Asthma Flashcards
What is asthma
Chronic inflammatory disorder of airways
Reversible airflow obstruction
What are some triggers for asthma
Pets House dust mites Mould Pollen Tobacco smoke Pollutants Cold air Exercise NSAIDs
Pathogenesis of asthma
Trigger results in TH2 activation which recruits mast, eosinophils, lymphocytes and dendritic cells
This leads to type 1 hypersensitivity reaction where large amounts of prostaglandins, histamine and leukotrienes are released (IgE receptors on mast cells bind to IgE leading to mast cell degranulation)
This results in airway narrowing because: smooth muscle contraction, hyper secretion of mucus, inflammatory cell infiltrate and remodelling (smooth muscle hyperplasia and collagen deposition in BM)
Symptoms of asthma
Wheeze Dry cough - usually in night, exercise induced Dyspnoea Chest tightness Airflow obstruction
Typical history in asthma
Eczema Hayfever Atopy (Passive) Smoker or mother smoked while pregnant Mould in home Pets Asthma symptoms (separate card)
Findings on examination with asthma
Chest deformities Barrel chest Tachypnoea Tracheal tug Recession between ribs Nasal flaring Accessory muscle use Hyper resonant on percussion Wheeze on auscultation
Investigations for asthma
Best of 3 peak expiratory flow and compare to predicted for age, sex and height
Spirometry - produce a vitalograph and flow volume loop (scalloping, low PEFR and low FEV1:FVC)
Results should improve with a month trial of bronchodilators by >15%
Pharmacological management of asthma
Short acting B agonist e.g salbutamol
Steroid
Long acting B agonist e.g salmeterol
What can trigger an asthma attack
Lack of treatment adherence
Viral infection of RT
Exposure to trigger
Features of mild asthma attack
O2 sats >92% Pulse <110 Resp rate <25 Speech normal Minimal wheeze PEFR >75% predicted
Features of moderate asthma attack
O2 sats >92% Pulse <110 Resp rate <25 Speech normal Severe wheeze PEFR 50-75% predicted
Features of severe asthma attack
O2 sats <92% Pulse >110 Resp rate >25 Can't complete sentences No wheeze PEFR 35-50% predicted
Features of life threatening asthma attack
O2 sats <92% Exhaustion from using accessory muscles Altered consciousness Silent chest PEFR <35% predicted
Treatment of life threatening asthma attack
O2 therapy
Salbutamol nebulisers
Might need to intubate
