Journal Feed Weekly Wrap-Up

We always work hard, but we may not have time to read through a bunch of journals. It’s time to learn smarter. 

Originally published at JournalFeed, a site that provides daily or weekly literature updates. 

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#1: Targeted Temperature for Non-shockable Rhythm

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If you’re a proponent of bystander CPR, you should probably also be a strong advocate for targeted temperated management (TTM) for non-shockable rhythm.

Why does this matter?
The 2015 AHA guidelines recommend TTM (32-36C) for all adult patients after ROSC who are comatose (i.e. lack of meaningful response to verbal commands). However, this endorsement of TTM for non-shockable rhythm is based on expert opinion and flimsy evidence. Retrospective case-series have shown conflicting results ranging between benefit, no benefit, and even harm. Therefore, a large randomized study has been long overdue.

Ice is back with a brand new invention.
Analyzing patients who achieved ROSC after a nonshockable rhythm, this study compared moderate hypothermia (33C) to normothermia (37C). It was a pragmatic, open-label, randomized, controlled trial. It included 581 patients from 25 French ICUs. Three-quarters of patients had out-of-hospital cardiac arrest. Two-thirds were presumed to have a non-cardiac etiology. The primary outcome was 90-day survival with a favorable neurologic outcome, defined as a CPC score of 1 or 2. They found 10.2% of the hypothermia protocol patients had a good neurologic outcome whereas only 5.7% in the normothermia group had a good neurologic outcome (absolute difference 4.5%, 95% CI 0.1% – 8.9%, p = 0.04). This equates to a NNT = 22. To put this in perspective, the NNT to prevent one death with bystander CPR is 15 and with epinephrine is 112.

Source
Targeted Temperature Management for Cardiac Arrest with Nonshockable Rhythm. N Engl J Med. 2019 Oct 2. doi: 10.1056/NEJMoa1906661. [Epub ahead of print]

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#2: POCUS for Abscess – How Accurate Is It?

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Point of care ultrasound (POCUS) was accurate for diagnosis of skin abscess, but the results of this review may have been inflated. It is likely most helpful in uncertain cases.

Why does the matter?
It is often difficult to distinguish cellulitis from abscess on clinical exam. How accurate is ultrasound in helping us distinguish the two?

Is it really that good?
This was a summary of a published systematic review of the diagnostic accuracy of POCUS for skin abscess. They found 8 studies with 747 patients, both children and adults. The sensitivity was 95.5% (95%CI 88.9 to 98.3) and specificity was 80.3% (95%CI = 56.4 to 92.7). There are several caveats. The gold standard for abscess differed from study to study. Most were convenience samples with cross contamination between clinicians and sonographers in medical decision making. All of this may have made the diagnostic accuracy look better than it actually was. Recent studies have show that POCUS is helpful in equivocal cases and unhelpful in cases in which the clinician was certain of the diagnosis prior to scanning. Overall, the authors ranked this yellow, which means POCUS has unclear benefit. They thought it was best in uncertain cases.

Source
Accuracy of Point-of-Care Ultrasound for Diagnosing Soft Tissue Abscess. Acad Emerg Med. 2019 Nov 1. doi: 10.1111/acem.13881. [Epub ahead of print]

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#3: Single Syringe Adenosine for SVT

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Giving adenosine 6mg in 20mL of saline as a single syringe push vs the usual 6mg push and rapid flush with 20mL saline was non-inferior for the treatment of SVT.

Why does the matter?
One of the challenges of giving adenosine is pushing and rapidly flushing it, given its ultrashort half life. Might giving it diluted in one syringe – a sort of push and flush together – work as well? This was first popularized on FOAM by ALiEM.

Don’t be alarmed when your heart stops
This was a non-blinded prospective study in which clinicians could choose a single-syringe (SS) (n = 26) or two-syringe (TS) with stopcock (n = 27) method of giving adenosine. They started with either 6mg in 18mL (total 20mL) of NS or 6mg and a 20mL flush via two-way stopcock. They thought the SS method would be at least 80% as effective as the TS method and set the non-inferiority margin at 20%. For the primary outcome of conversion to NSR with one dose, the SS group was non-inferior to the TS group; 73.1% (95%CI 0.55 to 0.91) to 40.7% (95%CI 0.21 to 0.61; noninferiority, p = 0.0176). There was one extravasation event in the TS group and none in the SS group. Of note, this was a small unblinded pilot study. However, it showed non-inferiority with the SS technique. I think I will try this with my next SVT patient.

Source
Single Syringe Administration of Diluted Adenosine. Acad Emerg Med. 2019 Oct 30. doi: 10.1111/acem.13879. [Epub ahead of print]

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