Asthma Overview Presented by Michelle Harkins MD University of New Mexico This session will cover Review asthma statistics Define asthma Outline key pathophysiologic features Review signs and symptoms of asthma ID: 569461
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Slide1
Asthma PathophysiologyAsthma Overview
Presented by:
Michelle Harkins, MD
University of New MexicoSlide2
This session will coverReview asthma statistics
Define asthma
Outline key
pathophysiologic
features
Review signs and symptoms of asthma
Reference to NAEPP – EPR-3: asthma severity classification system-including impairment and risk domains
Diagnosing asthmaSlide3Slide4
Prevalence vs Incidence
Prevalence
- the proportion or percentage of a population that has disease at a specific point or period of time
Incidence
– the number of new cases of disease that develop in a population of individuals at risk during a specific point or period of timeSlide5
1980-1996 prevalence of asthma in US increased
Since 1999, mortality and hospitalization due to asthma have decreasedSlide6
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide7
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide8
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide9
New Mexico BRFSS Results for 2010: Current Prevalence: Percent of New Mexico Children who Currently Have Asthma by Various Demographic Characteristics
Race/Ethnicity:
White, Non-Hispanic 8.1%
Hispanic 7.4%
Native American 13.1%
SOURCE: Centers for Disease Control and Prevention (CDC).
Behavioral Risk Factor Surveillance System Survey Data.
Atlanta, Georgia: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2009Slide10
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide11
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide12
Asthma age-adjusted hospitalization rates per 10,000 standard population
by county, New Mexico, 2007-2011 averageSlide13
Asthma hospitalization rates per 10,000 standard population among youth (0-14 years)
by county, New Mexico, 2007-2011 averageSlide14
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide15
Trends in Asthma Morbidity and Mortality. American Lung Association, Epidemiology and Statistics Unit, Research and Program Services Division.
September, 2012.Slide16
Asthma Age-Adjusted Death Rates Based on the 1940 and 2000 Standard populations, 1979-2005
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
1940
0.9
1.0
1.0
1.0
1.2
1.1
1.2
1.2
1.3
1.4
1.4
1.4
1.5
1.4
1.4
1.5
1.5
1.5
1.4
1.4
1.2
1.1
1.0
1.0
1.0
0.9
0.9
2000
1.3
1.4
1.5
1.5
1.7
1.6
1.8
1.8
1.9
2.0
2.1
2.1
2.2
2.0
2.1
2.2
2.2
2.2
2.1
2.0
1.7
1.6
1.5
1.5
1.4
1.3
1.3Slide17
0
Asthma Patient Demographics
US Population = 305.8 Million (US Census, 2/18/09);
Asthma Patients = 7.7% Prevalence (NHIS 2007)
Age
Asthma Physician
Market Dynamics
Study
3/99
–
10/99
NHIS 2007
Age 18+ y
16.2 million 71%
Age <18 y
6.7 million 29%
Severe persistent 16%
Moderate
persistent
31%
Mild
persistent
25%
Mild
intermittent
28%
22.9 Million asthma patients
Non-Hispanic Black 3.5 million 15%
Hispanic
2.8 million 12%
Non-Hispanic White
15.6 million 68%
Asthma
patients
Severity
Race
Gender
Men
9.5 million
44%
Women
13.4 million 56%
Asthma deaths
3,884
NCHS, NVSR. Deaths, Final Data for
2005.
Mortality
NHIS 2007
NHIS 2007
NHIS 2007Slide18
Asthma Impact – Economic Burden
Childhood asthma accounts for 14.4 million days missed from school annually
The
number-one
chronic condition causing children to be absent from school and the third highest ranked cause of pediatric hospitalizations in the United States
On average, a child with asthma will miss
one full week
of school each year due to the diseaseSlide19
Asthma Impact – Economic Burden
Adult asthma accounts for 14.2 million missed workdays annually
4th leading cause of missed work daysSlide20
National Burden of Asthma
$19.7 billion annually
$14.7 billion
in
direct
costs (prescription medications, hospital care, and physician services)
$5 billion
in
indirect
costs (lost productivity due to missed work or school and premature mortality)Slide21
Define Asthma
Develop a collaborative working definition of asthmaSlide22
Evolution of the Definition of Asthma
Episodic disease characterized by:
Reversible airway constriction
Increased airway responsiveness
Chronic disease characterized by:
Chronic airway inflammation
At least partially reversible airway obstruction
Increased airway responsiveness
1962
2007
American Thoracic Society, 1962.
NAEPP, EPR3, 2007. Slide23
3M Resource Cards
Doctors Designers
11-96Slide24
3M Resource Cards
Doctors Designers
11/96Slide25
3M Resource Cards
Doctors Designers
11-96Slide26
Pathophysiology of AsthmaSlide27
Epithelial Damage in Asthma
Asthmatic
NormalSlide28
Asthma: PathophysiologyInflammatory cell infiltrate consists of mainly of eosinophils and lymphocytes
“Sudden death” asthma associated with an infiltrate of neutrophils
Denudation of airway epithelium
Mucus gland hyperplasia and hypersecretion
Smooth muscle cell hyperplasia
Submucosal edema and vascular dilatation
Fibrin deposition/airway remodelingSlide29
Mast Cells
Macrophages
Eosinophils
T-Lymphocytes
Epithelial Cells
Platelets
Neutrophils
Myofibroblasts
Basophils
Multiple Mechanisms Contribute to Asthma: Inflammatory Mediators
Histamine
Lipid Mediators*
Peptides
†
Cytokines
‡
Growth Factors
Mediator
Soup
Bronchoconstriction
Microvascular Leakage
Mucus Hypersecretion
Airway
Hyperresponsiveness
*For example, prostaglandins and leukotrienes.
†
For example, bradykinin and tachykinin.
‡
For example, tumor necrosis factor (TNF).
Adapted with permission from Barnes PJ.
In: Barnes PJ et al, eds.
Asthma: Basic Mechanisms and Clinical Management
. 3rd ed. Academic Press; 1998:487-506.Slide30
NAEPP, EPR-3, pg. 15.
FACTORS LIMITING AIRFLOW IN ACUTE AND PERSISTENT ASTHMASlide31
Inflammation in Asthma
IgE = immunoglobulin E.
National Asthma Education and Prevention Program Guidelines, 1997.
Busse WW et al.
N Engl J Med
. 2001;344:350-362.
Bousquet J et al.
Am J Resp Crit Care Med
. 2000;161:1720-1745.
Airway Inflammation
Allergen/Trigger
T-cell
B-cell
IgE
Eosinophil
Mast cell
Cytokines
Histamine
MacrophageSlide32
Aftermath of Inflammation
Reversibility
Occurs in most asthma episodes
Airway returns to normal caliber
Flow of air through airways returns to normal “speed”
Remodeling
Airway lining builds up persistent fibrotic changes
Airway caliber remains abnormal
Air flow is decreased
Permanent changes appear to begin in childhood, but become recognizable in adultsSlide33
Asthma
is
a Chronic Inflammatory Disease: Pathophysiologic Changes
Hematoxylin and eosin stain.
Photographs courtesy of Nizar N. Jarjour, MD, University of Wisconsin.
Bronchial Mucosa From a Subject Without Asthma
Bronchial Mucosa From a Subject With Mild Asthma
Normal Architecture
Disrupted ArchitectureSlide34
Lumen
Epithelium
Subepithelial Collagen
Deposition
Consequences of Persistent Asthma:
Subepithelial Collagen Deposition
Reprinted with permission from Holloway L et al. In: Busse WW, Holgate ST, eds.
Asthma and Rhinitis
. Blackwell Scientific Publications; 1995:109-118.Slide35
FEV1
% Predicted
Duration of Asthma (years)
80
40
120
10
20
50
40
30
0
r = -0.47
n = 89
P
<.001
60
20
100
Consequences of Persistent Asthma:
Progressive Decline in FEV
1
FEV
1
= forced expiratory volume in 1 second.
Adapted with permission from Brown PJ et al.
Thorax
. 1984;39:131-136.Slide36
Chronic inflammatory disorder of the airwaysMast cells, eosinophils and lymphocytes infiltrate into airway lining
Airway hyperresponsiveness develops
Excessive reaction to “minor” irritants results in a host of deleterious airway changes
Bronchial wall edema
Smooth muscle contraction
Excess mucus production
Patchy, mostly reversible regions of airway narrowing cause asthma symptoms
Asthma is. . .Slide37
Acute Reaction to Triggers
Irritated airways become more inflamed after exposure to stimuli
Muscle layers around airway constrict
Airway lining swells
Excess mucus builds up in lumen
Result: symptoms of cough, wheeze, shortness of breath, chest tightnessSlide38
Genetic predispositionAtopy
Airway hyperresponsiveness
Gender
Race/Ethnicity
Risk Factors for Developing AsthmaSlide39
What Parameters Affect Disease ?
Intrinsic factors
Genetics
Duration of asthma
Severity of childhood asthma
Gender
Response to therapy
Extrinsic factors
Viral infections
Allergen exposure
Airway irritants
Exercise
Compliance
Season
Time of day
Occupational—10-15% of adult asthma
Western Lifestyle--obesitySlide40
Environmental Risk Factors for Development of Asthma
Indoor allergens
Outdoor allergens
Occupational sensitizers
Tobacco smoke
Air Pollution
Respiratory Infections
Parasitic infections
Socioeconomic factors
Family size
Diet and drugs
Obesity
Hygiene hypothesis Slide41
INFLAMMATION
Risk Factors
(for development of asthma)
Bronchial
Hyperresponsiveness
Airflow Obstruction
Risk Factors
(for exacerbations)
Symptoms
Genetic
Environmental
Asthma & Airway InflammationSlide42
Multiple Triggers Can StimulateAcute Reaction
Upper Respiratory Infections (URI’s)
Viral Respiratory infections are the #1 trigger behind asthma hospitalizations
Influenza vaccines are recommended for people with asthma
Allergens
Irritants
Sudden or extreme changes of weather
Exercise
Intense emotionsSlide43
Exercise Induced Bronchospasm
Bronchospasm caused by activity
Some activity more likely than others to trigger it
Cold environment: skiing, ice hockey
Heavy exertion: Soccer, long distance running
Exercising when you have a viral coldSlide44
Exercise Induced BronchospasmSymptoms include
Coughing
Wheezing
Chest tightness
Symptoms may begin during activity and peak in severity 10-20 minutes after stopping
Can spontaneously resolve 20-30 minutes after its onsetSlide45
EpidemiologyPrevalence 7-20% of the general population
80% of patients with asthma have some degree of EIB
Exercise is not a risk factor for asthma, rather a trigger
?Exercise may help prevent onset of asthma in children
Decrease in physical activity may play a role in increased in asthma prevalence
JACI 2005 Lucas SR,
Platts
-Mills TASlide46
Prevention of EIB
Use bronchodilator 10-15 minutes before onset of activity
Do warm-up/cool down exercises
Check ozone/allergy warnings
Never encourage anyone to “tough it out”Slide47
ManagementIncreasing fitness: decreases minute ventilation needs with exerciseLess severe if inspired air is warmer, more humid
(Evidence Class C)
Scarf or mask if cold weather
Warm-up period before exercise
Good asthma control: EIB more frequent in patients with poorly controlled disease
(Class A)
Check for asthma control
Treating appropriately will reduce frequency and severity of EIBSlide48
Impairment and Risk Domains
Impairment
-frequency and intensity of symptoms and functional limitations the patient is experiencing or has experienced
Risk-
the likelihood of either asthma exacerbations, progressive decline in lung function or risk of adverse effects from medication
NIH. NAEPP Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma, October 2007.Slide49
History of severe exacerbationsPrior intubation for asthmaPrior admission to Intensive Care Unit
2 or more hospital admissions in the past year
3 or more emergency room visits in the past year
Hospital or emergency room visit past month
Use of >2 canisters per month of inhaled short-acting beta2 –agonist
Risk Factors for Death from AsthmaSlide50
Chronic use of systemic corticosteroidsPoor perception of airflow obstruction or its severity
Co-morbid conditions (other diseases)
Serious psychiatric disease or psychosocial problems
Low socioeconomic status and urban residence
Illicit drug use
Sensitivity to alternaria-mold
Lack of written asthma action plan
Risk Factors for Death from AsthmaSlide51
Recurrent episodes of coughing or wheezeAsthma may be present without a wheeze - cough may be the sole symptomShortness of breath or difficulty breathing
Chest Tightness
Wheezing does not always mean asthma
Absence of symptoms and physical findings at the time of the examination does not exclude asthma
Diagnosing AsthmaSlide52
AsthmaDiagnosis by history of wheeze, shortness of breath, cough, chest
tightness
Spirometry
can help define the severity of the disease, however may be normal if asthma is under control
Lack of bronchodilator response does not rule out asthma
Following Peak Flows may be usefulSlide53
Spirometry should be performed:at initial assessmentafter treatment is initiated and symptoms and PEFs have stabilized
at least every 1-2 years to assess maintenance of airway function if well controlled
More often if poor asthma control
Measures of Assessment & MonitoringSlide54
Peak Flows may be performed: In all moderate and severe persistent asthmaticsestablish a personal best
useful in exacerbations and maintenance/ changes of therapy,
Can be helpful with ‘poor perceivers’
Measures of Assessment & MonitoringSlide55
< 2 Years Old: When Is It Asthma?Slide56
< 2 Years Old: When Is It Asthma?Slide57
Asthma Predictive Index
MAJOR CRITERIA
Atopic dermatitis
Parental Asthma
MINOR CRITERIA
Wheezing apart from colds
Allergic rhinitis
Blood eosinophilia
1 of 2 major criteria
or
2 minor criteria
> ¾ of children with a positive index had some active asthma symptoms between 6 and 13 years of age
In an infant or young child with > 3 episodes of wheezing in the past yearSlide58
Asthma: Children vs. AdultsSlide59
Asthma MisdiagnosisSlide60
Asthma Severity AssessmentsSlide61
Long-Term Management of Asthma in Children: Initiation of Control Therapy
Symptoms > 2 x week
Severe exacerbations < 6 weeks apart
2 or more burst of prednisone in 6 months for ages 0-4
2 or more burst of prednisone in 1 year for ages 5-11
Positive Asthma Predictive IndexSlide62
Questions?