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Asthma & Bronchiolitis in the Hospitalized Pediatric Patient • 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! • Asthma is an inflammatory disease! • 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.
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.
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
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