Emergency Medical Minute

Contributor: Travis Barlock, MD
Educational Pearls:
What is pulmonary edema? 
Pulmonary edema is the accumulation of fluid initially in the interstitium of the lungs, that when severe enough can also accumulate in the alveolar air sacs. It develops when the rate of fluid filtration through the pulmonary vasculature out-paces the lymphatics ability to drain the fluid. 

There are 2 theories for what causes pulmonary edema in the setting of naloxone administration: catecholamine surge vs negative pressure/barotrauma
Catecholamine Surge : Naloxone administration precipitates an acute opioid withdrawal in which epinephrine and norepinephrine surge causing marked vasoconstriction on both the heart and the lungs  

Negative Pressure/Barotrauma: This mechanism is not directly naloxone related but may be confounded by opioid effects. High dose synthetic opioids can induce sustained laryngospasm that is not mu-opioid mediated (thus not easily reversed by naloxone). With rapid awakening, respiratory muscles induce a negative pressure in the thoracic cavity against a closed glottis. This results in an alveolar barotrauma and a transudative pulmonary edema.

What is the treatment for pulmonary edema secondary to opioid overdose reversal?
Positive pressure ventilation is the mainstay treatment (CPAP/BiPAP) with oxygen supplementation.

Importantly, diuretics are not recommended. The patient is not fluid overloaded like in the case of other pulmonary edemas, and diuresing the patient can worsen kidney injury which is already at an increased risk in opioid overdoses (rhabdomyolysis in particular).  

 
References:
Saari TI, Strang J, Dale O. Clinical Pharmacokinetics and Pharmacodynamics of Naloxone. Clin Pharmacokinet. 2024;63(4):397-422. doi:10.1007/s40262-024-01355-6

DailyMed - NALOXONE HYDROCHLORIDE injection, solution. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=201fdedf-1736-4e52-9d7d-de14292547fd

Boyer EW. Management of Opioid Analgesic Overdose. New England Journal of Medicine. 2012;367(2):146-155. doi:10.1056/NEJMra1202561

Dezfulian C, Orkin AM, Maron BA, et al. Opioid-Associated Out-of-Hospital Cardiac Arrest: Distinctive Clinical Features and Implications for Health Care and Public Responses: A Scientific Statement From the American Heart Association. Circulation. 2021;143(16):e836-e870. doi:10.1161/CIR.0000000000000958

Kienbaum P, Thurauf N, Michel M, Scherbaum N, Gastpar M, Peters J. Profound Increase in Epinephrine Concentration in Plasma and Cardiovascular Stimulation after [micro sign]-Opioid Receptor Blockade in Opioid-addicted Patients during Barbiturate-induced Anesthesia for Acute Detoxification Anesthesiology. 1998;88(5):1154-1161. doi:10.1097/00000542-199805000-00004

Summarized by Dan Orbidan, OMS3 | Edited by Dan Orbidan & Ahmed Abdel-Hafiz, NREMT-P
 
Donate: https://emergencymedicalminute.org/donate/
 
Join our mailing list: http://eepurl.com/c9ouHf

Contributor: Alec Coston, MD
Educational Pearls:
Benign Paroxysmal Positional Vertigo (BPPV)
Common inner ear condition that can cause dizziness

Diagnosis of BPPV can help to avoid admissions and extra imaging

Three categories: positional, horizontal, and anterior

Positional is the most common 

Dizziness is not a positive indicator, a torsional nystagmus must be induced

Dix's hallpike maneuver is done to diagnose and an epley maneuver is then used for treatment 

Horizontal 

Usually determined to be the case if the vertigo seems positional and the dix hallpike does not work. A supine roll test would then be done to help diagnose.

Instead of a rotational nystagmus, a unilateral horizontal nystagmus is expected. The two patterns are termed geotropic and apogeotropic.

Geotropic means the fast phase beats toward the ground, and is treated by a barbeque roll maneuver. Apogeotropic means the fast phase beats toward the ceiling, and is treated by Gufoni maneuver.

Anterior is more rare

Most cases require neuro consults

Determined by attempting to induce a down-beating nystagmus, which is a higher risk nystagmus.

Treatment is tilting their head back up in a similar way

Inducing the nystagmus is not sided and is more central

 
References
You, P., Instrum, R. and Parnes, L. (2019), Benign paroxysmal positional vertigo. Laryngoscope Investigative Otolaryngology, 4: 116-123. https://doi.org/10.1002/lio2.230 

Ling X, Zhao D-H, Shen B, Si L-H, Li K-Z, Hong Y, Li Z-Y and Yang X (2020) Clinical Characteristics of Patients With Benign Paroxysmal Positional Vertigo Diagnosed Based on the Diagnostic Criteria of the Bárány Society. Front. Neurol. 11:602. doi: 10.3389/fneur.2020.00602

Rah YC. Advances in Benign Paroxysmal Positional Vertigo: Updated Insights on Diagnostic Pitfalls and Management. J Audiol Otol. 2026 Jan;30(1):1-12. doi: 10.7874/jao.2025.00717.

 
Summarized by Aaryn David | Edited by Aaryn David & Ahmed Abdel-Hafiz, NREMT-P
 
Donate: https://emergencymedicalminute.org/donate/
 
Join our mailing list: http://eepurl.com/c9ouHf

Contributor: Aaron Lessen, MD
Educational Pearls:
 Blunt cerebrovascular injury (BCVI)
BCVI is a traumatic injury to the carotid or vertebral arteries

Patients may initially have no neurologic symptoms

In some cases, a thrombus can form at the site of the injury and later cause ischemic stroke, sometimes hours after the original trauma

CT angiography (CTA) of the neck is a useful screening tool for BCVI

HIstorically, CTA was reserved for patients with high-risk mechanisms or neurologic symptoms

CTA screening has expanded as understanding of BCVIs and their prevention progresses

The Denver criteria were developed to identify patients with increased risk for BCVI

High-risk findings include cervical spine injuries and severe facial or skull-base fractures

Screening practices still vary between trauma centers, though expansion of proactive CTA is an increasingly common practice

 
References
Kim DY, et al. Evaluation and management of blunt cerebrovascular injury: A practice management guideline from the Eastern Association for the Surgery of Trauma. J Trauma Acute Care Surg. 2020.

Biffl WL, et al. Screening for and treatment of blunt cerebrovascular injuries: Western Trauma Association critical decisions algorithm. J Trauma. 2009.

Brommeland T, et al. Best practice guidelines for blunt cerebrovascular injury. Scand J Trauma Resusc Emerg Med. 2018.

Harper PR, et al. Routine CTA screening identifies blunt cerebrovascular injuries missed by clinical risk factors. Trauma Surg Acute Care Open. 2022.

 
Summarized by Sam Pahl | Edited by Sam Pahl & Ahmed Abdel-Hafiz, NREMT-P
 
Donate: https://emergencymedicalminute.org/donate/
 
Join our mailing list: http://eepurl.com/c9ouHf

Contributor: Aaron Lessen, MD
Educational Pearls:
Big question in cardiac arrest: is the rhythm shockable?

Shockable: ventricular fibrillation (VF) and pulseless ventricular tachycardia

Non-shockable: asystole and pulseless electrical activity (PEA)

Rhythm classification is typically based on ECG, but echocardiography can directly visualize myocardial fibrillation

Occult VF: a rhythm that appears non-shockable on ECG but demonstrates VF on echocardiography

A 2025 multicenter prospective study looked at 811 patients with out-of-hospital cardiac arrest

5.3% had occult VF detected by echocardiography

Of the patients with occult VF: 

81.4% had PEA on ECG

18.6% had asystole on ECG

Patients with occult VF were less likely to receive defibrillation because their ECG suggested a nonshockable rhythm

Clinical takeaway: echocardiography during cardiac arrest may reveal a potentially shockable rhythm hiding behind an apparently nonshockable ECG

This identifies a subset of cardiac arrest patients who would otherwise be managed as PEA or asystole based on ECG

 
References
Gaspari R, Adhikari S, Gleeson T, Kapoor M, Lindsay R, Noble V, Nomura JT, Weekes A, Theodoro D. Occult Ventricular Fibrillation Visualized by Echocardiogram During Cardiac Arrest: A Retrospective Observational Study From the Real-Time Evaluation and Assessment for Sonography-Outcomes Network (REASON). J Am Coll Emerg Physicians Open. 2025 Jan 13;6(1):100028. doi: 10.1016/j.acepjo.2024.100028. PMID: 40012664; PMCID: PMC11853361.

 
Summarized by Meg Joyce, MS3 | Edited by Meg Joyce & Ahmed Abdel-Hafiz, NREMT-P
 
Donate: https://emergencymedicalminute.org/donate/

Contributor: Taylor Lynch, MD
Educational Pearls: 
CPR is an important life-saving measure designed for anyone to perform.

Chest compressions works by two mechanisms: 

Cardiac pump: Direct squeezing of the heart

Thoracic pump: Increasing intrathoracic pressure, causing increased blood flow

Proper hand placement per current AHA guidelines: 

Hands are placed in the center of the chest, on the lower half of the sternum

A recent study challenged this approach, using TEE during chest compressions to visualize the cardiac structures being compressed.

They found that when hands were placed ~1cm to the left of the sternum, this compressed the left ventricular outflow tract, potentially restricting forward blood flow.

Hand placement ~4cm to the left of the sternum resulted in more effective compression of the left ventricle.

While this is not yet reflected in AHA guidelines, the study presents an interesting finding that may influence how CPR is performed in the future. 

Key takeaway: Always prioritize administering high quality compressions.




References: 
American Heart Association. 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2025;152(23_suppl_1). doi:10.1161/CIR.0000000000001378.

Chu S, Cheng C, Chang C, et al. Transesophageal echocardiography during CPR in patients with out-of-hospital cardiac arrest: the EXECT-CPR randomized clinical trial. JAMA Intern Med. 2026;186(5):557-566. doi:10.1001/jamainternmed.2026.0102.

 
Summarized by Ashley Lyons, OMS4 | Edited by Ashley Lyons & Ahmed Abdel-Hafiz, NREMT-P
 
Donate: https://emergencymedicalminute.org/donate/
 
Join our mailing list: http://eepurl.com/c9ouHf