11/18/2023 0 Comments First lipid emulsion therapy usedWhen should I use lipid emulsion therapy?Īt this point in time, there is no FDA approved indication for lipid emulsion therapy in drug toxicity. Enhanced cardiac metabolism theory: In situations of myocardial depression due to drug toxicity, it is thought that myocardial contractility might be improved by providing extra substrate in the form of fatty acids.Partitioning or “lipid sink” theory: Partitioning is thought to work by providing a “sink” for which lipophilic xenobiotics can reside thus removing them from accessibility to end organ receptors.There are two prevailing theories that are most often quoted: (Image courtesy of James Heilman, MD via Creative Commons license). 4įigure 2: 100mL bag of 20% lipid emulsion. 4–6 Case reports continue to be published highlighting lipid emulsion therapy for an ever-expanding number of drug toxicities including non-dihydropyridine calcium channel clockers, beta blockers, bupropion, lamotrigine, and tricyclic antidepressants. Since then, several other case reports have emerged and clinical guidelines have been developed for lipid emulsion therapy in severe local anesthetic toxicity. Following this treatment, the patient was successfully electrically cardioverted. Shortly before cardiopulmonary bypass was to be performed, 100 mL of 20% lipid emulsion was given intravenously, followed by 0.5 mL/kg/hr for 2 hours. Shortly after injection the patient had a generalized tonic-clonic seizure followed by a 20-minute cardiac arrest with various cardiac dysrhythmias. In 2006, the first case report was published in which an adult male patient was inadvertently injected intravenously with 20 mL of 0.5% bupivacaine and 20 mL of 1.5% mepivacaine in the context of a brachial plexus block for rotator cuff repair. 2 This led to further studies involving dogs and eventually humans. 2 Its use in toxicology dates to the late 1990s when rat models demonstrated a survival benefit in bupivacaine toxicity. Intravenous lipid emulsion has been around for a long time in the form of total parenteral nutrition and as a vehicle for lipophilic drugs most notably propofol. At the same time, you begin to think ahead to what vasoactive agent you might give, whether you will need antiarrhythmic agents, and what the evidence suggests for intravenous lipid emulsion in drug overdose. 1You gain intravenous access, initiate continuous cardiac monitoring, and begin administering intravenous sodium bicarbonate boluses. Remember that while some times lipids seem to do miraculous things, they don’t always work.Ĥ) S ignificant clinical signs are present. Lipids were not designed to prevent signs they were designed to treat signs. There is no current evidence to show using them prior to signs developing that they will help and it is possible they may increase absorption of the toxin from the gut.Figure 1: 12 lead ECG showing characteristic changes related to tricyclic antidepressant toxicity. So under what circumstances do toxicologists at the ASPCA’s Animal Poison Control Center reach for lipids? We look for situations that fit these four criteria:ġ) The toxin is lipid soluble. Knowing that one of the suspected mechanisms of action is the lipid sink theory, this one is pretty obvious. Remember that lipid sink is not the only proposed mechanism for lipids the role lipids may play with cardiovascular effects is being researched as well.Ģ) The therapeutic interventions are NOT lipid soluble. Remember that lipid emulsion therapy is not selective: it can affect lipid soluble therapeutic medications along with the toxic exposure.ģ) You’ve tried everything else, and the patient's condition continues to decline. Coma, respiratory depression, intractable cardiac arrhythmias: These are the types of symptoms APCC uses lipids for-cases that have gone through all the standard treatments unsuccessfully. It has great potential, and when it works seems nearly miraculous.īut like all things in medicine, it does not always work like we want it to and side effects do occur. Knowing the basics about lipid therapy and when to use it will increase the chances it will be successful for you and your patient. Lipid emulsion therapy is a hot topic these days in both veterinary and human medicine.
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