Of Hyperthermia, Rodenticides, and Ibogaine Toxicity

Summary

The TACO Technique for treating drug-induced hyperthermia is not yet ready for emergency department use, despite its potential effectiveness in other heat-related conditions. It involves using a tarp with water and ice to cool patients but requires significant resources and may not be suitable for those with co-morbidities. In cases of accidental exposure to superwarfarin in toddlers, routine vitamin K1 administration is unnecessary and could complicate follow-up. Additionally, ibogaine toxicity should be considered in patients with chaotic cardiac dysrhythmias, particularly those with opioid use history.

Study at a glance

Abstract

The 2024 North American Conference of Clinical Toxicology and the annual American College of Emergency Physicians Scientific Assembly yielded several thought-provoking ideas for emergency physicians, some that you should be employing and another, like this first one, that is not ready for the big time in the ED. Should the TACO Technique be Used to Treat Drug-induced Hyperthermia in the Emergency Department? Craig Smolin, MD, from University of California, San Francisco, noted in his talk, “The Crashing Toxicology Patient,” at the ACEP Scientific Assembly that drug-induced hyperthermia should be viewed as the STEMI of toxicology because timely and effective intervention is crucial to maximizing the chance of a good outcome. A core body temperature greater than 105.5°F can rapidly cause multiorgan cellular damage and permanent central nervous system dysfunction. The therapeutic goal—aside from initiating cardiopulmonary resuscitation if indicated—should be to get the core temperature down to between 102.2°F and 101°F within 30 minutes of collapse or treatment initiation. Careful monitoring of rectal temperature is essential in these cases because overshooting the mark can cause clinically significant hypothermia. The gold standard for cooling severely hyperthermic patients is immersion in an ice water bath, which can lower the core temperature at a rate of 0.3°F to 0.6°F per minute. Unfortunately, many emergency departments do not have the equipment to carry out this technique. Commonly used alternatives such as misting and fanning or applying ice packs to the axillae and groin may not reduce core temperature rapidly enough to prevent irreversible damage. Dr. Smolin suggested that a more effective alternative could be tarp-associated cooling with oscillation (TACO.) This relatively new technique involves placing the patient on a tarp or waterproof sheet, having at least three assistants hold the tarp so that the patient is in a semi-recumbent position, adding about 20 gallons of water and 10 gallons of ice, and moving the tarp so that all parts of the lower body and torso come into contact with the ice water. The procedure can be viewed in a brief video on YouTube (https://tinyurl.com/mujdmdwm). A recent study demonstrated under laboratory conditions that TACO can lower core temperature at a rate of approximately 0.3°F per minute. (Ann Emerg Med. 2017;69[3]:347.) I'd argue, however, that TACO is not yet ready for prime time for treating drug-induced hyperthermia. It has been studied and used only in exercise-induced or environmental heat stroke, where it has shown promise as a field intervention to treat military personnel, wilderness firefighters, and runners in marathons and other endurance athletic events. Hyperthermic patients in these situations tend to be otherwise healthy with good cardiorespiratory reserve. This is not at all the same patient population that can present with drug-induced hyperthermia from, say, serotonin syndrome. These patients are more likely to have co-morbidities with impaired circulation as well as continued excessive heat production from drug effects or interactions. I foresee many factors that could mitigate against generalizing use of the TACO technique in the emergency department. For one thing, it is resource intensive, requiring at least three team members—and probably several more—to lift and oscillate the tarp. Monitoring the patient would be difficult because ECG leads may not reliably attach to a wet body. In cases of ventricular fibrillation cardiac arrests, the skin of the torso would have to be dried thoroughly before defibrillation could be administered safely. The available evidence for using this technique in the emergency department is at least one TACO short of a combination plate at this time. Do Not Administer Vitamin K1 Routinely to Asymptomatic Toddlers After Possible Exploratory Exposure to Superwarfarin Rodenticides. Our poison control center is often consulted about rodenticides. Let's say a 3-year-old is brought in after being found playing with an open package of a superwarfarin long-acting anticoagulant rodenticide (LAAR). The parents think they may have seen traces of the product in the child's mouth. There is no evidence of bleeding, the physical exam is unremarkable, and coagulation studies (prothrombin time and INR) are normal. What is your next step? A. Give prophylactic vitamin K1 and send the child home. B. Give prophylactic vitamin K1 and admit to hospital for continued observation. C. Give four-factor prothrombin complex concentrate or fresh frozen plasma and admit. D. Send the child home and arrange for repeat laboratory testing in 48 hours. The answer is D: Do not give prophylactic vitamin K, discharge the child, and repeat coagulation studies in two days. Sean Nordt, MD, from Loma Linda University Medical Center, in a talk on pediatric ingestions, made the important point that prophylactic treatment with vitamin K1 is contraindicated in a possible inadvertent exploratory exposure to a long-acting anticoagulant rodenticide in an otherwise normal toddler. There are several reasons for this. The risk of a bad outcome in this situation is slim to none. Hundreds of similar cases have been reported to regional poison centers over the years, but to my knowledge there has never been a report of clinically significant coagulopathy or bleeding. Even after ingestion of a significant amount of LAAR, depletion of vitamin K-dependent coagulation factors occurs gradually and can last for months. An initial dose of vitamin K1 will provide no benefit and will not impede this progression. The most important reason, however, is that managing these inadvertent pediatric exposures typically involves rechecking PT/INR 48 hours after presentation. A normal coagulation profile at that time rules out significant exposure. Empiric administration of “prophylactic” vitamin K1 can delay onset of laboratory coagulopathy and complicate follow-up. Just don't do it. Consider Ibogaine Toxicity in the Differential Diagnosis of Chaotic Cardiac Dysrhythmias. Last year, I discussed ibogaine, a psychoactive alkaloid that can be purchased over the internet and is sometimes used by patients using opioids to kick the habit and alleviate withdrawal symptoms. (EMN. 2024;46[6]:5; https://tinyurl.com/4wtbhyx8.) I noted that ibogaine can cause bradycardia as well as polymorphic ventricular tachycardia (torsades de pointes) induced by QTc prolongation. In fact, bradycardia will increase the risk of torsades in the setting of a prolonged QTc. (Indian Pacing Electrophysiol J. 2010;10[10]:435; https://tinyurl.com/44h732jm.) These dysrhythmias can be persistent and long-lasting because noribogaine, an active metabolite, has a half-life of 24-48 hours. This striking and dangerous effect of ibogaine on the heart was vividly illustrated in a presentation at the 2024 NACCT conference. A young man with a history of opioid addiction presented with several days of life-threatening torsades alternating with episodes of bradycardia. No clarifying history was available. The case discussant correctly determined that the cause was ibogaine overdose. The key point for emergency physicians and toxicologists: When you see a patient with chaotic dysrhythmias, both tachycardia and bradycardia, without an obvious cause, think ibogaine, especially if the patient is a known or suspected opioid user. DR. GUSSOW is a voluntary attending physician at the John H. Stroger Hospital of Cook County in Chicago, an assistant professor of emergency medicine at Rush Medical College, a consultant to the Illinois Poison Center, and a lecturer in emergency medicine at the University of Illinois Medical Center in Chicago. Follow him on Bluesky at poisonreview.bsky.social, and read his past columns at http://tinyurl.com/EMN-Gussow.

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