Research and Reviews in the Fastlane 044

Research and Reviews in the Fastlane
Welcome to the 44th edition of Research and Reviews in the Fastlane. R&R in the Fastlane is a free resource that harnesses the power of social media to allow some of the best and brightest emergency medicine and critical care clinicians from all over the world tell us what they think is worth reading from the published literature.
This edition contains 10 recommended reads. The R&R Editorial Team includes Jeremy Fried, Nudrat Rashid, Soren Rudolph, Anand Swaminathan and, of course, Chris Nickson. Find more R&R in the Fastlane reviews in the R&R Archive, read more about the R&R project or check out the full list of R&R contributors

This Edition’s R&R Hall of Famer

Emergency Medicine, Cardiology
R&R Hall of Famer - You simply MUST READ this!
Nuotio I, Hartikainen JE, Grönberg T, Biancari F, Airaksinen KE. Time to cardioversion for acute atrial fibrillation and thromboembolic complications. JAMA. 2014 Aug 13;312(6):647-9. PMID: 25117135

  • This is an interesting research letter suggesting that we might be a little bit “button happy” with our defibs in the case of new onset AF. I’ve always been a big fan of DCC for new AF and assumed that the “within 48hrs” was a useful protection against stroke. This small research letter (with 5000 cardioversions) suggests the rate of thromboembolism might be as high as 1% in the first 30 days following unanticoagulated DCC. As it’s only a research letter there’s not much details in the way of methods but gives pause to think before you charge. Especially considering that rate control and anticoagulation seems to produce the same outcomes. Hat tip to @drjohnm for the link
  • This retrospective review challenges the widely accepted concept that patients with recent onset atrial fibrillation of less than 48 hours duration are safe for cardioversion without preceding anticoagulation. The authors report a 1.1% risk of thromboembolism after symptoms have been going for greater than 12 hours (vs 0.3% in the < 12 hour group). Before practice is completely changed, though, it should be noted that the rate of CVA after cardioversion in anticoagulated patients (3 weeks of therapeutic anticoagulation) may be as high as 0.8%. Additionally, this study suffers from the standard flaws of all retrospective studies. More research is needed to help answer this question and guide management.
  • Recommended by: Andy Neill, Anand Swaminathan
  • Read More: Shocking AF — What’s the rush? (Dr John M), Should the 48-hour Cardioversion Window Be Revised? (EM Literature of Note)

The Best of the Rest

Emergency Medicine
R&R Hot Stuff - Everyone’s going to be talking about this
Courtney DM et al. Prospective multicenter assessment of interobserver agreement for radiologist interpretation of multidetector computerized tomographic angiography for pulmonary embolism. J Thromb Haem 2010; 8: 533-9. PMID 20015156

  • This study looks at the agreement between radiologists in reading CTPAs for pulmonary embolism. They found that more than 10% of studies initially read as positive were later read as either negative or indeterminate. Many of the change in read occurred in subsegmental embolisms. This study throws further doubt on starting patients on long term anticoagulation based on the presence of a subsegmental pulmonary embolism.
  • Recommended by: Anand Swaminathan

Education

Raemer DB. Ignaz semmelweis redux? Simul Healthc. 2014 Jun;9(3):153-5. PMID: 24401925

  • As a rabid in situ simulationist it is good to be tempered now an then by a brilliant article. Dan Raemer, one of the many sim gurus from the Center for Medical Simulation and Harvard Medical School, writes about the pros and cons of in situ simulation. The cons provide food for thought.
  • Recommended by: Chris Nickson

Critical Care

R&R Hot Stuff - Everyone’s going to be talking about this


Marik PE. Iatrogenic salt water drowning and the hazards of a high central venous pressure. Ann Intensive Care. 2014 PMID: 25110606

  • If the author doesn’t make you want to read this, then the title will. Paul Marik’s talk on EMCrit took the FOAMiverse by storm – this article is really the distillation of his ideas about over-resuscitation, chloride toxicity and the uselessness of the CVP for assessing euvolaemia. IT is typically iconoclastic and persuasive. A word of caution, ideas like chloride being toxic are far from proven and though they may well turn out to be true we should guard against creating new dogma before the truth is really known.
  • Recommended by: Chris Nickson
  • Listen to more: Fluids in Sepsis, A New Paradigm – Paul Marik (EMCrit)

Resuscitation

R&R Hot Stuff - Everyone’s going to be talking about this

Driver BE, Debaty G, Plummer DW, Smith SW. Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation. Resuscitation. 2014 PMID: 25033747

Critical Care, Cardiology


Antonucci E, et al. Myocardial depression in sepsis: from pathogenesis to clinical manifestations and treatment. J Crit Care. 2014 Aug;29(4):500-11. PMID 24794044

  • An awesome bench to bedside review, summarizing the basics of the pathogenesis, diagnosis, and treatment of myocardial depression in sepsis.
  • Recommended by: Sa’ad Lahri

Resuscitation


Heradstveit BE, Heltne JK. PQRST – A unique aide-memoire for capnography interpretation during cardiac arrest. Resuscitation 2014 PMID 25063372

  • End tidal CO2 monitoring has become a mainstay in resuscitation. This article gives a mnemonic device for applying capnography during resuscitation. This tool can help bridge the gap from theory to application for many practitioners.
    P – Position of the tube
    Q – Quality of compressions
    R – Return of spontaneous circulation
    S – Strategy for further treatment
    T – Termination of resuscitation
  • Recommended by: Anand Swaminathan

Critical Care, Haematology, Infectious Disease


Rohde JM, et al. Health care-associated infection after red blood cell transfusion: a systematic review and meta-analysis. JAMA. 2014 PMID: 24691607

  • A meta analyses providing further evidence for a restrictive PRBC transfusion policy as those patients in liberal groups were more likely to acquire hospital associated infections. A goal of Hb <7 provided a NNT of 20 to reduce infection.
  • Recommended by: Jeremy Fried

Haematology

Sezik S, Aksay E, Kılıç TY. The Effect of Fresh Frozen Plasma Transfusion on International Normalized Ratio in Emergency Department Patients.  J Emerg Med. 2014 Jul 26. pii: S0736-4679(14)00636-2. doi: 10.1016/j.jemermed.2014.04.042. [Epub ahead of print] PMID 25074780

  • Fresh frozen plasma (FFP) is commonly used to reverse elevated international normalized ratios (INRs) in patients with coagulopathy and trauma or anticipated procedures.  While prior studies and recommendations have demonstrated that FFP does not reduce the iNR below 1.7, FFP is often given to patients with minimally elevated INRs.  This cross-sectional retrospective study of 87 patients who received FFP and had their INR re-checked within 6 hours found that the degree of improvement in INR is greatest in those with the most elevated INRs. They found the following reductions in INR per unit of FFP:
    INR <2:  0.03
    INR 2-5: 0.77
    INR 5-9: 2.14
    INR 9-12: 4.63
    The study has limitations and correcting numbers isn’t the same as fixing patients, but it’s good to know the gains of an intervention, especially as transfusions have associated risks.
  • Recommended by: Lauren Westafer

Emergency Medicine, Imaging


Carpenter CR, et al. Adult scaphoid fracture. Acad Emerg Med 2014; 21: 102-121. PMID 24673666

  • In this systematic review, only the absence of snuff box tenderness to palpation had an adequate negative likelihood ratio (- LR = 0.15) to affect management. MRI was found to be better than bone scan, CT or ultrasound for the diagnosis. This is in stark contrast with traditional teaching that only MRI can rule out occult scaphoid fractures in the acute setting.
  • Recommended by: Anand Swaminathan

The R&R iconoclastic sneak peek icon key

Research and Reviews The list of contributors R&R in the FASTLANE 009 RR Vault 64 The R&R ARCHIVE
R&R in the FASTLANE Hall of Famer R&R Hall of famer You simply MUST READ this! R&R Hot Stuff 64 R&R Hot stuff! Everyone’s going to be talking about this
R&R in the FASTLANELandmark Paper R&R Landmark paper A paper that made a difference R&R Game Changer 64 R&R Game Changer? Might change your clinical practice
R&R Eureka 64 R&R Eureka! Revolutionary idea or concept R&R in the FASTLANE RR Mona Lisa R&R Mona Lisa Brilliant writing or explanation
R&R in the FASTLANE RR Boffin 64 R&R Boffintastic High quality research R&R in the FASTLANE RR Trash 64 R&R Trash Must read, because it is so wrong!
R&R in the FASTLANE 009 RR WTF 64 R&R WTF! Weird, transcendent or funtabulous!

That’s it for this week…

That should keep you busy for a week at least! Thanks to our wonderful group of editors and contributors Leave a comment below if you have any queries, suggestions, or comments about this week’s R&R in the FASTLANE or if you want to tell us what you think is worth reading.

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End Tidal CO2 in TBI

Does End Tidal CO2 correlate with PaCO2 in Traumatic Brain Injury?

Your neurosurgeons and trauma team have accepted a transfer to your hospital for intensive management of a trauma patient who presented to a small community hospital with a traumatic subarachnoid hemorrhage and epidural hematoma after being involved in a motorcycle accident.

Upon arrival with the critical care transport team, the patient is already intubated and stable on a a ventilator with appropriate sedation and stable hemodynamics.  However, the neurosurgeons are in the operating room managing a spontaneous intraparenchymal hemorrhage and there are no available ICU beds due to multiple gun shot victims from a gang fight that you finished admitting.

While the patient is in the ED, the neurosurgeons recommend maintaining eucapnea for the patient since while there are no acute signs of herniation.(1). 

Can you use the end tidal CO2(etCO2) or do you need to rely on arterial blood gas (ABG) measurements to maintain PaCO2 between 35-40 mm Hg? 

In trauma patients the most robust evidence for the correlation between etCO2 and PaCO2 comes form a prospective observational study in Emergency department patients at a single center conducted by Lee et. al in 2009.(2)  The median difference of PaCO2 and etCO2 was 3.6 mm Hg and greater in patients with severe hypotension and lactates > 7 mm/L.  To have maximal safety it is safe to assume that the etCO2 generally underestimated the PaCO2 by at least 5 mm Hg and the PaCO2 can be at least equal but possibly higher than the etCO2.

However in poly trauma patients especially those with severe chest and abdominal trauma there was as little as a 29% acceptable correlation of 5mmHg between the etCO2 and the paCO2.(3)  In those cases Warner et al. in 2009 concluded that there is an unacceptable correlation between etCO2 and PaCO2 in the very sick and severely injured trauma patients.  It is more likely that the etCO2 is artificially low and is a measure of relative perfusion and less correlated with the PaCO2 and ventilation.  These patients should have arterial PaCO2 measurements performed by ABG and most likely will benefit from an arterial line for monitoring resuscitation efforts.

Case conclusion: Since the patient remained hemodynamically stable on the ventilator and only suffered from isolated TBI, you performed an initial ABG at found a PaCO2 of 37 mmHg and observed an etCO2 of 39-41 mm Hg by waveform capnography.  For the next 3 hours in the ED you continued to monitor the etCO2 and did not perform any repeat ABGs. 

Bottom Line:  End tidal CO2 will differ most from PaCO2 in the severely injured and in patients with shock.  In isolated hemodynamically stable Traumatic Brain Injury, the etCO2 should correlate relatively well by at least 5mm Hg.

For more details and a continually updated list of evidence for this topic see:
http://www.wikem.org/wiki/EBQ:End-Tidal_CO2_PaCO2_correlation 

  1. Badjatia N, Carney N, Crocco TJ. Guidelines for prehospital management of traumatic brain injury 2nd edition. Prehospital Emergency Care. 2008;12(s1):S1S52. doi:10.1080/10903120701732052.
  2.  Lee S-W, Hong Y-S, Han C, et al. Concordance of End-Tidal Carbon Dioxide and Arterial Carbon Dioxide in Severe Traumatic Brain injury. J Trauma. 2009;67(3):526530. doi:10.1097/TA.0b013e3181866432
  3. Warner KJ, Cuschieri J, Garland B, et al. The Utility of Early End-Tidal Capnography in Monitoring Ventilation Status After Severe Injury. J Trauma. 2009;66(1):2631. doi:10.1097/TA.0b013e3181957a25.
Edited by Manpreet Singh

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International traveling with medications?

It’s something that most don’t think about. Many readers of this blog are lucky enough to not have chronic medical problems, but not all are. Still, most of us regularly interact with an increasing number of patients with chronic conditions. And more and more of those patients are traveling internationally, potentially due to the treatments they are now able to receive. But what are the rules for people travelling with their medications and medical devices?

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These authors set out to figure out how hard it is to find the requirements for travellers who may need to bring medications or medical devices with them. They determined 25 popular destination countries for Australian tourists, and then searched their embassy websites for 5 categories of information pertaining to medications, required documentation, and customs information. They also sent an email to each embassy requesting information about the same topics. They then rated the embassy websites using the RATER scale, which is a modified Service Quality tool (SERVQUAL).

In 2 weeks, they got responses back from 11 of the 25 embassies they had emailed. This lack of service was mirrored by the impressively low scores the embassy websites received on their RATER scales. And even though the title and attempt of the study was to include medical equipment, neither the email responses nor the websites gave any guidance on medical equipment.

More concerning is the fact that no country followed the recommendations of the International Narcotics Control Board, which is an independent body that exists to help carry out the UN Drug Control Conventions.  All of them had more restrictive policies, some so severe as to require the patient to go to a local physician to certify that the medication is needed. Now, we mostly talking about narcotic and psychotropic medications, and generally supplies of less than 30 days. Anabolic steroids will also raise eyebrows in many countries.

Basically, the recommendations boil down to these.

  • Only possess your own medications
  • Carry the prescription or other documentation for those medications
  • Check with competent authorities in your destination countries well before travelling

For travelers planning on spending more than 30 days? Not much guidance, as you probably will have difficulty bringing it through customs initially, and you may have trouble getting prescriptions filled once there. And for those with medical devices (think neurostimulators), make sure to carry backup batteries and plenty of documentation for them.

Unfortunately, while the thought behind their study was valiant, the poor response rate combined with apparently terrible embassy websites means that each person travelling with controlled medications has their homework cut out for them. Still, without much else out there, it gives everyone a place to start.

Note that this doesn’t apply to medical providers carrying medications for expedition or humanitarian purposes. There is an entirely different set of rules for that.

Travelling with medications and medical equipment across international borders
http://www.travelmedicinejournal.com/article/S1477-8939(14)00133-1/abstract

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