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: TTM2 RCT – Cool Your Jets on Therapeutic Hypothermia

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Cooling comatose patients to 33°C after out-of-hospital cardiac arrest did not improve mortality or neurological outcomes compared to simply maintaining normothermia (<37.8°C).

Why does this matter?
Initiating therapeutic hypothermia in the ED for post-arrest patients is resource-heavy and time-intensive. Hyperthermia prevention is a more attainable goal for busy emergency clinicians, especially if the end results are equivalent.

TTM2: leaving therapeutic hypothermia out in the cold
In the words of fashion icon Mugatu, challenging dogma for various emergency therapies is “so hot right now.” Much like tPA use in acute stroke, however, enthusiasm for therapeutic hypothermia after OHCA continues to cool (horrible pun intended). The TTM2 study by Dankiewicz et al. randomized a whopping 1861 patients and featured a rock-solid methodological design, free of the flaws that have limited prior analyses of targeted temperature management.

No significant difference in the primary outcome of 6-month mortality was found between hypothermia and normothermia groups (RR 1.05, CI 0.94 to 1.14), even after subgroup analysis. Similarly, unfavorable neurological outcomes (modified Rankin scores ≥4) at 6 months were not significantly different between groups (RR 1.00, CI 0.92 to 1.09). Furthermore, a significantly higher rate of hemodynamically unstable arrhythmias was observed in the hypothermia group (24 % vs. 17%, P<0.001).

Notably, the TTM2 study did not include a control group without any temperature management. The question of whether fever prevention impacts mortality or neurological outcomes remains unsettled for now. Although therapeutic hypothermia will still maintain some loyalists, the results of this study have practice-changing implications for most EDs & ICUs.

Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest. N Engl J Med. 2021;384(24):2283-2294. doi:10.1056/NEJMoa2100591.

#2: Chest Ultrasound vs CXR for Pneumothorax in Trauma

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Chest ultrasound performed by trained emergency physicians appears to be more sensitive than supine chest x-ray in identifying pneumothorax in emergency department trauma patients.

Why does this matter?
Bedside ultrasound is fast, portable, noninvasive, and radiation free, and as ultrasound training continues to grow as a staple in emergency medicine residency curricula, we as emergency physicians keep finding more ways to utilize it to provide better care to our patients. Advanced Trauma Life Support guidelines continue to recommend chest x-ray as an adjunct to the primary survey, but should ultrasound be our go-to move to look for pneumothorax instead?

Better (lung) slide that ultrasound machine right into your trauma bay…
This was a Cochrane Database Systematic Review that included 9 total studies comprising 1,271 trauma patients with possible pneumothorax. Patients had to have both a supine chest ultrasound and supine chest x-ray, and confirmation of the ultimate diagnosis of pneumothorax was confirmed by either chest CT or tube thoracostomy. The primary goal was to compare diagnostic accuracy of chest ultrasound to that of chest x-ray, but some subgroup analyses also looked at differences by type of trauma (blunt vs penetrating), type of ultrasound operator (EM physician vs trauma surgeon), and type of ultrasound transducer used (linear vs curvilinear). The overall sensitivity of chest ultrasonography was 0.91 (95% CI 0.85 to 0.94) and specificity was 0.99 (95% CI 0.97 to 1.00). Chest x-ray had a sensitivity of 0.47 (95% CI 0.31 to 0.63) with a specificity of 1.00 (95% CI 0.97 to 1.00). It’s important to remember that ultrasound is very much an operator-dependent skill and not all pneumothoraces will be clinically important, but assuming proper training, ultrasound certainly appears to be the more sensitive study and should be utilized more frequently for the detection of traumatic pneumothoraces in the ED.

Is Chest Ultrasonography Superior to Supine Chest Radiography in Identifying Pneumothorax in Emergency Department Trauma Patients? Annals of Emergency Medicine. 2021 June. doi: 10.1016/j.annemergmed.2020.09.437

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In a population of older adults, serious central and peripheral nervous system adverse events were associated with increased odds of metronidazole exposure relative to clindamycin.

Why does this matter?
Metronidazole is a common antibiotic that has anecdotally been reported to have an association with central and peripheral nervous system toxicity. This was the first large-scale study directed at investigating this association. Although the researchers found that overall toxicity is likely rare, the sheer number of prescriptions for metronidazole means a large number of patients may be at risk for serious complications.

Weird and wobbly? Maybe it was that antibiotic
In this population-based nested case-control study, researchers identified 1,212 adults ≥66 years of age in Ontario, Canada with new-onset encephalopathy, cerebellar dysfunction, or peripheral neuropathy within 100 days of a receiving a prescription for metronidazole or clindamycin. These cases were matched to 12,098 controls without any symptoms but who also received metronidazole or clindamycin within the preceding 100 days. Neurologic adverse events were significantly more likely to be associated with prior metronidazole exposure compared to clindamycin (OR 1.72, 95% CI 1.53–1.94). This association held after adjusting for demographics, healthcare utilization history, comorbidities, and other medications. In those receiving metronidazole, overall incidence of neurotoxicity at 100 days was 0.25%. CNS effects in this population were four times more common than peripheral neuropathy. The mechanism for metronidazole toxicity is not yet known, but prescribers and clinicians should be aware of these rare but potentially serious side effects.

Metronidazole-associated Neurologic Events: A Nested Case-control Study. Clin Infect Dis. 2021 Jun 15;72(12):2095-2100. doi: 10.1093/cid/ciaa395.

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