Case 20.4 – Asthma (Acute Exacerbation)

CLINICAL: asthma is recurrent episodes of wheeze, cough and breathlessness. This is an oversimplification, because it is possible to have asthma without the triad of wheeze, cough and breathlessness. Furthermore, a minority of children with these symptoms will have other conditions.

PHYSIOLOGICAL: asthma is a condition associated with airway hyper reactivity and with reversible airways obstruction.

Objective measurement of airway hyper responsiveness can be obtained by measuring lung function such as peak expiratory flow (PEF) or forced expiratory volume in 1 second (FEV₁) in a bronchial challenge test. Airway hyper reactivity is defined as a significant fall (usually about 15-20%) in lung function after inhalation of chemicals (such as methacholine, histamine or mannitol), after inhalation of hypertonic saline, after cold, dry air or following exercise.

Airway hyper reactivity and reversible (or variable) airways obstruction also may be demonstrated by an increase in PEF or FEV₁ of more than 10% following a bronchodilator, or by fluctuations in PEF measurements obtained on a regular basis at home.

There are limitations to this physiological definition of asthma. These include the fact that most children are unable to cooperate with challenge tests to measure airway hyper responsiveness (AHR) until they are 5 or 6 years old, and that there is an imperfect correlation between children with AHR and clinical features of asthma.

PATHOLOGICAL: asthma relates to mucosal oedema, mucous hypersecretion and smooth muscle spasm in the small airways. Airway inflammation is prominent.

IMMUNOLOGICAL: asthma is on the atopic state. In an allergic response, degranulation of mast cells occurs, with the release of chemical mediators into the airways and a resultant asthmatic response. Our understanding of the cytokines that are important in asthma remains incomplete. Indeed, the mast cell, the eosinophil and the neutrophil all seem to have important roles in the pathogenesis of asthma.

The diagnosis of asthma (and ongoing symptoms in uncontrolled asthma) can be made make in the child who has:

• recurrent episodes of wheeze
• breathlessness
• cough

And who is

• completely well between attacks.

Other clinical presentations may be:

• nocturnal cough
• persistent cough in association with acute respiratory infections
• a history of 'rattly breathing' in the absence of a definite history of wheeze.

Assessment of the severity of an attack:

The severity of acute asthma can be classified as mild, moderate, severe or critical. The most reliable indicators are mental state and work of breathing (comprising accessory muscle use and recession).

Patients with an acute exacerbation of asthma requiring salbutamol every 3 h at home should be assessed by their Local Medical Officer or in the emergency department.

• The initial arterial O₂ saturation (SaO2) in air, heart rate and ability to talk should be used as additional features in assessing the severity of acute asthma.
• Wheeze intensity, central cyanosis, pulsus paradoxus, peak expiratory flow are not reliable or the assessment of the severity of acute asthma.
• Arterial blood gases, CXR and spirometry should not be routinely used in assessing the severity of acute asthma.

Sign	Mild	Moderate	Severe	Critical
Mental state	Normal	Normal	Agitated	Confused/drowsy
Work of breathing	Normal	Mildly increased	Moderately/markedly increased	Maximally increased or exhausted

Causes of asthma:

Predisposing

• Genetic: ?chromosomes 5, 6, 7, 11, 12

Inducers (sensitisers)

• Hygiene hypothesis
• Allergens
• Cigarette smoke
• Other irritants, such as ozone
• Occupational (rare in children)

Triggers

• Infections, e.g. viral, Mycoplasma, pertussis
• Exercise, especially in cold, dry air
• Allergens, e.g. house dust mite, pollen, animal dander, foods
• Environment, e.g. cigarette smoke, ozone, SO₂
• Emotional, such as laughing
• Chemicals, e.g. salicylates, metabisulphite

Sustainers (maintainers)

• Allergens
• Viruses
• Environmental irritants

Spirometry to measure FEV₁ and forced vital capacity before and after a bronchodilator may help assess severity and response to therapy. Between exacerbations, children with intermittent disease will have normal lung function and no further improvement after bronchodilators. Children with persistent symptoms may show airways obstruction with improvement after inhalation of a bronchodilator. Fixed airways obstruction suggests either severe asthma or an alternative diagnosis such as cystic fibrosis.

Medication	Indications	Contraindications / Precautions	Side effects
Beta-2 sympathomimetics Salbutamol Terbutaline	Acute asthma Symptom relief during maintenance treatment of asthma and COPD Protection against exercise-induced asthma	For oral and parenteral use consider: Cardiovascular disorders (including hypertension, ischaemic heart disease, heart failure, arrhythmias)—risk of cardiovascular adverse effects. Hyperthyroidism—risk of cardiovascular adverse effects. Diabetes—risk of hyperglycaemia (high dose). Treatment with other sympathomimetic amines—may increase adverse effects (tremor, tachycardia, headache); avoid combination or adjust dose as necessary	Common tremor, palpitations, headache Infrequent hyperglycaemia (high dose), tachycardia, muscle cramps, agitation, hyperactivity in children, insomnia Rare paradoxical bronchospasm, allergic reactions including urticaria, angioedema and anaphylaxis, lactic acidosis
Sodium chromoglycate Cromoglycate	Maintenance treatment in persistent asthma Protection against exercise-induced asthma		Common cough, throat irritation, bitter taste, transient bronchospasm Rare allergic reaction including severe bronchospasm
Leukotriene antagonists Montelukast Zafirlukast	Maintenance treatment in asthma		Common headache, abdominal pain, diarrhoea Rare Churg–Strauss syndrome (below), allergic reaction including urticaria, angioedema and anaphylaxis Churg–Strauss syndrome Cases have been reported with both montelukast and zafirlukast; the syndrome may have predated leukotriene-receptor antagonist treatment, or been unmasked when corticosteroid treatment was reduced; however, a causal role cannot be totally excluded.
Inhaled corticosteroids Beclomethasone Budesonide Ciclesonide Fluticasone	Maintenance treatment in persistent asthma Maintenance treatment in severe COPD with frequent exacerbations	Precautions COPD—inhaled corticosteroids may increase risk of pneumonia. Smoking—asthma patients who smoke may respond less well to inhaled corticosteroids than non-smokers and may require higher doses. Pregnancy Encourage pregnant women to continue using inhaled corticosteroids.
Oral corticosteroids	Used in a wide range of conditions for their anti-inflammatory and immunosuppressant effects	Latent TB—may be reactivated; Peptic ulcer disease—corticosteroids may increase the risk of peptic ulcers. Diabetes—corticosteroids worsen diabetes control and may cause hyperglycaemia in non-diabetics. Hypertension, heart failure—may be worsened due to sodium and water retention (mineralocorticoid effect). Psychiatric disorders—may be exacerbated. Glaucoma—intraocular pressure may increase. Osteoporosis—long term corticosteroid use increases the risk of osteoporotic fractures and accelerates bone loss. Myasthenia gravis—increased muscle weakness may occur during the first few weeks of treatment with corticosteroids; seek specialist advice.	Common adrenal suppression, increased susceptibility to infection, masking of signs of infection, sodium and water retention, oedema, hypertension, hypokalaemia, hyperglycaemia, dyslipidaemia, osteoporosis, fractures, increased appetite, dyspepsia, delayed wound healing, skin atrophy, bruising, acne, hirsutism, growth retardation in children, myopathy, muscle weakness and wasting, fat redistribution (producing cushingoid appearance), weight gain, amenorrhoea, psychiatric effects (below) Infrequent osteonecrosis, particularly of the femoral and humeral heads Intra-articular injection: headache, flushing, rashes, acute post-injection flare reactions, injection site irritation, joint discomfort (brief), increased blood glucose concentration (temporary) Rare peptic ulceration, posterior subcapsular cataracts, glaucoma, hypersensitivity reactions Intra-articular injection: periarticular calcification (reversible), arthropathies, progressive cartilage damage, muscle wasting, skin and subcutaneous tissue atrophy, skin pigmentation changes, sterile abscess formation Psychiatric effects Include euphoria, hypomania, depression, disturbances of mood, cognition, sleep and behaviour. Delirium or psychosis are less common.
Ipratropium bromide	Severe acute asthma Maintenance treatment in COPD and severe asthma	Closed angle glaucoma, prostatic hypertrophy—risk of aggravation.	Common dry mouth, throat irritation Rare urinary retention, constipation, acute angle closure glaucoma, dizziness, palpitations, allergy (eg itch, rash, angioedema, anaphylaxis)
Theophyllines Aminophylline Choline theophyllinate Theophylline	Severe airways obstruction, including acute asthma (aminophylline) Maintenance treatment in severe asthma and COPD	GORD—theophyllines increase gastric acid secretion and relax gastro-oesophageal sphincter. Arrhythmia—may be exacerbated. Heart failure, pulmonary oedema, severe hypoxia—reduce theophylline clearance; smaller dose may be needed. Thyroid dysfunction—hyperthyroidism increases theophylline clearance while hypothyroidism decreases its clearance; monitor theophylline concentration and adjust dose as needed when treating thyroid dysfunction. Smoking—increases theophylline clearance; larger dose may be needed. Epilepsy—theophyllines may lower seizure threshold. Acute febrile illness, viral infection—possibly increase theophylline concentration. Treatment with beta2 agonists—increases risk of hypokalaemia; monitor potassium concentration in severe asthma. Theophyllines have a narrow therapeutic range; toxicity is closely related to plasma theophylline concentration.	Common nausea, vomiting, diarrhoea, gastro-oesophageal reflux, headache, insomnia, irritability, anxiety, tremor, palpitations Rare seizures, arrhythmias (at high concentrations), tachycardia
Magnesium sulphate	Severe airway obstruction, including acute asthma	Need cardiac monitoring	Epigastric or facial warmth, flashing, pain and numbness at infusion site, dry mouth, malaise. Rapid IV infusion may precipitate hypotension, nausea, respiratory depression and cardiac arrhythmias.
Long acting beta agonists Eformoterol Salmeterol	Maintenance treatment of asthma (including nocturnal and exercise-induced asthma) in patients receiving inhaled or oral corticosteroids Maintenance treatment of COPD		Common tremor, palpitations, headache Infrequent hyperglycaemia (high dose), tachycardia, muscle cramps, agitation, hyperactivity in children, insomnia Rare paradoxical bronchospasm, allergic reactions including urticaria, angioedema and anaphylaxis, lactic acidosis

ASTHMA ACTION PLAN

© 2008 National Asthma Council Australia

Name: ………………………………………….….… Date: …………… Best Peak Flow* ……..…...…
*Not recommended for children under 12 years

WHEN WELL

Asthma under control (almost no symptoms)

Preventer ………………………………. Dose ………….………
Reliever ………………………………. Dose ………………….
Symptom controller (if prescribed) ………………………………. Dose ………………….
Combination medication (if prescribed) ……………………………. Dose ………………….

Peak flow above ………………………..

WHEN NOT WELL

Asthma getting worse (waking from sleep, first sign of a cold, using more reliever)

Preventer ………………………………. Dose ………….………
Reliever ………………………………. Dose ………………….
Continue Symptom controller (if prescribed) ………………………………. Dose ………………….
Continue Combination medication (if prescribed) ……………………………. Dose ………………….

Continue on this increased dosage for …………………….. before returning to the dose you take when well

Peak flow between            and           

IF SYMPTOMS GET WORSE

Asthma is severe (difficulty with normal activity, feel that asthma is out of control)

Start prednisolone/prednisone and contact doctor Dose ………….………

• Stay on this dose until your peak flow is above ……………..….. on two consecutive mornings
• Reduce prednisolone/prednisone to dose ……….. daily for …………. days, then cease.

Extra steps to take: ……………………………………………………………….

When your symptoms get better, return to the dose you take when well

Peak flow between            and           

DANGER SIGNS

(symptoms get worse very quickly, need reliever more than 2 hourly)

Continue reliever ………………………………………………

Peak flow below           

Doctor's stamp and/or contact details:

Pharmacist's stamp and/or contact details:

Dial 000 for ambulance

Detailed Guidelines:

WHEN WELL

You will

• be free of regular night-time wheeze or cough or chest tightness
• have no regular wheeze or cough or chest tightness on waking or during the day
• be able to take part in normal physical activity without getting asthma symptoms
• need reliever medication less than 3 times a week (except if it is used before exercise)

WHEN NOT WELL

You will

• have increasing night-time wheeze or cough or chest tightness
• have symptoms regularly in the morning when you wake up
• have a need for extra doses of reliever medication
• have symptoms which interfere with exercise

(You may experience one or more of these)

IF SYMPTOMS GET WORSE, THIS IS AN ACUTE ATTACK

You will

• have one or more of the following: wheeze, cough, chest tightness or shortness of breath
• need to use your reliever medication at least once every 3 hours or more often

DANGER SIGNS

• Your symptoms get worse very quickly
• Wheeze or chest tightness or shortness of breath continue after using reliever medication or return within minutes of taking reliever medication
• Severe shortness of breath, inability to speak comfortably, blueness of lips

IMMEDIATE ACTION IS NEEDED: CALL AN AMBULANCE

Take this Asthma Action Plan with you when you visit your doctor.

To order more Asthma Action Plans, please visit the National Asthma Council Australia website: www.NationalAsthma.org.au