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Three Part Question

In [patients with acute severe asthma] does [a single dose if IV magnesium sulphate] help [improve bronchodilation]?

Clinical Scenario

A young healthy adult with known asthma presents to the emergency department with an acute severe asthma attack. Following the BTS guidlines, you use salbutamol and ipratropium nebulisers and IV hydrocortisone, and wonder if a single dose if IV magnesium sulphate would be beneficial.

Search Strategy

MEDLINE -
1996 to date (MEDL) using the Dialog Datastar interface. (ASTHMA.TI. AND INTRAVENOUS.TI. AND MAGNESIUM.TI. AND ADULT# AND LG=EN)

Search Outcome

5 papers found of which 2 were irrelevant or of insufficient quality.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Porter RS, Nester, Braitman LE, Geary U, Dalsey WC March 2001 USA	Adult asthmatics between the ages of 18 and 55 presenting to the emergency department with a peak expiratory flow (PEF) of < 100 l/min or < 25% of predicted flow.	RCT	Improvement of PEFR	No improvement	Small Study
			Reduction of admission rates to hospital	No improvement
Boonyavorakul C, Thakkinstian A, Charoenpan P September 2000 Thailand	Patients, aged 15-65 years with acute severe asthma attack, whose severity scores were greater than 4	RCT	Improvement in severity score (in which PEFR was included)	No improvement	Very small trial
			Reduction of admission rates to hospital	No improvement
Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA Jr September 2000 USA	Patients presenting with acute asthma and were treated with intravenous magnesium sulfate versus placebo	Systemic Review	Improvement of PEFR overall	No Improvement
			Improvement of PEFR in patients with severe asthma	Improved by 52 L/min (95% CI 27 to 78
			Reduction of admission rates to hospital overall	No improvement
			Reduction of admission rates to hospital in aptients with severe asthma	Reduced, with odds ratio 0.10, 95% CI 0.04 to 0.27

Comment(s)

The smaller studies do not demonstrate a signifiant improvement in either PEFR or reduction of hospital admission rates in moderate to severe asthmatics. However, if a distinction is made, it is demonstrated that intravenous magnesium sulphate does improve both PEFR and reduce hospital admission rates in the severe subgroup.

Clinical Bottom Line

Intravenous magnesium sulfate appears to be improve PEFR compared to placebo in patients who present with acute severe asthma.

References

1. Porter RS, Nester, Braitman LE, Geary U, Dalsey WC Intravenous magnesium is ineffective in adult asthma, a randomized trial. European journal of emergency medicine Mar 2001, vol. 8, no. 1, p. 9-15
2. Boonyavorakul C, Thakkinstian A, Charoenpan P Intravenous magnesium sulfate in acute severe asthma. Respirology Sep 2000, vol. 5, no. 3, p. 221-5
3. Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA Jr Intravenous magnesium sulfate treatment for acute asthma in the emergency department: a systematic review of the literature. Annals of emergency medicine Sep 2000, vol. 36, no. 3, p. 181-90