asthma what is asthma ?. 1952 definition: “the presence of widespread narrowing of the airways...
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AsthmaAsthma
What is Asthma ?
What is Asthma?
1952 Definition:
“The presence of widespread narrowing of the airways which alters in severity either spontaneously or as a result of treatment”
Asthma
Chronic inflammatory disorder of the airways
Inflammation associated with Airways hyperresponsiveness Airflow limitation (at least partially reversible) Respiratory symptoms (wheeze, cough, tight chest)
Airway inflammation can be present even in mild disease
National Asthma Education and Prevention Panel, Expert Panel Report II “NAEPP Guidelines”, National Institutes of Health, 1997
What is Asthma?
Asthma
The “Tip” of the Iceberg
Airway inflammation
Airflow obstruction
Bronchial hyperresponsiveness
TITANIC Symptoms
Asthma
Symptoms of Asthma
Wheeze, cough, chest tightness (“dyspnea”)
Nocturnal awakenings
Recurrent attacks related to specific triggers
Asthma
Special Aspects of Asthma• Allergic (or extrinsic) asthma
• Nocturnal asthma
• Exercise-induced bronchoconstriction (EIB)
• Aspirin-sensitive
• Cough-variant
• Occupational
Asthma
Asthma Prevalence by Age37%
30%
21%
12%
15-19y
6-14y
< 6y
10%
19%
8%0%
0-19y 20-39y 40-59y 60+y
5%
10%
15%
20%
25%
30%
35%
40%
AGE (years)
Per
cen
tag
e o
f
Ast
hm
atic
Po
pu
lati
on
Asthma
AsthmaAsthmaBurden of Asthma
…on society
Asthma in the United States -- a growing problem
17.4 million Americans have asthma– Prevalence rose 75% 1980-1994– Prevalence rose more in children (160% in 0–4 y.o.’s)
1.9 million ER visits (in 1995) and466,000 hospitalizations (in 1993)– Office Visits doubled (from 1975 to 1995)
3 per 10,000 asthmatic patients die (1994)– Deaths doubled (for 5–24 y.o.’s from 1980 to 1993)
from National Center for Health StatisticsAsthma
Asthma is the Most Common Chronic Illness of Childhood
13 million physician visits/year 87% of asthmatic children had unscheduled physician visits in the prior
year
Third-ranking cause of hospitalization in children <15 and the highest-ranking cause among chronic conditions
200,000 hospitalizations/yearMost common chronic illness resulting in school absences
10.1 million lost school days a year On average: 1 week absent per asthmatic child
Asthma
Asthma Mortality
Higher risk of death from asthma– African Americans– Males
0
5
10
15
20
25
30
35
40
45
'79-'80 '81-'83 '84-'86 '87-'89 '90-'92 '93-'95
Caucasian
African AmericanRate of Asthma
Deaths(per 1,000,000)
Asthma
Pediatric Asthma Mortality Asthma deaths have more than doubled
for 0- to 14-year-olds from 1979 to 19951
Number of Asthma Deaths
0
20
40
60
80
100
120
140
160
'79-'80 '81-'83 '84-'86 '87-'89 '90-'92 '93-'95
0-4 yo
5-14 yo
Most patients who died – not seen as “high risk”2
Some patients who died had mild diseaseAsthma
AsthmaAsthmaBurden of Asthma
…on the patient
Asthma’s Impact
The highest-ranking chronic condition causing hospitalization in children
The most common chronic illness of childhood
Children with asthma have 3x the school absences of children without asthma
40% of children with asthma have sleep disturbances, 1 to 2 nights/week even if the child is not absent from school, he or she may
have reduced school performance due to sleep disturbances
Asthma
Asthma’s Impact
23% of adults with asthma missed work during the prior year due to asthma
36% of parents of asthmatics missed work in the prior year
50% of parents and 49% of patients say asthma limits the range of activities a family can do together
78% of parents of asthmatics report that asthma has a negative impact on the family
Asthma
AsthmaAsthma
Diagnosis
Diagnosis of AsthmaSymptoms
Wheeze, cough, chest tightness (“dyspnea”)
Nocturnal awakenings
Recurrent attacks related to specific triggers
Response to asthma-specific therapy
Asthma
Diagnosis of AsthmaLung Function Measurements
• Changes in lung function over time (Spontaneously or in response to therapy)
- Spirometry (FEV1)
- Peak expiratory flow rate(PEFR or “peak flow”)
• Airway hyperresponsiveness to stimuli
- Methacholine challenge test
- Exercise challenge test
Asthma
Bronchial Provocation
20
0
Low PD20 High BHR
High PD20 Low BHR
FEV1 %
fall from
baseline
A
B
C
Increasing dose of methacholine
Asthma
The Early and Late Asthmatic Response
50
25
1 2 3 4 5 6 7 8 9 10 11 12
75
100
Time (hours)Inhaled allergen
AAR
AAR = Acute asthmatic response LAR = Late asthmatic response
FE
V1 (
% p
red
icte
d)
LAR
Asthma
Spirometry
1
1
2
2
3
3
4
4
5 6
Time (seconds)
FEV1 post-bronchodilator
FEV1 pre-bronchodilator
Before bronchodilator
After bronchodilator
FVC
Exh
aled
vo
lum
e (L
)
Asthma
Uses of Daily Peak Flow Monitoring
Acutely:
• Assess severity of exacerbations
Short term:
• Evaluate therapy
• Establish temporal relationship to triggers
Long-term:
• Detect changes in disease status
• Evaluate treatment
• Provide patient with a written action plan
Asthma
Normal Asthma
Circadian Changes in PEFR
Morning peak flowEvening peak flow
PE
FR
(%
Pre
dic
ted
)
100%
50%
100%
50%
PEFR recorded twice-daily over 2 weeks
Asthma
AsthmaAsthmaDiagnosis
…per the guidelines
Asthma Guidelines: Recent evolution
NAEPP Guidelines 1997• National Asthma Education and Prevention Panel,
Expert Panel Report II, National Institutes of Health (“NIH”), National Heart, Lung, and Blood Institute (NHLBI))
GINA Guidelines 1998• Global INitiative for Asthma,
Asthma Management and Prevention Report, NHLBI and World Health Organization (WHO)
Pediatric Asthma: Promoting Best Practices 1999• American Academy of Allergy, Asthma & Immunology (AAAAI),
American Academy of Pediatrics (AAP), National Heart, Lung, and Blood Institute (NHLBI), NAEPP, etc
Asthma
NAEPP and GINA GuidelinesAsthma severity: Classified the same
3344
2211
Severe PersistentSevere Persistent
Moderate PersistentModerate Persistent
Mild PersistentMild Persistent
Mild IntermittentMild Intermittent
Severity is classified before therapy begins
• Symptoms
• Activity levels
• Exacerbations
• FEV1/PEFR
• PEFR variability
Classified by:
Severity is classified before therapy beginsAsthma
Asthma GuidelinesSeverity: Mild Intermittent
Mild Mild IntermittentIntermittent
Clinical features before treatment• Symptoms < 2x per week
• Brief exacerbations
• Nighttime symptoms < 2x per
month
• Asymptomatic with normal lung
function between exacerbations
• FEV1 and PEF > 80% predicted
• PEF variability < 20%
11
Asthma
Clinical features before treatment
• Symptoms > 2x per week but
<1x
per day
• Exacerbations may affect
activity
• Nighttime asthma symptoms >
2x
per month
• FEV1 and PEF > 80%
predicted
• PEF variability 20 - 30%
22Mild Mild PersistentPersistent
Asthma GuidelinesSeverity: Mild Persistent
Asthma
Clinical features before treatment
• Daily symptoms
• Exacerbations > 2x per week
affect activity
• Nighttime asthma symptoms >
1x
per week
• Daily use of short-acting ß
agonist
• FEV1 and PEF > 60% and <
80%
predicted
• PEF variability > 30%
33Moderate Moderate PersistentPersistent
Asthma GuidelinesSeverity: Moderate Persistent
Asthma
Clinical features before treatment
• Continuous symptoms
• Frequent exacerbations
• Frequent nighttime symptoms
• Limited activity
• FEV1 and PEF < 60% predicted
• PEF variability > 30%
44Severe Severe PersistentPersistent
Asthma GuidelinesSeverity: Severe Persistent
Asthma
Management of Asthma
Assessment and monitoringControl of factors contributing to
asthma severityPharmacotherapyEducation
Asthma
Eosinophils
MediatorsMediators
Histamine Histamine
Leukotrienes Leukotrienes
Prostaglandins Prostaglandins
Mast cell tryptase Mast cell tryptase
Eosinophil cationic proteinEosinophil cationic protein
Cytokines (IL-4, IL-5)Cytokines (IL-4, IL-5)
Mast cells
T lymphocytes
manyother cells
Inflammatory Cell-Derived Mediators
Asthma
Asthma
Asthma