Asthma Flashcards
What is asthma
Chronic hyper responsiveness of airway - type I
Reversible bronchospasm = obstruction
Smooth muscle contraction
Inflammation + mucous = narrowing
What are the types of onset of asthma
Early infant / VIW Childhood Adult Exertional Occupational - normal peak flow when not at work (refer to specialist)
What causes asthma / RF
Genetic factors - to be hyper allergic / responsiveness
Environment - childhood exposure to allergens / maternal smoking
Familial atopic tendency / atopy - tendency to be hyper allergic and produce IgE
Occupation - smoke decreased FEV1 and increases wheeze
Other
- LBW
- Not breast
What is atopy and what happens in atopy
1st exposure sensitises T cells, B cells produce IgE which binds to mast cells
2nd exposure mast cells release contents
What do mast cells release and what does this cause
Histamine, leukotrienes and inflammatory cells
Oedema, mucous and smooth muscle contraction
What triggers asthma
What drugs should be avoided
Exercise Cold air Aspirin BB NSAID Sedatives Allergies - Pets, Pollen, Food Smoke / parenteral smoking URTI / infections Poor inhaler technique
What are the symptoms of asthma
VARIABLE + REVERSIBLE
Often worse at night - diurnal variation
Expiratory wheeze - narrow airways = turbulent
SOB - more effort to inflate hyper inflated lungs
Cough - dry, exertion, nocturnal
Chest tight - voluntary contract muscles
Haemoptysis
What are the signs of asthma
Tachycardia Tachypoea Hypercpania + hypoxaemia Cyanosis Reduced PEFR Hyperinflated CXR as air is trapped Acccessory muscles
What are complications of asthma
Pneumothorax - parenchyma ruptures due to increased alveolar pressure
What is a delayed eosinophil response
Atopic triad - Conjunctivitis 'Hayfever' - Allergic Rhinitis - Dermatitis Bronchiole constriction
How does asthma present in children
NO WHEEZE = NO ASTHMA Dry nocturnal cough Respiratory difficulty / obstruction Sooking in of ribs - recession <18 months = more infection
What suggests its not asthma
Dizzy Productive cough Smoking Hx Cardiac disease Normal PEFR when symptomatic Clubbing Stridor - harsh vibrating Asymmetrical expansion Dull percussion Crepitations No response to RX Unilateral Sx
What is suggestive of asthma
Wheeze / SOB / tight chest Diurnal variation Exercise / allergic / cold air worsens Aspirin / BB worsens Evidence of atopy FH atopy Low FEV1 / PEF Blood eosinophilia
How do you investigate asthma
Spirometry with bronchodilator reversibility = 1st line
FeNO - released by eosinophil and show atopy
Peak flow variability over 2 weeks
What does spirometry look at
Amount of air and speed during exhalation
FEV1 <70% = suggestive
FVC = normal
Ratio reduced
What does bronchodilator reversibility show
Large increase in FEV1 >12%
What are other investigations
CXR - old / smoking HX PEFR for 2 weeks - >15% variability = suggestive + diurnal variation >2% PFT to exclude COPD - Helium dilution - CO gas transfer = normal Bronchial hyper responsiveness Skin prick for allergen Total IgE FBC
What do you do if >17
Spirometry
BDR
FeNO
What do you do 5-17
Spirometry + BDR
FeNO if normal but still suspect
What do you do in <5
Clinical
Trial of Rx
If unsuccessful = refer
What do you do for occupational asthma
Serial peak flow
Exposed and unexposed periods
If Sx better on holiday
Refer to occupational health
What should you ask about in the Hx
Variation - Diurnal / Weekly variation / better in holiday / annual - pollen ? Triggers - inc drugs that worsen Childhood asthma / bronchitis / hay fever / excema FH Days of work Sleep disturbance Acid reflux - Rx improves spirometry
What drugs are CI in asthma
BB NSAID Aspirin Sedatives Esp if nasal polyps
