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. 
Follow Dr. Clay Smith at @spoonfedEM, and sign up for email updates here.

#1: Can We Detect Central Vertigo on Exam?

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HINTS and STANDING exams performed by emergency physicians (EPs) formally trained in both techniques demonstrated very high sensitivity for detecting central causes of vertigo in the ED.

Why does this matter?
Differentiating posterior circulation stroke from peripheral vertigo is challenging, and 10-30% of these strokes are missed in the ED. Studies have shown that EPs frequently misuse or misinterpret important techniques like the HINTS exam when evaluating patients with vertigo. This study suggests EPs, after completing focused training on the HINTS and STANDING exams, can reliably use these tests to rule out central vertigo in many cases (see STANDING Figure and tortured acrostic).

Take a HINT…S exam training to improve rule out of posterior stroke
This single-center study analyzed 300 prospectively enrolled ED patients presenting with vertigo. All underwent HINTS and STANDING exams in the ED as well as an eventual confirmatory brain MRI. HINTS and STANDING exams were administered by study team members with 6 hours of dedicated training on both techniques.

The HINTS exam demonstrated sensitivity of 96.7% for central vertigo, which rose to 97.9% when non-stroke etiologies of central vertigo were excluded. This latter value corresponds to a NPV of 99.4%, suggesting that a patient with overtly peripheral findings on HINTS exam had <1% chance of having a posterior circulation stroke. The STANDING exam, which uses Frenzel glasses to enhance detection of nystagmus but does not test for skew, exhibited lower sensitivity (93.4%) but higher specificity (75%) than the HINTS exam (67.4%).

The single-center nature of this study limits its broad applicability. The findings do, however, suggest that formal training in the HINTS exam can significantly improve an EP’s ability to rule out posterior circulation stroke without MRI or a specialist consult. Adding Frenzel glasses to the ED toolkit may also improve detection of nystagmus and reduce false positive HINTS results.

Source
Differentiating central from peripheral causes of acute vertigo in an emergency setting with the HINTS, STANDING, and ABCD2 tests: A diagnostic cohort study [published online ahead of print, 2021 Jul 10]. Acad Emerg Med. 2021;10.1111/acem.14337. doi:10.1111/acem.14337


#2: How to Use Silver Nitrate for Recurrent Epistaxis

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This video and summary article describes how to perform silver nitrate cauterization for recurrent epistaxis at the bedside.

Why does this matter?
Recurrent epistaxis is a common reason for seeking medical care. After the bleeding is controlled, consider performing silver nitrate cauterization, as it is an effective and simple procedure to treat this condition.

No more nosebleeds
Obtain a focused history of the patient’s epistaxis, including a personal and family history of bleeding disorders. Thoroughly examine the head and neck in addition to the nasal cavity. A nasal speculum can aid in anterior rhinoscopy, noting any prominent blood vessels in the mucosa. Active or recurrent anterior epistaxis that interferes with quality of life is an indication for nasal cauterization.

Prepare the equipment:

  • Nasal speculum, if available

  • Light source

  • Cotton balls with forceps to apply topical anesthetic agent (e.g. 4% lidocaine +/-  topical vasoconstrictor)

  • Topical silver nitrate, several applicators

  • Back-up equipment for possible bleeding (i.e. topical vasoconstrictors, packing materials, suction)

Place the cotton ball soaked in topical anesthetic in the anterior nasal cavity for approximately 10 minutes, then remove. Apply silver nitrate to the prominent blood vessel and surrounding mucosa, making sure to address the entire course of the vessel.

After the procedure, topical saline gel can be applied to protect the area as it heals. Advise use of topical vasoconstrictors in addition to compression for recurrent bleeding. Bedside humidifiers will reduce the risk of recurrence.

Source
Nasal Cauterization with Silver Nitrate for Recurrent Epistaxis. N Engl J Med. 2021 Jun 24;384(25):e101. doi: 10.1056/NEJMvcm2020073.
Full video available at: https://www.nejm.org/doi/full/10.1056/NEJMvcm2020073

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D-dimer can be safely used to rule out venous thromboembolism (VTE) in pregnant adults with non-high pre-test probability (PTP).

Why does this matter?
Pregnancy increases risk for VTE, which is a leading cause of maternal mortality. Though pregnant patients have historically been excluded from VTE research, recent studies (like this and this) suggest that D-dimer can be safely used to rule out VTE in pregnancy. However, international guidelines remain conflicted. If D-dimer is a safe screening test, why not use it to potentially avoid further diagnostic studies that carry risk to mother and fetus?

Stop on a Dimer
This systematic review and meta-analysis included four studies (of 836 patients) that used D-dimer to rule out suspected VTE in pregnant/postpartum adults. Patients included had low/intermediate or unlikely PTP according to a clinical decision tool or regardless of PTP in one study where a tool was not used. The reference standard was ultrasound, CTPA, or VQ scan at baseline and/or three-month follow-up.

Overall, sensitivity (99.5%) and NPV (100%) were high (95%CI 95.0-100.0; I2, 0%; 95%CI 99.19-100.0; I2, 0%). The pooled failure rate (three-month VTE events in patients untreated after negative D-dimer) was 1/312 (0.32%; 95% CI, 0.06-1.83). VTE was present in 7.4% of patients (95% CI, 3.8-12; I2, 83%). A total of 34.2% of patients had a negative D-dimer (95%CI 15.9-55.23; I2, 89%).

I’ll continue to use D-dimer when evaluating non-high-risk pregnant patients with suspected VTE. This could save 1/3 of patients from a radiation or contrast load, with a very low “miss” rate. *We have the YEARS clinical decision tool, which was specifically validated in the pregnant population as a guide to risk stratification at present. You can try it out on MDCalc – just click the button that says pregnant patient to “Yes.” I’d like to see future work on the optimal D-dimer cutoff during pregnancy and maybe even more decision tools to risk stratify.*

Another Spoonful
Want more PE pearls? Bo Stubblefield put together this epic review of the latest recommendations.

Source
D-Dimer to rule out venous thromboembolism during pregnancy: a systematic review and meta-analysis. J Thromb Haemost. 2021 Jun 23. doi: 10.1111/jth.15432. Online ahead of print.

*This section amended from original post.

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