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I note with interest the recent correspondence concerning the use of lipid rescue for cardiac arrest caused by local anaesthetic toxicity [1, 2], and the theories about the possible mechanisms of action. I would like to ask those who have had successfully used lipid rescue in resuscitation whether they have ever had the opportunity to evaluate whether the regional block was still working after the lipid infusion had been administered? If the block had disappeared, this might imply that the lipid acts as a ‘lipid sink’[3]. If, however, the block remains, this would give weight to the argument that the lipids influence acylcarnitine exchange in cardiac mitochondria [4].

A rare complication of peripheral nerve block is that it may persist for days or even weeks, causing concern for patients and anaesthetists alike. This is difficult to explain on the basis of the pharmacokinetic and pharmacodynamic properties of local anaesthetics [5]; however, it may be equally difficult to attribute the symptoms to direct nerve injury. The use of lipid outside its licence would need to be discussed in detail with the patient, but perhaps a lipid infusion might also be helpful in these unusual circumstances?

References

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  2. References
  • 1
    Litz RJ, Popp M, Stehr SN, Koch T. Successful resuscitation of a patient with ropivacaine-induced asystole after axillary plexus block using lipid infusion. Anaesthesia 2006; 61: 8001.
  • 2
    Rosenblatt MA, Abel M, Fischer GW, Itzkovich CJ, Eisenkraft JB. Successful use of a 20% lipid emulsion to resuscitate a patient after a presumed bupivacaine-related cardiac arrest. Anesthesiology 2006; 105: 2178.
  • 3
    Weinberg GL, VadeBoncouer T, Ramaraju GA, Garcia-Amaro MF, Cwik MJ. Pretreatment or resuscitation with a lipid infusion shifts the dose–response to bupivacaine-induced asystole in rats. Anesthesiology 1998; 88: 10715.
  • 4
    Weinberg GL, Palmer JW, VadeBoncouer TR, Zuechner MB, Edelman G, Hoppel CL. Bupivacaine inhibits acylcarnitine exchange in cardiac mitochondria. Anesthesiology 2000; 92: 5238.
  • 5
    Sasada M, Smith S. Drugs in Anaesthesia and Intensive Care, 3rd edn. Oxford: Oxford University Press, 2003.