Asthma

• Recurrent episodes of dyspnoea, cough and wheeze caused by reversible airways obstruction

  factors contribute to airway narrowing:

  1. Bronchial muscle contraction

  2. Mucosal inflammation

  3. Increased mucus production
• Asthma is one of several atopic conditions that can run in families
• Investigations for asthma:

  • Peak flow - 20% or more diurnal variation
  • Spirometry - obstructive pattern
  • Bronchodilator reversibility test - 12% or more improvement in FEV1 or increase in volume of 200ml or more
  • FeNO test
• Presentation of asthma:

  • Intermittent dyspnoea
  • Expiratory polyphonic wheeze
  • Nocturnal cough
  • Triggers - cold, dust, animal fur, smoke and exercise
  • Potential history of other atopic conditions
• Be sure to screen for occupational asthma

  • Do symptoms improve when not at work?
• If there is a high clinical probably of asthma a treatment trial can be started, if there is an improvement of symptoms a diagnosis can be made
• Asthma patients should receive a yearly review and flu vaccination
• Salbutamol is an example of a short acting beta agonist

  It activates specific B2 adrenergic receptors on smooth muscle cells which leads to relaxation and bronchodilation

  Side effects include a fine muscle tremor and tachycardia
• Beclomethasone is an example of an ICS used in asthma

  it inhibits the recruitment and survival of inflammatory cells in the airway that cause the bronchoconstriction and excess mucus

  Side effects: thinning/bruising of skin, reduced immunity, increased risk of pneumonia and oral thrush
• Acute exacerbation of asthma can be life-threatening. A silent chest is a tell tale sign of a life-threatening attack

  • PEFR > 50-75 % of predicted - moderate attack
  • PEFR 33-50 % - acute severe attack
  • PEFR < 33 % - life threatening
• Management of an acute asthma attack is step wise until control is achieved:

  1. Salbutamol via spacer
  2. SABA + SAMA nebulisers
  3. Oral prednisolone
  4. IV hydrocortisone
  5. IV magnesium sulphate - bronchodilator
  6. IV salbutamol
  7. IV aminophylline
• After an acute attack, management involves:

  • Optimising long-term asthma management 
  • Individual written asthma self-management plan
  • Considering a rescue pack of oral steroids to start early in an exacerbation
  • NICE suggest referral to a specialist after 2 attacks in 12 month
• Non-modifiable risk factors:

  • Personal or family history of atopy
  • Male sex - asthma development
  • Female sex - persistence to adulthood
  • Prematurity and low birth weight
• Modifiable risk factors:

  • Exposure to tobacco smoke, inhaled particulates and occupational dust
  • Obesity
  • Social deprivation
  • Infections in infancy
• Typical asthma symptoms:

  • Wheeze
  • Cough
  • Breathlessness
  • Symptoms are characteristically episodic
  • Diurnal - worse at night and early morning
• Important areas to cover in the history:

  • Triggers - pets, carpets, temperature
  • Occupation - exposure to dusts and chemicals
  • Frequency of exacerbations and previous hospital admissions
  • Personal or family history of atopy
  • Best expected and recent peak expiratory flow rate
  • Adherence with treatment
  • Smoking - including passive
• Typical clinical findings in asthma may include:

  • Around the bedside: oxygen, inhaler and spacer, PEFR meter
  • Inspection: increased work of breathing, cyanosis, cough, audible wheeze
  • Peripheries: fine tremor (salbutamol use), tachycardia, oral candidiasis (steroid inhaler use)
  • Chest: polyphonic expiratory wheeze
• Respiratory complications of asthma include:

  • Pneumonia
  • Collapse and pneumothorax
  • Respiratory failure
  • Status asthmaticus
• Features of acute severe asthma exacerbation:

  • PEFR 33-50% of best or predicted
  • Respiratory rate of 25 or more
  • Pulse of 110 or more
  • Inability to complete sentences in one breath
• Features of life-threatening asthma exacerbation:

  • PEFR <33%
  • Oxygen saturation <92%
  • Silent chest
  • Cyanosis
  • Poor respiratory effort
  • Bradycardia
  • Hypotension
  • Confusion
  • Exhaustion
• Near-fatal asthma exacerbation

  Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures.