Podcast 994: Biphasic Anaphylaxis
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: What is anaphylaxis and what are its treatments? Anaphylaxis is a broad term for potentially life threatening allergic reactions that can progress to cardiovascular collapse (anaphylactic shock). It is triggered by IgE and antigen cross-linking on mast cells to induce degranulation and the release of histamines, which can cause diffuse vasodilation and respiratory involvement with end-organ hypoperfusion. First line treatment is the immediate administration of epinephrine at 0.01 mg/kg (max dose for pediatrics is 0.3 mg and for...
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Podcast 993: Personalized Gene Editing Therapy
Emergency Medical Minute
Contributor: Alec Coston, MD Educational Pearls: Disclaimer: this has nothing to do with the ER but is too cool to not talk about. Condition: Carbamoyl phosphate synthetase 1 (CPS1) deficiency Rare inborn error of metabolism Inability to properly break down ammonia Leads to severe hyperammonemia and hepatic encephalopathy Natural history: Without treatment, typically fatal within the first few weeks of life Even with current standard treatments, life expectancy is often limited to ~5–6 years Breakthrough treatment: A team of researchers at the Children’s Hospital of...
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Tox Talks 2025 Recap 2, Methemoglobinemia and Errors
Emergency Medical Minute
Contributors: Travis Barlock MD, Ian Gillman PA, Jacob Altholz MD, Jeffrey Olson MS4 In this episode, EM attending Travis Barlock and medical student Jeffrey Olson listen in to the two remaining cases presented from EMM’s recent event, Tox Talk 2025. Talk 1- Methemoglobinemia- Ian Gillman Cyanosis + chocolate-colored blood + normal PaO₂ + pulse ox stuck at ~85% = Methemoglobinemia → Treat with methylene blue The medications that can cause it can be remembered with… Watch out with methylene blue as it can cause serotonin syndrome While treating with methylene blue the...
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Podcast 992: Fentanyl for Asthma
Emergency Medical Minute
Contributor: Alec Coston, MD Educational Pearls: BiPAP is often effective in severe asthma, but many patients struggle with mask tolerance due to intense air hunger–driven anxiety, often compounded by hypoxia. Benzodiazepines are commonly used for anxiety, but they can depress respiratory drive, making clinical improvement difficult to interpret (a lower RR may reflect sedation rather than true physiologic improvement). Low-dose fentanyl is a useful alternative when patients cannot tolerate BiPAP despite coaching. Opioids blunt the perception of dyspnea and are well established for...
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Episode 991: BRASH
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls BRASH Syndrome: Bradycardia Renal Failure AV Nodal Blockade Shock Hyperkalemia Clinical Features: Profound bradycardia and shock in patients on AV nodal blockers: Commonly, Beta Blockers or Calcium Channel Blockers Etiology: Caused by an inciting kidney injury: Common triggers include precipitating illness, dehydration, or medications Results in hyperkalemia The enhanced effect of the combination of AV nodal blockade and hyperkalemia leads to a more profound presentation of shock. ...
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Episode 990: Tramadol, or rather, Trama-don’t
Emergency Medical Minute
Contributor: Taylor Lynch, MD Educational Pearls: What is tramadol and how does it work? Tramadol is a Schedule IV opioid analgesic used for moderate pain and is often perceived as safer than other opioids due to lower abuse potential. It is a prodrug with weak direct μ-opioid receptor activity. The parent compound also inhibits serotonin and norepinephrine reuptake, giving it SSRI/SNRI-like properties. Tramadol is metabolized by CYP2D6 into O-desmethyltramadol (ODT), which has significantly stronger μ-opioid receptor agonism than the parent drug. What are the concerns with...
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Episode 989: Young Strokes
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: The Case 24F brought in for anxiety. Patient is tearful, not talking, and potentially hyperventilating. History from boyfriend is that she suddenly stopped talking and started crying and it was hard to understand what she was saying. On exam, patient appears anxious and has a gaze preference for the right side and is still having difficulty speaking. Decision is made to stroke alert patient. CT shows early MCA stroke and M2 occlusion. Patient is treated by IR with mechanical thrombectomy. What are the risk factors for strokes in young...
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Episode 988: Infant Botulism
Emergency Medical Minute
Contributor: Aaron Lessen, MD Educational Pearls: A 2025 multistate outbreak of infant botulism has been linked to ByHeart infant formula As of December 10-17th, there have been at least 51 infants with suspected or confirmed botulism who were exposed to this formula across 19 states All reported cases resulted in hospitalization but no deaths reported to date Infant botulism Occurs when C. botulinum spores germinate in the infant’s intestine, producing toxin Spores are classically found in honey but can also be in dirt or contaminated in infant formula Infants are...
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Carepoint Journal Club: Trauma Discussion
Emergency Medical Minute
Carepoint Journal Club is a quarterly series with discussions about a medical topic, brought to you by Carepoint's Emergency Physicians.
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Episode 987: Cough Suppressants
Emergency Medical Minute
Contributor: Meghan Hurley, MD Educational Pearls: OTC Medications Dextromethorphan (DM) Most common OTC cough suppressant Minimal efficacy: Little evidence that it shortens the duration or severity of cough. Potential side effects: At recommended doses: Mild dizziness, drowsiness, GI symptoms Higher doses: Decreased consciousness, dissociative effects Guaifenesin Found in Mucinex and other severe cough/cold products Thins secretions and loosens mucus in airways No more effective than increasing oral fluid intake Prescription Medications Codeine-containing products ...
info_outlineContributor: Aaron Lessen, MD
Educational Pearls:
What is anaphylaxis and what are its treatments?
- Anaphylaxis is a broad term for potentially life threatening allergic reactions that can progress to cardiovascular collapse (anaphylactic shock).
- It is triggered by IgE and antigen cross-linking on mast cells to induce degranulation and the release of histamines, which can cause diffuse vasodilation and respiratory involvement with end-organ hypoperfusion.
- First line treatment is the immediate administration of epinephrine at 0.01 mg/kg (max dose for pediatrics is 0.3 mg and for adults is 0.5 mg) as well as removal of the offending agent causing the reaction.
- Additional pharmacologic treatments such as anti-histamines and steroids should be considered but not used instead of epinephrine when anaphylactic shock is evident as the sole therapy.
What is biphasic anaphylaxis and what is its occurrence?
- Biphasic anaphylaxis is the return of anaphylactic symptoms after the initial anaphylactic event. Previous studies have reported an incidence ranging from 1-20% of patients having an initial anaphylactic reaction having biphasic anaphylaxis, at a range of time from 1-72 hours.
- The mechanism of biphasic anaphylaxis is not completely known, but can be contributed to by initial interventions wearing off (and why patients will be monitored for 2-4 hours after initial symptoms and treatment), or delayed immune mediators beginning to take effect.
- Recent studies show that the rate of biphasic anaphylaxis may be closer to 16% occurrence with a median time of occurrence being around 10 hours.
What is the key take away and patient education on biphasic anaphylaxis?
- After patients have been observed for the initial 2-4 hours in the emergency room, they are generally safe to go home.
- Patients should be informed of the need to carry an Epi-Pen for similar anaphylactic reactions, and informed that there is a chance within the next day (10-20 hours) that they may have the symptoms occur once again.
- The biphasic reaction may be more mild, and patients should be educated on how to treat it and to seek immediate emergency care if the symptoms do not improve.
References
- Golden DBK, Wang J, Waserman S, et al. Anaphylaxis: A 2023 practice parameter update. Annals of Allergy, Asthma & Immunology. 2024;132(2):124-176. doi:10.1016/j.anai.2023.09.015
- Rubin S, Drowos J, Hennekens CH. Anaphylaxis: Guidelines From the Joint Task Force on Allergy-Immunology Practice Parameters. afp. 2024;110(5):544-546.
- Weller KN, Hsieh FH. Anaphylaxis: Highlights from the practice parameter update. CCJM. 2022;89(2):106-111. doi:10.3949/ccjm.89a.21076
- Gupta RS, Sehgal S, Brown DA, et al. Characterizing Biphasic Food-Related Allergic Reactions Through a US Food Allergy Patient Registry. The Journal of Allergy and Clinical Immunology: In Practice. 2021;9(10):3717-3727. doi:10.1016/j.jaip.2021.05.009
Summarized by Dan Orbidan OMS2 | Edited by Dan Orbidan & Jorge Chalit OMS4
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