Quiz 123, July 30th, 2021

Welcome to the 123th FOAMed Quiz.

 

Question 1

Source image: www.acc.org

A 35-year-old male presents with symptoms of dyspnea on exertion and palpitations, which have been present for the last two weeks. His ECG shows sinus tachycardia of 125 bpm. X-ray shows evidence of pulmonary edema and cardiomegaly. POCUS reveals poor left ventricular function. He has no cardiovascular risk factors, no past medical history and no relevant family history. You suspect him of having myocarditis.

What statement about myocarditis is true?

A: Absence of ECG changes has a high negative predictive value

B: The extent of troponin elevation can be used as a prognostic factor

C: Regional wall motion abnormalities on echocardiography can distinguish between acute coronary syndrome and myocarditis: myocarditis causes diffuse systolic dysfunction

D: One of the most common viral causes of myocarditis in developed countries are enteroviruses like coxsackie B

The correct answer is D.

JournalFeed highlighted this recently published paper in the Journal of Emergency Medicine about myocarditis this week. The review presents a nice overview of the diagnosis and management of myocarditis.

Myocarditis has viral, toxic, or autoimmune etiologies. Viral infections compromise the majority of cases in Western countries. The most common viral causes are coxsackie B viruses and adenoviruses.

The ECG may be normal in myocarditis. ECG changes include non-specific ST-changes, dysrhythmias, findings consistent with pericarditis and heart blocks.

Troponin levels are commonly elevated, but normal values can’t be used to exclude myocarditis. They cannot be used as a prognostic factor either.

Echocardiography can reveal regional wall abnormalities, dilated heart chambers, reduced left ventricular ejection fraction or right ventricular dysfunction.

Question 2

Source image: emergencymedicinecases.com

Your 74 year old patient presents with chest discomfort. His ECG shows mild (0,5 mV) St elevation in leads III and AVF. You are trying to distinguish inferior occlusion myocardial infarction (OMI) from pericarditis. You also notice a negative T and subtle ST depression in lead AVL.

What does the subtle ST depression in lead aVL tell you in this case?

A: This is most likely pericarditis

B: This is most likely inferior OMI

C: ST depression in aVL will not help you distinguish between the two

The correct answer is B.

Dr. Smith’s ECG blog was about subtle inferior OMI last week. This paper is about the value of ST depression in aVL in the setting of ST elevation in the inferior leads.

In case of inferior ST-segment elevation, the presence of any ST depression in lead aVL is highly sensitive for coronary occlusion in inferior myocardial infarction and very specific for differentiating inferior myocardial infarction from pericarditis.

Question 3

Source image: www.chromagar.com/

A 65 year old patient presents to your emergency department with urosepsis. She has a known penicillin allergy. The previous urine culture showed Pseudomonas aeruginosa and you want to start piperacillin – tazobactam.

Which of the following statements is true regarding the safety of administering piperacillin – tazobactam in patients with penicillin allergy?

A: Never give piperacillin – tazobactam to patients with a penicillin allergy, for the rate of cross-reactivity is high due to a similar side chain

B: Patients with known penicillin allergy should never receive beta lactam antibiotics, because the allergy is caused by reactivity to the core beta-lactam ring which is equal in all beta lactams

C: As penicillin allergy is caused by reactivity to a side chain, the rate of cross reactivity between penicillin and piperacillin – tazobactam is very low

The correct answer is C.

Josh Farkas covered beta lactam allergies on EMCrit last week.

Allergy to beta-lactam antibiotics is mediated by the R side chain, rather than the core structure.

There doesn’t seem to be consistent allergic cross-reaction between piperacillin-tazobactam and penicillin, because the side chain of piperacillin is structurally distinct from penicillin.

There are occasional patients with piperacillin-tazobactam allergy who are also allergic to penicillin or amoxicillin, but this probably doesn’t represent a true cross-allergic reaction.

PulmCrit – Is piperacillin-tazobactam safe in patients with penicillin allergy?

Question 4

Source image: www.aliem.com

When a patient needs rapid fluid resuscitation, the choice of IV catheter type makes a huge difference.

Which of the following options gives the potentially highest fluid flow?

A: Saline through a 18 Gauge, 16cm long, central triple lumen cath

B: Saline through a 18 Gauge, 32 mm long, peripheral IV

C: Packed cells through a 22 Gauge, 32 mm long, peripheral IV

D: Saline through a 22 Gauge, 32 mm long, peripheral IV

The correct answer is B.

This week the Trauma Pro discussed the physics behind rapid fluid infusion.

In short: a larger internal diameter (lower Gauge size), shorter line length and lower viscosity of the liquid, lead to a higher flow.

So with a multilumen line, the flow is often lower as these are generally long.

Rapid Infusers: How Fast Can They Go?

Question 5

Source image: www.theguardian.com

Your 50 year old patient presents to the ED with a prolonged erection. You want to differentiate between ischemic and non-ischemic priapism. This can be done based on history and laboratory results.

Which of the following is NOT typical for ischemic priapism?

A: Severe pain

B: Often caused by trauma

C: Often medication induced or related to sickle cell disease

D: Acidotic penile blood gas

The correct answer is B

This week EmDocs covered Priapism last week.

Low flow (ischemic) priapism is more common than high flow (non-ischemic) priapism (only 2%).

Drugs such as intracavernosal injections, PDE5 inhibitors (sildenafil and tadalafil), anti-hypertensives, neuroleptics and cocaine and marijuana can cause ischemic priapism. A baseline penile blood gas can be performed dan in case of low flow priapism it will turn out dark, hypoxemic and acidotic.

EM Cases: Priapism and Urinary Retention: Nuances in Management

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This quiz was written by Sophie Nieuwendijk, Denise van Vossen, Gijs de Zeeuw, Nicole van Groningen and Joep Hermans

Reviewed and edited by Rick Thissen