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39 Cards in this Set
- Front
- Back
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Definition
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-Chronic inflammatory disorder of the airways
-Causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing -Often reversible -Increased bronchial hyperresponsiveness |
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Most patients diagnosed by age
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5
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Caused by
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-Bronchoconstriction
-Airway edema -Airway hyperresponsiveness -Airway remodeling |
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Bronchoconstriction caused by
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-Allergic reaction
-Aspirin and NSAIDS -Exercise -Cold air -Stress |
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Steps of Early Phase Allergic Reaction
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1)Antigens taken up by antigen-presenting cells
2)Antigens presented to T-lymphocytes and response is activated 3)Antigen interacts with IgE on mast cells 4)Bronchoconstriction results *Lasts ~1 hour after antigen exposure |
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Steps of Late Phase Allergic Reaction
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1)Activated airway cells release inflammatory cytokines and chemokines
2)Milder bronchoconstriction as well as airway hyperresponsiveness and inflammation occur |
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Additional Contributors to Airway Narrowing
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-Airway edema
-Airway smooth muscle contraction -Airway thickening -Mucus hypersecretion |
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Airway Remodeling
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-Airflow limitations may only be partially reversible
-Permanent structural changes -Progressive loss of lung function |
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Contributing factors to airway remodeling
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-Airway smooth muscle increases
-Blood vessels dilate -Mucus hypersecretion |
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Epithelial cells
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-Participate in inflammation
-Activated by IgE -Epithelial shedding occurs |
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Eosinophils
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-Release inflammatory mediators such as leukotriens and granule proteins to injure airway tissue
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T-Lymphocytes
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-TH1 used for cellular defense mechanisms
-TH2 mediate allergic inflammation |
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Mast Cells
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-Found on surface of IgE
-Lead to bronchoconstriction |
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Alveolar macrophages
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-May release inflammatory mediators and cytokines
-Also produce chemotactic factor to further amplify the inflammatory response |
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Neutrophils
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-Unclear role
-High numbers found on those patients who died from sudden onset of fatal asthma |
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Fibroblasts and Myofibroblasts
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-Produce connective tissue components
-Involved in airway remodeling |
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Histamine
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-Induces smooth muscle constriction and bronchospasm
-Stimulated by physical stimuli |
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Chemokines
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Recruit inflamm. cells in the airways
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Cytokines
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Direct and modify inflamm. response in asthma and determine severity
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Cysteinyl leukotrienes
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Potent bronchoconstrictors and proinflammatory mediators
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Prostaglandin D2
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Potent bronchoconstrictor
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Nitric oxide
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Potent vasodilator
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Host Factors
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-Genetic predisposition
-Obesity -Sex |
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Hygiene Hypothesis
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-Develop TH2 instead of TH1
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Lower risk of asthma in children who:
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-Live on farms
-Have large # of siblings -Enroll early in child care -Are exposed to fewer antibiotics |
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Environmental factors influencing Asthma
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-Allergen exposure
-Socioeconomic status -Urbanization -Family size -Occupational stimuli -Active smoking or secondhand smoke -Air pollution -Decreased exposure to childhood infectious agents |
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Agents and Events Triggering Asthma
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-Respiratory infections
-Allergens -Occupational stimuli -Environment -Emotions -Exercise -Drugs/preservatives |
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Viral Respiratory Infections
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-Particularly in children <10 years old
-Rhinovirus most common cause |
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psychological factors
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-Associated with increased stress
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GERD
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-Symptoms of GERD common in asthma patients
-Nocturnal asthma may be associated with nocturnal reflex -Bronchoconstriction so acid doesn't go into lungs -Medications used to decrease airway smooth muscle tone also have a relaxant effect on gastroesophageal spincter tone |
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Female Hormones
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30-40% of women report premenstrual worsening of asthma
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Signs of chronic Asthma
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-Expiratory wheezing on auscultation
-Dry hacking cough -Signs of atopy Allergic rhinitis Eczema |
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Symptoms of Chronic Asthma
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-Dyspnea
-Chest tightness -Coughing -Wheezing -Symptoms may occur in association with exercise or in association with known allergens |
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Diagnosis of Chronic Asthma
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-No single test for diagnosis
-Based primarily on history -Physical examination -May have a family history of allergy or asthma or have symptoms of allergic rhinitis -Spirometry |
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Spirometry
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-Give patients B2-agonist administration
-At least 12% improvement in FEV1 |
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Signs of Acute Asthma Exacberation
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-Expiratory and inspiratory wheezing on auscultation
-Breath sounds diminished with severe obstruction -Dry hacking cough -Tachypnea -Tachycardia -Pale or cyanotic skin -Hyperinflated chest -Hypoxic seizures -Anxious -Severe dyspnea -Only able to say a few words with each breath -Symptoms unresponsive to usual measures (B2 agonist administration) |
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Diagnostic labs
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-PEF and FEV1 less than 40% of normal predicted values
-Decreased arterial oxygen -O2 saturations by pulse oximetry -Decreased arterial or capillary CO2 -Blood gases to assess metabolic acidosis -CBC -Electrolytes -Chest x-ray |
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Exercise Induced Bronchospasm
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-Drop in FEV1 > 15% of baseline
-Exact cause is unknown -Heat and/or water loss play a role -More common in cold, dry air -Reflection of BHR |
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Nocturnal Asthma
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-Worsening asthma during sleep
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