Episode 953: Penicillin Allergies
Emergency Medical Minute
Contributor: Geoff Hogan MD Educational Pearls: Penicillin allergies are relatively uncommon despite their frequent reports 10% of the population reports a penicillin allergy but only 5% of these cases are clinically significant 90-95% of patients may tolerate a rechallenge after appropriate allergy evaluation Penicillin Allergy Decision Rule (PEN-FAST) on MD Calc Useful tool to assess patients for penicillin allergies Five years or less since reaction = 2 points (even if unknown) Anaphylaxis or angioedema OR Severe cutaneous reaction = 2 points Treatment required for...
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Episode 952: Heart Transplants
Emergency Medical Minute
Contributor: Travis Barlock, MD Educational Pearls: Key clinical considerations when managing heart transplant patients due to their unique pathophysiology 1. Arrhythmias A transplanted heart is denervated, meaning it lacks autonomic nervous system innervation The lack of vagal tone results in an increased resting heart rate Adenosine can be used since it primarily slows conduction through the AV node Atropine is ineffective in treating transplant bradyarrhythmia because its mechanism is to inhibit the vagus nerve - but the heart lacks vagal tone Allograft rejection can...
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Episode 951: Pediatric Febrile Seizures
Emergency Medical Minute
Contributor: Taylor Lynch, MD Educational Pearls: Pediatric febrile seizures are defined as seizures that occur between the ages of six months to five years in the presence of a fever greater than or equal to 38.0 ºC (100.4 ºF). It is the most common pediatric convulsive disorder, with an incidence between 2-5% What are the types of seizures? Simple: Tonic-clonic seizure, duration <15 minutes, only one occurrence in a 24-hour period, ABSENCE of focal features, ABSENCE of Todd’s paralysis Complex: Duration >15 minutes, requires medication to stop the seizing, multiple...
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Episode 950: Ultrasound Pulse Check During Cardiac Arrest
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: Point-of-care ultrasound (POCUS) is used to assess cardiac activity during cardiac arrest and can identify potential reversible causes such as pericardial tamponade Ultrasound could be beneficial in another way during cardiac arrest as well: pulse checks Manual palpation for detecting pulses is imperfect, with false positives and negatives Doppler ultrasound can be used as an adjunct or replacement to manual palpation for improved accuracy Options for Doppler ultrasound of carotid or femoral pulses during cardiac arrest: ...
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Episode 949: Hoover's Sign
Emergency Medical Minute
Contributor: Travis Barlock, MD Educational Pearls: What is Hoover’s sign used to identify? This physical exam maneuver differentiates between organic vs. functional (previously known as psychogenic) leg weakness. Organic causes include disease processes such as stroke, MS, spinal cord compression, guillain-barre, ALS, and sciatica, among others In Functional Neurologic Disorder, the dysfunction is in brain signaling, and treatment relies on more of a psychiatric approach How is Hoover's Sign performed? Place your hand under the heel of the unaffected leg and ask the patient to...
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Episode 948: CYP Inducers and Inhibitors
Emergency Medical Minute
Contributor: Jorge Chalit-Hernandez, OMS3 Educational Pearls: CYP enzymes are responsible for the metabolism of many medications, drugs, and other substances CYP3A4 is responsible for the majority Other common ones include CYP2D6 (antidepressants), CYP2E1 (alcohol), and CYP1A2 (cigarettes) CYP inducers lead to reduced concentrations of a particular medication CYP inhibitors effectively increase concentrations of certain medications in the body Examples of CYP inducers Phenobarbital Rifampin Cigarettes St. John’s Wort Examples of CYP inhibitors -azole...
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Episode 947: Hypercapnia
Emergency Medical Minute
Educational Pearls: Physiologic stimulation of ventilation occurs through changes in levels of: Arterial carbon dioxide (PaCO2) Arterial oxygen (PaO2) Hypercapnia is an elevated level of CO2 in the blood - this primarily drives ventilation Hypoxia is a decreased level of O2 in the body’s tissues - the backup drive for ventilation Patients at risk of hypercapnia should maintain an O2 saturation between 88-92% Normal O2 saturation is 95-100% In patients who chronically retain CO2, their main drive for ventilation becomes hypoxia An audit was performed of SpO2 observations...
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Episode 946: Time to Defibrillation
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: Quick background info Cardiac arrest is when the heart stops pumping blood for any reason. This is different from a heart attack in which the heart is still working but the muscle itself is starting to die. One cause of cardiac arrest is when the electrical signals are very disrupted in the heart and start following chaotic patterns such as Ventricular tachycardia (VTach) and Ventricular fibrillation (VFib) One of the only ways to save a person whose heart is in VFib or VTach is to jolt the heart with electricity and terminate the...
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Episode 945: Ketorolac vs. Ibuprofen
Emergency Medical Minute
Contributor: Ricky Dhaliwal, MD Educational Pearls: Ketorolac and ibuprofen are NSAIDs with equivalent efficacy for pain in the emergency department Oral ibuprofen provides the same relief as intramuscular ketorolac IM ketorolac is associated with the adverse effect of a painful injection IM ketorolac is slightly faster in onset but not significant Studies have assessed the two medications in head-to-head randomized-controlled trials and found no significant difference in pain scores IM ketorolac takes longer to administer and has a higher cost Ketorolac dosing ...
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Episode 944: Colchicine Overdose
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: Colchicine is most commonly used for the prevention and treatment of gout There is research investigating the anti-inflammatory and cardioprotective effects of colchicine This drug has a narrow therapeutic index: a small margin between effective dose and toxic dose Colchicine overdoses can be unintentional or intentional and are associated with poor outcomes Phase 1: 10 - 24 hours after ingestion Patient looks well but may have mild symptoms mimicking gastroenteritis Phase 2: 24 hours - 7 days after ingestion ...
info_outlineContributor: Jorge Chalit-Hernandez, OMS3
Educational Pearls:
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Serotonin syndrome occurs most commonly due to the combination of monoamine oxidase inhibition with concomitant serotonergic medications like SSRIs
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Examples of unexpected monoamine oxidase inhibitors
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Linezolid - a last-line antibiotic reserved for patients with true anaphylaxis to penicillins and cephalosporins
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Methylene blue - not mentioned in the podcast due to its uncommon usage for methemoglobinemia
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Other medications that can interact with SSRIs to cause serotonin syndrome
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Dextromethorphan - primarily an anti-tussive at sigma opioid receptors that also has serotonin reuptake inhibition
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Clinical presentation of serotonin syndrome
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Altered mental status
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Autonomic dysregulation leading to hypertension (most common), hypotension, and tachycardia
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Hyperthermia
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Neuromuscular hyperactivity - tremors, myoclonus, and hyperreflexia
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Hunter Criteria (high sensitivity and specificity for serotonin syndrome):
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Spontaneous clonus
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Inducible clonus + agitation or diaphoresis
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Ocular clonus + agitation or diaphoresis
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Tremor + hyperreflexia
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Hypertonia, temperature > 38º C, and ocular or inducible clonus
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Management of serotonin syndrome
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Primarily supportive - benzodiazepines can help treat hypertension, agitation, and hyperthermia. Patients often require repeated and higher dosing of benzodiazepines
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Avoid antipyretics to treat hyperthermia since the elevated temperature is due to sustained muscle contraction and not central temperature dysregulation
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In refractory patients, cyproheptadine (a 5HT2 antagonist) may be used as a second-line treatment
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Patients with temperatures > 41.1º C or 106º F require medically induced paralysis and intubation to control their temperature
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References
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Boyer EW, Shannon M. The serotonin syndrome [published correction appears in N Engl J Med. 2007 Jun 7;356(23):2437] [published correction appears in N Engl J Med. 2009 Oct 22;361(17):1714]. N Engl J Med. 2005;352(11):1112-1120. doi:10.1056/NEJMra041867
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Dunkley EJ, Isbister GK, Sibbritt D, Dawson AH, Whyte IM. The Hunter Serotonin Toxicity Criteria: simple and accurate diagnostic decision rules for serotonin toxicity. QJM. 2003;96(9):635-642. doi:10.1093/qjmed/hcg109
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Ramsay RR, Dunford C, Gillman PK. Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. Br J Pharmacol. 2007;152(6):946-951. doi:10.1038/sj.bjp.0707430
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Schwartz AR, Pizon AF, Brooks DE. Dextromethorphan-induced serotonin syndrome. Clin Toxicol (Phila). 2008;46(8):771-773. doi:10.1080/15563650701668625
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Thomas CR, Rosenberg M, Blythe V, Meyer WJ 3rd. Serotonin syndrome and linezolid. J Am Acad Child Adolesc Psychiatry. 2004;43(7):790. doi:10.1097/01.chi.0000128830.13997.aa
Summarized & Edited by Jorge Chalit, OMS3