Asthma Flashcards
3 cardinal features of asthma
- airway inflammation
- reversible airflow obstruction
- airway hyper responsiveness
why are lungs hyper inflated in asthma
- mucus is obstructing the airway lumen and air cannot get out.
T2 high asthma phenotypes secrete
- IL-4,5,13
aspirin exacerbated respiratory disease characterized by
- asthma
- recurrent sinus with nasal polyps
- sensitivity to aspirin and other NSAIDS
pathology of allergic asthma
- dendritic cells infiltrate airway and sample antigens in airway lumen
- dendritic cells migrate to regional lymph nodes and present to T cells.
- T cells differentiate into Th2 and produce IL-4, 5, 13
- IL-4 cause B lymphocytes to switch to IgE
- IgE antibodies bind to mast cells
how are mast cells activated in allergic asthma
- 2 IgE antibodies on mast cell bind antigen
result of mast cell activation in allergic asthma
- rapid synthesis of arachadonic acid metabolites (prostaglandins and leukotrienes)
- synthesis of pro-inflammatory cytokines
result of pro-inflammatory mediators in allergic asthma
- airway smooth muscle - bronchoconstriction
- blood vessels - vasodilation and increased permeability
- epithelial cells - mucous cell metaplasia (mucous cells where they shouldn’t be)
how do eosinophils get involved in asthma
- IL-5 and eotaxin produced by Th2 lymphocytes and mast cells release eosinophils from bone marrow
result of eosinophils in allergic asthma
- pro-inflammatory effects
what is a transcription factors in TH2 cells that is critical for production of TH2 cytokines IL-4,5,13
- GATA-13
what is late-onset eosinophilic asthma associated with
what is it not associated with
- associated with eosinophils
- not associated with allergy
non-allergic, late-onset eosinophilic asthma mediator
what do they react to
- ILC2
- TSLP, IL-25, IL-33
result of stimulation of ILC2 in non-allergic, late-onset eosinophilic asthma
- secretes IL-5 and IL-13
why is non-allergic, late-onset eosinophilic asthma referred to as non-allergic?
- does not make IL-4 for IgE class switching
- and no mast cells involved
how does aspirin exacerbated respiratory disease work?
- blocks cyclooxyrgenase
- shunts everything down leukotriene path (LTC4)
result of LTC4
- vasodilate
- increased capillary permeability
- mucous cell metaplasia and mucous production
- bronchoconstriction
Th17 cells involved in which asthma
airways domination is by
- neutrophilic asthma
- neutrophils
Th-17 secretes which cytokines (and their role
- IL-17 (recruit neutrophils)
- IL-21 (stimulates NK cells, B cells and Th17 cells)
between eosinophils and neutrophils, which is steroid responsive?
- eosinophils
3 remodeling changes in asthmatic airways
- basement membrane thickening from fibrosis
- smooth muscle hyperplasia
- mucous cell metaplasia
MOA of albuterol
- activates beta 2 adrenergic receptors on airway smooth muscle
- increases intracellular cAMP
- relaxes airway smooth muscle
airflow obstruction in asthma results from narrowing of airway lumen and intraluminal obstruction by
- mucus
flow-volume curve in asthma
- low peak expiratory flow
- scooped out appearance during expiration
FEV1 in asthma
- reduced FEV1
FVC is mild/moderate asthma
why
- generally normal
- most air will eventually be exhaled
FEV1/FVC ratio in mild/moderate asthma
- reduced
FEV1 versus FVC in severe asthma
impact on ratio
- FEV1 falls much greater than FVC
- so ratio is still low
DLCO in asthmatics
- normal or elevated
DLCO in COPD
- reduced
how do we see airway hyper responsiveness in asthmatics
- airways constrict even further after exposure to stimuli that do not affect caliber of airways in normal individuals
what is a good test to diagnose asthma in patients suspected of having asthma whose baseline spirometry is normal
- methacholine test
asthma symptoms
- cough
- chest tightness
- wheeze
- dyspnea
wheezing is indicative of what airway obstruction
- lower airway obstruction
upper airway obstruction is indicative of what sound
- stridor
wheezing in heard on inspiration/expiration?
- expiration usually
stridor is heard on inspiration/expiration?
- both
skin symptoms of asthma
- eczema
upper airway symptoms of asthma
- enlarged nasal turbinates
- pale or inflamed nasal mucosa
symptoms of asthma during severe exacerbations
- accessory muscle use
- intercostal retractions
- decreased breath sounds
what is the clinical indication of a significant response in FEV1 post bronchodilator
- > 12% improvement
how does the methacholine test work
- inhale methacholine and watch for drop in FEV1
what is PC20
- provocative concentration that causes FEV1 to fall by 20%
what is a gas also high in asthmatics
- exhaled nitric oxide
what would you look for in sputum of asthma
- eosinophils
- Carcot-Leyden crystals
- Curschmann’s spirals
- Creola bodies
what is the rescue medication for asthma treatment
side effect
what do you give if side effect is present
- albuterol sulfate
- tachycardia
- levalbuterol
MOA of nebulizer ipatropium
- anti-cholinergic
- blocks M3 receptors on airway smooth muscle
- blocks contraction
asthma patients are started on
- inhaled corticosteroids
if inhaled corticosteroid medications are insufficient, what do we give patients
- inhaled corticosteroids + long acting beta agonists
patients with severe airway obstructions who are mechanically ventilated with a high respiratory rate get what
what will come next
- breath stacking
- dynamic hyperinflation
- auto peep
how auto peep causes cardiogenic shock
- increased intrathoracic pressure from auto-peep
- increased RV afterload
- decreased RV preload
- decreased RV cardiac output
- decreased LA and LV filling
- cardiac shock
treatment for cardiogenic shock and auto peep in patients with obstructive airway disease
- remove from ventilator
- start vent at lower respiratory rate giving patient more time to exhale
