by Dr. Sam Stellpflug MD
You’re headed to Hospital Medicine 2014 in Las Vegas in ten days, and that means you are dedicated to making yourself a well rounded and state of the art Hospitalist. As a provider that takes pride in staying up-to-date and knowledgeable, how do you feel about being told that some of what you’re doing is wrong and potentially wasteful and dangerous? Does it make it any tougher to swallow if that information is coming from an ER doc? That’s what’s going to be happening from 11:45-12:25 on Wednesday, March 26th, in Mandalay Bay E.
I’m going to be drawing on my experience as both an Emergency Medicine Physician and a Medical Toxicologist to walk through a number of important issues in the realm of poisoned patients. Some of the topics I’ll touch on will simply reinforce your practices in working through the differential diagnosis of the tox patient. Some of the issues I’ll bring up will directly challenge your current practice patterns. I’ll offer some anecdote, some theory, and hopefully plenty of evidence.
I will be covering a number of tests and common poisons, but just a few here to give you a sample. Two tests frequently ordered by hospitalists are the urine tox screen and the ECG. Hospitalists also frequently need to test patients for methanol or ethylene glycol ingestion, so I will touch on that, too. Here is just a bit of what we’ll be discussing and some things to think about:
Hospitalists likely order the urine tox screen immunoassay screen for patients that have overdosed. If you order it because you think it will impact your short-term management, you’re likely being misled as often as you’re being helped. You probably would be better off flipping a coin than wasting your resources on this test because the urine tox screen immunoassay is one of the least accurate consistently ordered tests. I’ll talk you through why this test should go by the wayside, and also instances where it could be outright bad practice. Here’s an article to help you as you consider these points leading up to HM14.
Hospitalists also commonly order ECGs on patients that have overdosed. It is taught that normal QRS might be up to about 120ms, but toxicology convention is to treat the QRS if it’s 100ms or above. When the QRS is long, there is likely a sodium channel blocking agent on board. Give sodium bicarbonate, 100 meq bolus, and then recheck the ECG to see if the QRS narrows. I will review how to make an isotonic sodium bicarbonate infusion bag to chase the boluses, which is critical. Now look at the QTc. Is it longer than the upper normal of 450ish ms? Is it longer than the 500ms where we usually treat? You want to look at the QTc because of the possibility of potassium channel-blockade. Give magnesium and potentially potassium.
Finally, how do you diagnose an ingestion of methanol or ethylene glycol? If you’re using the serum osm gap to rule out toxic alcohol ingestions, you’re going to get burned; I’ll tell you why. Everything you think you know about a serum osm gap is probably leading you to dangerous conclusions. There isn’t a true normal osm gap that would allow you to rule out an exposure. Check out this article from the Journal of Toxicology – Clinical Toxicology; it’s a nice study, but even more importantly it provides good commentary. Note that the article is from the early 90s, which means we’ve known the dogma regarding using the osm gap to rule out toxic alcohol ingestion has been wrong for 20 years.
Please join me on the 26th at HM14 to learn more about these three tox points and more. Hopefully you’re ready to have some of your paradigms reinforced and some of them shifted.
Dr. Samuel J. Stellpflug MD primarily practices, teaches, and learns as a faculty physician within the Regions Hospital Department of Emergency Medicine in St. Paul, MN. He is the Director of the Regions Hospital Clinical Toxicology Service and also Program Director of the Twin Cities Medical Toxicology Fellowship. He serves as a consultant for the Hennepin Regional Poison Center and has an academic appointment as Assistant Professor of Emergency Medicine at the University of Minnesota Medical School.
After finishing medical school at the University of Wisconsin he completed residency in emergency medicine at Regions Hospital followed by the medical toxicology fellowship in the Twin Cities, a joint effort between Regions Hospital and the Hennepin Regional Poison Center. He maintains active clinical practice and research in both EM and Tox. Sam’s main research interest is poison-induced cardiogenic shock, among other things.