LipidRescue™ Resuscitation

Hi Konstantin,
Thanks for this extremely interesting case and giving me another chance to get on the 'genetic disorder' soap box. Believe it or not, in a previous life I was a medical geneticist, and still carry the card.

You did all the right things and the patient recovered without a problem. It is clear that the majority of cases of local anesthetic toxicity are NOT the result of anesthesiologists' mistakes: they usually occur after incremental injections and frequent, negative aspirations of an acceptable total local anesthetic dose. This leads me to believe that some patients are more susceptible than the general population. A susceptible population would apparently include those with ischemic heart disease or conduction defects - this statement is based on the many patients described in case reports of lipid rescue who have bundle branch block, and/or angina or past MI.

Interestingly, the index patient for all of my studies of local anesthetic toxicity was a patient with isovaleric acidemia who also had severe carnitine deficiency. She became toxic after a SQ injection of 22mg bupivacaine (she weighed ~ 80kg). The point to make here is that mitochondrial myopathies and local anesthetics don't mix and these patients comprise another subgroup that may exhibit sensitivity to local anesthetics. Also note that Dr. Morgan et al have shown that many such patients also exhibit lower-than-normal MAC values, suggesting the sensitivity extends to volatiles.....but that's another subject.

Can you tell where I'm going with this? Sheldon-Freeman syndrome (see the OMIM link: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=193700) is an extremely heterogeneous muscle disorder and wiht the exeption of a few pedigrees (myosin heavy chain) the precise mutations are not well worked out. So, forgive the hindsight, but I would recommend generally coming down inon the dose of local anesthetic for myopathic patients or those with possible mitochondrial disease.A catheter technique using lidocaine or mepivacaine would probably also be preferred to ropiv or bupiv in such patients.

See what I mean about soap-box? Thanks for posting this very neat case. I'm very glad it all worked out well.
Guy

Great question, Gary. Overall, I think the most important piece in that patient is airway management. Avoiding any hypoxia or acidosis. I believe is your best chance to prevent progression to cardiovascular collapse. Assuming you do this, the next question is how best to suppress seizures and I think benzodiazepine is the best choice because it is not a direct cardiac depressant. Now, what about propofol. The amount of lipid in propofol is NOT enough to prevent cardiovascular collapse, so if you want to use propofol, the only advantage would be that it is readily available. Pentothal or propofol MIGHT be ok in small doses to suppress seizures, but I do not encourage this use. Finally, the other question: Is it reasonablet to use lipidrescue early in the toxic syndrome to supress seizures and prevent cardiac arrest. There will soon be some case reports in the literature to support early use of lipid to reverse CNS symptoms and I also support this. because of cases I've heard of, for instance, that of Andrew Spence posted on this site under "post your cases" and i recommend you check it out.
Best of luck to you, thanks for the excellent question.
guy