Asthma - IM PLAT Flashcards
Etiopathogenesis of Bronchial asthma
Heterogenous disease
Characterized by:
- Chronic airflow inflammation that varies markedly both spontaneously and with treatment
Associated with airway hyperresponsiveness and airflow inflammation.
Cells:
- Mast cells
- Eosinophils
- T-cells
- Neutrophils
Measures how much air an individual can exhale during a forced breath during the first second
Forced Expiratory Volume in 1 second (FEV1)
Total amount of air exhaled during the FEV test
Forced vital capacity (FVC)
FEV1/FVC Ratio
(FEV1%)
- Normal: 75-80%
- Reduced: Obstructive diseases
- Asthma
- COPD
- May be normal or increased in Restrictive diseases
- Fibrosis
Individual’s maximum speed of expiration, measured by a peak flow meter
Peak Expiratory flow
Clinical Manifestations of Asthma
Typical symptoms: (worse at night or early morning and vary over time and intensity)
- dyspnea
- wheeze
- cough
- chest tightness
Symptoms usually demonstrates REVERSIBILITY AND VARIABILITY
Most frequent PE abnormality in Bronchial Asthma
Expiratory weheezing or rhonchi on ausculation
Asthma Phenotypes
- Allergic Asthma
- Non-Allergic Asthma
- Late-onset Asthma
- Asthma with fxed airflow limitation
- Asthma with obesity
Allergic asthma
- Most frequent
- Atopy
- Sputum examination
- eosinophilic airway inflammation
- Responds well to inhaled corticosteroids
Non-allergic asthma
- Sputum examination
- neutrophilic or paucigranulocytic airway inflammation
- Less responsive to ICS
Late-onset Asthma
- Common in women
- Adulthood
- Requires higher doses of ICS or are relatively refractory to ICS
Asthma with fixed airflow limitation
- Seen in patients with long standing asthma who develop fixed airflow limitation due to airway wall remodeling
Asthma with obesity
- Obesisty
- little eosinophilic inflamamtion
- prominent respiratory symptoms
Diagnostic Criteria for asthma
1. History of variable Respiratory symptoms
- Cough, dyspnea, Wheezing, chest tightness
- More than one respiratory symptom
- Occurs variably
- Worse at night or early morning
- Triggered by exercise, allergies, viral infections, laughter
2. Confirmed Variable Expiratory Airflow Limitation
- Documented excessive variability in lung function AND
- Documented Airflow limitation
- FEV1 low, FEV1/FVC reduced (0.75-0.80)
- The greater the variation, the more likely the Dx of asthma
Tests to Document Variable Expiratory Limitation
-
Positive bronchodilator Reversibility test
- Increase in FEV1 >12% and >200ml from baseline
- 10-15 mins after albuterol 200-400 mcg or equivalent
- Bronchodilator meds witheld
- >4 hours for SABA
- >12 hours for LABA
-
Excessive VAriability in PEF
- Average diurnal variability : >10%
- calculated from twice daily readings, average for over 2 weeks
- Day’s Highest - Day’s lowest / (mean of day’shighest and lowest PEF)
-
Increase in lung function after 4 weeks of anti-inflammatory treatment
- FEV1 >12% and >200ml from baseline after 4 weeks of treatment
-
Others
-
Positive Exercise test
- fall in FEV1 <10% and >200 ml from baseline
- (+) bronchial challenge test
- fall in FEV1 >20% with methacholine or histamine or >15% with hyperventilation, saline, mannitol
- Excessive variation in lung function between visits
-
Positive Exercise test
Assesing Asthma Symptom Control
Risk Factors for Poor Asthma Outcomes
Measure FEV1 start of treatment, after 306 months of controller treatment, then periodically
Presence of 1 or more increases the risk of exacerbations
-
Potentially Modifieble independent risk factors for exacerbations
- Uncontrolled asthma sx
- High SABA use
- Inadequate ICS
- Low FEV1 (<60%)
- Major psychological or socioeconomic problems
- Exposure: smokinh, allergen
- Comorbidities
- Sputum or blood eosinophilia
- elevated FENO
-
Others
- History of intubation or ICU admission for asthma
- >1 severe exacerbation per year
Goals of Asthma Therapy
- Minimal (ideally no) chronic symptoms, including nocturna sx
- Minimal exacerbations
- No emergency visits
- Minimally use of as required B2-agonist
- No limitations on activities
- PEF circadian variation <20%
- Normal PEF
- Minimal or no adverse effects from medications