Articles of the month (July 2017)

Welcome back to another edition of the articles of the month. I am considering changing the format of my article reviews going forward. Because multiple articles are grouped together in a single post, I frequently have a hard time finding articles I have reviewed when I am looking for them. I might start posting each article as its own blog post, with 8-10 posts over the course of a month. I’d love to hear what people think of that idea – whether it would be better or worse for your reading habits. Either way, Casey and I will still discuss the best articles each month on the Broome Docs podcast.

Maybe giving contrast isn’t a CIN?

Hinson JS, Ehmann MR, Fine DM. Risk of Acute Kidney Injury After Intravenous Contrast Media Administration. Annals of emergency medicine. 2017; 69(5):577-586.e4. PMID: 28131489

I’ve covered at least 2 papers on this topic before, and there should be a whole bunch more here soon, as I think this is going to be the topic of an EM Cases Journal Jam podcast soon. This is a single centre chart review that looked at 17,934 adult emergency department patients over a 5 year period. To be eligible for the study, you had to have a creatinine drawn in the 8 hours before a CT scan, and a second level drawn 48-72 hours later. There was also a control group with no CT imaging. The rate of acute kidney injury was lower in the group of patients who received contrast, but that difference disappeared with propensity matching. Depending on your definition of AKI, it occurred between 7 and 10% in all groups. However, in terms of patient oriented outcomes, only 2-4% had chronic kidney disease at 6 months, 0.5% had dialysis, and 0.1% had a kidney transplant. Contrast didn’t affect any of these outcomes. This is some of the strongest emergency department based data we have to date, but of course it is a retrospective study from a single institution, and without randomization, no matter how well you think you control for them, there will be confounders. However, the bulk of the literature seems to indicate that CIN is either a myth, or at least so rare, in terms of patient important outcomes, that it shouldn’t influence our decision to get time dependant scans in emergency department patients. Although this one paper is not enough to change your practice, hopefully I will have a deep dive into this topic finished sometime soon.

Bottom line: Contrast induced nephropathy is not evident in this dataset, and the risk is probably overblown in our minds.

The new YEARS protocol for PE

van der Hulle T, Cheung WY, Kooij S. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. Lancet (London, England). 2017; PMID: 28549662

This is yet another possible diagnostic approach to PE, but as much as that might sound painful, there is probably some value here. They used the YEARS decision tool, which is really just 3 parts of the Well’s score: clinical signs of DVT, hemoptysis, and “is PE the most likely diagnosis”? If you had none of those criteria, you used a D-dimer cutoff of 1000 ng/mL instead of the normal 500 ng/mL. If you had one or more of the criteria, you used the standard cutoff of 500 ng/mL. The study is a multicenter prospective observational study that included 3616 consecutive patients with suspected PE. They excluded pregnant patients. Their overall rule in rate was 13%. Of the patients ruled-out at the index visit, 0.6% had a VTE in the next 3 months. It was 0.4% among the patients who didn’t need a CT, and 0.8% among patients who had a negative CT in the emergency department. This is a good reminder that the negative CT isn’t perfect, and that high risk patients will have VTEs. These probably aren’t misses, but rather VTEs that develop in high risk patients, so don’t kick yourself too hard about the occasional bounce back. Even without the D-dimer, the rate of VTE in patients with 0 YEARS criteria approached the test threshold, at 3.2%. If they had added in the remaining Well’s criteria, they might not have needed a D-dimer at all. (This would fit with previous literature, which indicates that a Well’s score of 0 in emergency department patients puts you below the test threshold and is enough to stop the workup.) Using the traditional approach (Well’s plus usual d-dimer) 65% of these patients would have needed a CTPA. Using the new approach, they decreased this to 50%. (This is a high risk group of patients.) Using an age adjusted D-dimer, the rate of CT would have been somewhere in the middle. I don’t think this strategy is necessarily any better than what most of us are using right now. I definitely wouldn’t want to see more D-dimers being ordered to satisfy these criteria (and the crazy part of this study is that they ordered a D-dimer on every single patient). But the nice thing about tools designed to be highly sensitive, but not specific, is that you can use more than one depending on the patient. I will continue to stop my workup for most patients if the Well’s score is 0. However, assuming these numbers are confirmed in a validation, this allows me to take the patient with a triage heart rate of 102 but 0 of the YEARS criteria and apply a higher D-dimer cutoff. That makes sense to me.

Bottom line: We will need to see further validation of this rule, but it looks like something that we might be able to use to our patients’ and our departments’ benefit.

Once again, tetracaine doesn’t melt eyeballs

Waldman N, Winrow B, Densie I. An Observational Study to Determine Whether Routinely Sending Patients Home With a 24-Hour Supply of Topical Tetracaine From the Emergency Department for Simple Corneal Abrasion Pain Is Potentially Safe. Annals of emergency medicine. 2017. PMID: 28483289

I have written at length about this myth before. This is a retrospective study in an emergency department that changed it’s policy to allow emergency physicians to prescribe topical 1% tetracaine drops every 30 minutes as needed for 24 hours in patients with corneal abrasions. Here, they retrospectively look at 1576 patients with corneal abrasions, 532 of which were classified as simple and 1044 were non-simple. Tetracaine was prescribed for 459 of these patients (after the policy change) and there were zero serious complications (upper bound of 95% confidence interval is 0.8%). 1 patient in the standard care versus 4 in the tetracaine group required reassessment with the ophthalmologist, although none with significant issues. There were a handful of patients given tetracaine who were ultimately diagnosed with something other than a corneal abrasion, such as herpetic keratitis or recurrent corneal erosions, which emphasizes the importance of a thorough history and examination, as well as the need to limit topical anesthetic use to a short course so as to not mask important symptoms.

Bottom line: It is becoming more and more clear that topical anesthetics are safe and effective at managing pain from corneal abrasions.

The threat challenge assessment

Vine SJ, Uiga L, Lavric A, Moore LJ, Tsaneva-Atanasova K, Wilson MR. Individual reactions to stress predict performance during a critical aviation incident. Anxiety, stress, and coping. 28(4):467-77. 2015. PMID: 25396282

Emergency medicine is stressful. Dealing with an engine failure while flying a plane is stressful. I usually hate the comparisons made between the airline industry and medicine, but I think the insights into stress this paper provides may be applicable in the resuscitation room. This was a flight simulation study, so not only is the study non-medical, it is also simulated. For me to even be talking about it, my critical appraisal machinery must be on the fritz. Maybe it is all my personal bias, but I still like this study. They had 16 pilots perform high fidelity simulation of the very stressful scenario of an engine failure on takeoff. Before starting the simulation, they told the pilots what would occur in the scenario, and then asked them some questions. The pilots’ performance correlated with their answers to two specific questions:

• How demanding do you expect the task to be?
• How able are you to cope with the demands of the task?

The more pilots saw the scenario as a threat, the worse they performed in the simulator. However, if they felt well prepared and looked at the scenario as a challenge, they performed well. These effects held true even when the age and experience of the pilot was controlled for. I think this applies in the resuscitation room as well. If you walk into a room feeling overwhelmed, approaching the situation as a threat, your performance suffers. I have seen this happen to others and I have seen it in myself. If you want to perform at your best, you really need to prepare, ensuring that you will have all the resources you need at the moment of crisis. This treat/challenge assessment is discussed in (a lot) more detail in my post on performance under pressure.

IcatiCANT?

Sinert R, Levy P, Bernstein JA. Randomized Trial of Icatibant for Angiotensin-Converting Enzyme Inhibitor-Induced Upper Airway Angioedema. The journal of allergy and clinical immunology. In practice. 2017. PMID: 28552382

Although we love to jump on the newest and most exciting medications, there is a reason for the randomized control trial. There have been a number of reports indicating excellent symptom improvement for patients with angioedema after administration of icatibant. However, with no control group, the question was always: would those patient have improved anyway? There was a small industry sponsored phase 2 trial that indicated more rapid resolution of edema. This is a phase 3 RCT that randomized 121 adult patients with moderate to severe acute (within 12 hours) ACE inhibitor induced angioedema to icatibant or placebo. There was no difference in time to discharge, using prespecified and sensical discharge criteria (4 hours in both groups). There was also no difference in time to symptom relief, admission to hospital, or ICU use.

Bottom line: At this point, there is probably no role for the use of this expensive medication in the management of ACE inhibitor induced angioedema outside of study protocols.

Just a little prick

Thelle A et al. Randomised comparison of needle aspiration and chest tube drainage in spontaneous pneumothorax. The European respiratory journal. 2017; 49(4). PMID: 28404647

The ideal management of spontaneous pneumothorax has always been a little confusing to me, as different guidelines provide us with very contradictory advice, and practice seems to vary dramatically around the world. This is a randomized trial from 3 hospitals in Norway, looking at 127 adult patients with spontaneous pneumothorax, and randomizing them to either needle aspiration or chest tube. To get into the trial, you needed to have a pneumothorax that was large enough to require intervention, which they defined as a size greater than 30% of a PA chest x ray or the patient feeling more breathless than usual. Needle aspiration was done using a 16 gauge subclavian catheter attached to a 3 way stopcock and a 60 mL syringe. It was most commonly done in the midclavicular line at the 2nd intercostal space. They stopped when no more air could be aspirated or if more than 3.5 L of air had been aspirated. After aspiration, they performed a repeat chest x ray. If the pneumothorax was less than 20% and the patient was asymptomatic, they monitored the patient for 6 hours, performed another chest x ray, and then discharged the patient home. They could perform a second aspiration if the first wasn’t adequate, but then went on to chest tube. For the chest tubes, they were all connected to water seals and left overnight. Their primary outcome was length of hospital stay, and it was twice as long in the chest tube group (4.6 vs 2.4 days). This is a very different system than I work in, where the length of hospital stay, even when I am using a chest tube, is always measured in hours. About 50% of the aspirations had an adequate response, and another 50% of the second attempts at aspiration were adequate. There were no complications of needle aspiration, as compared to 15 with chest tube (4 wound infections, 2 bleeds, 7 subcutaneous emphysema, 1 pneumonia, and 1 empyema). They don’t report any patient oriented numbers, such as pain or satisfaction. Clearly, there are some problems interpreting this data, depending on what you are doing right now. This is a really long protocol. I don’t observe patients for 6 hours, but was that really necessary? If I could aspirate and do a repeat chest x ray at say 1 or 2 hours, saving half of my patients a chest tube, I think that would be a worthwhile intervention. Admission decreased by 2 days, but given that these patients are out of my department in just a few hours, that obviously isn’t relevant to me. The adverse events with standard chest tubes a very concerning. Without great follow up, I’m not sure what my adverse event rates are, but that difference alone is worth consideration of practice change. Also, although convenience and pain weren’t measured here, I would assume they favour needle aspiration. At this point, there will be readers from around the world wondering why I spent so long on this, because I know this is routine practice in some places, but I have never seen an aspiration performed in Canada.

Bottom line: The results here aren’t perfect, but I think they support consideration of needle aspiration as a first line intervention in patients with spontaneous pneumothorax.

A little more pneumo

Tschopp JM, Bintcliffe O, Astoul P. ERS task force statement: diagnosis and treatment of primary spontaneous pneumothorax. The European respiratory journal. 2015; 46(2):321-35. PMID: 26113675 [free full text]

This is the statement of the European Respiratory Society Task Force. They summarize a few other studies that indicate needle aspiration is a reasonable initial intervention, although failure can be expected in 25-50% of aspirations. The major point I wanted to pull out of this guideline is that they suggest that you should be considering the symptoms of the patient, not the size of the pneumothorax on x ray, when deciding on your intervention. They emphasize that conservative management (observation) is appropriate in many cases. If you are putting in a chest tube, make it a small one, and you don’t have to routinely use suction.

Bottom line: Less is more for most pneumothoraces

If there ain’t pus, it aint MRSA

Moran GJ, Krishnadasan A, Mower WR. Effect of Cephalexin Plus Trimethoprim-Sulfamethoxazole vs Cephalexin Alone on Clinical Cure of Uncomplicated Cellulitis: A Randomized Clinical Trial. JAMA. 2017; 317(20):2088-2096. PMID: 28535235

With MRSA ubiquitous now, and a recent study indicating that trimethoprim-sulfamethoxazole might improve outcomes for some bad abscesses, it is reasonable to ask whether we should routinely be adding MRSA coverage in patients with uncomplicated cellulitis. The short answer is no. This is a multicenter, double-blind, randomized trial that included 500 patients over 12 years of age with uncomplicated cellulitis (no abscess, purulent drainage, or wound). All patients were treated with cephalexin 500mg orally 4 times a day, and then randomized to either trimethoprim-sulfamethoxazole 4 single strength pills twice a day or placebo. The primary outcome was a relatively complicated, but sensical, definition of clinical cure. There was no difference, with 84% cure in the trimethoprim-sulfamethoxazole group and 86% cure with placebo. There were no changes in any of the secondary outcomes. Adverse events were not statistically different, but GI upset occurred 7% more often in the trimethoprim-sulfamethoxazole group.

Bottom line: MRSA makes pus. You don’t need to cover for it in uncomplicated cellulitis.

Million dollar ride

Reichert S, Lin C, Ong W, Him CC, Hameed S. Million dollar ride: Crime committed during involuntary scopolamine intoxication. Canadian family physician. 2017; 63(5):369-370. PMID: 28500194 [free full text]

Apparently common in South America, I was completely unaware of the use of scopolamine in robberies. We are probably all aware of the anticholinergic effects of scopolamine, but in reducing declarative memory, it can cause submissive and obedient behaviour. Criminals will blow the drug in a person’s face, or just lace a drink. Subsequently, the victim will apparently follow most commands, including withdrawing large sums of money from the bank and handing them over. Because it appears voluntary, it will not look like a crime to witnesses, and the victim will often have no memory of the event. Medically, speaking, there isn’t much of a role for us. The management of anticholinergic poisoning remains primarily supportive. Unfortunately, we will also have to consider the possibility of sexual assault.

Bottom line: Toxicology is cool, but humans can be downright awful.

Cheesy Joke of the Month

What is the difference between a patient in the emergency department for foot pain and person in a security line at an airport?

The person in the security line has their shoes off.