Transcript PowerPoint Presentation – Asthma Pathophysiology

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.
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 optionvaried 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