Bronchopulmonary dysplasia (chronic lung disease of preterm infants) Viral bronchiolitis Gastroesophageal reflux Causes of bronchiectasis→Cystic fibrosis Immune deficiency

In early life, chronic coughing and wheezing can indicate recurrent aspiration Tracheobronchomalacia a congenital anatomic abnormality of the airways foreign body aspiration cystic fibrosis bronchopulmonary dysplasia In older children and adolescents, vocal cord dysfunction (VCD) can present as intermittent daytime wheezing the vocal cords close inappropriately, during inspiration and sometimes exhalation producing shortness of breath Coughing throat tightness often audible laryngeal wheezing and/or stridor spirometric lung function Speech therapy is the treatment of choice for VCD.

LABORATORY FINDINGS. Lung function tests can help to confirm the diagnosis of asthma and determine disease severity. Pulmonary Function Testing Forced expiratory airflow measures are helpful in diagnosing monitoring asthma in assessing efficacy of therapy Spirometry is helpful as an objective measure of airflow limitation usually feasible in children >6 yr of age on 3 attempts, the FEV 1 (forced expiratory volume in 1 sec) is within 5%, then the highest FEV 1 effort of the 3 is used

Lung Function Abnormalities in Asthma Spirometry (in clinic) Airflow limitation Low FEV1 (relative to percentage of predicted norms) FEV1/FVC ratio <0.80 Bronchodilator response (to inhaled β-agonist) Improvement in FEV1 ≥12% or ≥200 mL Exercise challenge→aerobic exertion or running for 6–8 min Worsening in FEV1 ≥15% Daily peak flow or FEV 1 monitoring: day to day and/or AM-to-PM variation ≥20%

Radiology. Chest radiographs (posteroanterior and lateral views) in children with asthma often appear to be normal, aside from subtle and nonspecific findings of hyperinflation peribronchial thickening Chest radiographs can be helpful in identifying abnormalities that are hallmarks of asthma masqueraders aspiration pneumonitis hyperlucent lung fields in bronchiolitis obliterans complications during asthma exacerbations Atelectasis Pneumomediastinum Pneumothorax

A 4-year-old boy with asthma. Frontal (A) and lateral (B) radiographs show pulmonary hyperinflation and minimal peribronchial thickening. No asthmatic complication is apparent.

The Goals of Asthma Therapy: (Asthma Control) Reducing impairment prevent chronic and troublesome symptoms require infrequent use (≤ 2 days a week) of inhaled SABA for symptoms maintain (near) “normal” pulmonary function maintain normal activity levels meet patients’ and families’ satisfaction with care Reducing risk prevent recurrent exacerbations of asthma. prevent progressive loss of lung function provide optimal pharmacotherapy

The 4 Components of Asthma Management Component 1: Measures of Asthma Assessment and MonitoringComponent 1 Component 2: Education for a Partnership in Asthma CareComponent 2 Component 3: Control of Environmental Factors and Comorbid Conditions That Affect AsthmaComponent 3 Component 4: MedicationsComponent 4:

 Component 1: REGULAR ASSESSMENT AND MONITORING Component 1  Asthma checkups  Every 2–4 wk until good control is achieved  2–4 per yr to maintain good control  Lung function monitoring  PEF monitoring is feasible in children as young as 4 yr old  The green zone (80–100% of personal best) indicates good control  the yellow zone (50–80%) indicates less than optimal control  the red zone (<50%) indicates poor control  Component 2: Control of Environmental Factors and Comorbid Conditions That Affect Asthma Component 2  Eliminate or reduce problematic environmental exposures  Treat co-morbid conditions:  rhinitis  detected in ≈90%  sinusitis  nasal saline irrigations, intranasal corticosteroids, 2–3 wk course of antibiotics  gastroesophageal reflux  incidence of up to 64%  8 to 12 wk  Annual influenza vaccination (unless egg-allergic)

Indoor Asthma triggers include:Other triggers include: Secondhand smoke Pollen and outdoor molds Dust MitesActivity Pets Cold and other infections MoldWeather Cockroaches..

Component 3: ASTHMA PHARMACOTHERAPY Component 3 Long-term-control vs quick-relief medications Classification of asthma severity for anti-inflammatory pharmacotherapy is based on the following parameters: (1) frequency of daytime (2) nighttime symptoms (3) degree of airflow obstruction by spirometry (4) PEF variability Step-up, step-down approach Asthma exacerbation management Component 4: PATIENT EDUCATION Component 4: Provide a two-part care plan Daily management Action plan for asthma exacerbations

FOR ADULTS AND CHILDREN AGE > 5 YEARS WHO CAN USE A SPIROMETER OR PEAK FLOW METER NIGHTS WITH SYMPTOMS DAYS WITH SYMPTOMS STEPCLASSIFICATION PEF Variability (%)FEV 1 or PEF % Predicted Normal 30<60≥FrequentContinua4Severe persistent 30< 60 >1/wkDaily3Moderate persistent ≥>2/mo>2/wk, but <1 time/day 2Mild persistent < 2080 ≥<2/mo≤2/wk1Mild intermittent Classification of Asthma Severity

Step 4 Severe persistent Symptoms/Night →continual / frequent Preferred treatment High-dose inhaled corticosteroids Long-acting inhaled β 2 -agonists Step 3 Moderate persistent Symptoms/Night → daily / > 1night per Wk Preferred treatment — Low-dose inhaled corticosteroids+long-acting inhaled β 2 - agonists Medium-dose inhaled corticosteroids. Alternative treatment — Low-dose inhaled corticosteroids + either leukotriene receptor antagonist or theophylline

Step 2 Mild persistent Symptoms/Night → > 2per Wk 2night per mo Preferred treatment Low-dose inhaled corticosteroid (with nebulizer or MDI with holding chamber with or without face mask or DPI) Alternative treatment Cromolyn (nebulizer is preferred or MDI with holding chamber) leukotriene receptor antagonist. Step 1 Mild intermittent Quick Relief All Patients Symptoms/Night → ≤ 2 days per Wk /≤ 2 nights / mo No daily medication needed.

Spacer devices (1)decrease the coordination required to use MDIs, especially in young children; (2)improve the delivery of inhaled drug to the lower airways (3)minimize the risk of propellant-mediated adverse effects (thrush).

INHALED CORTICOSTEROIDS (ICS). daily ICS therapy as the treatment of choice for all patients with persistent asthma reduce asthma symptoms improve lung function reduce AHR reduce “rescue” medication use most important, reduce urgent care visits Hospitalizations prednisone use for asthma exacerbations by about 50%

Asthma control CharacteristicControlledPartly controlledUncontrolled Daytime symptomsTwice or less/week>Twice/week3 or more Limitation of activity NoneAny Nocturnal symptoms NoneAny Need for relieverTwice or less/week>Twice/week Lung functionNormal<80%predicted ExacerbationNone1 or more/yearOne in any week

Asthma Exacerbation Management (Status Asthmaticus) RISK ASSESSMENT ON ADMISSION Focused history Onset of current exacerbation → during sleep (between midnight,8 am) Frequency and severity of daytime and nighttime symptoms and activity limitation Frequency of rescue bronchodilator use Current medications and allergies Potential triggers History of systemic steroid courses, emergency department visits, hospitalization, intubation, or life-threatening episodes Clinical assessment Physical examination findings: vital signs, breathlessness, air movement, use of accessory muscles, retractions, anxiety level, alteration in mental status Pulse oximetry Lung function (defer in patients with moderate Risk factors for asthma morbidity and death

Risk Factors for Asthma Morbidity and Mortality BIOLOGIC Previous severe asthma exacerbation Severe airflow obstruction History of rapidly occurring attacks Severe airways hyperresponsiveness (AHR) Increasing and large diurnal variation in peak flows Decreased chemosensitivity and perception of dyspnea Poor response to systemic corticosteroid therapy Male gender Low birthweight Nonwhite (especially black) ethnicity ENVIRONMENTAL Allergen exposure Environmental tobacco smoke exposure Air pollution exposure Urban environment

ECONOMIC AND PSYCHOSOCIAL Poverty Crowding Mother <20 yr old Mother with less than high school education Inadequate medical care Inaccessible Unaffordable No regular medical care (only emergent) No care sought for chronic asthma symptoms Delay in care of asthma exacerbations Inadequate hospital care for asthma exacerbation Psychopathology in the parent or child Family problems Alcohol or substance abuse

Home Management of Asthma Exacerbations. A written home action plan can reduce the risk of asthma death by 70%. immediate treatment with “rescue” medication (inhaled SABA, up to 3 treatments in 1 hr). A good response is characterized by resolution of symptoms within 1 hr, no further symptoms over the next 4 hr, improvement in PEF to at least 80% of personal best. The child's physician should be contacted for follow-up If bronchodilators are required repeatedly over the next 24–48 hr. If the child has an incomplete response to initial treatment with rescue medication a short course of oral corticosteroid therapy (prednisone 1–2 mg/kg/day [not to exceed 60 mg/day] for 4 days)

Emergency Department Management of Asthma Exacerbations. the primary goals of asthma management include correction of hypoxemia rapid improvement of airflow obstruction prevention of progression or recurrence of symptoms. Indications of a severe exacerbation include breathlessness, dyspnea, retractions, accessory muscle use tachypnea or labored breathing cyanosis mental status changes a silent chest with poor air exchange severe airflow limitation (PEF or FEV 1 <50% ) Initial treatment includes supplemental oxygen inhaled β-agonist every 20 min for 1 hr if necessary, systemic corticosteroids given either orally or intravenously Inhaled ipratropium An intramuscular injection of epinephrine

The patient may be discharged to home if there is sustained improvement in symptoms normal physical findings PEF >70% of predicted or personal best an oxygen saturation >92% on room air for 4 hr Discharge medications include administration of an inhaled β-agonist up to every 3–4 hr plus a 3–7 day course of an oral corticosteroid

Management of Asthma During Surgery. Patients with asthma are at risk from disease-related complications from surgery such as bronchoconstriction asthma exacerbation Atelectasis impaired coughing respiratory infection latex exposure A systemic corticosteroid course may be indicated for patients who are having symptoms FEV 1 or PEF <80% of the patient's personal best who have received more than 2 wk of systemic corticosteroid moderate-to-high dose ICS therapy →intraoperative adrenal insufficiency.

PROGNOSIS. Recurrent coughing and wheezing occurs in 35% of pre–school-age children. Of these, ⅓ continue to have persistent asthma into later childhood, while ⅔ improve on their own through the preteen years. Asthma severity by the ages of 7–10 yr of age Children with moderate to severe asthma and with lower lung function measures