Friday Board Review

Board Review by Dr. Vidhi Parikh

12-month-old who was born full term is brought in by mom after patient was found to be cyanotic. Patient with vaccines UTD. Patient has been teething and mom notes that she has been applying benzocaine teething gel. Patient on arrival to the ER has perioral and digital cyanosis. His vital signs are as follows: T- 98.6 rectal; HR- 140; RR- 35; BP- 94/56; SpO2- 89% on RA. Patient is given blow by O2 with no improvement to oxygenation. What is the diagnosis? 

  1. Patent Foramen Ovale
  2. Aspirin Toxicity 
  3. Methemoglobinemia 
  4. Iron toxicity 
  5. Carbon monoxide poisoning 

Answer: C. Methemoglobinemia 

Patient has methemoglobinemia from the application of benzocaine for teething. Methemoglobinemia occurs when iron is oxidized from the ferrous (Fe2+) to the ferric (Fe3+) state. The ferric hemes of the methemoglobin do not bind O2. The ferric heme in the hemoglobin also has an increased affinity to O2 and therefore causes the hemoglobin dissociation curve to shift to the left causing less oxygen delivery. 

Farkas, Josh. “Methemoglobinemia.” EMCrit Project, 2 Oct. 2021,

Madrazo, Lorenzo. “Methemoglobinemia.” The Intern at Work, 31 Oct. 2021,

Swaminathan, Anand. “CORE EM: Methemoglobinemia.” – Emergency Medicine Education, 28 Dec. 2018, Accessed 31 May 2024.

Friday Board Review

Board Review by Dr. Edward Guo (Edited by Dr. Parikh)

A 65 year old male with a past medical history of type 2 diabetes and hyperlipidemia presents via EMS as a stroke alert. Patient developed confused speech and right upper extremity weakness 1 hour ago. Vital signs and point of care glucose are within normal limits. CT head and CTA head and neck demonstrate no acute intracranial abnormalities, and thrombolytics are administered. Ten minutes later, the patient develops rapidly progressive tongue and lip swelling. There is no response to intramuscular epinephrine. What is the likely etiology of the patient’s change in condition?

A: Hemorrhagic transformation

B: IgE-mediated hypersensitivity to thrombolytics

C: Mast cell activation from IV contrast

D: Thrombolytic side effect

Answer: D. Thrombolytic side effect

This patient is most likely experiencing orolingual angioedema, a known side effect of thrombolysis that is overall rare but in some reports has an incidence as high as 17%. It is caused by complement and kinin pathway activation by plasminogen. Patients who are already taking ACE inhibitors are at increased risk. Treatment involves discontinuing thrombolysis and managing similarly to other causes of angioedema. 

It is unlikely that intracranial hemorrhage would cause airway swelling. IgE-mediated hypersensitivity reactions require an initial sensitization exposure which makes this answer unlikely without prior administration of thrombolytics. Mast cell activation from IV contrast is possible but would likely have response to intramuscular epinephrine in addition to other physical exam findings such as urticaria or wheezing. 


Go S, Kornegay J. Stroke Syndromes. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 9e. McGraw-Hill Education; 2020.

Astin, Matt. “TPA-Associated Angioedema- Rebel EM- Emergency Medicine Blog.”REBEL EM- Emergency Medicine Blog, https://www., 3 Apr. 2014,

Wednesday Image Review

What’s the Diagnosis? By Dr. Vincent Li

30 year old female is brought by EMS from an outpatient surgery center for evaluation of persistent hypotension and vaginal bleeding after an elective abortion and D&E at approximately 20 weeks gestation. Initial vitals on arrival were T 98.6 F, HR 99, BP 62/palp, RR 21, O2 100%. On exam, patient was pale and lethargic but mentation intact. There is scant vaginal bleeding on pelvic exam. A bedside FAST is performed and shown below. What is the interpretation of the FAST, and which views demonstrate free fluid if present?

Answer: Free Fluid in RUQ, LUQ, and Pelvis

The patient received 2 units of uncrossed pRBCs in addition to 1g TXA IV and was taken emergently to the OR with OBGYN for exploratory laparotomy. She was found to have 1500 ccs of hemoperitoneum from an actively bleeding R uterine artery laceration. She did well post-op and was discharged a few days later!

Focused Assessment with Sonography for Trauma

  • High sensitivity and specificity for detecting intra-abdominal free fluid in hypotensive trauma patients.
  • Four views: RUQ, LUQ, cardiac, and suprapubic
  • Where you’ll find free fluid:
    • RUQ: 1. Subdiaphragmatic space, 2. Hepatorenal space (Morrison’s pouch), and 3. Caudal edge of the liver
      • Most sensitive area for intra-abdominal free fluid is the RUQ – more specifically, the caudal edge of the liver (contiguous with right paracolic gutter)
    • LUQ: 1. Subdiaphragmatic space, 2. Splenorenal space, and 3. Inferior pole of the left kidney
    • Cardiac: 1. pericardial effusion
    • Pelvis: 1. Between the bladder and uterus (in females), 2. Posterior to the uterus (in females), and 3. Posterolateral to the bladder
      • Fluid in the pelvis will first accumulate in the rectouterine pouch of Douglas in females, and the posterior bladder margin in males. Prostate may be confused with free fluid but is generally more hyperechoic and discrete in structure.

Key learning point for this case: clotted blood is more hyperechoic and can start to resemble tissue or other structures. Easy to miss if not looking closely.


  1. Lobo V, Hunter-Behrend M, Cullnan E, Higbee R, Phillips C, Williams S, Perera P, Gharahbaghian L. Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam. West J Emerg Med. 2017 Feb;18(2):270-280. doi: 10.5811/westjem.2016.11.30435. Epub 2017 Jan 19. PMID: 28210364; PMCID: PMC5305137.
  2. Ultrasound Guidelines: Emergency, Point-of-Care and Clinical Ultrasound Guidelines in Medicine. Ann Emerg Med ​​. 2017 May;69(5):e27-e54. Doi: 10.1016/j.annemergmed.2016.08.457.
  3. “Fundamentals.” Core Ultrasound Courses, Accessed 2 May 2024.
Tuesday Advanced Cases & Procedure Pearls

Critical Cases – Periodic Paralysis

By Dr. Jacob Martin, MD


  • 30 yo healthy male p/w generalized fatigue, b/l UE and LE weakness and pain for several hours
  • Denies strenuous activity, change in diet, falls, trauma, midline back pain, bowel and or bladder incontinence
  • Hospitalized 3 months prior for unexplained hypokalemia (K <2.0) that resolved with IV repletion


Vitals: BP 182/78 | Pulse 61 | Temp 97.7 °F (Oral) | Resp 22 | SpO2 100% 

  • Awake and alert, appears fatigued
  • Dry MM, cap refill greater than 3 seconds
  • 4/5 strength b/l UE
  • 3/5 strength b/l LE
  • Sensation to light touch intact in bilateral upper and lower extremities
  • 2+ patellar reflexes bilaterally
  • Unable to ambulate due to weakness

Ddx for Generalized Weakness:

  • Hypokalemia/hyperkalemia vs rhabdomyolysis vs periodic paralysis vs spinal cord compression vs Guillain-Barre syndrome

Initial Diagnostics:

  • Initial labs notable for K 1.9, Mg 1.5, and Phos 1.1
  • Initial ECG (see below)


  • Electrolytes repleted as follows…
    • 40 mEq oral K, 20 mEq IV K
    • 2 gm Mg over 2 hours
    • 2 tablets of Neutra-Phos

Case Progression:

  • Ultimately diagnosed with hyperthyroidism, likely secondary to Graves’ disease
    • TSH <0.01
    • Ultrasound thyroid
      • Enlarged heterogeneous thyroid with diffusely increased vascularity
      • Thyroid nodule of the isthmus
  • Started on Methimazole and Propranolol
  • Presenting symptoms and electrolyte abnormalities attributed to thyrotoxic periodic paralysis

Thyrotoxic Periodic Paralysis (TPP)

  • Potentially life-threatening
  • Defined as the triad of
    • Muscle paralysis
    • Acute hypokalemia
    • Hyperthyroidism
  • Less than half of TPP patients exhibit clinical signs of hyperthyroidism
  • Rapid recognition and termination are mandatory to avoid potentially fatal complications of severe hypokalemia
    • Cardiac arrhythmias
    • Respiratory failure
  • Management complicated by the thin line between refractory hypokalemia and rebound hyperkalemia
  • KCl supplementation is essential but often not enough to control TPP
  • IV propranolol has been reported to reverse weakness and hypokalemia in patients unresponsive to KCl administration


Bilha S, Mitu O, Teodoriu L, Haba C, Preda C. Thyrotoxic Periodic Paralysis-A Misleading Challenge in the Emergency Department. Diagnostics (Basel). 2020;10(5):316. Published 2020 May 18. doi:10.3390/diagnostics10050316

Lin SH, Huang CL. Mechanism of thyrotoxic periodic paralysis. J Am Soc Nephrol. 2012;23(6):985-988. doi:10.1681/ASN.2012010046

Monday Back to Basics & Pharmacology

From the Archives: Cardiac Tamponade with Dr. Rebecca Fenderson

What is cardiac tamponade?

-Cardiac tamponade is a medical or traumatic emergency that occurs when enough fluid accumulates in the pericardial sac to cause compression of the heart, leading to a decrease in cardiac output and obstructive shock.

Risk factors for tamponade:

-Besides hemorrhage (from something such as a stab wound or a left ventricular wall rupture s/p MI), other risk factors include infection (i.e., TB, myocarditis), autoimmune diseases, neoplasms, uremia, inflammatory disorder such as pericarditis.

True or false: the size of the pericardial effusion directly correlates with the risk of developing tamponade.

-FALSE! The rate at which fluid accumulates in the pericardial sac correlates with the risk of developing tamponade. The classic example is a traumatic cardiac injury which leads to hemopericardium. The rapid build-up of blood in the sac quickly leads to the inability of the chambers relax, which leads to decreased venous return, decreased diastolic filling, and decreased cardiac output.

-In situations such as neoplasms where the effusions grow at a much slower rate, there is time for the pericardial sac to stretch; these volumes can be substantially higher without causing tamponade physiology to develop.

What is one of the first compensatory vital signs seen in tamponade physiology, and also the most common EKG finding?

-Sinus tachycardia. The classic finding of electrical alternans is only present to 5-10% of cases of tamponade.

How does the patient present? What are their physical exam findings?

-Patients present with symptoms consistent with obstructive shock – lethargy, tachypnea, chest pain, palpitations. In severe cases, patients can experience dizziness, syncope, and/or altered mental status.

-Beck’s Triad: hypotension, jugular venous distention, muffled heart sounds.

-Pulsus paradoxus is defined as a decrease in systolic blood pressure of >10mmHg with inspiration. It is an important finding suggesting tamponade but may be absent in people with an elevated diastolic blood pressure, ASD, pulmonary hypertension, or aortic regurgitation.

What are ultrasound findings suggestive of cardiac tamponade?

-A plethoric IVC is the most sensitive finding of tamponade. IVC plethora is defined by a diameter equal or greater to 2 cm with less than 50% collapsibility during inspiration. 

-Right ventricular free wall collapse during diastole is considered to be the most specific sonographic finding of tamponade. RV free wall collapse can also be used as a measurement of severity. Initially, collapse of the RV free wall will only be present during expiration, but as the pressure increases, detection is possible throughout the respiratory cycle.

-Right atrial collapse (most often during systole, when the intra-atrial pressure is low) is often observed before right ventricular collapse. RA collapse longer than 1/3 of the total cardiac cycle has been described as an 100% sensitive and specific finding of tamponade.


Stashko E, Meer JM. Cardiac Tamponade. [Updated 2021 Aug 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from:

Kalter HH, Schwartz ML. Electrical alternans. NY State J Med. 1948;1:1164-66.

Pérez-Casares, Alejandro et al. “Echocardiographic Evaluation of Pericardial Effusion and Cardiac Tamponade.” Frontiers in pediatrics vol. 5 79. 24 Apr. 2017, doi:10.3389/fped.2017.00079

Mugmon, Marc. “Electrical alternans vs. pseudoelectrical alternans.” Journal of community hospital internal medicine perspectives vol. 2,1 10.3402/jchimp.v2i1.17610. 30 Apr. 2012, doi:10.3402/jchimp.v2i1.17610