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Three Part Question

In [adult patients in cardiac arrest due to local anaesthetic toxicity] is [lipid emulsion more effective than placebo] at [preserving life]?

Clinical Scenario

A twenty-five year old female receives an axillary block allowing a procedure may be carried out pain free. Ten minutes after receiving a dose of bupivacaine she becomes unresponsive and goes into cardiac arrest. What is the best treatment option in this situation?

Search Strategy

[exp Anesthesia, Local or (local adj1 anaesthe$).mp or exp Anesthetics, Local/] AND [exp Fat Emulsions, Intravenous/ or IFE.mp or intralipid.mp or Intravenous lipid emulsion.mp] Limit english language and humans.
Using Ovid interface; Medline 1950 to June week 4 2010, Embase 1980 to 2010 week 26, Cochrane database of systematic reviews 2005 May 2010

Search Outcome

[exp Anesthesia, Local/ OR (local adj1 anaesthe$).mp OR exp Anesthetics, Local/ OR exp bupivacaine$/ OR bupivacaine$.mp. OR lidocaine$/ OR lidocaine$.mp. OR exp prilocaine$/ OR prilocaine$.mp. OR exp lignocaine$/ OR lignocaine$.mp. OR exp marcaine$/ OR marcaine$.mp.] AND [exp Fat Emulsions, Intravenous/ OR IFE.mp OR intralipid.mp. OR Intravenous lipid emulsion.mp.] LIMIT to English language and humans.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Jamaty C et al 2010 Canada	16 published and 23 unpublished human case reports of those administered with IFE for local anaesthetic toxicity. 7 of the unpublished in cardiac arrest and 8 of the published in cardiac arrest. The others administered prior to this.	Systematic review	Mortality	Cardiac arrest resolved in all cases, 1 case returned to asystole 13hrs later. 1 case died of bronchopneumonia 9 days later (had been intubated),	Incorrect analysis of results, incorrect figures in mortality result discussion. Incorrect referencing within review Does not rate the methodological quality of the case reports. Not clear what was measured in mental state discussion. Unpublished reports used of very poor quality, some incomplete.

Comment(s)

Although in all cases where lipid emulsion was used, cardiac arrest was resolved, all were receiving standard advanced life support alongside. The evidence is very weak due to the systematic review only containing case reports, none graded on the quality of their evidence. No clinical studies on humans have been done on this subject. Although evidence is poor there is no proven alternative that may be used. More evidence is needed to make a recommendation that this is an efficient treatment, until that point it would be advised intravenous lipid emulsion should not be used.

Clinical Bottom Line

Inconclusive evidence to support the use of intravenous lipid emulsion in the treatment of cardiac arrest due to local anaesthetic toxicity. Conventional resuscitation methods advised over the use of lipid emulsion.

References

1. Jamaty C et al Lipid emulsions in the treatment of acute poisoning: a systematic review of human and animal studies. Clin Toxicol (Phila). 2010 Jan;48(1):1-27.