Author: Ryan Radecki

Warning: Jolt At Your Own Risk…

A guest post by Rory Spiegel (@CaptainBasilEM) who blogs on nihilism and the art of doing nothing at emnerd.com.

Jolt accentuation is a means of perturbing the meninges of a patient presenting with a headache, in the hopes of delineating those who have meningitis from those with a more benign cause. Similar to the “rock the gurney” test in appendicitis or the Dix-Hallpike in BPPV, we are exacerbating the patient’s symptoms in the hopes of better understanding their illness. It has been claimed that the jolt accentuation test is the most sensitive physical exam finding available to rule out meningitis. A recent article published in American Journal of Emergency Medicine suggests otherwise.

This elegantly constructed prospectively gathered cohort was performed at two inner city hospitals over a 4-year period. Authors enrolled all neurologically intact patients older than 18 years old presenting with symptoms suspicious for meningitis. Physicians were asked to answer a questionnaire of physical examination findings before receiving CSF results.  Cunningly the authors surreptitiously placed the LP trays at the research staff’s station to ensure capture of eligible candidates.

47 patients (20%) out of 230 total enrolled were found to have CSF pleocytosis (defined as > 5 WBC ). The jolt accentuation test performed poorly at identifying these patients, with a sensitivity of 21% and a specificity of 82%. Kerning sign, Brudzinski sign, and nuchal rigidity performed no better with sensitivities and specificities of 2%, 2%, 13% and 97%, 98%, 80% respectively. Dishearteningly, the Emergency Physicians overall gestalt performed just as poorly with a sensitivity of 44% and a specificity of 40%.

Unfortunately the authors do not tell us how the jolt accentuation test performed in patients diagnosed with bacterial or fungal meningitis.  In this cohort only 3 of the 230 patients had culture positive meningitis, with only 2 from bacterial or fungal sources (one Cryptococcal and one Meningococcal ). The Emergency Physician identified both of these cases as high-risk upon initial evaluation. The authors failed to mention whether the jolt accentuation was positive in either of these patients. To truly examine jolt accentuation’s diagnostic performance, further studies using culture positive bacterial meningitis rather than pleocytosis as our diagnostic criteria are needed. This would require a much larger cohort, including a significantly larger quantity of cases of bacterial meningitis. But until then perturb with caution…

“Jolt accentuation of headache and other clinical signs: poor predictors of meningitis in adults” www.ncbi.nlm.nih.gov/pubmed/24139448

Irreproducible Research & p-Values

I circulated this write-up from Nature last week on Twitter, but was again reminded by Axel Ellrodt of its importance when initiating research – particularly in the context of studies endlessly repeated, or slightly altered, until positive (read: Big Pharma).

The gist of this write-up – other than the fact the p-value was never really intended to be a test of scientific validity and significance – is the important notion a universal cut-off of 0.05 is inappropriate.  Essentially, if you’re familiar with Bayes Theorum and the foundation of evidence-based medicine, you understand the concept that – if a disease is highly unlikely, the rule-in test ought to be tremendously accurate.  Likewise, if a scientific hypothesis is unlikely, or an estimated effect size for a treatment is small, the p-value required to confirm a positive result needs to be greater than the one-in-twenty approximation of the traditional 0.05 cut-off.  The p-value, then, functions akin to the likelihood ratio – providing not a true dichotomous positive/negative outcome, but simply further adjusting the chance a result can be reliably replicated.

This ties back into the original purpose of p-value in research – to initially identify topics worth further investigation, not to conclusively confirm true effects.  This leads very obviously into the recurrent phenomenon through clinical and basic science research of irreproducible research.  And, indeed, Nature’s entire segment of the challenges of reproducibility in research is an excellent read for any developing investigator.

“Scientific method: Statistical errors”
http://www.nature.com/news/scientific-method-statistical-errors-1.14700

“Challenges in Irreproducible Research”
http://www.nature.com/nature/focus/reproducibility/index.html

The Eloquence of Stroke Neurologists

Entertainingly enough, as tPA proponents continue their push for longer time windows and less-stringent inclusion criteria, Stroke recently published a sort of head-to-head debate regarding tPA within the 3 – 4.5h window.

Despite the breathless madness typically exhibited by stroke neurologists and the current Level B recommendations from the AHA, Lawrence Wechsler from the University of Pittsburgh writes a very reasonable critique of ECASS III, incorporating data from ATLANTIS and IST-3.  His general point, overall, is the theoretical effect size, if any, is small beyond 3 hours.  Therefore, he proposes patients should be carefully selected – perhaps by penumbral perfusion imaging.

His opponents, from Germany, in their response, offer a critique featuring this well-written, professional, academic segment:

Is advanced imaging necessary to make this decision? Why, No?! Would a lacunar versus nonlacunar syndrome make a difference here? No!! It would not make a difference within 3 hours, would it? And what about an MRI without perfusion imaging/diffusion weighted imaging mismatch or with proof of a lacunar stroke, would this make a difference? Hell, no!!! There is no evidence at all for this conclusion. And is there any reason to believe that rt-PA does not work in the 3- to 4.5-hour time window or that it does work only in “a carefully selected set of patients”? What the h…, No, No No!!!!

In keeping with Patrick Lyden’s lovely ad hominem attacks on Anand Swaminathan (“young”, “naive”), it is yet again abundantly clear some proponents of tPA have no response in reasonable, scientific debate other than nonsensical, authoritative bluster.

“The 4.5-Hour Time Window for Intravenous Thrombolysis With Intravenous Tissue-Type Plasminogen Activator Is Not Firmly Established”
http://www.ncbi.nlm.nih.gov/pubmed/24526061

“4.5-Hour Time Window for Intravenous Thrombolysis With Recombinant Tissue-Type Plasminogen Activator Is Established Firmly”
http://www.ncbi.nlm.nih.gov/pubmed/24526060

Finding Value in Emergency Care

The Choosing Wisely initiative is, despite its flaws, an necessary cultural shift in medicine towards reducing low-value expenditures.  In a fee-for-service health system, and given the complicated financial framework associated with training and reimbursing physicians, noble endeavors such as these face significant challenges.

Regardless, many specialties – including ACEP – have published at least one “Top 5” list of recommended practices to improve value.  The ACEP Choosing Wisely list, while certainly reflecting sound medical practice, are of uncertain incremental value or applicability over current practice.  Additionally, the methods and stakeholders involved remain opaque.  Luckily, in a coincidental parallel, Partners Healthcare embarked on an unrelated internal process to improve the affordability of healthcare and reduce costs.  This study provides a transparent look at a such a process, as well as the ultimate findings.

Using an expert panel, 64 potential low-value care practices were identified in a brainstorming session, subsequently narrowed down to 17.  Then, 174 physicians and clinical practioners responded to a web-based survey, ranking the value of each.  Based on this feedback, then, the original expert panel voted again on a final “Top 5”:

  • Do not order computed tomography (CT) of the cervical spine for patients after trauma who do not meet the National Emergency X-ray Utilization Study (NEXUS) low-risk criteria or the Canadian C-Spine Rule.
  • Do not order CT to diagnose pulmonary embolism without first risk stratifying for pulmonary embolism (pretest probability and D-dimer tests if low probability). 
  • Do not order magnetic resonance imaging of the lumbar spine for patients with lower back pain without high-risk features. 
  • Do not order CT of the head for patients with mild traumatic head injury who do not meet New Orleans Criteria or Canadian CT Head Rule. 
  • Do not order coagulation studies for patients without hemorrhage or suspected coagulopathy (eg, with anticoagulation therapy, clinical coagulopathy).

It always surprises me to see these lists – which, essentially, just constitute sound, evidence-based practice.  That said, given my exposure primarily to an academic, teaching environment, rather than a community hospital environment concerned with expediency and revenue generation, these may be larger problems than I expect.  This list also does not address the estimated cost-savings associated with adherence to these “Top 5” best practices.  While many of these may result in significant cost-savings through reductions in imaging, the yield would be variable based on the quality of care already in place.

Regardless, this list is as much about the derivation process itself, rather than the resulting “Top 5”.  Certainly, the transparency documented in this study is superior to the undocumented process behind ACEP’s contribution.  That said, this list ultimately reflects the biases and practice patterns of a single healthcare network in Massachusetts; your mileage may vary.  Many of the final “Top 5” had overlapping confidence intervals on the Likert Scale for benefit and actionability, suggesting a different survey instrument may have provided better discrimination.  Finally, while we are culturally enamored with “Top 5” lists – all 64 of their original set are important considerations for improving the value of care.

We, and all of medicine, have a long way to go – but these are steps along the right path.  It is also critically important we also (wisely) choose our own destiny – rather than wait for government or insurance administrators to enforce their misguided priorities upon our practice.

“A Top-Five List for Emergency Medicine: A Pilot Project to Improve the Value of Emergency Care”
https://archinte.jamanetwork.com/article.aspx?articleid=1830019

ADAPTing & Improving

By far, the most promising of the publications to yet emerge from the ADAPT cohort – 1,974 patients evaluated for acute chest pain in the Emergency Department – is this re-analysis and decision instrument.

The original ADAPT publication, despite over 80% of the patients having no major cardiac event at 30 days, was only able to identify 20% of patients as “low-risk”.  The HEART Score and the Vancouver Chest Pain Rule improve on this, but only incrementally.  This publication, however, improves the identification of a low-risk cohort to nearly 50%.  By incorporating and weighting 37 different predictor variables, then adding a layer of expert review and acceptability evaluation, these authors ultimately arrive at the “Emergency Department Assessment of Chest Pain Score (EDACS)”.  Using age, gender, history, and symptoms, when combined with negative ECG and 0 and 2 hour troponins, a score of 16 constitutes a breakpoint for a decision instrument with ~99% sensitivity and ~55% specificity for MACE at 30 days.

As far as decision instruments go, it’s relatively reasonable – although, certainly, nothing you’d be able to keep in your head.  Scores for age range from +2 to +20, while four different symptoms and signs have varying positive and negative values.  However, in the age of computerized decision-support, at least, mildly complex rules are not as burdensome as they once were.

I would like to see, at least, prospective validation in a North American population – but this appears to be a lovely step forward.

“Development and validation of the Emergency Department Assessment of Chest pain Score and 2 h accelerated diagnostic protocol“
http://onlinelibrary.wiley.com/doi/10.1111/1742-6723.12164/abstract

Again on Giving tPA to TIAs

When I suggested to Jeff Saver in JAMA his analysis of the Get With the Guidelines Registry may have become unbalanced due to the presence of TIAs within the tPA cohort, he went back to the NINDS data and identified seven patients from the placebo arm with TIAs.  Because 3 were in the 58 to 90 minute cohort and 4 were in the 91 to 180 minute cohort, he concludes there is an equal distribution of TIAs – and thus confounders – across all time periods.  This, of course, is nonsense – he is generalizing a handful of patients from the placebo arm from NINDS, a carefully controlled trial run by stroke neurologists, to the GTWG-Stroke registry, a cohort of community hospitals rushing to hit time-based stroke quality measures.  The contemporary evidence, such as this observational series from Japan, is that most TIAs present early in their symptom course – and earlier, if symptoms are more severe.

These authors retrospectively identified 464 patients admitted to 13 stroke centers in Japan with ultimate diagnosis of TIA based on complete clinical resolution of symptoms.  233 of them (55%) presented within the first three hours and the next 65 (15%) within six hours.  The common elements for the TIAs presenting earliest were the greatest severity of symptoms, primarily motor and speech disturbances.  A full 42% of their cohort had persistent symptoms upon arrival.

In the brave new world of tPA, hospitals are falling over themselves to treat these patients with thrombolytics – patients that ultimately would experience full clinical resolution of symptoms without intervention, and receive only the risks associated with tPA administration.  These patients ultimately make their way into the GWTG-Stroke registry, and come out the back end analysis looking like tPA miracles, “proving” time-to-treatment matters with tPA.  As “code stroke” protocols become more widespread, we will see even further such collateral damage.

“Factors Associated With Onset-to-Door Time in Patients With Transient Ischemic Attack Admitted to Stroke Centers”
http://www.ncbi.nlm.nih.gov/pubmed/24262324

No LVADs Were Harmed in the Making of This Blog Post

A guest post by Rory Spiegel (@CaptainBasilEM) who blogs on nihilism and the art of doing nothing at emnerd.com.

Do not perform chest compressions on an LVAD patient in arrest is a pseudoaxiom for the 21st century. The concern is the force of the compressions will dislodge the cannula, turning a critically ill patient into a critically ill patient with an LVAD-sized hole in their left ventricle. The manufacturers staunchly warn against performing compressions at the risk of causing the sky to fall, our patient’s chest to explode, and an incredibly enraged cardiothoracic surgeon to magically appear at bedside spewing hellfire and brimstone.

Authors of this recent retrospective case series attempt to disprove this modern day axiom. This series describes 8 LVAD patients who presented to their facility, Sharp Memorial Medical Center, in arrest over a 4 year span, all of whom received external chest compression as part of the resuscitative efforts. They assessed device integrity post-arrest in two fashions, either by blood flow data from the LVAD control monitor or examination of the device itself on autopsy (a poor prognostic indicator for the patient). 7/8 patients had flow data post-arrest recorded, all of which indicated a functionally intact VAD. 3/8 had an autopsy performed, including the patient with missing flow data. All confirmed an anatomically intact VAD. The authors conclude that at least in this small case series no VADs were harmed during chest compressions. Whether they were helped is another question all together. These are complex patients with multiple variables including the function of both the VAD and the patient’s intrinsic heart. In this series, 5 out of 8 patients arrested due to pump malfunction, 4 of which were due to accidental disconnection (yikes!). Even in this cohort of a seemingly correctable malady (just plug the thing back in), only one patient had return of neurological function.

A case series of 8 patients is clearly not a large enough n to prove chest compressions are safe in the LVAD patient.  What can be said for sure is the sky did not fall and no angry cardiothoracic surgeons materialized from thin air spewing fire and brimstone. Well, at least a half a psuedoaxiom disproven…

“Chest compressions may be safe in arresting patients with left ventricular assist devices (LVADs).” www.ncbi.nlm.nih.gov/pubmed/24472494

Droperidol Never Killed Anyone

The bearer of a black box and the scourge of Pharmaceutical and Therapeutics committees, droperidol has a long history – a history where, for the most part, it is used safely for decades.

This is a small case series from a prospective trial of treatment for acute agitation in the Emergency Department.  In this study, patients requiring treatment for agitation received 10mg of IM droperidol as an initial dose, followed by a second dose within 15 minutes as needed, and further doses of droperidol as needed and in consultation with a toxicologist.  An ECG was obtained, and continuous telemetry monitoring was applied as soon as safely possible.

42 patients qualified for droperidol in this study, 29 of whom received 10mg of droperidol, 11 received 20mg, 3 received 30mg, and 3 received 40mg.  Of these, 4 patients receiving 10mg or 20mg had prolonged QT observed on ECG – to a maximum of 534ms.  The authors write, then, in their conclusion: “QT prolongation was observed with high-dose droperidol.”

A more accurate conclusion, however, would probably be: “In a limited case series, no dose-dependent relationship between droperidol and QT prolongation was observed.  QT prolongation of uncertain clinical significance was noted in a small number, but confounding co-ingestants limit the reliability of this finding.”

There ought to be, at this point, little legitimate concern over the clinical significance of the QT prolonging effects of these medicines in nearly all clinical situations.  Thanks to Ariel Cohen for sending this in!

“High dose droperidol and QT prolongation: analysis of continuous 12-lead recordings”
http://www.ncbi.nlm.nih.gov/pubmed/24168079

2-Handed BVM – Many Hands Make Light Work

A guest post by Anand Swaminathan (@EMSwami) of EM Lyceum and Essentials of EM fame.

I’ve been teaching ACLS and airway workshops for years and I always make a point of focusing on the proper technique for bag-valve-mask (BVM) ventilation. I’ve always taught people both the 1-handed and the 2-handed techniques and said that they’re basically equivalent as long as you feel like you’re getting a good seal. This study brings the efficacy one-hand BVM into question.

The authors performed an interesting study. They took a group of providers (EM residents, attendings, nurses, paramedics and ICU nurses) and had them hold face masks on simulation mannequins with 1-handed and 2 different 2-handed techniques. A ventilator provided a 600 ml tidal volume and then measured the volume returned. Since this is a closed circuit, the volume returned should be equal to the set tidal volume – whatever leaked around the “seal” created by the provider.
What they found was surprising. For the 1-handed only 31% of the set tidal volume was expired while that number was 85% for both of the 2-handed techniques. This difference was found to be statistically significant and I imagine it would also be clinically significant. A study done earlier last year by Hard et al had similar findings.1
So what stands in the way of us completely stopping the teaching and application of 1-handed BVM (unless necessary due to staffing) and embracing 2-handed BVM? Unfortunately, the study is done on simulation mannequins and not on people. What we prefer is to see the application of the study to human patients. But this isn’t always possible. In the same issue of Annals, Wang and Yealy comment in an editorial that not only would it be virtually impossible to do this study in real human patients but also that it’s likely unnecessary.2 BVM is a technique that lends itself well to being studied in a simulation model.
What we have here are two studies showing benefit of a 2-hand BVM technique on mannequins that requires no increased equipment and a minimal increase in necessary resources. Using a 2-hand system is likely a better way to bring the mandible forward and open the nasopharynx allowing for nasal oxygenation. Since we’re unlikely to see a study done on actual patients, this should be enough to change practice.
Article:
“Comparison of Bag-Valve-Mask Hand-Sealing Techniques in a Simulated Model.”
References:
1. “Face Mask Ventilation: A Comparison of Three Techniques.”
2. “Emergency Airway Research: Using All Tools to Bridge the Knowledge Gaps.”

The Rat Around Your Neck

Physicians as plague carriers – but, rather than rats, as in the Middle Ages, suppose it may be our stethoscopes.

In this observational study out of Ethiopia, 176 stethoscopes belonging to healthcare workers and students in a hospital were swabbed and cultured.  Naturally, the authors were able to grow bacteria off 86% of these, half of which were pathologic strains such as S. aureus, Klebsiella, Citrobacter, Proteus, and P. aeruginosa.  The swabs taken from the ICU harbored the greatest percentage of isolates for pathogenic strains.  Most strains demonstrated some level of antibiotic resistance, such as 27% of S. aureus which proved methicillin-resistant.

Colonization, which has previously been demonstrated on the white coats of physicians, is not proof of transmission – but it is not unreasonable to suspect this may yet occur.  However, only 3% of respondents in this study regularly disinfected their stethoscope after each patient.  Even the mildest improvement in hygiene would likely go a long way towards reducing the theoretical risks.

“Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital”
http://www.ann-clinmicrob.com/content/12/1/39