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Asthma Diagnosis: Anatomy and Pathophysiology of Asthma
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Transcript of Asthma Diagnosis: Anatomy and Pathophysiology of Asthma
Asthma Diagnosis:Anatomy and Pathophysiology of
Asthma
Karen Meyerson, MSN, RN, FNP-C, AE-CAsthma Network of West Michigan
April 21, 2009Acknowledgements: LeRoy M. Graham, MD, Atlanta, GA
Allan T. Luskin, MD, Madison, WI
Definition of Asthma
Chronic inflammatory disease of the airways characterized by: Recurrent episodes of wheezing Shortness of breath Chest tightness/pain Coughing
Airflow limitation is at least partially reversible Airways are supersensitive and react to a variety of
stimuli or triggers
Asthma Pathophysiology
In response to a trigger: Airway inflammation Bronchial smooth muscles constriction
(bronchospasm) Increased mucus production The airways become narrow and breathing
becomes difficult
Normal Airways
Asthma Airways
Mechanisms Underlyingthe Definition of Asthma
INFLAMMATIONINFLAMMATION
Risk FactorsRisk Factors(for development of asthma)(for development of asthma)
AirwayAirwayHyperresponsivenessHyperresponsiveness Airflow LimitationAirflow Limitation
SymptomsSymptomsRisk FactorsRisk Factors
(triggers)(triggers)
Asthma Airways
Before 10 Minutes After Allergen Challenge
Airway Remodeling
AsthmaticAsthmaticNormalNormalJeffery P. Asthma. 1998.
The “Tip” of the Iceberg
Airway inflammation
Airflow obstruction
Bronchial hyperresponsiveness
ASTHMA Symptoms
National Asthma Education and Prevention Program. Highlights of the Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD., May 1997. NIH Publication No. 97-4051A.
Factors Predicting Persistent Asthma Family history of asthma (maternal > paternal) Atopy (IgE/positive skin tests, eczema, rhinitis) Allergen exposure (dust mites / animals) Viral (RSV) infection Gender (males > females) Smoking (passive or active) The strongest predictor for wheezing that
develops into asthma is ATOPY
Asthma Diagnosis
Symptoms Medical history Physical exam Measurements of lung function
Diurnal variation in peak flow
Evaluation of allergic status Exclude alternative diagnoses
Bronchiolitis, cystic fibrosis, GERD, foreign body aspiration
Asthma DiagnosisAssessing Symptoms
Cough Wheeze Dyspnea Nocturnal symptoms Activity affected?
Recurrent episodes of cough (+ wheeze) are frequently due to asthma Coughing may be the only symptom present
Asthma DiagnosisMedical History
Repeated cough, wheeze, chest tightness
Repeated diagnoses of reactive airway disease, allergic bronchitis or wheezy bronchitis
Symptoms worsened by viral infection, smoke, allergens, exercise, weather
Symptoms occur/worsen at night
Reversible airflow limitation
Wheezing may or may not be present
Asthma DiagnosisPhysical Exam
Coughing, wheezing Prolonged forced expiration Use of accessory muscles Retractions Hyperexpansion of the chest Signs of other allergic diseases:
Atopic dermatitis Allergic rhinitis
Physical examination of the chest may be normal
Asthma Predictive Index (API)High risk children (under age 3) who:
have had > 4 wheezing episodes in the past year that
lasted more than one day and affected sleep are significantly more likely to have persistent asthma after the age of 5 if they have either (1) of the following:
Castro-Rodriguez J et al. Castro-Rodriguez J et al. AJRCCM AJRCCM 2000; 162:1403-1406.2000; 162:1403-1406.
One major criteria Parent with asthma Physician diagnosis of
atopic dermatitis Evidence of sensitization
to aeroallergens
Two minor criteria Evidence of sensitization
to foods >4 percent blood
eosinophilia Wheezing apart from colds
OROR
Asthma Predictive Index (API)
Birth cohort followed through 13 years of age. 76% of children diagnosed with asthma after 6
years of age had a positive asthma predictive index before 3 years of age.
97% of children who did not have asthma after 6 years of age had a negative asthma predictive index before 3 years of age.
Castro-Rodriguez J et al. Castro-Rodriguez J et al. AJRCCM AJRCCM 2000; 162:1403-1406.2000; 162:1403-1406.
Asthma DiagnosisMeasurements of Lung Function
FEV1 (Forced Expiratory Volume in 1 Second) – this is the volume of air expired in the first second during maximal expiratory effort. The FEV1 is reduced in both obstructive and restrictive lung disease.
FVC (Forced Vital Capacity) – this is the total volume of air expired after a full inspiration.
FEV1/FVC – this is the percentage of the vital capacity which is expired in the first second of maximal expiration.
Spirometry: Flow-Volume LoopObstruction
Asthma DiagnosisMeasurements of Lung Function
Spirometry: An FEV1 response of >12% post-bronchodilator is
suggestive of asthma
BUT, Spirometry is difficult in children <4 years old Some children cannot perform spirometry
adequately until >7 years of age
Alternative assessment: PEF variability
?Cough
especially if:• after exertion• breathing cold
air• at night• after colds• paroxysmal
Wheezing• tightness
• noisy
breathing Dyspnea(Breathlessness
)
especially if:• intermittent or
variable• after exertion• at night
Asthma Diagnosis
?Cough
especially if:• after exertion• breathing cold
air• at night• after colds• paroxysmal
Wheezing• tightness
• noisy
breathing Dyspnea(Breathlessness
)
especially if:• intermittent or
variable• after exertion• at night
Asthma Diagnosis
?Cough
especially if:• after exertion• breathing cold
air• at night• after colds• paroxysmal
Wheezing• tightness
• noisy
breathing Dyspnea(Breathlessness
)
especially if:• intermittent or
variable• after exertion• at night
Asthma Diagnosis
?Cough
especially if:• after exertion• breathing cold
air• at night• after colds• paroxysmal
Wheezing• tightness
• noisy
breathing Dyspnea(Breathlessness
)
especially if:• intermittent or
variable• after exertion• at night
Asthma Diagnosis
Cough
especially if:• after exertion• breathing cold
air• at night• after colds• paroxysmal
Wheezing• tightness
• noisy
breathing Dyspnea(Breathlessness
)
especially if:• intermittent or
variable• after exertion• at night
Asthma Diagnosis
Questions?
Download the Guidelines at: http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf
Download the Summary Report at: http://www.nhlbi.nih.gov/guidelines/asthma/asthsumm.pdf