Lec 10 Asthma Flashcards
Which pts most prevalently have asthma?
mostly children/young adults
low SES more at risk
What is radial traction?
idea that as you inhale –> pull airway and increase cross sectional area of airway
What happens to pleural pressure with inspiration?
decreases = bigger airway
Is ashtma obstructive or restrictive?
obstructive
What is intrathoracic vs extrathoracic obstruction?
intrathoracic: expiratory airway flow limitation; have wheeze on expiration
extrathoracic = wheezing on inspiration
What happens with asthma on pulm function test? what if you give bronchodilator?
FEV1/FVC < 07 or lower limit of normal
have scooped out look on pulm function graph
with bronchodilator have normalization of FEV1/FVC or FEV1 increase by 200 mL
What is peak expiratory flow?
if tubes have high resistance = can’t have flow as big
What is air trapping? What does this mean to lung volumes
increase resistance to expiration –> less flow out –> more air left in alveoli
= same TLC but bigger residual volume and smaller vital capacity
What happens to gas exchange in asthma?
- increased airway resistance not evenly distributed
will have some degree of hypoxemia from V/Q mismtach
What happens to gas exchagne in mild vs severe asthma attack?
mild = pCO2 falls b/c other alveoli able to participate in gas exchange = primary respiratory alkalosis
severe = pCO2 rises b/c can’t ventilate properly; exacerbated by respiratory muscle fatigue
What is pulsus paradoxus?
systemic atrial P falls by < 10 during inspiration
can be caused by large swings in pleural pressure by asthma
How does asthma cause pulus paradoxus
negative intrathoracic P in inspiration –> increase blood return to RV –> septal bulging and decrease LV preload
increase LV afterload b/c of negative intrathoracic P
in expiration –> reversal
What is allergic asthma?
- have underlying allergies, eczema, elevated IgE
- exacerbated by exposure to allergens
- family history of asthma or allergies
What is mech of allergic asthma
- allergen inhaled
- TH2 response –> eosinophils –> IgE
- IgE cross-links on mast cells at re-challenge –> increase vascular permeability, bronchoconstriction, inflammatory cell recruitment, etc
What is pathology of asthma?
- cellular infiltrates and edema within bronchial wall
- epithelial damage
- smooth muscle layer hypertrophy
- increase mucous glands
What is hygiene hypothesis?
- if exposure to microbes earlier in life –> TH1 mediated immune response down regulated TH2 response
- if lack of exposure to microbes early in life –> overactive TH2 mediated immune response
What is action of each of the following TH2 cytokines?
IL4
- IL-5
- IL-9
- IL-13
- IL4 directs B cells to synthesizes IgE
- IL-5 essential for eosinophil maturation
- IL-9 mediates mast cell recruitment and function
- IL-13 causes airway hyperresponsiveness and mucous hypersecretion
What happens in exercise induced asthma?
pathogenesis involves cooling of airway = breathing and hyperventilating –> dry cold air enters –> dries mucosa
–> bronchoconstriction
provokes bronchoconstriction in pt with hyperreactive airways
What is aspirin-exacerbated respiratory disease?
- involved arachidonic acid path
- inhibit cyclooxygenase path –> produce bronchoconstrictor leukotrienes
What is samter’s triad for aspirin exacerbated respiratory disease?
- asthma
- aspirin/NSAID sensitivity
- nasal polyposis
What kind of remodelling with asthma
- increase smooth muscle mass
- inflammatory cell persistence
- muscle gland increase
What are symptoms of asthma?
- cough, dyspnea, wheezing, chest tightness
What do you see on physical exam with asthma?
wheezing, prolonged expiratory phase
or may have no wheezing if not in midst of asthma attack or because no flow
What is status asthmaticus?
severe asthma attack
doesnt respond to bronchodilators
may require assisted ventilation
