Asthma

Published on 02/04/2015 by admin

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Last modified 22/04/2025

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99 Asthma

Instruction

Examine this patient’s chest.

Salient features

History

• Determine whether there is a reversible airway obstruction by history: whether the wheezing and breathlessness is reversible

• Tightness in the chest

• Recurrent cough

• Exacerbation of the cough or wheeze at night or after exercise

• Improvement of the cough or wheeze with bronchodilator therapy

• Fever, yellowish sputum

• History of atopy (eczema, hay fever)

• History of rhinitis, nasal polyps

• History of trigger factors such as cold air, emotion, vapors, dust, drugs (e.g. beta-blockers), pollution, viral infections, pets, pollen.

Examination

• Bilateral scattered wheeze

• Examine the sputum cup.

Comment on accessory muscles of respiration, tachycardia, pulsus paradoxus and whether the patient can speak sentences without stopping to take a breath.

Diagnosis

This patient has a history of hay fever and bilateral scattered wheeze (lesion) caused by bronchial asthma (aetiology), and is breathless at rest (functional status).

Questions

Mention a few trigger factors known to aggravate asthma

• Infection

• Emotion

• Exercise

• Drugs, e.g. beta-blockers

• External allergens.

What do you understand by the term asthma?

Asthma is an inflammatory disorder characterized by hyper-responsiveness of the airway to various stimuli, resulting in widespread narrowing of the airway. The changes are reversible, either spontaneously or through therapy. The inflammatory response includes T lymphocytes, mast cells and eosinophils, and it is associated with exudation of plasma, oedema, smooth muscle hypertrophy, deposition of matrix, mucus plugging and epithelial damage.

Advanced-level questions

What do you understand by intrinsic asthma?

Intrinsic asthma is of non-allergic aetiology and usually begins after the age of 30 years. It tends to be more continuous and more severe; status asthmaticus is common in this group.

What do you understand by extrinsic asthma?

Extrinsic asthma has a clearly defined history of allergy to a variety of inhaled factors and is characterized by a childhood onset and seasonal variation.

What are the indications for steroids in chronic asthma?

• Sleep is disturbed by wheeze

• Morning tightness persists until midday

• Symptoms and peak expiratory flows progressively deteriorate each day

• Maximum treatment with bronchodilators

• Emergency nebulizers are needed.

What is the effect of reducing or discontinuing inhaled budesonide in patients with mild asthma?

Early treatment with inhaled budesonide results in long-lasting control of mild asthma (i.e. the forced expiratory volume is >85% of predicted value). Maintenance therapy can usually be given at a reduced dose, but discontinuation of treatment is often accompanied by exacerbation of the disease.

How would you manage a patient with acute asthma?

• Nebulized beta-agonists, e.g. terbutaline or salbutamol

• Oxygen, using a high concentration

• High-dose steroids: intravenous hydrocortisone or oral prednisolone or both

• Blood gases

• Chest radiography to rule out pneumothorax (Fig. 99.1)

• When life-threatening features are present:

• add ipratropium to nebulized beta-agonist
• intravenous aminophylline or salbutamol or terbutaline.
image

Fig. 99.1 Asthma. During a severe attack, hyperinflation (arrows) occurs, similar to that seen in COPD. Most patients with asthma have normal chest radiographs when not in an attack (compare with COPD in Fig. 100.1).

(With permission from Mettler 2004.)

What do you know about the British Thoracic Society step care regimen for the management of chronic asthma in adults?

Patients should be started on treatment at the step most appropriate to the initial severity (Thorax 1997;52:S1–24). A rescue course of prednisolone may be needed at any time and at any step. Stepwise reduction in treatment should be undertaken after the asthma has been stable over a period of 3–6 months.

Step 1, mild intermittent asthma: inhaled short-acting beta2-agonist used as required for symptom relief. If required more than once, go to step 2.

Step 2, regular preventer therapy: step 1 plus inhaled steroid therapy (200–400 µg/day).

Step 3, initial add on therapy: long-acting beta2-agonist (LABA) and assess control of asthma:

(a) If good response, continue LABA
(b) If some response, increase inhaled steroid to 400 µg/day (if not already on dose
(c) If no response, stop LABA and increase steroids to 400 µg/day
(d) If control still inadequate consider sustained-release theophylline or leukotriene receptor antagonist.

Step 4, persistent poor control:

• Consider trial of inhaled steroid 2000 µg/day
• Consider adding a fourth drug such as leukotriene receptor antagonist (e.g. montelukast), sustained-release theophylline
• Consider adding tablet of beta2 agonist.

Step 5, continuous use of oral or frequent steroids:

• Consider low-dose oral steroids
• Maintain inhaled steroid at 2000 µg/day
• Consider other therapies to minimize steroid therapy
• Refer to respiratory physician.

What are the features of acute severe asthma?

• Inability to complete a sentence in one breath

• Respiration rate >25 breaths/min

• Pulse rate >110 beats/min

• Peak expiratory flow rate <50% of predicted or best.

What are the life-threatening indicators in acute asthma?

• Peak expiratory flow rate <33% of predicted or best

• Exhaustion, confusion, coma

• Silent chest, cyanosis or feeble respiratory effort

• Bradycardia or hypotension.

Note: Arterial blood gases should be measured if any of these features are present or if oxygen saturation is <92%.

What are the indicators of a very severe, life-threatening attack?

• Normal (5–6 kPa, 36–45 mmHg) or increased carbon dioxide tension (>6 kPa or 45 mmHg)

• Severe hypoxia of <8 kPa (60 mmHg)

• Low or falling arterial pH.

What is the value of assessing pulsus paradoxus in a patient with acute severe asthma?

It is a poor guide to the severity of acute asthma as it compares poorly with the measurement of peak flow.

In which other conditions is wheeze a prominent sign?

COPD, left ventricular failure (cardiac asthma), polyarteritis nodosa, eosinophilic lung disease, recurrent thromboembolism, tumour causing localized wheeze.

What are the indications for mechanical ventilation with intermittent positive pressure ventilation?

• Worsening hypoxia (arterial partial pressure of oxygen (Pao) <8 kPa) despite 60% inspired oxygen

• Hypercapnia (Paco2 >6 kPa)

• Drowsiness

• Unconsciousness

• Intermittent positive pressure ventilation.

What do you understand by the term severe brittle asthma?

This condition is characterized by life-threatening attacks, which can develop within hours or sometimes even within minutes and can lead to sudden death.

What do you know about Beta receptor polymorphisms in asthma?

Glycine homozygous patients do well on regular beta2-agonists whether short or long acting.

Long- and short-acting beta2-agonists produce disparate responses: for example a lack of increased bronchial hyper-responsiveness associated with long-acting beta2-agonists but is commonly seen with short-acting beta2-agonists.

All genotypes and beta2-agonists are associated with receptor desensitization but not associated with worsening asthma.

Specific label changes for long-acting beta-agonists

1 The use of LABAs for asthma in patients of all ages is contraindicated without concomitant use of an asthma-controller medication such as an inhaled corticosteroid.

2 Stop use of the LABA, if possible, once asthma control is achieved and maintain the use of an asthma-controller medication, such as an inhaled corticosteroid.

3 Recommend against LABA use in patients whose asthma is adequately controlled with a low- or medium-dose inhaled corticosteroid.

4 Recommend that a fixed-dose combination product containing a LABA and an inhaled corticosteroid be used to ensure compliance with concomitant therapy in pediatric and adolescent patients who require the addition of a LABA to an inhaled corticosteroid.

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