Asthma Flashcards
(41 cards)
Asthma is a common condition, what percentage of the population are affected?
10% population
What 3 factors contribute to airway narrowing in asthma?
- Bronchial hyper-responsiveness due to triggers
- Mucosal swelling and inflammation due to mast cell and basophil degranulation which releases inflammatory cytokines
- Increased mucus production which further narrows the airway and can block it
What is the atopic march?
combination of asthma, hay fever and eczema
Asthma can be divided into eosinophilic and non-eosinophilic. Which cells are involved in each?
Eosinophilic: eosinophils are recruited which damage the epithelium. Th2 cells make pro-inflammatory cytokines
Non-eosinophilic: Th1 cells
non-eosinophilic asthma can be divided into what?
non-smoking non-eosinophilic
smoking associated
obesity related
eosinophilic asthma can be divided into what?
atopic: occupation, pets, common autoallergens, fungal allergens.
non-atopic
What is atopy?
Genetic pre-disposition or tendency to have IgE mediated allergen sensitivity.
Atopic march: allergic asthma, atopic dermatitis, allergic rhinitis.
what type of hypersensitivity reaction is atopy?
type 1
occupational asthma is what type of hypersensitivity reaction?
type 3 - bakeries, hospitals, pet shops, farms, zoos
What is the key to diagnosing occupational asthma?
PEF diaries during work and on holidays
What happens in the initial sensitisation in asthma?
- Inhalation of allergens results in type 1 hypersensitivity in the airways (Th2)
- Th2 cells produce cytokines (IL4 and IL5) leading to production of IgE antibodies which coat mast cells and cause them to release histamine, leukotrienes and prostaglandins and histamine causes the smooth muscle to contract
- IL5 activates eosinophils which promote an immune response releasing more cytokines and leukotrienes
What happens in the early phase in asthma?
- Minutes after the exposure to the allergen, smooth muscle around the bronchioles start to spasm and there is increased mucus secretion.
- This narrows the airways making it difficult to breathe
- Increased vascular permeability and recruitment of additional immune cells from the blood
What happens in the late phase of asthma?
Additional immune cells are recruited from the blood hours after the early phase causing damage to the endothelium of the lungs and over years, oedema, scarring and fibrosis build up in the lungs which permanently reduces the airway diameter
What are the clinical features of asthma?
Cough Dyspnoea Diurnal variation Episodic wheeze Brittle disease Chest tightness Poor sleep
Clinical signs of asthma?
Bi-lateral, polyphonic, expiratory wheeze
Absence of crackles
Tachypnoea
Signs of a severe asthma attack
- Tachypnoea
- Cyanosis
- Tachycardia
- Inability to complete sentences
- Exhaustion
- Reduced respiratory effect
- Silent chest
- Altered conscious level
What are some associated problems with asthma?
Acid reflux - 40/60% of those with asthma Eczema Hayfever Nasal disease Food allergies or drug allergies
What family and social history is important in asthma diagnosis?
do they smoke atopy is inherited fam hx of asthma, eczema or hayfever pets in the home psychological illness
What occupational history is important in asthma diagnosis? What question can we ask?
exposure to dust, fumes or allergens in the work place
lab workers, vet staff, animal breeders, bakers, paint sprayers
Is your asthma worse at work or better when you go on holidays?
What blood tests can we do for asthma?
- eosinophils
- tests for atopy
- CXR often useful
- Skin prick tests for allergies
Name some triggers for asthma
- Infections
- Night and early morning time
- Menstrual cycle - just before period in some women
- Exercise
- Animals
- Pollution
- Cigarette smoke
- Damp and Cold air
- Dust and mold
- Strong Emotions
- NSAIDs
- B-blockers
What are some ways we can categorise the severity of asthma?
- Level of treatment required (number of inhalers)
- A&E attendances, admission, HDU/ITU care, ventilation (ventilation on ICU dictates severe asthma and high risk for attacks)
- Attendance at GP for courses of antibiotics and steroids
Day to day control - recent nocturnal waking, interference with ADLs
Exacerbations - A&E attendances, GP visits, admissions, ITU admissions
What lung function tests are available for diagnosing asthma?
Spirometry - Measures the flow and volume of air during inhalation and exhalation
PEFR
FeNO
What results do you expect to see in an obstructive lung disease? (FVC and FEV1/FVC ratio)
FVC normal but often low due to air trapping
FEV1 reduced
FEV1/FVC: <70%
