2. Asthma Flashcards
What is the pathophysiology of asthma?
Chronic inflammatory disease of the airways
Airway obstruction that is reversible (but not completely so in some subjects), either spontaneously or with treatment = bronchial muscle contraction, mucosal inflam, increased mucus production
Increased airway responsiveness (airway narrowing) to a variety of stimuli
Outline the aetiology of asthma
Not fully understood
Strongest risk factors are a combination of genetic predisposition with environmental exposure to inhaled substances that may provoke allergic reactions
What are the symptoms and signs of asthma?
Intermittent dyspnoea
Wheeze
Cough
Inability to complete sentences
RR >25
Pulse 110/min
Disturbed sleep
Precipitants = cold air, exercise, emotion, allergens
How should asthma be investigated?
Peak flow 33-50%
Lung function testing = scooped curve, FEV1:FVC <70, DLCO normal, reversible
CXR
How should acute asthma be managed?
Assess pt very carefully - severe or near fatal
Peak flow = assess severity
A-E assessment = high flow O2, ABG, CXR
O = oxygen, high flow 15
S = 2.5-5mg salbutamol neb
H = IV 100mg hydrocortisone
I = 500mcg ipratropium neb
T = theophylline 250-500mg/12hrs oral
M = IV 2g magnesium over 20 mins
E = escalate care
How should chronic asthma be managed?
S = Smoking cessation, skin prick = identify allergen
I = Inhaler technique
M = monitoring
P = pharmacotherapy (below)
L = lifestyle
E = education
- Short acting beta 2 agonist (salbutamol) = symptoms relief
- Add inhaled steroid (beclomethasone) = dose for disease severity
- Add long acting beta 2 agonist (salmeterol) = can increase dose, if no effect stop it
- Beclomethasone 2000 micrograms/d, theophylline, oral beta 2 agonist
- Oral prednisolone
Name some possible complications of asthma
Pneumonia
Lung collapse
Respiratory failure
What are the features of moderate asthma?
Increased symptoms
PEF >50-75%
No features of acute severe asthma
What are the features of severe acute asthma?
Peak flow <33-50%
Inability to complete sentences
RR >25
Pulse >110/min
What are the features of life threatening asthma?
Peak flow <33%
Silent chest
Bradycardia
Diminished resp effort
Hypotension
Exhaustion
Coma
Signs of hypercapnia
What ward based test would be most helpful to decide what type of asthma is present?
Peak flow monitoring
What are the histological features of asthma?
Bronchial obstruction
Thickening of the basement membrane
Mucosal thickening
Mucus plugging
Bronchial smooth muscle hypertrophy
What are common triggers of acute asthma?
Cold air
Exercise
Allergens = pollution, dust mites, pollen, fur
Infection
Smoking/passive
NSAIDs
Beta-blockers
What does the term “Controlled Oxygen” refer to?
Administration of oxygen on a dose-response basis
Oxygen is regarded as a drug = only the smallest amount of it is used to obtain a desired therapeutic effect
