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15 Cards in this Set
- Front
- Back
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Define asthma according to NHLBI?
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chronic inflammatory disease manifested by recurrent episodes of wheezing, breathlessness, chest tightness, and coughing.
- is an obstructive lung dx |
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What are the 3 key features of asthma? (Triad)
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3 key features:
1. reversible airflow obstruction 2. airway inflammation 3. hyperresponsive airway |
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What is the pathophysiologic manifestations of airflow obstruction?
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Airflow obstruction: narrowing airway lumen
airflow slowing increased airflow resistance - dec FEV1/FVC - dec FEV1 - dec PEFR (peak expiratory flow rates) - inc expiratory time - hyperinflation of lungs due to air trapping - inc residual volume - inc functional residual capacity - inc total lung capacity - left compliance shift - unequal ventilation/perfusion distribution |
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What is the pathophysiologic manifestations of reversible airflow obstruction?
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1. Acute bronchoconstriction (smooth muscle contraction & hypertrophy)
2. Cellular changes (eisonphil & lymphocyte infiltration, mast cell activation) 3. airway edema (inc microvascular permeability & leakage) 4. Chronic mucus plug formation & airway obstruction 5. airway remodelling (permanent architectural changes) |
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What is the pathophysiologic manifestations of increased airway responsiveness? (AHR = Airway Hyperresponsiveness or BHR = Bronchial Hyperresponsiveness)
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Exaggerated bronchoconstrictor response to variety of stimuli-> propensity to narrow easily and too much
- BHR is quantified by det amt of histamine or methacholine required to induce a 20% fall in FEV1 - not fixed characteristics but changes w/ time |
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What are the gross findings of bronchial asthma?
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1. Hyperinflation of the lungs (due to air trapping)
2. Patchy atelectasis (alveolar collapse) 3. Edema and erythema of bronchial mucosa - mucosal lining appears swollen, red |
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What are the microscopic findings of asthma?
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1. infiltration of bronchial submucosa by inflammatory cells (principally eisonophils)
2. Degeneration and exfoliation of bronchial epithelium 3. Thickened basement membrane 4. Thickened bronchial smooth muscle 5. Thick mucous secretions in bronchial lumens (Curschmann's spirals) 6. Goblet cell hyperplasia |
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What is the characteristic cells of asthma?
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1. Eosinophils
- increased numbers in airways in response to allergen challenge - mediators released by eosinophil: - cationic proteins (MBP, ECP, EPO) - lipid mediators (LTC4, PAF) 2. Mast cells (not increased numbers but increased activation state) 3. Lymphocytes (common inflammatory cell in NL airway) 4. Macrophages (airway and alveoli) |
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What is the neurogenic mechanism associated w/ asthma?
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- Autonomic control of airways is very complex.
- Classical cholinergic, adrenergic, neuropeptides, non-adrenergic, and non-cholinergic nerve fibers may play a part Neuropeptides involved incl: - substance P - vasoactive intestinal peptide - neurokinin |
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What is the timetable of asthma?
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1. Early asthmatic response:
- onset 10-15 minutes - Purely bronchospastic event (i.e. primarily due to smooth muscle contraction) - Inhibited by 2-agonists and sodium cromoglycate - No change in BHR 2. Late asthmatic response - Begins 5-8 hrs after challenge & may last 24 hrs or more - airway narrowing - prevented by corticosteroids & sodium cromoglycate - leads to increased BHR |
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What is the difference between triggers and risk factors?
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Triggers - agents that cause exacerbations of disease or provoke airway narrowing (allergen exposure, exercise, etc)
Risk Factors- those that are associated w/ cause of dx (genetics, atopy, resp infections) |
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What are clinical manifestations of asthma?
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1. Chest tightness, cough, wheezing, dyspnea
2. Patient may experience any, all or none (between attacks) of these 3. May or may not be able to identify cause or trigger 4. Onset may be slow or rapid 5. Frequency of recurrence variable (from years to nearly continuous) |
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What are part of the laboratory evaluation of asthma?
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1. Lab values NL except mild eosinophilia
2. CXR: hyperinflation, peribronchial cuffing, atelectasis 3. ABGs: mildly low PaO2 & PCO2 4. RFTs: red. FEV1, FEV1/FVC or PEFR |
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What are included in the differential diagnosis of asthma?
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A. COPD
B. Heart failure C. Pulmonary embolism D. Upper airway obstruction E. Foreign body aspiration F. Acute bronchiolitis (in kids) |
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How is asthma managed?
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A. Patient education
B. Objective measurement of lung function C. Pharmacologic therapy (step-care approach depending on severity as outlined by NHLBI) D. Environmental control measures directed toward allergens and irritants |
