asthma Flashcards
what is asthma?
An inflammatory disease of the airways characterized by:
Recurrent reversible airways obstruction in response to irritant stimuli
Hypersecretion of mucus by bronchial epithelial cells
Eosinophil infiltration
Bronchial smooth muscle cells hyperplasia causing airway hyper-responsiveness and bronchospasm
whats the difference in structure between a healthy airway, with asthma and asthma attack?
Asthma: smooth muscle cells increased in airway
asthma attack: constricted airway, contracted smooth muscle cells
Hyperplasia of goblet cells
glandularsimple columnarepithelialcellswhose function is to secretemucin,
what is hyperplasia?
increase in the number of cells in an organ or tissue.
what is hypertrophy?
Hypertrophy =increase in size of of smooth muscle suspected to contribute to the irreversible airflow obstruction and permanently impaired pulmonary function observed in patients with chronic asthma
what is airway hyper responsiveness?
Airway hyperresponsiveness is a characteristic feature of asthma and consists of an increased sensitivity (abnormal sensitivity) of the airways to chemicals, cold air, stimulant drug e.g., an inhaled constrictor agonist, a steeper slope of the dose-response curve, and a greater maximal response to the agonist. Certain inhaled stimuli, such as environmental allergens, increase airway inflammation and enhance airway hyperresponsiveness.
what is bronchospasm?
Bronchospasmis an abnormal contraction of the smooth muscle of the bronchi, resulting in an acute narrowing and obstruction of the respiratoryairway.
what are the causes of asthma? (pathogenies)
Factors increasing chances to develop the condition: identified!
A family history of asthma /allergic conditions Bronchiolitis as a child Exposure to tobacco smoke Being born prematurely Type of job- occupational exposures
what are the triggers of asthma?
Triggers: Indoor environment House dust mites Moulds & fungi Pollen Food drugs Stress or even a fit of laughter cold and viral infection
what is intrinsic asthma?
Intrinsic asthma/Or Not obvious allergic bases: : historical definition: asthma caused by substances from “within the body.” These patients usually have a negative allergy skin test, and therefore do not have allergies and do not benefit from allergy shots or allergy medications
intrinsic asthma
what is extrinsic asthma?
Extrinsic asthma/Allergic bases: historical definition asthma caused by inhaling or ingesting foreign substances (later known as allergens) from “without the body.” Some causes were in the air, such as horse hair, plant pollens, and feather dust, and some were in the foods ingested, such as eggs, berries, fish and cereals
what are the symptoms of asthma?
Wheeze Breathlessness Cough (occasionally) Daily or seasonal variation Chest tightness Any triggers that make symptoms worse?
what are objective tests for asthma ?
Airway inflammation measurement
Lung function tests
Airway hyperreactivity measurement
how does Airway inflammationmeasurement work?
Measure Fractional exhaled Nitric Oxide in the breath (FeNO).
normal epithelial cell release minimal NO
during imflammation , activated epithelial cell increase production of NO
Where is the NO coming from?
In inflammatory diseases, such as asthma, the increase in exhaled NO may reflect, at least in part, induction of NOS2.
In adult asthmatic patients there is evidence of increased expression of NOS2 in airway epithelial cells
Pro-inflammatory cytokines, which may at times be involved in asthmatic inflammation, induce the expression of NOS
Patients with asthma caused by allergic airway inflammation have high levels of FeNO that decrease with corticosteroid treatment
Knowing whether airway inflammation is present can help avoid an empiric trial of steroids
Positive test:
FeNO level of 40parts per billion (ppb) or more(adult)
what is the lung function test?
Obstructive spirometry
Measure lung volumes and capacity to determine the presence of an obstructive or a restrictive diseases. FEV1 and FVC changes will differe depending on the type of diseases.
Obstructive spirometry
Forced Expiratory Volume 1 sec= volume of air exhaled during the first second of the FVC
Forced Vital Capacity= maximal amount of air that can be exhaled after a maximal breath
Positive test for obstructive airway disease: FEV1/FVC <70% or below the lower limit of normal
what is lung function test? Bronchodilator reversibility (BDR) test
Bronchodilator reversibility (BDR) test
Spirometry after inhaling short-acting b2AR agonist
Positive test for reversibility:
an improvement in FEV1 of 12% or more, AND with an increase in volume of 200ml or more
Rationale for this test:
Determine the presence of a reversible airways obstruction
what is lung function test?
peak flow variability?
Rationale for this test:
Determine the presence of daily variability of air peak flow.
Peak flow variability
Monitor peak flow variability for 2to 4weeks
If the difference between the highest and lowest values divided by their mean exceeds 20% (and is at least 60 l/min) the diagnosis of asthma is strongly supported.
