Episode 90 – Low and Slow Poisoning

This is EM Cases Episode 90 - Low and Slow Poisoning. One of the things we need to think about whenever we see a patient who’s going low and slow with hypotension and bradycardia is an overdose. B-blockers, calcium channel blockers (CCB) and digoxin are some of the most frequently prescribed cardiovascular drugs. And inevitably we’re going to be faced with both intentional and unintentional overdoses from these drugs in the ED. On this EM Cases podcast the Medical Director of The Ontario Poison Control Centre and Emergency Physician at St. Michael's Hospital, Dr. Margaret Thompson, along with Dr. Emily Austin, Emergency Physician and Toxicologist at St. Michael's Hospital, help us to recognize these overdoses early and manage them appropriately. Written Summary and blog post written by Keerat Grewal & Anton Helman, edited by Anton Helman January, 2017 Cite this podcast as: Helman, A, Thompson, M, Austin, E. Low and Slow Poisoning. Emergency Medicine Cases. January, 2017. https://emergencymedicinecases.com/aortic-dissection-em-cases-course/. Accessed [date]. Differential Diagnosis of Low and Slow Non-toxicological causes: * MI with cardiogenic shock * Hyperkalemia * Myxedema coma * Spinal cord injury * Hypothermia Toxicological causes: * Calcium channel blockers * Beta-blockers * Digoxin * Opiates * Alpha-2 antagonists (e.g., clonidine) * Sodium channel blockers (e.g., TCA, carbamazepine, flexeril, antipsychotics, propranolol, cocaine) Management of Seizures in the Toxicology Patient There are several modifications of the usual algorithm for treating adult seizures when it comes to the poisoned patient. Avoid Sodium Channel Blockers Benzodiazepines are the first line treatment for treating seizures in patients with an overdose. In toxicological seizures, do not treat with antiepileptic drugs that have sodium channel blockade (i.e., phenytoin, fosphenytoin) because many poisons block sodium channels and additional sodium channel blockade may result in cardiac instability. If seizures persist, even after large doses of benzodiazepines, consider advancing to phenobarbital or propofol. Bicarbonate In patients with an overdose who are seizing and have evidence of sodium channel blockade (wide QRS on EKG), give sodium bicarbonate. Naloxone Consider naloxone in patients who may have an opioid overdose and are seizing. Some opioids can cause seizures (i.e., meperidine). Opioids may also cause hypoperfusion, which can lead to seizures. General Approach to the Management of Beta Blocker and Calcium Channel Blocker Overdoses A) Fluids Establish two IVs and give the patient a fluid bolus of normal saline (1-2 liters) to start. B) Decontamination Activated charcoal Consider decontamination with a dose of activated charcoal. The dose of activated charcoal is determined by the dose of the drug ingested in a 10:1 ratio of charcoal to drug. For example, a single 240mg tablet of Diltiazem requires only 2.4g of activated charcoal. Factors to consider in the decision to give activated charcoal: * Does the drug bind to charcoal? Charcoal does not bind lithium or iron, therefore, should not be given for overdoses of these drugs. * Was the drug ingested within one hour? For most drugs, activated charcoal is indicated within one hour of ingestion only. * Is the drug likely to stay in the stomach for a prolonged time (beyond the one hour post-ingestion)? Some drugs will stay in the stomach or upper intest...