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Flashcards in Lec 10 Asthma Deck (46):

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?



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?

- 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


What are the 2 substances administered in bronchoprovocation tests? what do you test?

- methacholine
- mannitol

give the substance then measure PC20 = provocative concentration for a fall in FEV1 by 20% with methacholine

normal PC20 < 8 for asthmatics


What is methacholine?

- derivative of ACh

directly stimulates airway smooth muscle receptors


What is manniotol?

increases osmolarity of airway surface and causes realease of mast cell mdiators


How do you diagnose asthma?

no features really unique and universal


What is treatment for asthma?

- bronchodilators
- anti-inflammatory agnets
- targeted therapy


What is action of sympathomimetics in asthma?

activate B receptor --> increase cAMP --> airway smooth muscle relaxation + inhibition of chemical mediator release from mast cells

B2 specific preferred to avoid adverse cardiac effects of B1


What are examples of sympathomimetics used in asthma?


albuterol = short acting 3 hrs
salmetrerol, formoterol = long action, for prophylaxis


What is action of anticholinergics in asthma? 2 examples?

- decrease bronchoconstrictor cholinergic tone to airways

ipratropium = lasts 6 hrs; blocks M1, M2, M3
tiotropium = lasts 24 hrs; blocks M1, M3


What is action of methylxanthines in asthma? 2 examples? down sides?

- inhibit phosphodiesterase which degrades cAMP --> increase cAMP --> bronchodilation
- inhibits adenosine receptors
- may be antiinflammatory

theophylline = oral
aminophylline = IV or PO

down sides = many side effects --> nausea, diarrhea, arrhythmias, CNS excitation


What is action of corticosteroids in asthma treatment?


inhibit synthesis of cytokines; inactivate NF-kB the transcription factor that induces production of TNF-alpha

1st line therapy for chronic asthma


What are the 2 main corticosteroids used in chronic asthma?

- beclomethasone
- fluticasone


What is use of predinosine in asthma?

used for acute asthma attacks then tapered off


What is action of montelukast/zafirlukast?


both antileukotrienes
block leukotriene receptors

good for aspirin induced asthma


What is action of zileuton?


an antileukotriene

inhibits 5-lipoxygenase pathway
blocks conversino of arachidonic acid to leukotrienes


What is action of omalizumab in astham?

- monoclonal IgE antibody
binds mostly unboudn serum IgE and blocks bindg to FceRI

used in allergic asthma resistant to inhaled steroids and long acting B2 agonists


What is action of antihistamines in asthma?

- block H1 receptor which mediates: bronchila smooth muscle contraction, increased nasal mucus production, vasodilation, increased vascular permeability etc


What are the 2 first gen H1 blockers? downside?

diphenhydramin and hydroxyzine

cause significant sedation b/c easily cross BBB


What are the three 2nd gen H1 blockers?

- loratadine, fexofenadine, certirizine

lipophobic so don't have the bad CNS effects


What is action of IL-4

- IL4 directs B cells to synthesizes IgE


What is action of IL-5

- IL-5 essential for eosinophil maturation


What is action of IL-9

- IL-9 mediates mast cell recruitment and function


What is action of IL-13

- IL-13 causes airway hyperresponsiveness and mucous hypersecretion