Asthma Flashcards
Definition of asthma
Chronic reversible airway disease characterised by
REVERSIBLE AIRWAY OBSTRUCTION + AIRWAY HYPERRESPONSIVENESS +
INFLAMED BRONCHIOLES
and mucous hypersecretion
What are the 2 types of asthma?
Allergic (70%)
Non allergic (30%)
What is allergic asthma?
What is it due to?
What should we consider with allergic asthma?
IgE mediated, EXTRINSIC, T1 hypersensitivity
Due to environmental triggers (pollen, dust, mould, antigens) - often present early eg. in children
Consider genetics and HYGIENE HYPOTHESIS
What is hygiene hypothesis?
decreased exposure to pathogens at a young age can increase TH2 response and susceptibility to asthma infection
What is non allergic asthma?
When may it present?
Trigger?
Non IgE mediated, INTRINSIC
May present later, harder to treat, associated with smoking (or perfumes) - like COPD
Triggers of asthma?
Infection
allergens
cold weather
exercise
drugs (BB, aspirin)
What is the atopic triad?
What is this triad caused by?
Atopic rhinitis (nasal dryness)
Asthma
Eczema
(some people have these 3 synonymously, known as ATOPY)
Too many TH2 cells in all 3
What is Samter’s triad?
Nasal Polyps
Asthma
aspirin sensitivity
What is aspirin sensitivity?
How does it affect asthma?
Aspirin inhibits COX-1/2 therefore shunts more arachidonic acid down LPOx pathway which produces leukotrienes LT B4,5,6 = Proinflammatory
What is the pathology of the early phase (mins) from TH2 cells to bronchial constriction?
Overexpressed (too many) TH2 cells in airway exposed to trigger
TH2 cytokine release IL3,4,5,13 which produce IgE production and eosinophil recruitment
IgE mast cells degranulate and release : Histamines, leukotriene, try-take
Eosinophils release toxic protein eg. MBP
Causes bronchial constriction and mucus hypersecretion
What happens over time to the bronchus?
Chronic remodelling (irreversible)
Bronchial scarring = lower lumen size = lots of mucus
Sx of asthma?
Wheeze, dry cough, chest tightness, SOB
What may microscopy of mucus show?
Curschmann spirals and Charcot leyden crystals
How often do asthma attacks occur and why?
age?
Typically episodic with trigger and diurnal (day) variation
often younger Px
What 4 categories are episodes classed as and what is the PEF for each?
Moderate - PEF 50-75%
Severe - PEF 33-50% - can’t finish sentences
Life threatening - PEF <33% - decreased consciousness, silent chest
Fatal - hypercapnia, pKa 6+
Dx of asthma?
Spirometry
High FeNO
Spirometry shows obstruction (FEV1:FVC <0.7)
After bronchodilator administered, what values mean it is reversible and irreversible and the diseases behind each one?
Reversible when >12% FEV1 increased = Asthma
Irreversible when <12% FEV1 increased = COPD
Tx for asthma?
- SAB2A
- SAB2A + ICS
- SAB2A + ICS + LTRA
- SAB2A + ICS + LAB2A +/- LTRA
- increase ICS dose
What are examples of a drug of the class…
SABA
LABA
SAMA
LAMA
Salbutamol
salmeterol
ipatropium bromide
tiotropium bromide
For exacerbations, what’s the acronym?
OSHITME
What does OSHIT me stand for?
O2
nebulised Saba
ics Hydrocortisone
IV MgSO4 (bronchodilator)
IV Theophylline
MgSO4 IV
Escalate
What else could be done if breathing is bad, exacerbation?
CPAP/BIPAP
For asthma = always BIPAP
+/- Abx if infection present
viral infection = common trigger
