History taking -- Asthma.
Introduction:
Questions to be asked in history taking.
Wheeze, dyspnoea or cough? Disturbed sleep?
Exercise (quantify distance to breathlessness).
Days per week off work or school.
Diurnal variation?
Precipitating factors: emotion, exercise, infection, allergens and drugs.
Any other atopic diseases like eczema, hay fever, allergy.
Any Family history of asthma?
Any Acid reflux? Occupational history?
Examination: widespread polyphonic, high pitched wheezes.
Chronic asthma may give a barrel chest thorax with indrawn, costal margins (Harrison's sulci). Air entry may be inadequate to generate any wheeze (the silent chest - an ominous sign).
Tests: teach to record PEFR 4hourly for a week.
Severity markers:- CXR (hyperinflation), spirometry (FEV1/FVC is reduced), residual volume (increase means marked air trapping), blood gases, FBC (eosinophils), sputum and prick test (aspergillus plugs, eosinophils).
DD: pulmonary oedema, COAD, large airway obstruction (producing stridor) eg. foreign body, pneumothorax, pulmonary embolism.
Natural history: most childhood asthmatics either grow out of their disease in adolescence, or suffer much less as adults.
Management: stop smoking. Avoid any relevant allergens. Education.
Drugs available: Salbutamol, side effects: tachyarrhythmias, hypokalaemia, tremor and anxiety. If more than 2 puffs are needed, add an inhaled steroid. Avoid all NSAID's and beta-blockers: they worsen asthma.
Corticosteroids: are best inhaled, beclomethasone spacer: act by decreasing bronchial mucosal inflammation. The patient should gargle after inhaled steroid to prevent oral candidiasis.
Aminophylline: decreases bronchoconstriction. It is usually given as a prophylactic agent. It has a narrow therapeutic ratio causing arrhythmias, GI upset and fits in the toxic range. Therapy should be controlled by checking blood theophylline levels and by monitoring ECG.
Anticholinergics: Ipratropium may reduce muscle spasm synergistically with beta agonists.
Cromoglycate: can only be inhaled. It is sometimes useful for prophylaxis in mild asthma, and exercise induced asthma in children.
Refer: Asthma management.