Quiz 65, March 6th, 2020

Welcome to the 65th FOAMed Quiz. 

Enjoy!

Eefje, Joep and Rick

Question 1

 

The Surviving Sepsis Campaign guidelines recommend blood cultures should be drawn before starting antimicrobial treatment. However, obtaining blood cultures prior to antibiotics may be challenging at times. Does administration of antibiotics really have an influence on the amount of positive blood cultures taken after administration of these antibiotics?

Recently, the FABLED Trial, was published in Annals of Internal Medicine to answer this question. 325 patients were included in the study. They obtained the sensitivity of blood cultures obtained before and within 120 minutes of initiation of antimicrobial treatment as their primary outcomes.

What did the authors find?

A: The percentage of positive blood cultures was significantly higher if obtained before the administration of antibiotics compared to blood cultures obtained after administration of antibiotics

B: The percentage of positive blood cultures was not statistically different if obtained before the administration of antibiotics compared to blood cultures obtained after administration of antibiotics

C: The percentage of positive blood cultures was significantly lower if obtained before the administration of antibiotics compared to blood cultures obtained after administration of antibiotics

The correct answer is A

Salim Rezaie from REBEL EM covered this paper this week.

This multicenter study was performed in 7 Emergency Departments (EDs) in North America. It is the first study to prospectively quantify the decrease in sensitivity of blood culture sensitivity from the time of antimicrobial initiation.

The percentage of positive blood cultures before administration of antibiotics was 31.4% compared to 19.4% after administration of antibiotics. This absolute difference of 12% (95% CI 5.4 to 18.6%) was statistically significant with a P-value of <0.001. The authors mentioned in their discussion that taking blood cultures after administration of antibiotics would lead to false-negative blood cultures to 1 in every 6.7 patients.

The clinical take home point is that drawing blood cultures after administration of antibiotic treatment reduces culture sensitivity which could affect downstream optimization of treatment as well as safe de-escalation of treatment.

The FABLED Trial: Blood Cultures 1st, Then Antibiotics in Sepsis

Source image: https://radiopaedia.org/

Question 2

A 50-year old male presents to your Emergency Department after being assaulted. His right orbita is swollen and shows a big hematoma. He mentions severe headache and does not remember exactly what happened. Physical examination shows tenderness of his upper orbital wall and zygoma. You are worried that he might have orbital fractures.

Which of the following statements is true about orbital wall fractures?

A: The superior and medial wall are the weakest and therefore most commonly fractured

B: A ‘’teardrop sign’’ on computed tomography (CT) indicates a fracture of the inferior orbital wall and should make you aware of possible entrapment of the inferior rectus muscle

C: Around 10% of patients with orbital fractures have concomitant ocular trauma

D: There is clear evidence to support oral antibiotics in orbital fractures

The correct answer is B

 

Jessica Tsao from Core EM covered orbital fractures this week. 

The orbita can be divided into four walls, made of multiple bones. The superior wall (frontal bone), lateral wall (zygome and sphenoid), inferior wall (zygoma and maxilla) and medial wall (ethmoid, including the lamina papyracea). The inferior and medial walls are the weakest and therefore most commonly fractured.

 

A study done in 2003 showed ocular trauma in ⅓ of patients with orbital wall fractures so therefore a thorough eye exam should always be done. Look for visual acuity, eye movements, teardrop pupil, enophtalmos or proptosis.

 

Although there is really poor evidence for routine use of antibiotics, they are routinely prescribed in patients with orbital fractures.

 

Orbital Blow-Out Fractures

Source image: www.pixabay.com

Question 3

Which of the following treatments for migraine is not supported by a proper amount of evidence?

A: Haloperidol

B: Metoclopramide

C: Dexamethasone 10mg to 25mg (to prevent headache recurrence)

D: Ketorolac or another NSAID

The correct answer is A

Taming the SRU covered the treatment of migraine this week. 

It seems the use of prochlorperazine and metoclopramide, ketorolac and dexamethasone are supported by evidence. The evidence of haloperidol however is very weak. 

Another treatment supported by evidence is the occipital nerve block. A recent meta-analysis  demonstrated reduction in headache severity, amount of headache days, and amount of medication consumed for headache in patients receiving occipital nerve blocks. 

Source image: www.emottowablog.com

Question 4

A 54 year old male is brought in by EMS after being found unconscious in a park. The outside temperature is -5 degrees Celsius (that is 23 degrees Fahrenheit). His core temperature turns out to be 27 ℃ (80 ℉). As you want to rewarm this patient, you doubt which method would be most effective. Put the following methods of rewarming in the correct order, starting with the least effective and finishing with the most effective method.

A: Bladder lavage, thoracic lavage, dialysis, VV-ECMO

B: Bladder lavage, dialysis, thoracic lavage, VV-ECMO

C: Thoracic lavage, dialysis, bladder lavage, VV-ECMO

D: Dialysis, Bladder lavage, VV-ECMO, thoracic lavage

The correct answer is A

EMOttawa covered the hypothermic patient last week.

It turns out bladder lavage is the least effective warming method (0.5-1 ℃ / hour), next is thoracic lavage (1-2 ℃ / hour, however the risks outweigh the benefits). Then dialysis (2-3 ℃ / hour and finally ECMO 4-10 ℃. 

 

Source image: www.pixabay.com

Question 5

Which of the following finding has the highest positive likelihood ratio for an elevated intracranial pressure (ICP > 20 mmHg)?

A: Midline shift >10 mm on CT

B: GCS score ≤8

C: Compression or absence of basal cisterns on CT

D: Any pupillary dilation

The correct answer is C

Clay Smith covered this recently published paper last week on Journal Feed.

This was a systematic review of 40 studies with 5,123 patients to determine the diagnostic accuracy of physical exam and imaging findings for the diagnosis of increased ICP, compared with a gold standard of invasive ICP monitoring. 

It turns out none of the examined features alone were very helpful at ruling in or out elevated ICP. Compression or absence of basal cisterns on CT had the highest positive likelihood ratio (2.20). Pupillary dilatation only had a positive likelihood ratio of 2.00 and a midline shift >10 mm on CT only had a positive likelihood ratio of 1.92. 

 

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This quiz was written by Eefje Verschuuren and Joep Hermans

Reviewed and edited by Rick Thissen

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