Authors: Martyn Harvey, M.D., F.A.C.E.M. et al
Commentary: Effect of Intralipid® on the Dose of Ropivacaine or Levobupivacaine Tolerated by Volunteers: A Clinical and Pharmacokinetic Study
Anesthesiology 9 2016, Vol.125, 451-453.
LORD Cyril Asquith, son of a British Prime Minister, and himself an English Law Lord, once remarked “A Judge of the first instance should be brief, courteous, and wrong. This is not to imply that the Judge of Appeal should be long-winded, rude and right, for this is a privilege confined to the House of Lords.” Such sentiment appears apt when weighing our evolving understanding of the antidotal mechanism of lipid emulsions. Initial thinking attributed recovery from cardiotoxicity to sequestration of lipophilic local anesthetics into a newly created intravascular lipid phase—arise the “lipid sink.” This theory was altogether brief, courteous in its inherent simplicity, and if not entirely wrong, then at very least only a partial truth. No “truth” can ever be thought robust until the passage of time has presented new data that it must attempt to explain. And with the passing of time, and the diligent work of a number of investigative groups, our comprehension of the pharmacokinetic and pharmacodynamic sequelae of infusing a concentrated triglyceride microemulsion in local anesthetic systemic toxicity (LAST) has become clearer. The underlying mechanism(s) of lipid emulsions have been demonstrated as “long-winded,” in that they are multiple and multimodal. Rude, for their inherent complexity has required complicated modeling techniques to decipher. Ultimately, however, they are far more right than our original musings.