Monday, October 29, 2012

Still Overpromising Benefit of PCI After Cardiac Arrest

The folks in France have been promoting PCI universally after cardiac arrest for quite some time.  It's an appealing concept – when you look at subgroups of out-of-hospital cardiac arrest, there's a significant portion of folks who clearly have a primary cardiac cause, and clearly will benefit from emergency or early PCI.

However, this study inappropriately tries to make the case for all patients to receive PCI and therapeutic hypothermia after out-of-hospital cardiac arrest.  This is a retrospective, cohort study spanning eight years of resuscitation, coordinated between Paris, France and Seattle, Washington.  They used vital records follow-up to determine patient status for each OHCA patient surviving to hospital discharge, and then looked for associations between survival and whether they received PCI or hypothermia in-house.  The most absurd statement is as follows:
"A beneficial survival association was evident among those with and without ST-elevation MI. This finding is provocative given the current debate about whether patients without evidence of ST elevation following resuscitation can benefit from PCI and should undergo early and routine coronary catheterization."
Retrospective studies such as this suffer from substantial selection bias, in which the patients who are selected for particular therapies have interactions and confounders that simply cannot be controlled or adjusted.  Patients benefit from PCI when they have a disease process amenable to intervention – and this is clearly not every cardiac arrest patient. The patients in this study who received PCI – and hypothermia – likely had specific features that identified them to treating physicians as candidates to benefit from these therapies.

The reasonable conclusion from the data presented is exactly that – cardiac arrest patients that have specific features that make them candidate for these therapies will benefit.  PCI following cardiac arrest should not be considered to be "routine".

"Long-Term Prognosis Following Resuscitation From Out of Hospital Cardiac Arrest - Role of Percutaneous Coronary Intervention and Therapeutic Hypothermia" 

Friday, October 26, 2012

ALTEs That Need Admission Need Admission

Coming from the west-coast PEM powerhouses of Harbor-UCLA, CHLA, and USC, this prospective observational study attempts to distill the clinical characteristics of "apparent life threatening events" requiring hospitalization.  Traditional teaching has always errs on the side of admission for ALTEs, despite the typical low-yield nature of the admission.

They collected data on 832 ALTEs, 191 (23%) of which they felt truly necessitated admission for a set of predefined criteria.  Based on this data, they came up with a simple decision rule to identify ALTEs for admission:
 - They obviously need to be admitted.
 - Concerning medical history/prematurity/congenital comorbidities.
 - >1 ALTE in 24 hours.

This captured 89% of necessary hospitalizations with a specificity of 61%, with an AUC of 0.71.

It's a bit of an odd rule that includes "obvious need for admission", but, I suppose it's rather pragmatic.  However, the adoption of a rule such as this – after prospective validation – would depend on the "acceptable miss rate" in an infant with a possible life-threatening condition.  A sensitivity of 89% probably isn't going to cut it, so, in the end, what this study is only good for is perusing the interesting data they've collected along the way.

"Apparent Life-Threatening Event: Multicenter Prospective Cohort Study to Develop a Clinical Decision Rule for Admission to the Hospital"

Thursday, October 25, 2012

November Annals of EM Journal Club

Our EM Journal Club group down here at UT-Houston collaborated to write the Annals of Emergency Medicine monthly Journal Club installment, published in the November issue.

You get the questions now – at least, they're available online starting today – but you'll have to wait in suspense for months to hear our "answers".

I don't know if it was an editorial decision to put our thinly veiled IST-3 critique on page 666 of this year's volume, but I can't imagine it's just a coincidence....

"rt-PA and Stroke: Does IST-3 Make It All Clear or Muddy the Waters?"

Wednesday, October 24, 2012

More Probably Unnecessary Head CTs/Admissions

I work at one of only two trauma centers in a city of four million potential patients, and I have firsthand experience with this issue.  The issue is to determine the best management strategy for patients with mild traumatic brain injury and bleeding.  We already know what to do with major bleeding – but patients with minor bleeding are a little more of a dilemma.  They almost universally do well, but we observe them and repeat tests on nearly all of them.

This is a retrospective review of 36 months of trauma admissions to a level one trauma center in New Jersey, trying to describe the natural progression of mild traumatic intracranial bleeding.  Historically, 1/3rd of these patients have bleeding that progresses, but only 1-3% will require neurosurgical intervention.  This review found 341 patients with mild injuries and bleeding, and noted that 69% of these patients had no interval change in head CT results when repeated at 24 hours.  Of the remaining patients, either no CT was performed (25 patients) because the injury was too insignificant or there was interval progression – including 11 patients who received neurosurgical intervention.  But, the point of the article is generally supposed to be shown in Figure 2 – estimating the number of ongoing hemorrhages at each time point in the first 24 hours.  Essentially, >80% of the bleeding ceases to expand within the first few hours from injury.

This is a useful jumping off point to perform the sort of work that isn't featured in this article – characterizing the characteristics of patients and bleeding that progresses.  If patients with bleeding unlikely to progress can be safely discharged rather than being observed for interval CT, this is a useful reduction in ED length of stay, observation admissions, or CT use.

"The temporal course of intracranial haemorrhage progression: How long is observation necessary?"

Monday, October 22, 2012

The Emergency Medicine Literature is Tragic

This is a survey of the top twelve Emergency Medicine journals, as ranked by impact factor, providing a descriptive analysis of the features of the studies contained within.  The authors manually reviewed 330 articles and found a mere 8.8% were randomized studies.  Most (65.5%) were cross-sectional studies and 23.6% were cohort studies.  57.3% were prospective, 47.9% were from the U.S., and the minority of studies (31.2%) used informed consent or mentioned waivers of informed consent.

Compared with other fields, the surveyed EM literature was less likely to mention IRB approval, less likely to be prospective, less likely to be blinded and controlled, and enrolled fewer patients per study.

There are many barriers to research in the Emergency Deparment – particularly prospective, randomized, controlled research.  However, the establishment of an office for emergency services research at the National Institutes of Health may improve the ability of U.S. researchers to obtain grant funding.  

Of course, this will then only exacerbate the bias inherent in the already U.S.-centric published literature.

"Quality of publications in emergency medicine"

Friday, October 19, 2012

Normal Procalcitonin Rules-Out Line Sepsis

The use of procalcitonin in sepsis has been evolving rapidly in the recent literature.  The theory behind procalcitonin is that, typically, it is rapidly converted to calcitonin.  However, in the presence of gram-positive and gram-negative sepsis, circulating endotoxin results in a rapid rise in procalcitonin levels not seen during viral infection.  There's a nice study showing use of procalcitonin levels allows for reductions in antibiotic use in the ICU, without a corresponding increase in mortality – which makes it a promising test to assist in antibiotic stewardship.

This is a little bit different spin on the question addressing the use of procalcitonin levels in a population that is febrile all the time – pediatrics.  Most of the time, when children are febrile, the infectious etiology is either readily identifiable as bacterial or presumed to be viral.  However, in the subset of children with indwelling central venous catheters – they're treated presumptively as line sepsis until proven otherwise, despite the preponderance of viral etiologies.

This is a small case series of 62 children with indwelling lines, 14 of whom eventually grew positive blood cultures.  Using procalcitonin levels drawn in the Emergency Department to rule out bacteremia gave an AUC of 0.82 (0.70 to 0.93) with the "optimal" cutoff at 0.3 ng/mL giving a sensitivity of 93% and specificity of 63%.  I'm not sure I'd settle for anything less than 100% sensitivity for line sepsis, but there is a point at which the risks associated with healthcare delivery are equivalent to the risks of bloodstream infection.  This is a nice idea I wasn't previously familiar with that hopefully will be confirmed in subsequent evaluation.

"Procalcitonin as a Marker of Bacteremia in Children With Fever and a Central Venous Catheter Presenting to the Emergency Department"

Wednesday, October 17, 2012

New & Improved Glasgow Blatchford Score

Clinical decision instruments that predict short-term interventions and outcomes are fabulous things – precisely the sort of instruments that help Emergency Department physicians decide who will benefit from hospitalization.

This is the Glasgow Blatchford Score, a decision instrument applicable to presentations for upper gastrointestinal bleeding.  It has been "improved" by physicians from Kaiser, who have performed addition by subtraction – eliminating variables without a significant change in performance.  The original score has eight clinical features – the "improved" version has five, dropping chronic disease, melena, and syncope from the criteria.  Despite this, the AUC for therapeutic endpoints as well as for rebleeding and mortality is no different than the original score – at 0.85 and 0.83, respectively.

It is only a 200 patient cohort, and they don't break down exactly how many patients were in each quartile of possible modified GBS, but essentially, a score of 0 or 1 means <5% chance of needing a clinical intervention, scores of 2-6 about 20% need an intervention, and anything above that is 70% chance of intervention.  The incremental improvement over regular physician judgement is not examined, but, more objective evidence is always better.

"A modified Glasgow Blatchford Score improves risk stratification in upper gastrointestinal bleed: a prospective comparison of scoring systems"

Monday, October 15, 2012

A Month's Supply of Ketamine

This is a highly entertaining, short, qualitative survey of ketamine use in April 2011 at U.C. Davis.  Ketamine is quite popular outside the United States – but hasn't reached widespread, routine use here.

Specifically, this study looks at "low-dose ketamine" a supplementary analgesia in the Emergency Department.  Usually defined in the range of 0.1mg/kg to 0.3mg/kg, the authors use 0.2mg/kg.  Ketamine was generally efficacious, and adverse events were mild – highly limited by the size of their cohort, a mere 24 patients.  But the entertaining bit are the qualitative patient comments, including:

“I was in a science fiction movie.” 
“I was on TV.”
“I was a hippie.”
“It was pure euphoria.”
“I was scared.”
“I was hot.”

“It made me sleepy.”
“I was itchy.”

 ...and many others.

"Low-dose ketamine analgesia: patient and physician experience in the ED"

Friday, October 12, 2012

When Cardiologists Risk-Stratify Heart Failure

This is the "MARKED" score, a multi-marker prognostic risk score derived from emergency department patients presenting with acute dyspnea.  The authors state they've presented a "simple, straightforward" score that "may help the treating physician at the ED to decide on urge of intervention, admission, and timing of re-evaluation."

Sounds perfect!  A valuable tool to determine which patients are at high-risk for short-term mortality, possibly to predict which patients may have unanticipated poor outcomes if discharged home?

Ah, sadly, no.

When these cardiologists risk-stratify heart failure, they're using 90-day mortality – an endpoint almost certainly irrelevant to acute evaluation of dyspnea.  The authors recognize the "single-center" aspect of their study as a limitation – but, considering this comes from a dedicated "cardiology ED" in Holland, the external validity is extraordinarily limited.  The authors also do not offer any practical suggestion regarding how this score might be used in practice – or how decision-making using this score effectively changes outcomes compared with usual care.

Finally, this "simple" score features the commonly used laboratory tests such as NT-proBNP, high-sensitivty cardiac troponin T, Cystatin-C, high-sensitivity C-reactive protein, and Galectin-3.  It should be no surprise a few authors receive compensation from Roche Diagnostics and ACS Biomarker B.V.

"Multimarker Strategy for Short-Term Risk Assessment in Patients With Dyspnea in the Emergency Department"

Wednesday, October 10, 2012

tPA of The Future

"The potential benefits associated with this approach are faster reperfusion, lower risk of hemorrhage, and earlier initiation of fibrinolytic therapy, possibly by first responders."  

Sounds lovely, yes?  This is the pie-in-the-sky version of tPA, complete with flying cars and hoverbuses.  It's a "Clinical Implications of Basic Research" article from NEJM covering a Science article about shear-activated nanoparticles.

Essentially, in a mouse model of acute arterial thrombosis and pulmonary embolism, researchers bound tPA to aggregated nanoparticles.  In normal vasculature, these aggregates remain unaffected.  However, in regions of turbulence and shear associated with stenosis, the aggregates break apart, exposing the biochemically active tPA in greater quantities.  The authors, taking cue from the current political season, promise potential 100-fold reductions in dosing of tPA associated with this serendipitously targeted approach rather than standard systemic therapy.

So, someday, instead of taking an aspirin and calling 911 – home thrombolytics?

"The Shear Stress of Busting Blood Clots"

Monday, October 8, 2012

The Drivers of Inefficient Medicine

This is a lovely feature piece in the BMJ concisely detailing that surging occult demon consuming healthcare resources under the guise of "improved health" – overdiagnosis.  It's really quite lovely to see the cultural changes coming in medicine, where increasing awareness of costs in the face of questionable benefit will reshape our profession in the years to come.

These authors, from Australia, describe twelve categories of "disease" that are expanding without obvious clinical benefit, as well as a brief overview of the sorts of practices that drive overdiagnosis.  It's a bit of a lead-in to next year's conference, Preventing Overdiagnosis, at Dartmouth University.

The entire article is worth reading, but I thought their table with the drivers of overdiagnosis was a nice summary:

  • Technological changes detecting ever smaller “abnormalities”
  • Commercial and professional vested interests
  • Conflicted panels producing expanded disease definitions and writing guidelines 
  • Legal incentives that punish underdiagnosis but not overdiagnosis
  • Health system incentives favouring more tests and treatments
  • Cultural beliefs that more is better; faith in early detection unmodified by its risks 
"Preventing overdiagnosis: how to stop harming the healthy"

Saturday, October 6, 2012

EMLitofNote on EM:RAP

With Rob Ormon[sic] of ERcast, discussing how (hopefully) coronary CT angiograms don't become as popular as July's discussants propose.

Sorry, I don't have my own readily distributable copy of the clip – but I do have an article coming in a few weeks in EMJ BMJ summarizing my views.

"CT Angio Again!"

Friday, October 5, 2012

Death By Horticulture

This case report, by the surgeons across the street at Baylor, describes a novel cause for bowel obstruction in children.  Apparently, in the course of plant cultivation, it is useful to have water-retaining gel spheres.  Advertised to retain water and grow to 400 times their original size, a child swallowed a "Water Balz" and developed a small bowel obstruction requiring laparoscopy and enterotomy.

More interestingly, the surgeons obtained five of these balls and evaluated their growth pattern.  The balls began life at ~0.95cm in diameter and, after 96 hours, reached a diameter of ~5.5cm, most of the growth in the first 12 hours.  Based on this, the surgeons estimate any swallowed balls would likely easily pass through the pylorus before resulting in complete bowel obstruction.

The claim of growth to 400 times size, however, is unfounded.  The balls they studied only grew to 200 times original size.

"Water-Absorbing Balls: A “Growing” Problem"

Wednesday, October 3, 2012

Trauma, the Hard Way

Anyone who has been to a surgery morbidity and mortality conference understands the cultural bias behind the desire to "pan-scan" all trauma patients.  If an injury is missed, and the body part wasn't scanned, someone is going to need to stand up and look foolish.

However, this article describes a trauma center in Boston that made a concerted effort to reduce CT scanning.  They came up with fifteen evidence-based guidelines for various scans and made a consensus to use these decision instruments to assist in their assessment for need for CT.  And, as you might expect, they identified significant reductions in CT scanning during their study period – 37% total reduction in number of CT scans.  If 37% doesn't sound like a big enough number, perhaps the $1.1M absolute difference in brain, chest, and abdomen/pelvis scan costs is enough to get your attention.

However, they have rather some weaknesses.  They state there were "no missed injuries", which is unusual because every study of CT in trauma patients fails to achieve 100% sensitivity – even in patients with liberal use of CT.  Then, they do have twice as many "complications" in their evidence-based scan group, as well as three times as many 30-day readmissions.  I'm not sure each complication follows from the scanning strategy, but it is an oddly significant difference.

Interestingly, they excluded patients who did not survive 24 hours.  Perhaps it complicated their abstraction process, but it is of slightly greater clinical interest to evaluate for potential missed injuries that resulted in immediate demise, rather than the misses that resulted in slightly longer-term morbidity.

"Evidence-based guidelines are equivalent to a liberal computed tomography scan protocol for initial patient evaluation but are associated with decreased computed tomography scan use, cost, and radiation exposure"

Monday, October 1, 2012

Pediatric Intubation – Not Always Successful

This is an observational study of pediatric medical resuscitation, published in Annals of Emergency Medicine, using video to evaluate the frequency of various adverse events during pediatric intubation.

As expected in a teaching institution, there is a fair bit of variability in initial success rates – ranging from 35% first-pass success for pediatrics residents up to 89% for PEM or anesthesia attendings.  Overall 52% had success on the first attempt.  Unfortunately, 61% experienced at least one adverse event during intubation.  These were typically not clinically important with regard to patient-oriented outcomes.

However,  what is more entertainingly concerning is how few of the complications make it into the medical record.  The written documentation overestimates first-attempt success, underestimates desaturation during the procedure, and even completely omits any mention of one of the two episodes of CPR required during resuscitation.

My guess is that Cincinnati Children's may have had a documentation quality review after this data were collected.

"Rapid Sequence Intubation for Pediatric Emergency Patients: Higher Frequency of Failed Attempts and Adverse Effects Found by Video Review"