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Related Subjects: Asthma |Acute Severe Asthma |Exacerbation of COPD |Pulmonary Embolism |Cardiogenic Pulmonary Oedema |Pneumothorax |Tension Pneumothorax |Respiratory (Chest) infections Pneumonia |Fat embolism |Hyperventilation Syndrome |ARDS |Respiratory Failure |Diabetic Ketoacidosis

Definition

• Asthma is a chronic respiratory illness with acute exacerbations with expiratory wheeze and reversible airways obstruction.
• Reversibility is key. Can be established by history, examination, PEFR records and spirometry
• Asthma is increasing worldwide and each year in the UK 1000-2000 people die of Asthma.

Aetiology

• Commoner in those with hay fever, urticaria and eczema and raised IgE and eosinophils - Allergic asthma.
• It is this rise in 'allergy' that may account for the overall rise in asthma incidence
• Excess of Th2 > Th1 in nasal and bronchial mucosa.
• Th2 lymphocytes secrete cytokines, inducing the production of IgE and cause maturation and recruitment of mast cells and eosinophils.

Pathology

• Chronic inflammatory condition
• Thickening of the lamina reticularis. Eosinophilia seen in bronchial biopsies.
• Curschmann's spirals containing eosinophils and Charcot-Leyden granules suggest steroid responsiveness

Precipitating factors

• Cigarette smoke, Cold air and Irritant gases as well as Perfume and Deodorants
• House dust mite allergen, Aspergillus spores, Viral infections, Exercise and Emotional stresses
• Drugs - NSAIDs, Aspirin (associated with Nasal polyps), Beta-blockers. Tartrazine ( a colourant), Other chemicals - see occupational asthma
• Types of response to precipitant: Early bronchospasm post-exposure to precipitant. Delayed bronchospasm is seen in 1/3rd even up to 10 hours after initial exposure

Clinical Classification

• Intrinsic: Non atopic, Do not have evidence of raised IgE, Older patients with late onset asthma.
• Extrinsic: Atopic, Allergic asthma is commoner in children and young adults, Elevated IgE

Clinical

• Expiratory dyspnoea and wheeze
• Chest tightness and cough (Cough often at night)
• Reduced chest expansion

Diagnosis:Clinical history compatible with asthma and

• Improved FEV by at least 12% (200 ml) after Salbutamol/trial of steroids. A 15% improvement is stronger evidence.
• More than 20% diurnal variation on = 3 days in a week for 2 weeks on PEF diary
• FEV1 = 15% decrease after 6 mins of exercise

Investigations

• Bloods: FBC, U&E. CRP/ESR normal - usually normal unless infective component.
• Atopy
  • Elevated Eosinophils
  • Elevated IgE
  • Elevated FENO
• CXR will in most cases be normal. However
  • Lobar collapse with mucus plugging
  • Infiltrates : aspergillus
  • Broncheictasis
• Spirometry: Measure FVC FEV1. FEV1/FVC ratio < 70% (or below the lower limit of normal if this value is available) is a positive test for obstructive airway disease
• PEFR shows variability > 20% with time and treatment. Predicted PEFR and diary of PEFR readings can show variability.
• An improved FEV1.0 by > 15% after 2 weeks of Prednisolone 30 mg od confirms the diagnosis.
• Fractional exhaled nitric oxide shows airway inflammation > 40 ppb in adults or 35 in children/young adults
• Bronchodilator reversibility (BDR) test (BDR) test: Increase FEV1 > 12% or more and increase in volume of 200 ml is positive
• Skin prick testing may be used to identify possible allergens to avoid. Aspergillus antibodies if eosinophilia or CXR shadowing

Management

• Short acting beta agonist (SABA)
  • Salbutamol metered dose "blue" inhaler used PRN as reliever therapy.
  • Terbutaline inhaler used PRN as reliever therapy.
  • Salbutamol nebuliser used in severe disease acute severe asthma.
• Long acting beta agonist (LABA) : Salmeterol.
• Anticholinergics: Ipratropium blocks muscarinic receptors.
• Inhaled corticosteroids (IHC):
  • Low dose: Budesonide 200-400 mcg/day or equivalent
  • Moderate dose: Budesonide 400-800 mcg/ay or equivalent
  • High dose Budesonide 800-2000 mcg/day or equivalent
• Oral or IV Corticosteroids
  • Prednisolone 30 mg short course for acute severe asthma.
  • Hydrocortisone is used IV for acute severe asthma
  • Steroid sparing agents
    • Methotrexate
    • Ciclosporin
    • IV Immunoglobulin
    • Anti IgE monoclonal antibody Omalizumab
    • Etanercept, Infliximab, Lebrkizumab
• Mast cell stabiliser: Sodium cromoglycate - inhibits. Cysteinyl Leukotriene receptor antagonist LT1 and LT2 receptors. Some are responsive. Give a trial.
• Phosphodiesterase inhibitor. Aminophylline
• Biologicals: Omalizumab - monoclonal ab binds to free IgE.
• Antibiotics: if evidence of infection.
• Steroid sparing agents: Cyclosporin, Methotrexate
• Magnesium: Used in acute severe asthma

Standard escalation process

References