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: Orthostatics – Still Mostly Useless

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In patients ≥60 years, abnormal orthostatic vital signs (OVS) did not predict 30-day serious outcomes.

Why does this matter?
We recently discussed OVS in depth. They have a limited role but are so often present in normal people and absent in people with true volume loss, that it renders them largely useless. Yet, the 2017 AHA syncope guidelines still recommend they be done. Please take a moment to read Thomas Davis’ comments (at the bottom) when he reviewed my summary this week. He is spot on.

Orthostatics – still mostly useless
This was a planned secondary analysis of a different syncope study with 1,974 patients ≥60 years who had OVS performed. Of these, 37.7% had abnormal OVS (the usual HR/BP criteria). They compared 30-day serious outcome* among those who were orthostatic and those who were not. There was no difference, 15.3% OVS abnormal vs 14.7% OVS normal; adjusted OR 0.82 (95%CI, 0.62-1.09). Bear in mind, this secondary analysis did not include all the patients in the original study, because not all of them had OVS done. So, there is some selection bias inherent to this analysis. Those who had OVS performed tended to be older, have coronary disease, heart failure, dyspnea, abnormal ECG, higher physician risk estimate, and were more likely to be hospitalized. When adjusting for these factors, there remained no difference. I was able to find one advantage to performing OVS in Appendix D of the article – they may “protect” patients from cardiac intervention, 52 (4.2%) 17 (2.3%) p=0.034. I say this tongue in cheek, but one wonders…

*30-day serious outcome includes: “cardiac arrhythmias, myocardial infarction, cardiac intervention, new diagnosis of structural heart disease, stroke, pulmonary embolism, aortic dissection, subarachnoid hemorrhage, cardiopulmonary resuscitation, hemorrhage/anemia requiring transfusion, with major traumatic injury from fall, recurrent syncope, and death.”

Orthostatic vital signs do not predict 30 day serious outcomes in older emergency department patients with syncope: A multicenter observational study. Am J Emerg Med. 2019 Mar 25. pii: S0735-6757(19)30186-X. doi: 10.1016/j.ajem.2019.03.036. [Epub ahead of print]

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Reviewed by Thomas Davis – His comments this week were so helpful that I have included them here in full:

“There were data that suggested OVS may be associated with increased mortality, which prompted this study. But it feels like the research has gotten side tracked from the whole reason AHA recommends OVS. AHA recommends OVS not as a way to risk stratify for mortality/admission (although many falsely use it that way) but rather to identify patients whose presenting symptoms may be controlled through lifestyle and medication adjustments (as orthostatics may be a sign of neurogenic OH or volume depletion). Therefore, as I read the AHA guidelines, they never intended OVS to be a tool to address mortality but rather quality of life. I’d like to see more research focused on whether OVS actually achieves this outcome–not mortality. After all, there are 2 outcomes we care about in medicine: 1) dead vs alive and 2) happy vs sad.”

#2: NACSTOP – Safety of a 12-hour NAC Protocol

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A 250mg/kg, 12-hour N-acetylcysteine (NAC) protocol was as effective as the usual 300mg/kg, 20-hour protocol in patients at lower risk for hepatotoxicity.

Why does this matter?
What if it was safe to medically clear a potential APAP overdose in 12 hours instead of 24? That would be good, but is it safe?

Stop the NAC
This was a cluster RCT with about 50 patients per group. To be enrolled in the study, they had to have a 4-hour level of at least 150mg/L but be considered low risk for hepatotoxicity, with “normal serum alanine transaminase (ALT) and creatinine on presentation and at 12 hours, and less than 20 mg/L acetaminophen at 12 hours.” Exclusions included: “pregnancy, acetaminophen modified-release ingestion, and other supratherapeutic ingestions (i.e., unintentional ingestions of more than 10 g or more than 200 mg/kg over 24 hours, more than 6 g/day over 48 hours).”

Patients received a fairly standard 20-hour 300mg/kg NAC protocol (consisting of 200 mg/kg over 4 hours followed by a further 100 mg/kg over 16 hours) or an abbreviated 12-hour 250mg/kg NAC protocol. The truncated protocol held the last 8 hours (50mg/kg) of the infusion if the serum ALT was <40, creatinine was normal, and acetaminophen was < 20 mg/L. There was no difference in the primary outcome of hepatic injury at 20 hours, defined as a doubling of the ALT and peak >100. There was also no difference in secondary outcomes, including ALT > 1,000, peak INR, or adverse drug reaction. Zero patients had hepatic injury in each group; none had delayed hepatic injury; none died; all were well at phone follow up on day 14.

Another Spoonful
I saw this article first in the excellent publication – Journal Watch.

The NACSTOP Trial: A Multicenter, Cluster-Controlled Trial of Early Cessation of Acetylcysteine in Acetaminophen Overdose. Hepatology. 2019 Feb;69(2):774-784. doi: 10.1002/hep.30224. Epub 2019 Jan 19.

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#3: Is a 20ga in the AC Essential for CTPA?

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There was no statistical difference in inadequate vascular filling for CT pulmonary angiogram (CTPA) if the IV catheter was smaller than 20 gauge (ga) or if it was not in the antecubital fossa (AC) or forearm.  Read on for the caveats.

Why does this matter?
When pushing IV contrast under pressure for CTPA, the American College of Radiology recommends at least a 20 ga IV in the AC or forearm to accommodate the high flow rate needed and to optimize contrast timing.  But this appears to be based on expert opinion.  Might a smaller, more peripherally, or atypically located vein work?

Move over AC fossa
Of 1,500 CTPA reports retrospectively reviewed, 19.3% were technically inadequate, with more than half of those due to poor filling of the pulmonary arteries.  Patients with a 20 ga or larger IV in the AC fossa or forearm had inadequate filling 9.2% of the time; smaller or non-AC/forearm sites had poor filling 13.2% of the time.  There was no statistically significant difference (4.0%, 95% CI -1.7%-9.7%).  I would add a word of caution.  This study did not look at rate of IV extravasation, and the number of studies with a 22ga or atypically located IV was small.  The gravity flow rate of a 22ga is 35mL/min; CT contrast for PE goes in at 4-5mL/sec.  How is it possible that 10/13 (77%) with a 22ga were technically adequate?  Authors spoke with BD Medical and, “they claim that [their 22ga] can be safely used for power injection as long as the pressure is limited to 300 pounds per square inch.”  There are limits; no patients had an IV smaller than 22ga.  The number of people with hand, wrist, neck, or other non-AC/forearm IVs was small, 76 in total.  Rate of inadequate filling in a hand IV appeared higher, 7/38 (18.4%), though the 95%CI on that would be quite wide.  Only 13 people had 22ga IV catheters, and 3/13 (23.1%) had poor filling.  Generally speaking, a larger, more proximal IV is a best practice when obtaining a CTPA.  But if you can’t get other access and really need the scan, you may have success with a 22ga or non-AC/forearm location.

Rethinking Intravenous Catheter Size and Location for Computed Tomography Pulmonary Angiography.  West J Emerg Med. 2019 Mar;20(2):244-249. doi: 10.5811/westjem.2018.11.40930. Epub 2019 Feb 6.

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