Emergency Medical Minute

Contributor: Travis Barlock MD Educational Pearls: What is the ST segment? The ST segment on an ECG represents the interval between the end of ventricular depolarization (QRS) and the beginning of ventricular repolarization (T-wave).  It should appear isoelectric (flat) in a normal ECG. What if the ST segment is elevated? This is evidence that there is an injury that goes all the way through the muscular wall of the heart (transmural) This is very concerning for a heart attack (STEMI) but can be occasionally caused by other pathology, such as pericarditis What if the ST segment is depressed? This is evidence that only the innermost part of the muscular wall of the heart is becoming ischemic This has a much broader differential and includes a partial occlusion of a coronary artery but also any other stress on the body that could cause a supply-and-demand mismatch between the oxygen the coronaries can deliver and the oxygen the heart needs This is called subendocardial ischemia What else should you look for in the ECG to identify subendocardial ischemia? The ST-depressions should be at least 1 mm The ST depressions should be present in leads I, II, V4-6 and a variable number of additional leads. There is often reciprocal ST elevation in aVR > 1 mm The most important thing to remember when you see subendocardial ischemia is…history Still, keep all cardiac causes on your differential, such as unstable angina, stable angina, Prinzmetal angina, etc. Also consider a wide array of non-cardiac causes such as severe anemia, severe hypertension, pulmonary embolism, COPD, severe pneumonia, sepsis, shock, thyrotoxicosis, stimulant use, DKA, or any other state that lead to reduced oxygen supply to the subendocardium and/or increased myocardial oxygen demand. References Birnbaum, Y., Wilson, J. M., Fiol, M., de Luna, A. B., Eskola, M., & Nikus, K. (2014). ECG diagnosis and classification of acute coronary syndromes. Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc, 19(1), 4–14. https://doi.org/10.1111/anec.12130 Buttà, C., Zappia, L., Laterra, G., & Roberto, M. (2020). Diagnostic and prognostic role of electrocardiogram in acute myocarditis: A comprehensive review. Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc, 25(3), e12726. https://doi.org/10.1111/anec.12726 Cadogan, E. B. a. M. (2024, October 8). Myocardial Ischaemia. Life in the Fast Lane • LITFL. Retrieved December 7, 2024, from https://litfl.com/myocardial-ischaemia-ecg-library/#:~:text=ST%20depression%20due%20to%20subendocardial,left%20main%20coronary%20artery%20occlusion. Summarized by Jeffrey Olson, MS3 | Edited by Meg Joyce & Jorge Chalit, OMS3 Donate: https://emergencymedicalminute.org/donate/  

Contributor: Alec Coston MD Educational Pearls: Causes of seizures in a fairly well-appearing child with diarrhea: Electrolyte abnormalities: hypocalcemia, hyponatremia Also hyperkalemia which causes arrhythmias and syncope - can appear like seizures Hypoglycemia If the child has diarrhea and appears very sick, differential diagnosis may include: Hemolytic uremic syndrome (HUS): simultaneous occurrence of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury Typically caused by Shiga-like toxin producing Escherichia coli (also known as EHEC, or enterohemorragic E. coli) One of the main causes of acute kidney injury in children Toxic ingestions such as salicylates, lead, or iron In this case, the child had a seizure but appeared well and was afebrile: Consult with neurology led to a diagnosis of benign convulsions with mild gastroenteritis (CwG) First identified in 1982 in Japan Viral gastroenteritis with diarrhea and convulsions but does not include fever, severe dehydration, or electrolyte abnormalities Uncommon illness caused by rotavirus and norovirus pathogens Criteria for discharge is similar to a febrile seizure - the patient had one seizure that lasted less than 15 minutes and he quickly returned to his baseline, so he was able to be safely discharged home This diagnosis does not predispose him to epilepsy later in life References Lee YS, Lee GH, Kwon YS. Update on benign convulsions with mild gastroenteritis. Clin Exp Pediatr. 2022 Oct;65(10):469-475. doi: 10.3345/cep.2021.00997. Epub 2021 Dec 27. PMID: 34961297; PMCID: PMC9561189. Mauritz M, Hirsch LJ, Camfield P, et al. Acute symptomatic seizures: an educational, evidence-based review. Epileptic Disorders. 2200;1(1). doi:https://doi.org/10.1684/epd.2021.1376 ‌Noris, Marina*; Remuzzi, Giuseppe*, †. Hemolytic Uremic Syndrome. Journal of the American Society of Nephrology 16(4):p 1035-1050, April 2005. | DOI: 10.1681/ASN.2004100861    Summarized by Meg Joyce, MS1 | Edited by Meg Joyce & Jorge Chalit, OMS3 Donate: https://emergencymedicalminute.org/donate/  

Contributor: Aaron Lessen MD Educational Pearls: Induction agent selection during rapid sequence intubation involves accounting for hemodynamic stability in the post-intubation setting Many emergency departments use ketamine or etomidate A recent study sought to explore the rates of post-induction hypotension of ketamine compared with propofol Single center retrospective cohort study of patients between 2018-2021 Ketamine and propofol were both significantly associated with post-induction hypotension Ketamine adjusted odds ratio = 4.50 Propofol adjusted odds ratio = 4.88 50% of patients became hypotensive after induction with either propofol or ketamine These findings suggest post-induction hypotension is mainly due to sympatholysis rather than the choice of agent itself References Tamsett Z, Douglas N, King C, et al. Does the choice of induction agent in rapid sequence intubation in the emergency department influence the incidence of post-induction hypotension?. Emerg Med Australas. 2024;36(3):340-347. doi:10.1111/1742-6723.14355 Summarized & Edited by Jorge Chalit, OMS3 Donate: https://emergencymedicalminute.org/donate/  

Contributor: Aaron Lessen MD Educational Pearls: Can opioids cause cardiac arrest? Opioids can cause respiratory suppression and the subsequent low oxygen levels can lead to arrhythmias and eventually cardiac arrest. In 2023, 17% of out-of-hospital cardiac arrests (OHCA) were attributable to opioids. Given that this is a rising cause of cardiac arrest, should we just treat all cardiac arrest with naloxone (Narcan)? Naloxone is correlated with an increased chance of return of spontaneous circulation (ROSC) Additionally, a wide variety of individuals can be exposed to opioids and therefore opioid overdose should be considered in all cases of OHCA But does naloxone improve neurologic outcomes? Yes, naloxone, especially when given early on in the resuscitation can improve neuro outcomes What is the dose? 2-4 mg IN/IV depending on access. High suspicion for opioid overdose consider going with an even higher dose such as 4-8 mg IN/IV References Orkin, A. M., & Dezfulian, C. (2024). Recognizing the fastest growing cause of out-of-hospital cardiac arrest. Resuscitation, 198, 110206. https://doi.org/10.1016/j.resuscitation.2024.110206 Quinn, E., & Du Pont, D. (2024). Naloxone administration in out-of-hospital cardiac arrest: What's next?. Resuscitation, 201, 110307. https://doi.org/10.1016/j.resuscitation.2024.110307 Saybolt, M. D., Alter, S. M., Dos Santos, F., Calello, D. P., Rynn, K. O., Nelson, D. A., & Merlin, M. A. (2010). Naloxone in cardiac arrest with suspected opioid overdoses. Resuscitation, 81(1), 42–46. https://doi.org/10.1016/j.resuscitation.2009.09.016 Wampler D. A. (2024). Naloxone in Out-of-Hospital Cardiac Arrest-More Than Just Opioid Reversal. JAMA network open, 7(8), e2429131. https://doi.org/10.1001/jamanetworkopen.2024.29131 Summarized by Jeffrey Olson, MS3 | Edited by Meg Joyce MS1 & Jorge Chalit, OMS3 Donate: https://emergencymedicalminute.org/donate/