Asthma & Bronchiolitis in the Hospitalized Pediatric Patient October 2008 Brian W. Temple, MD Childhood Health Associates of Salem October 2008 Brian W. Temple, MD Childhood Health Associates of Salem

Goals for today General definition of asthma and bronchiolitis Natural history of both disease processes What’s happening in the lungs? Treatment Asthma vs Viral Bronchiolitis

What is asthma? Asthma is a chronic disease characterized by increased responsiveness of the airways to various stimuli and manifested by widespread obstruction, which changes in severity either spontaneously or as a result of therapy.

Chronic disease When can you diagnose? When do you treat? Don’t fear “label” since correct diagnosis leads to correct treatment.

Natural History Median age of onset is 4 years with 20% developing symptoms in first year of life. Risk factors include family history, presence of other inflammatory diseases (like eczema), and early RSV infection. 60% resolve by young adulthood. 50% that remit during adolescence will return as adult History of RSV without family history of asthma or eczema more likely to improve in first few years.

Pathophysiology Asthma is an inflammatory disease!

Common Triggers Infections: viral respiratory illness (rhinovirus, influenza, RSV, parainfluenza, human metapneumovirus), sinus infections Allergens: seasonal allergens, indoor allergens, pets Irritants: cigarette smoke, wood smoke, other pollutants, weather changes

Airway hyperresponsiveness Primarily smooth muscle mediated. Can occur at any age. Reversible with albuterol. Primarily expiratory wheezes. Results in air trapping / obstruction (can be quantified on PFT’s). Variable throughout lungs. May cause atelectasis on x-ray. Primary process for wheezing due to cold air, exercise, pet allergens.

Airway Inflammation More often triggered by infections and chronic allergies. IgE mediated triggering mast cell release. Causes “fixed” obstruction not responsive to albuterol and more often has an inspiratory component. Strong genetic contribution. Needs steroids.

A Closer Look

Symptoms Coughing and wheezing are the most common symptoms of childhood Asthma Breathlessness, chest tightness or pressure, and chest pain also are reported Poor school performance and fatigue may indicate sleep deprivation from nocturnal symptoms

Cough Nocturnal cough, recurring seasonal cough, or cough in response to specific exposures Although wheezing hallmark of asthma, cough is often sole presenting complaint Most common cause of chronic cough in children older than 3 years is asthma

Wheeze Wheezing is a high-pitched, expiratory sound produced when air forced through narrow airways Asthma wheeze tends to be polyphonic (varied in pitch) When airflow obstruction severe, can appreciate wheeze with inspiration and expiration.

Acute Treatment Albuterol and steroids. Neb vs MDI PO vs IV steroids Oxygen for hypoxia Fluid support if dehydration

Oxygen Hypoxia primarily due to ventilation / perfusion mismatch and air trapping Albuterol may actually worsen V/Q mismatch. Don’t use oximetry alone in assessing response to therapy.

Asthma Classification Mild intermittent daily symptoms < 2/week night symptoms < 2/month Mild persistent daily sx >2 per week but < daily night > 2/month Moderate persistent daily symptoms sx > 2x / week affect activity night symptoms > 1/week Severe persistent continuous symptoms limited activity

Outpatient Chronic Treatment Mild intermittent albuterol prn Mild persistent low dose inhaled corticosteroid or Singulair© albuterol prn Moderate persistent low to medium dose inhaled corticosteroid and long acting beta2-agonist Severe persistent high dose inhaled corticosteroid and long acting beta2-agonist consider daily po corticosteroids

What else can be done? Avoid and manage triggers Treatment of allergies. Treatment of chronic infections. Management of household irritants and allergens.

Is it really asthma? Foreign body Laryngotracheomalacia Other congenital abnormalities (congenital heart disease, vascular ring, TE fistula) Gastroesophageal reflux Cystic fibrosis

Is it really asthma? Asthma vs Croup Inspiratory problem or expiratory problem? Course of illness? Age of patient? Patient’s and family’s history?

Is it really asthma? Asthma vs bronchiolitis Age of the patient? Patient’s history of wheezing? Family history of asthma or other allergic disorders? Response to therapy?

Bronchiolitis Bronchiolitis, a lower respiratory tract infection that primarily affects small airways (bronchioles), is a common cause of illness and hospitalization in infants and young children

Definition of Bronchiolitis First episode of wheezing in a child younger than 12 to 24 months with physical findings of a viral respiratory infection and has no other explanation for wheezing Broader definition: an illness in children <2 years of age characterized by wheezing and airways obstruction due to primary infection or re-infection, resulting in inflammation of the bronchioles

Microbiology Typically caused by viral infection Respiratory Syncytial Virus (RSV) is the most common cause Less common causes include parainfluenza virus, human metaneumovirus, influenza virus, adenovirus, rhinovirus, coronavirus, and human bocavirus

Respiratory Syncytial Virus RSV is most common cause of bronchiolitis RSV is ubiquitous throughout world and causes seasonal outbreaks

Epidemiology RSV is responsible for major of cases of bronchiolitis Bronchiolitis typically affects infants younger than 2 years of age Peak incidence is 2 to 6 months of age Leading cause of hospitalization in infants and young children

Risk Factors for severe disease Prematurity (<37 weeks gestation) Low birth weight Age less than 6 to 12 weeks Chronic pulmonary disease Significant congenital heart disease Immunodeficiency

Pathogenesis Viruses penetrate the terminal bronchiolar epithelial cells, causing direct damage and inflammation in small bronchi and bronchioles Edema, excessive mucus, and sloughed epithelial cells lead to obstruction of small airways and atelectasis

The Bronciolitic Lung

Clinical Features Increased respiratory effort and wheezing Tachypnea and intercostal and subcostal retractions with expiratory wheezing Auscultation: expiratory wheeze, prolonged expiratory phase, and both coarse and fine crackles Bronchiolitis is diagnosed clinically

Hospital Treatment of Bronchiolitis Respiratory support: keep oxygen saturation above 90% Fluid administration to ensure adequate hydration and avoid aspiration Chest PT does not appear to improve clinical course Pharmacologic therapy: a number of therapies of been shown to improve outcome

Pharmacologic Therapy Inhaled Bronchodilators (e.g. albuterol, Epinephrine), Do they work? No to oral bronchodilators Glucocorticoids may be beneficial to infants with chronic lung disease and/or asthma component to illness Ribavirin is not routinely recommended

Nonstandard Therapies Heliox- mixture of helium (70-80%) and oxygen (20-30%) Anti-RSV preparations: Palivizumab Surfactant Hypertonic saline

Inhaled Bronchodilators Trial of bronchodilator medication is an option- varied clinical results Albuterol should be tried first with assessment within 1 hour of use, if no improvement, Epinephrine should be tried, if no improvement within hour, Consider discontinuation of bronchodilators

Discharge Criteria Respiratory rate <70 breaths/min Caretaker can clear infants airway Patient is stable without supplemental O2 Adequate oral intake Caretaker confident they can provide care Education of family is complete

Education Expected clinical course: <24 months is 12 days Proper techniques for suctioning the nose Indications to contact primary care provider