Asthma

Asthma is an obstructive lung disease characterised by episodic and reversible airway bronchoconstriction, as a result of airway inflammation and bronchial hyper-responsiveness. It's a Type 1 hypersensitivity reaction. There’s resulting airway remodelling, characterised by bronchial smooth muscle hypertrophy, bronchoconstriction, mucous gland hypertrophy, vasodilation, and increased vascular permeability.

In children, it primarily presents with recurrent symptoms of cough, breathlessness, wheezing, and chest tightness.

Severity of attack:

Moderate:

• Peak flow > 50%

• Normal speech

Severe:

• Peak flow < 50%

• Unable to complete sentences in one breath

• Sats < 92%

• Respiratory distress

• Tachypnoea

• Tachycardia

Life-threatening - 33, 92 CHEST:

• PEF < 33%

• Sats < 92%

• Cyanosis

• Hypotension

• Exhaustion, altered consciousness

• Silent chest

• Tachyarrhythmias

Investigations:

The main investigations to do are:

• Spirometry w/bronchodilator reversibility - Will show an obstructive pattern with an FEV1/FVC < 0.7, which will normalise after a bronchodilator is given

• PEF - variability > 20% (diary of measurements can be kept for 2-4 wks.)

• FeNO (Fractional exhaled nitric oxide) - 40+ in adults, 35+ in children - good indicator of level of airway inflammation

Chronic management:

Non-pharmacological - Avoid precipitants, Review inhaler technique

Stepwise approach based on BTS guidelines:

• SABA inhaler (reliever) + Low-dose ICS (preventer)

• Add LABA

  • If little benefit - Continue LABA and increase ICS dose

  • If no benefit - Stop LABA and increase ICS dose

• Trial of oral LTRA (e.g. montelukast), high-dose steroid, or oral B2-agonist

Acute management of an attack

• Supplementary O2

• Bronchodilators – Followed as:

  • Salbutamol

  • Ipratropium bromide

  • Magnesium sulphate - use if nebulisers aren't working

  • Aminophylline

  • For moderate/severe cases, oral Prednisolone or iv Hydrocortisone is given

• ABG!

  • Pay attention to a raised CO2, which could indicate that the child is becoming tired, therefore not able to ventilate effectively.