Quiz 95, December 18th, 2020

Welcome to the 95th FOAMed Quiz

Nicole, Joep, Sophie and Rick
Source image: www.thebottomline.org.uk

Question 1

Veno-arterial extracorporeal membrane oxygenation (ECMO) is increasingly used in patients with out of hospital cardiac arrest (OHCA). Nevertheless, evidence regarding ECMO is fairly limited and mainly consists of three observational studies (Wang 2017, Dennis 2016  and Dennis 2020).

The ARREST trial is the first randomized controlled trial of ECMO CPR in OHCA.

The authors included adult patients with OHCA with an initial shockable rhythm without return of spontaneous circulation (ROSC) after three defibrillation defibrillation attempts and an estimated transfer time to the ED of <30 minutes.

The authors compared ECMO CPR to standard ALS. Their primary outcome was survival to hospital discharge.

What did they find?

A: Survival to hospital discharge was better in the ECMO group compared to the standard ALS group

B: Survival to hospital discharge was not significantly different between the ECMO group compared and the standard ALS group

C: Survival to hospital discharge was worse in the ECMO group compared to the standard ALS group

The correct answer is A

The ARREST trial was covered by Justin Morgenstern on First10EM this week.

A total of 30 patients (83% male, 17% female) with a mean age of 59 years were included. Survival to hospital discharge was more frequent in the ECMO group compared to the standard ALS group (43% vs 7%). Survival to 3 and 6 months was also significantly better in the ECMO CPR group ( 43% vs 0%, p=0.006%). Cumulative 6-month survival was also significantly better in the early ECMO group than in the standard ACLS group.

Although these results are impressive, some limitations have to be taken into account. 83% of patients were male while previous research shows that females tend to have worse outcomes. Furthermore, ECMO was performed in the cath lab so every patient in the ECMO group received an immediate angiogram while the standard ALS group only underwent angiography if ROSC was obtained and the cath was warranted by clinical protocol (13 patients in the ECMO group vs 2 patients in the standard ALS group).


Source image: www.pixabay.com

Question 2

While in the Netherlands we are awaiting the verdict of the European Medicines Agency (EMA), the UK and USA are already deploying the Pfizer vaccine. Last week the results of Pfizer’s phase 3 trial were published.

21,669 patients received the vaccine (of which 98.4 percent received both doses) and 21,728 received placebo.

How many patients contracted COVID-19 ≽7 days after the second dose?

A: 153 in the vaccine group and 159 in the placebo group

B: 72 in the vaccine group and 323 in the placebo group

C: 14 in the vaccine group and 28 in the placebo group

D: 9 in the vaccine group and 172 in the placebo group

The correct answer is D

RebelEM covered the Pfizer paper last week.

Yes, it is a manufacturer sponsored trial and no one knows how long its effects will last. But these results are very promising.

The incidence of minor systemic adverse events was quite frequent, the incidence of serious adverse events was similar between groups (vaccine 0.6% vs placebo 0.5%).

COVID-19 Update: The COVID-19 Pfizer Vaccine

Source image: www.emdocs.net

Question 3

This ECG shows diffuse ST depression and ST elevation in aVR (and perhaps a little bit in III).

Which of the following statements about ECG’s this pattern (diffuse ST depression with ST elevation in aVR) is true?

A: 50 percent of patients with a similar ECG have left main ACS

B: This pattern is associated with very high mortality

C: 65 percent of patients with a similar ECG have ACS (not just left main)

The correct answer is B

ST elevation in aVR with diffuse ST depression is covered on dr. Smith’s ECG blog this week.

While this pattern is frequently thought to represent either left main occlusion or 3 vessel disease, the rate of ACS in patients with these ECG’s turns out to be quite low (24 percent). The pattern represents subendothelial ischemia, which can have numerous causes (like valvular disease, severe anemia and everything that can cause decreased oxygen supply to the myocardium).

However, it is clear that patients with an ECG-pattern like this have a very high mortality.

Source image: www.coreultrasound.com

Question 4

In ultrasound guided peripheral nerve blocks, a nerve and a tendon can 
appear very similar.

Which of the following ultrasound artifacts can be used to distinguish the two?

A: Reverberation

B: Blooming artifact

C: Acoustic shadowing

D: Anisotropy

The correct answer is D

Jacob Avila covered nerve block basics on Core Ultrasound this week.

Anisotropy is the property of a material which allows it to change or assume different properties in different directions. Tendons will appear less echogenic (will be less bright) if you increase or decrease the angle (less perpendicular). Nerves keep their echogenecity.


Source image: www.emottowablog.com

Question 5

Which of the following findings on Point of Care UltraSound (PoCUS) makes a pneumothorax very likely?

A: Lung pulse

B: Lung sliding

C: Lung point

D: Presence of comet tails

The correct answer is C.

EMOttawa covered the diagnosis of pneumothorax last week.

A lung pulse, lung sliding and comet tails can only be present if there is no air between the pleural membranes, so they make a pneumothorax very unlikely. On the other hand, a lung point (visualisation of the location at which the anterior pleural membranes make contact, so showing lung sliding on one side and no lung sliding on the other) makes a pneumothorax very likely.

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This quiz was written by Nicole van Groningen and Joep Hermans

Edited by Rick Thissen