Monday, July 2, 2012

Warfarin and tPA Mix - If They're Subtherapeutic

These authors almost have a conclusion I can't quibble with - but, rather than "Among patients with ischemic stroke, the use of intravenous tPA among warfarin-treated patients (INR ≥1.7) was not associated with increased sICH risk compared with non-warfarin-treated patients" I would add the caveat to say "after multiple adjustments".

This is a retrospective registry review published in JAMA, comparing the rate of sICH in warfarin-treated patients with non-warfarin-treated patients who received tPA for ischemic stroke.  And, 5.7% of warfarin patients developed sICH vs. 4.6% in the non-warfarin group.  However, after adjustments for multiple variables - the warfarin group tended to be older, had more previous strokes, and had higher NIHSS - the OR was 1.01.  Not terribly surprising there wasn't much difference, considering the mean INR in the warfarin cohort was only 1.2.  Their confidence intervals start getting very wide above 1.6, but there's suggestion of a clear association with increasing sICH as the INR increases.

There are plenty of reasons not to give tPA, but subtherapeutic warfarin use probably should not exclude patients from consideration.

"Risks of Intracranial Hemorrhage Among Patients With Acute Ischemic Stroke Receiving Warfarin and Treated With Intravenous Tissue Plasminogen Activator"

Friday, June 29, 2012

Xigris Isn't Dead - Just Hibernating

Activated Protein C, also known as Xigris, which has had an infamous and circuitous career of sorts, is back.

After a short life of use in severe sepsis, the continued investigations into its efficacy have finally been unable to establish its benefit.  Although many expensive therapies without conclusive benefit are still in use in medicine, we'll score this one (belatedly) for the good guys.

This early animal research, published as a letter in Nature Medicine, reports on interventions targeting the aPC pathway to prevent lethal radiation injury to hematopoietic cells.  They say that starting infusions of aPC within 24 hours of lethal radiation exposure mitigated radiation mortality in mice.  Probably quite a long way off for real-world usage, but any potential treatment is better than none.

"Pharmacological targeting of the thrombomodulin–activated protein C pathway mitigates radiation toxicity"

Wednesday, June 27, 2012

Failings of Modern Medicine

A brilliant piece that eloquently states many of the ideas espoused on this blog, focusing on pulmonary embolism as the poster child for over-testing, over-diagnosis, and lack of sound evidence underlying treatment.

These authors, in the Archives of Internal Medicine, accurately describe the chimeric nature of pulmonary embolism - historically described as a dreaded disease, diagnosed clinically from the manifestations of pulmonary infarction, to the modern manifestation of filling defects noted on CTA during an episode of pleuritic chest pain.  They discuss the handful of patients who benefited from the first heparinization for treatment, and argue the disease for which anticoagulation is the treatment is not the disease we are diagnosing today.

This article covers so many excellent points, and ties the clinical problems so tightly into the underlying principles, that it's almost the sort of must-read article to which medical students should be exposed - in order to bring about that frightening moment of maturity in medicine in which you realize the emperor is distinctly lacking in clothes.

Lovely work!

"The Diagnosis and Treatment - of Pulmonary Embolism: A Metaphor for Medicine in the Evidence-Based Medicine Era"

Monday, June 25, 2012

Impaled in a Rowing Accident

This article I dredged up from the archives is mostly of sentimental value - although, I could claim it's related to Olympic sport-related trauma with the upcoming Games.

This is from the series "Case records of the Massachusetts General Hospital", which run the gamut all the way out to some of the most esoteric diagnoses possible.  This particular article describes the management and outcomes of a man impaled by a rowing shell while on the Charles River.  Eight-person rowing shells are ~17 meters in length, have a crewed weight of nearly 1,000 kg, and travel fast enough that a water skier may be towed behind.  There is a small rubber bumper affixed to the, otherwise sharp, wooden or carbon-fiber bow that is meant to reduce the potential for injury in event of a collision.  In this incident, the momentum of a head-on impact dislodged the bow ball and resulted in the unfortunate impalement incident described.  A fascinating little read.

Rowing collisions are uncommon, injuries are rare, and this is probably nearly unique.

"Case records of the Massachusetts General Hospital. Case 10-2007. A 55-year-old manimpaled in a rowing accident."

Friday, June 22, 2012

Nephropathy Was As Common as PE after CTPA

It's Jeff Kline Week at EMLitOfNote, with the second Carolinas paper this week - and, as a Patient Safety and Quality Fellow, I just can't help but cite articles that deal with the consequences of otherwise well-meaning practice.

This small study followed 174 patients undergoing CTPA demonstrated a yield of 7% for PE.  On the other hand, this same cohort demonstrated a yield of 14% for contrast-induced nephropathy - as defined by an increase in serum Cr of 0.5 mg/dL or >25%.  Three of the 24 patients with CIN progressed to severe renal failure, two of whom died.  The proportion of CIN and renal failure were similar to the outcomes observed in the additional 459 patients they followed for CT imaging on other contrast protocols.

So, the rate of CIN is not insignificant - particularly compared to the rate of diagnosis of PE at this institution.  It seems to be suggested by this study, although not shown, that the relative risk of death conferred by receiving contrast and developing CIN might even exceed the number of adverse events that might have occurred from PE if left undiagnosed or untreated.

"Prospective Study of the Incidence of Contrast-induced Nephropathy Among Patients Evaluated for Pulmonary Embolism by Contrast-enhanced Computed Tomography"

Wednesday, June 20, 2012

Chest Pain - Here, Your Problem Now

In the United States, a quarter of our medical malpractice payments result from missed myocardial infarctions.  Therefore, in states with sub-optimal liability environments, emergency physicians are stuck in a quagmire of conflicted interests and fear of litigation if a discharged patient has an MI.

Therefore, a common strategy is to make low-risk chest pain Someone Else's Problem.  And, this article from Archives of Internal Medicine shows the internist evaluating the patient simply makes the same surrender to defensive medicine.  In this retrospective cohort, 2,107 admitted patients underwent 1,474 stress tests during their two-year study period.  Of those 1,474, 12.5% were abnormal.  Of those 184 patients, only 11.6% underwent cardiac catheterization, and a grand total of 9 patients received a revascularization.

So, the authors suggest two salient points:
 - 2,107 admissions to yield 9 (supposedly) beneficial interventions - how crazy is that?
 - What about the 88.4% of patients with abnormal stress tests that didn't undergo an invasive test within 30 days - why are we using an evaluation strategy we don't act on?

The authors think we might be able improve upon this practice pattern.

"Outcomes of Patients Admitted for Observation of Chest Pain"

Monday, June 18, 2012

National Quality Measure for Pulmonary Embolism

The overuse of CTA in the Emergency Department and the over-diagnosis of pulmonary emboli of non-physiologic significance has been demonstrated as a significant societal harm.  In response to this, the National Quality Forum has been looking at developing a quality measure aimed at reducing CTA use in the Emergency Department.

The NQF estimated 7 to 25% of CTAs in the ED might be unnecessary.  From Jeff Kline's shop at Carolinas, they prospectively gathered data on all their potential pulmonary emboli and attempted to determine which scans were "inappropriate."  For their purposes, a scan was "inappropriate" if it was a low-risk patient with a negative D-dimer assay, or it was a low-risk patient without D-dimer testing.  11% were D-dimer negative and 22% were low-risk without D-dimer testing performed, which sums to 32% potentially avoidable imaging.

Of the 1,205 "potentially avoidable" scans, there were 58 positives.  The clinical significance of these potential misses is uncertain.  Whether this represents an acceptable miss rate for a quality measure in a liability prone environment is another matter entirely.

"Evaluation of Pulmonary Embolism in the Emergency Department and Consistency With a National Quality Measure"

Friday, June 15, 2012

How to Be Popular at the Beach

The summer is a great time for swimming - and, luckily, there's an evidence-based systematic review of treatment of jellyfish stings available from Annals of Emergency Medicine.  Unfortunately, it's only the relatively benign and inconvenient species from North America, rather than the life-threatening species found more commonly in the southern hemisphere.

Literally, everything has been tried on jellyfish stings in an attempted in treatment, from vinegar, to ammonia, to ethanol, to meat tenderizer, to magnesium chloride, and the list goes on.  Essentially, the attempted treatments fall into two camps - wash off the nematocysts without inducing discharge, or simply to treat the pain and tissue damage from the venom itself.

The American Red Cross First Aid consensus suggests the use of vinegar - which, according to this review, induces nematocyst discharge in everything but some Physalia species.  The real answer single agent reliably inactivates nematocysts from every organism.  The authors recommend simply using readily available saltwater to wash the affected area.  For post-envenomation pain, topical anesthetics such as lidocaine and hot water were found to be most reliably effective.  Given the limited availability of anesthetics to laypersons, the best treatment is likely to be hot water submersion to help inactivate the toxins.

"Evidence-Based Treatment of Jellyfish Stings in North America and Hawaii"

Wednesday, June 13, 2012

A Little Proof of Harms from CTs

It is popular to worry about the harms of CT scans in small children.  A retrospective Swedish study suggests decreased intelligence.  And, our models based on nuclear weapon exposure data combined with dummy CT exposure suggest these scans are likely to result in an increased risk of malignancy.

This is another retrospective study in the National Health Service of Britain comparing malignancy outcomes with their exposure to CT in childhood.  The scary headline: CT scan radiation triples the risk of leukemia and primary brain malignancy.  Of course, triple the risk is essentially 1 additional case of leukemia and 1 additional case of primary brain malignancy in the first 10 years after exposure.  So, this is potentially another study you can use to discuss the Number Needed to Harm with families when discussing the need for CT radiation in pediatric cases.

Now, whether articles like this trigger a wave of legal trolling for malignancies preceded by CT remains to be seen....

"Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours:  a retrospective cohort study"

Monday, June 11, 2012

News Flash: Diagnostic Tests Take Time

It's a little more insightful than my cynical title indicates, but it is, essentially an article that tries to quantify what we already know - blood tests, MRI, and CT all add to ED length-of-stay.

While the article isn't specifically earthshaking, it interests me in the context of patient flow through the Emergency Department and the utilization of finite ED resources.  Every ED has a waiting room - and, if you're like me, sometimes you look at the board and there are 34 waiting - on a good day.  In that sense, one becomes acutely aware of the value of space in the ED with which to evaluate new patients.  If blood tests and imaging tests are adding over an hour to ED LOS for each of your bed, then it would seem prudent to minimize those tests whenever possible.  It might also, perhaps, even be feasible to consider "standard of care" to be a malleable concept based on a need to ration testing specifically to increase patient flow, balancing the risks of diagnostic uncertainty against the risks of prolonged waiting room times.

Just brought to mind some interesting issues.

"Effect of Testing and Treatment on Emergency Department Length of Stay Using a National Database"

Friday, June 8, 2012

Daily Aspirin Harms More Than It Helps

Patients with cardiovascular disease are routinely placed on daily, low-dose aspirin for primary prevention of cardiac events.

Unfortunately, antiplatelet effects promote other types of bleeding, while the cyclooxygenase pathway has a deleterious effect on the gastric mucosal.  This 4.1 million patient propensity matched retrospective database study from Italy demonstrated approximately 2 excess cases of major bleeding events - whether intracranial or gastrointestinal - per 1000 patients treated per year.

Which is approximately the number of major cardiovascular events prevented by the daily aspirin use during the same time period.

Not specifically relevant to Emergency Medicine, but yet another example of how it's naive to think many treatments in medicine - even those (or particularly those!) that have been part of routine practice for eons - are benefiting patients without a significant risk of harms.

"Association of Aspirin Use With Major Bleeding in Patients With and Without Diabetes"

Wednesday, June 6, 2012

The Ehrlanger HEARTS3 Score

I hate using the TIMI score to risk-stratify patients in the Emergency Department.  It wasn't derived from a question asked in the Emergency Department, but has been co-opted by hundreds of studies as it has some value as part of our common language with inpatient medicine and cardiology teams.  We're familiar enough with it's shoehorning into our environment that we can use it to assist in some rough decisions about prognosis, but, clearly a better tool must exist.

A couple years back, the HEART score came out of the Netherlands.  In a small derivation and validation cohort, it did a reasonable job of predicting outcomes, using language and variables more relevant to the Emergency Department.  However, these authors from Ehrlanger in Chattanooga recognized one of the limitations of the HEART score was the somewhat arbitrary "expert" weighting of the various elements.  They therefore undertook a study with the goal of using logistic regression and likelihood ratios of the various included elements to expand the score and modify the weighting.

The good news: they improved the AUC of the scoring system from 0.827 and 0.816 for acute MI and 30-day ACS, respectively, to 0.959 and 0.902.  At the reasonable cut-off, the HEARTS3 score gets up close to ~98% sensitivity with ~60% specificity for 30-day ACS.

The bad news: a complex clinical situation requires a complex clinical decision instrument.  No one will be able to hold this in their head like the NEXUS criteria, the TIMI score, or Wells criteria - if we were even bothering to hold all these hundreds of decision instruments in our heads to start.  Luckily, smartphones, the Internet, and decision-support built-in to electronic health records is making progress towards readily available peripheral brains with which to quickly reference risk-stratification instruments such as this.

It still needs external validation, but this is one of the tools seeming to have the greatest potential I've recently seen

"Improving risk stratification in patients with chest pain: the Erlanger HEARTS3 score"

Monday, June 4, 2012

How Many Emergency Physicians Are On Twitter?


Or, at least, that's how many self-identified in their Twitter profiles as professional physicians in Emergency Medicine at the time this descriptive study was undertaken.  According to the author estimates, this accounts for ~1.6% of the ~20,000 U.S. board-certified Emergency Physicians.  The true number may be higher, owing to profiles that do not identify themselves professionally.

About half were "active" with a tweet within the last 15 days, and the other half were "inactive".  Active accounts followed more users and were followed by more users.  They also have a visualization figure showing the interconnectedness of the active Twitter accounts, and, unsurprisingly, everyone tweets to the same group of twits, and vice versa.

So, it's a small social media extension of the greater online presence of Emergency Physicians.  I'd probably say that the primary flaw with the service, regarding promoting wider interaction between online EPs, is that it is a closed, self-contained system separate from the other online resources visited by EPs.  The value is probably most to those who communicate and interact professionally in an active manner, whereas it doesn't have as much to offer the passive observer.

"Analysis of emergency physicians’ Twitter accounts"