Respiratory: Asthma

Question 1

What is the pathophysiology of asthma?

Answer 1

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

Question 2

Outline the aetiology of asthma

Answer 2

Not fully understood

Strongest risk factors are a combination of genetic predisposition with environmental exposure to inhaled substances that may provoke allergic reactions

Question 3

What are the symptoms and signs of asthma?

Answer 3

Intermittent dyspnoea

Wheeze

Cough

Inability to complete sentences

RR >25

Pulse 110/min

Disturbed sleep

Precipitants = cold air, exercise, emotion, allergens

Question 4

How should asthma be investigated?

Answer 4

Peak flow 33-50%

Lung function testing = scooped curve, FEV1:FVC <70, DLCO normal, reversible

Question 5

How should acute asthma be managed?

Answer 5

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

Question 6

How should chronic asthma be managed?

Answer 6

S = Smoking cessation, skin prick = identify allergen

I = Inhaler technique

M = monitoring

P = pharmacotherapy (below)

L = lifestyle

E = education

1. Short acting beta 2 agonist (salbutamol) = symptoms relief
2. Add inhaled steroid (beclomethasone) = dose for disease severity
3. Add long acting beta 2 agonist (salmeterol) = can increase dose, if no effect stop it
4. Beclomethasone 2000 micrograms/d, theophylline, oral beta 2 agonist
5. Oral prednisolone

Question 7

Name some possible complications of asthma

Answer 7

Pneumonia

Lung collapse

Respiratory failure

Question 8

What are the features of moderate asthma?

Answer 8

Increased symptoms

PEF >50-75%

No features of acute severe asthma

Question 9

What are the features of severe acute asthma?

Answer 9

Peak flow <33-50%

Inability to complete sentences

RR >25

Pulse >110/min

Question 10

What are the features of life threatening asthma?

Answer 10

Peak flow <33%

Silent chest

Bradycardia

Diminished resp effort

Hypotension

Exhaustion

Coma

Signs of hypercapnia

Question 11

What ward based test would be most helpful to decide what type of asthma is present?

Answer 11

Peak flow monitoring

Question 12

What are the histological features of asthma?

Answer 12

Bronchial obstruction

Thickening of the basement membrane

Mucosal thickening

Mucus plugging

Bronchial smooth muscle hypertrophy

Question 13

What are common triggers of acute asthma?

Answer 13

Cold air

Exercise

Allergens = pollution, dust mites, pollen, fur

Infection

Smoking/passive

NSAIDs

Beta-blockers

Question 14

What does the term “Controlled Oxygen” refer to?

Answer 14

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