Authors: Andy Neill, Dave McCreary, Jacob De Wolff, Dan Horner, Chris Walsh, Fin McNicol / Codes: CC7, CP1, CP2, PhC1, PhC4, PhP2, SLO1, SLO10, SLO11, SLO2, SLO3, SLO7, VC2Published: 02/04/2018


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Andy Neill

Dave McCreary

Title: Diagnostic Accuracy of the Aortic Dissection Detection Risk Score Plus D- Dimer for Acute Aortic Syndromes: The ADvISED Prospective Multicenter Study

Author: Nazerian, Circulation, 2017

Background: Aortic dissection is a rare and immediately life threatening disease. It can present in a myriad of ways and a missed diagnosis is often fatal. There is no doubt that the diagnosis is missed frequently and a famous CT surgeon is renowned for stating that missing the diagnosis on the first presentation could be considered standard of care. Can a score, something like Wells or HEART help us to pick it up?


– multicentre prospective observational study

– only included if someone in the ED included dissection as a possibilty in their differential. This is the major downfall as it tell us nothing about the missed ones.

– once included they had to get a d dimer and this was not blinded to the docs looking after the patient and deciding on the work up (another problem)

– this was combined with their Acute Aortic Syndrome Risk Score

– primary outcome was the failure rate of this dimer/risk score combination to rule out

– they did have a power calculation aiming to get the failure rate below 2%


–  1850 pts collected prospectively

– 40% had +ve dimer

– 13% (241 pts) had acute aortic syndrome (half were type A dissection)

– in terms of their clinical risk score, very few were zero risk and most were somewhere in between

– dimer was 97% sensitive overall and 64% specific (which seems quite high to me…)

– still 8 people with negative dimer and aortic syndrome  (3% of their +ve scans)

– when they combined the risk score and dimer it was better and they only missed one but the risk score had to be zero

– about half didn’t get definitive imaging and outcomes here are based on 14 day follow up

The Score

– Predisposing (marfans etc, fhx, known AV disease, known aneurysm, recent aortic manipulation) 1 Point

– Pain features (abrupt,severe, ripping, tearing) 1 Point

– Physical finding (pulse difference, focal neuro, diastolic murmur, shock) 1 Point

Overall – i don’t think I would use this as an algorithm tomorrow but the risk score has interesting features that are worth documenting on everyone.

I always find it interesting what a reasonable positivity rate should be for any given condition. 10-20% rule in rate seems reasonable for PE (a much less serious condition) and a 7% rule in rate for SAH (in the Perry Study) so 13% for something like acute aortic syndrome seems very reasonable and if anything we should be scanning more.

Other Links:



Charlotte Davies

Jacob De Wolff

Codes: CAP22

Back in May we reviewed a paper saying that contrast nephropathy probably wasn’t really a “thing”and in this podcast, we have a further look in to it, because a large meta analysis is in pre-publication!

Acute Kidney Injury After Computed Tomography: A Meta-analysis

Ryan D. Aycock, MD, MS MD, MS Ryan D. AycockEmail the author MD, MS Ryan D. Aycock, Lauren M. Westafer, DO, MPH, Jennifer L. Boxen, MLS, MA, Nima Majlesi, DO, Elizabeth M. Schoenfeld, MD, MS, Raveendhara R. Bannuru, MD, PhD

Invasive procedures are different to contrast nephropathy, but even they probably don’t have risk


Andy Neill

Dave McCreary

Clinical Question:

Is intraosseous (IO) access associated with improved survival in out of hospital cardiac arrest?

Title of Paper:

Intrasosseous Vascular Access Is Associated With Lower Survival and Neurologic Recovers Among Patients With Out-of-Hospital Cardiac Arrest

Journal and Year:

Annals of Emergency Medicine. 2017.

Lead Author:

Takahisa Kawano


•IO is a quick way and reliable of gaining vascular access in a cardiac arrest patient

•It is thought that it minimises interruptions in CPR, decreases time to vascular access and therefore potentially improves outcomes

Recently published data questions this, showing an associated between IO access and decreased survival to hospital with no improvement in outcomes at hospital discharge.

Study Design:

•Secondary analysis of PRIMED trial’s prospectively collected dataset

Patients Studied:

•Adults with non traumatic out-of-hospital cardiac arrest with either IV or IO access


◦Patients with failed attempts at either IV or IO access

◦Patients with both means of access

◦Patients with no vascular access


•Intraosseous access as initial access route


•Intravenous access as initial access route


•Favourable neurologic outcome at hospital discharge

Modified Rankin Scale score 0-3

Summary of Results:

•13,155 cardiac arrests analysed

◦660 IO (5%)

◦12,495 IV (95%)


◦Intraosseous = 23.9%

◦Intravenous = 38.3%

•Survival to hospital discharge:

◦Intraosseous = 3.8%

◦Intravenous = 10.3%

•Favourable neurological outcome:

◦Intraosseous = 1.5%

◦Intravenous = 7.5%

•IO group had:

◦More non-shockable rhythms

◦Fewer public location and witnessed arrests

◦ALS paramedics arrival

•IV group had:

◦More fibrinolytics (1.3 vs 5.7%)

◦More interventional catheterisation (12 vs 24%)

Clinical Bottom Line:

No evidence to change practice here.  If we’ve said it once, we’ve said it a hundred times – “association does not equal causation” and this study is no different.  There are a multitude of reasons why IO patients in this study will have had worse outcomes.  The question needs an RCT if it is to be answered.


Dan horner

Andy Neill

Codes: CAP6, CAP7

Dan Horner (@RCEMProf) is a dual trained EP and intensivist in Manchester. He writes on St Emlyns and has a special interest in VTE research.


1. Douma RA, le Gal G, Sohne M, Righini M, Kamphuisen PW, Perrier A, et al. Potential of an age adjusted D-dimer cut-off value to improve the exclusion of pulmonary embolism in older patients: a retrospective analysis of three large cohorts. BMJ (Clinical research ed). 2010 Mar 30;340(mar30 3):c1475–5.

2. Whiting PF, Rutjes AWS, Westwood ME, Mallett S, Deeks JJ, Reitsma JB, et al. QUADAS-2: a revised tool for the quality assessment of diagnostic accuracy studies. Ann Intern Med. American College of Physicians; 2011 Oct 17;155(8):529–36.

3. van Es J, Mos I, Douma R, Erkens P, Durian M, Nizet T, et al. The combination of four different clinical decision rules and an age-adjusted D-dimer cut-off increases the number of patients in whom acute pulmonary embolism can safely be excluded. Thromb Haemost. 2012;107(1):167–71.

4. Jaffrelot M, Le Ven F, Le Roux P-Y, Tissot V, Rame E, Salaun P-Y, et al. External validation of a D-dimer age-adjusted cut-off for the exclusion of pulmonary embolism. Thromb Haemost. Schattauer Publishers; 2012 Apr 30;107(5):1005–7.

5. Penaloza A, Roy PM, KLINE J, Verschuren F, le Gal G, Quentin-Georget S, et al. Performance of age-adjusted D-dimer cut-off to rule out pulmonary embolism. Journal of Thrombosis and Haemostasis. 2012 Jul 3;10(7):1291–6.

6. Schouten HJ, Geersing GJ, Koek HL, Zuithoff NPA, Janssen KJM, Douma RA, et al. Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis. BMJ (Clinical research ed). 2013 May 3;346(may03 1):f2492–2.

7. Righini M, Van Es J, Exter Den PL, Roy P-M, Verschuren F, Ghuysen A, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism. JAMA. 2014 Mar 19;311(11):1117.

8. Jaconelli T, Crane S. Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 2: Should we use an age adjusted D-dimer threshold in managing low risk patients with suspected pulmonary embolism? Emergency Medicine Journal. BMJ Publishing Group Ltd and the British Association for Accident & Emergency Medicine; 2015 Apr;32(4):335–7.

9. Flores J, de Tena JG, Galipienzo J, García-Avello Á, Pérez-Rodríguez E, Tortuero JI, et al. Clinical usefulness and safety of an age-adjusted D-dimer cutoff levels to exclude pulmonary embolism: a retrospective analysis. Internal and Emergency Medicine. Springer Milan; 2015 Sep 2;11(1):69–75.

10. Han C, Zhao Y, Cheng W, Yang J, Yuan J, Zheng Y, et al. The performance of age-adjusted D-dimer cut-off in Chinese outpatients with suspected venous thromboembolism. Thrombosis Research. Elsevier Ltd; 2015 Oct 1;136(4):739–43.

11. Crawford F, Andras A, Welch K, Sheares K, Keeling D, Chappell FM. D-dimer test for excluding the diagnosis of pulmonary embolism. Cochrane Database Syst Rev. 2016 Aug 5;(8):CD010864.

12. Takach Lapner S, Julian JA, Linkins LA, Bates SM, Kearon C. Questioning the use of an age-adjusted D-dimer threshold to exclude venous thromboembolism: analysis of individual patient data from two diagnostic studies. J Thromb Haemost. 2016 Aug 31;14(10):1953–9.

13. Monks D, Neill A, D B, Moughty A, A M, Timmons A, et al. Age Adjusted D-Dimer for exclusion of Pulmonary Embolism: a retrospective cohort study. Irish Medical Journal. 2017 Aug 9;110(7):1–6.

14. van der Hulle MD T, MD WYC, MD SK, MD LFMB, van Bemmel MD T, van Es MD J, et al. Simplifed diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. The Lancet. Elsevier Ltd; 2017 May 22;:1–9.


Chris Walsh

Chris Connolly

This was recorded at EMTA 2017 with our own Dr Chris Walsh, a man with a PHD in E-learning with a heavy slant on FOAMed!


Dave McCreary

Andy Neill

Codes: CC21

Author: Chiew, Clinical Toxicology 2017

Background: We like to think that we know paracetamol toxicity inside out. But we’ve seen some recent changes in the UK guidance surrounding staggered OD that we’ve covered on RCEM Learning before. There are some tox experts who feel massive paracetamol OD should be managed slightly differently too.


– data from a prospective database coordinated by Aussie poison centres

– >40g OD arbitrarily defined as massive here and they only included these

– they want to see if charcoal administration and a higher does of NAC in the third bag was associated with reduced concentrations at 16 hrs and ultimately less hepatotoxicity


– 200 pts

– they found 14% heaptotoxicity overall (some of these were post 8hrs, but some were treated within 14 hrs)

– quite  a few had double paracetamol peaks (these were given AC) and they think this might be pharmacobezoar

– getting AC was associated with better outcomes

– some got high doses of NAC and they seemed to do better too


– I think it’s useful in highlighting the limitations of guidance for one of the most common ODs that we see every shift.

The occasional massive one should probably be managed with expert help

– the high lactate within the first few hours

– very high levels

– give the AC even if late

– continue to measure levels

– possible increased does of NAC in the 3rd bag

it’s of course all retrospective and observational but a useful way to think of paracetamol ODs – just like all PEs are not the same so all paracetamol ODs are not the same.

Further Reading:

– Found this via Bryan Hayes site, in a broader discussion of charcoal


Fin Mcnicol

Nikki Abela


Fin is director of communications at Aintree Hospital and this was recorded at the RCEM ASC in Liverpool in 2017


Dave McCreary

Andy Neill

Clinical Question:

Is IV paracetamol superior to PO paracetamol as an adjunct to opioids for moderate to severe pain?

Title of Paper:

Intravenous versus oral paracetamol for acute pain in adults in the emergency department setting: a prospective, double-blind, double-dummy, randomised controlled trial

Journal and Year:

EMJ. 2017.

Lead Author:

Jeremy Furyk


We (and likely our patients) like to think that if you give paracetamol “through a drip” then it must be better…it must…mustn’t it? That’s the case for some antibiotics, and other analgesics like morphine. And I’ve certainly been guilty of the “more expensive therefore better” approach when it comes to buying gadgets…booking hotels…ordering dinner…

There is method to our madness in that IV must have better bioavailability, achieving target plasma concentration more quickly, and avoiding first pass hepatic metabolism.  The thought is that this will provide faster onset of action, increased analgesic effect, and therefore a decrease in opiate use and the side effects that go along with them.

But is this the case with IV paracetamol? There have been some studies previously comparing its efficacy to that of IV morphine for a renal colic, back pain, and limb trauma in the ED.  They found it to be at least effective, though none have demonstrated superiority, and there haven’t been studies comparing IV to good old fashioned (and exquisitely cheap) oral paracetamol.

Patients Studied:

•Adults with acute pain ≥ 40mm on VAS at 5 minutes post at least 1 dose of opioid

Intervention / Comparison:

•1g of oral paracetamol OR oral placebo

•AND 1g of IV paracetamol OR IV placebo (normal saline)


•Primary: Reduction of the VAS from baseline at 30 minutes

•Secondary: VAS reduction at other time points; adverse events; reduce analgesia; patient satisfaction; ED LOS; proportion of patients achieving “clinically significant” reduction in pain (≥ 50% of baseline on VAS)

•Powered to detect difference of 15mm, requiring sample of 44 in each group

◦n=87 for final analysis (47 IV and 40 PO)

Summary of Results:

Primary outcome:

•No Difference in mean VAS at t=3-mins IV vs PO

◦IV group – mean VAS 65.0mm -> 51.5mm (-13.5mm)

◦PO group – mean VAS 71.3mm -> 54.2mm (-17.1mm)

◦Difference -2.6mm (P 0.62)

Secondary outcomes (IV vs PO):

•Rescue opioids: 86% vs 84% (P 0.69)

•Patient satisfaction: 100% vs 90% (P 0.10)

•ED LOS: 195 minutes vs 203 (P 0.95)

•Reduction in VAS ≥ 50%: 25.5% vs 20.0% (P 0.54)

Clinical Bottom Line:

Cheap and cheerful wins the day.  At least when it comes to generalised use, oral paracetamol is as effective as IV.  There are probably some patients that will benefit, but maybe this should encourage us to give some thought before we crack out the expensive stuff.