B. IV magnesium sulphate – Explanation

Current guidelines do not support the routine use of non-invasive ventilation in asthmatics.
Asthma: acute severe

Patients with acute severe asthma are stratified into moderate, severe or life-threatening

Moderate	Severe	Life-threatening
• PEF > 50% best or predicted • Speech normal • RR < 25 / min • Pulse < 110 bpm1	• PEF 33 – 50% best or predicted • Can’t complete sentences • RR > 25/min • Pulse > 110 bpm	• PEF < 33% best or predicted • Oxygen sats < 92% • Silent chest, cyanosis or feeble respiratory effort • Bradycardia, dysrhythmia or hypotension • Exhaustion, confusion or coma

British Thoracic Society guidelines

magnesium sulphate recommended as next step for patients who are not responding (e.g. 1.2 – 2g
IV over 20 mins)
little evidence to support use of IV aminophylline (although still mentioned in management plans)
if no response consider IV salbutamol

Explanation