Asthma

Question 1

Define

Answer 1

Chronic inflammatory airway disease characterised by variable reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation

Question 2

What are the risk factors?

Answer 2

• Genetic Factors

Family history

Atopy (tendency for T lymphocytes to drive production of IgE on exposure to allergens)

Genes associated with disease – ADAM 33, dipeptidyl peptidase 10, PHD finger protein 11, prostanoid DP1 receptor, TNF, chromosome 12q

• Environmental Factors

House dust mites

Pollen

Pets

Cigarette smoke

Viral respiratory tract infections

Bacterial infections (mycoplasma pneumonia or chlamydia pneumonia)

Aspergillus fumigatus spores

Occupational allergens

Question 3

What is the pathophysiology?

Answer 3

There are 2 major elements in the pathophysiology: inflammation and airway hyper-responsiveness (AHR). The large airways and the small airways with diameters <2 micrometres are the sites of inflammation and airway obstruction.

 

Question 4

What’s the epidemiology?

Answer 4

Affects 10% of children

Affects 5% of adults

Prevalence appears to be increasing

40-60% have acid reflux disease

Other associated diseases – polyarteritis nodosa, Churg-Strauss syndrome

Question 5

What are the presenting symptoms?

Answer 5

Episodic history

Dyspnoea

Expiratory Wheeze

Breathlessness

Cough (worse in the morning and at night)

IMPORTANT: ask about previous hospitalisation due to acute attacks - this gives an indication of the severity of the asthma

Check for history of atopic disease (e.g. allergic rhinitis, urticaria, eczema)

Question 6

What are the precipitating factors?

Answer 6

-Precipitating Factors

Cold

Viral infection

Drugs (e.g. beta-blockers, NSAIDs)

Exercise

Emotions

Question 7

What are the signs of asthma?

Answer 7

Tachypnoea

Use of accessory muscles

Prolonged expiratory phase

Polyphonic wheeze

Hyperinflated chest

Hyperresonant percussion

Question 8

What are the signs of an acute severe attack?

Answer 8

PEFR 33-50% predicted

Pulse > 110bpm

RR > 25/min

Inability to complete sentences in one breath

Question 9

What are the signs of a life threatening attack?

Answer 9

PEFR < 33% predicted

Silent chest

Cyanosis (low O2, normal CO2, SpO2<92%)

Arrythmia, Hypotension

Exhaustion/ Confusion/ Coma

ABG (normal or high CO2, PaO2 low or sats <92%)

Question 10

What investigations for acute asthma?

Answer 10

FEV1/FVC ratio - <80% of predicted

Peak flow

Pulse oximetry

ABG if sats <92%/ life threatening features

CXR - to exclude other diagnoses (e.g. pneumonia, pneumothorax), may be hyperinflated

FBC - raised WCC if infective exacerbation

CRP

U&Es

Blood and sputum cultures

Question 11

What investigations for chronic asthma?

Answer 11

Peak flow monitoring - often shows diurnal variation with a dip in the morning

Pulmonary function test

Bloods - check:

Eosinophilia

IgE level

Aspergillus antibody titres

Skin prick tests - helps identify allergens

Question 12

How would you manage acute asthma?

Answer 12

ABCDE

Assess severity of attack (using the above guidelines, warn ICU if life threatening)

Immediate treatment:

Supplemental O2 to maintain sats at 94-98%

Salbutamol 5mg (or terbutiline 10mg) nebulized with O2

If severe/life threatening, add in ipratropium bromide 0.5g/6h to nebulizers

Hydrocortisone 100mg IV or prednisolone 40-50mg PO

Reasses every 15 mins

If PEF <75%, give salbutamol nebuliser every 15-20mins or 10mg/h continuously

Monitor ECG for arrhythmias

If life threatening and no response to initial therapy – consider IV magnesium sulphate 1.2-2g over 20mins

If no improvement – ITU referral, IV salbutamol if following signs present:

Deteriorating PEF

Worsening hypoxia

Hypercapnia

ABG – low pH or high H

Exhaustion, feeble respiration

Drowsiness, confusion

Respiratory arrest

If improving within 15-30mins:

Continue nebulized salbutamol every 4-6h

Prednisolone 40-50mg PO on discharge for 5-7days

Keep monitoring

If PEF>75% 1h after initial treatment, consider discharge with outpatient follow up

Question 13

When would you discharge an acutely ill patient?

Answer 13

PEF > 75% predicted with diurnal variation < 25%

Inhaler technique checked

Stable on discharge medication for 24 hours

Patient owns a PEF meter, written management plan

Patient has steroid (inhlaed and oral) and bronchodilator therapy

Arrange follow-up – GP appointment in 2d and resp clinic appointment in 4w

Question 14

How would you treat chronic asthma?

Answer 14

Start on the step that matches the severity of the patient’s asthma

STEP 1

Inhaled short-acting beta-2 agonist used as needed

If used > 1/day or night time symptoms, then move onto step 2

STEP 2

Step 1 + regular inhaled low-dose corticosteroids (e.g. beclometasone 200 mcg/day) or start at dose appropriate to severity

STEP 3

Step 2 + inhaled long-acting beta-2 agonist (e.g. salmeterol 50mcg/12h)

If inadequate control with LABA, increase steroid dose (800 mcg/day)

If no response to LABA, stop LABA and increase steroid dose (800 mcg/day)

STEP 4

Increase inhaled steroid dose (2000 mcg/day)

Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet)

STEP 5

Add regular oral prednisolone

Maintain high-dose inhaled steroids

Refer to specialist care

Question 15

What advice can you give?

Answer 15

Teach proper inhaler technique

Help to quit smoking

Explain important of PEFR monitoring

Avoid provoking factors

Question 16

What are the possible complications?

Answer 16

Growth retardation

Chest wall deformity (e.g. pigeon chest)

Recurrent infections

Pneumothorax

Respiratory failure

Death

Question 17

What’s the prognosis?

Answer 17

Many children improve as they grow older

Adult-onset asthma is usually chronic