Acute severe asthma — the severity and the escalation

The severity classification:

• The moderate — the peak flow 50 to 75 per cent, the saturation 92 per cent or above, the full sentences.
• The acute severe — the peak flow 33 to 50 per cent, the respiratory rate 25 or above, the heart rate 110 or above, the single-word speech.
• The life-threatening — the peak flow below 33 per cent, the saturation below 92 per cent, the silent chest, the cyanosis, the exhaustion, the altered consciousness, the bradycardia, the hypotension, the normal or the rising carbon dioxide.
• The near-fatal — the rising carbon dioxide requiring the ventilation.^[3]

The escalation:

1. The moderate — the salbutamol, the steroids, consider observation or the discharge with the plan.
2. The severe — the oxygen, the nebulised salbutamol and the ipratropium, the early steroids, the magnesium.
3. The life-threatening — the escalation to the intravenous salbutamol, the aminophylline, the anaesthetics, and the intubation with the ketamine and the low-rate long-expiration ventilation for the deteriorating or the rising carbon dioxide (heliox has no routine role — Cochrane found no admission benefit).^[4]
4. The near-fatal — the ventilation and the intensive care.

The key principles: the severity drives the escalation; the rising carbon dioxide is the ominous; the steroids are early; the magnesium for the severe; the intubation is the high-risk last resort with the careful ventilation; and the avoidance of the sedatives.^[3]