Tuesday, November 22, 2011

Another Call to Retire Dopamine

The slow, gradual shift from dopamine to norepinephrine as the vasopressor of choice in septic shock has another piece of ammunition - this time a meta-analysis of the observational and randomized trials.

They perform two separate analyses - an analysis of five observational trials and an analysis of six randomized trials.  They find heterogeneity and no difference in the observational analysis - and then drop the observational trial responsible for the heterogeneity, and find an RR for mortality of 1.23 favoring norepinephrine.  Then, with the randomized trials, they find an RR for mortality of 1.10 favoring norepinephrine.  The RR for arrhythmias associated with dopamine use was 2.34 in their pooled analysis.

Of the RCTs, most of the patients came from one trial with 1044 patients and includes four trials with fewer than 50, so it's not exactly as though this analysis adds a lot of statistical power - but it's enough to reinforce the trends from each trial.

It is reasonable to suggest that norepinephrine is superior to dopamine - but I would also suggest the magnitude of that difference, given the data we have so far, has only been shown to be small.

"Dopamine versus norepinephrine in the treatment of septic shock: A meta-analysis"
http://www.ncbi.nlm.nih.gov/pubmed/22036860

Monday, November 21, 2011

Prolonged QT - Don't Believe The Hype?

Much ado is made about the risk of QT prolongation and the development of malignant arrhythmias, particularly Torsades de Pointes - but how frequently does TdP actually occur in these patients who QT prolongation?  Should we be worried about every EKG that crosses our paths with a prolonged QT?

It seems, like so many things, the answer is yes and no.  This is a prospective observational study from a single institution that installed cardiac monitoring that enabled minute-by-minute measurement and recording of QT intervals in their monitored inpatient population.  They evaluated 1,039 inpatients for 67,648 hours worth of time, and found these patients spent 24% of their monitored time with a prolonged QTc (>500ms).  One single patient had a cardiac arrest event where TdP was evident on the monitoring strip - a comorbidly ill heart failure patient whose QTc ranged as high as 691ms.

The authors then went back to attempt to determine whether the prolonged QT was associated with all-cause mortality with the 41 patients who died during their study period, and they found that 8.7% had QT prolongation versus 2.6% who did not.  However, as you can imagine, there are massive baseline differences between the QT prolonged population and the non-QT prolonged population, many of which contribute greater effects to in-hospital all-cause mortality.  The authors attempt logistic regression and finally come up with an OR of 2.99 for QT prolongation for all-cause mortality - which is lower in effects than CVA, obesity, pro-arrhythmic drug administration, and high serum BUN.

It's reasonable to say that patients with a prolonged QT are at higher risk for death - but it's also reasonable to say that sick patients at a higher risk of death are more likely to have a prolonged QT.  Torsades was rare, even with the thousands of hours of QT prolongation noted.  I would not get over-excited about QT prolongation in isolation, but, rather, only in the context of multiple risk factors for mortality in acute illness.

"High prevalence of corrected QT interval prolongation in acutely ill patients is associated with mortality: Results of the QT in Practice (QTIP) Study"
http://www.ncbi.nlm.nih.gov/pubmed/22001585

Saturday, November 19, 2011

Health Information Exchanges Might Save Money

Though, from this data, it's not clear through what mechanism.

This is an retrospective billing database evaluation of Memphis Emergency Department visits between 2007 and 2008.  In Memphis, 12 EDs participate in an online data repository, which may be accessed by secure web connection.  The authors compared patients presenting to the Emergency Department for whom this medical record was accessed to patients for whom this record was not.

There were no baseline differences between the demographics of the study groups, although, this retrospective evaluation cannot account for the factors contributing to why physicians chose to access the information exchange for individual patients.

The results are rather odd.  The authors cite cost savings as a result of an OR of 0.27 for inpatient hospitalization after accessing the information exchange.  However, the frequency of basically every other type of activity stayed flat or increased - in fact, the OR for Head CT was 5.0 and a chest x-ray was 4.3 if information exchange records were accessed.

More tests?  Fewer admissions?  I'm not sure it's practical to generalize the effects of an information exchange on medical decision making in a retrospective fashion such as this.

"The financial impact of health information exchange on emergency department care."
www.ncbi.nlm.nih.gov/pubmed/22058169

Friday, November 18, 2011

Skipping the LP in Infants 30-90 Days - Eh.

This is another one of those "practice-changing" types of articles, where the authors try to debunk some specific aggressive diagnostic or therapeutic modality that is over-utilized in a low-prevalence, high-risk population.  This article, which you may have already seen, is regarding the need for a lumbar puncture in infants between 30 and 90 days.

They perform a retrospective review of nonconsecutive infants between 30 and 90 days of age who presented to the Emergency Department and received the "septic workup" - urinalysis/culture, blood culture, and lumbar puncture/CSF culture.  They analyze a data set of 392 infants, the overwhelming majority of which are completely culture negative.  52 of them are culture positive on their urinalysis, 13 are culture positive in the blood, and 4 are CSF culture positive.  The authors note that only one patient who had a positive urinalysis also had a positive CSF fluid culture – and that infant did not qualify as a low-risk infant by the Rochester criteria – so a well-appearing infant with a positive urinalysis need not undergo LP.

So, essentially, this study tells us only that meningitis is rare and that UTIs are common.  The authors attempt to make the flawed logical argument against LP in their discussion by emphasizing the negative predictive value for meningitis in the setting of an abnormal UA is 98.2%.  However, they erroneously discount the negative likelihood ratio of 0.87 (95% CI, 0.5–1.5).  Therefore, statistically speaking, based on their results, repeating this study 100 times could lead to nearly half the study results showing a positive urinalysis favored concomitant meningitis.

Now, in a clinical sense, the authors are likely correct.  An infant who looks well, meets the Rochester criteria, has an identified source for fever, and will be receiving antibiotics is at low risk for meningitis – by prevalence alone, not by anything this study shows – and is probable to have a good clinical outcome since they're receiving antibiotics (in the event that same organism is resulting in a well-appearing, subclinical systemic and cerebrospinal bacteremia).  The argument should not be that you can generate a zero-risk population with their combination of +UA and Rochester, but that the risk of bad outcome may be similar to the risk of harms associated with the lumbar puncture, false positives, and follow-on treatment/testing.

"Is a Lumbar Puncture Necessary When Evaluating Febrile Infants (30 to 90 Days of Age) With an Abnormal Urinalysis?"

Wednesday, November 16, 2011

ED Nursing Hand-Offs & Stroke Outcomes

Yet again, in the "little things matter more" series of dull, but important, Emergency Department literature.  TPA or no, what matters more in terms of their ultimate outcome is everything that happens down the line.

This is a retrospective review of consecutively-collected prospective registry data for acute ischemic stroke patients in Louisiana, looking at patients who were present in the ED during shift change.  They simply reviewed and compared the outcomes of 366 consecutive patients, looking at good outcome, neurologic worsening, discharge status, and development of pneumonia.

There are, unfortunately, huge, irreconcilable differences between the shift-change and non-shift change groups - the group that was in the ED had milder strokes and was less likely to have TPA 9.5% vs. 4.5% - but still ended up developing more pneumonia.  After their mathematical adjustments for various baseline differences, being present during shift change ended up with a five-fold increased odds of developing pneumonia, resulting in decreased likelihood of discharge to home or rehab.  The authors attribute this primarily to non-adherence with stroke unit dysphagia precautions, which is probably reasonable.  This is just retrospective and observational, but it probably identifies an important operations issue for the Emergency Department.

So, perhaps it does matter whether you give TPA or not - if TPA gets them out of the ED faster, that will help more than anything.

"Emergency Department Shift Change Is Associated With Pneumonia in Patients With Acute Ischemic Stroke"
http://stroke.ahajournals.org/content/42/11/3226.short

Tuesday, November 15, 2011

The Cure For Bleeding is More Bleeding?

Intraventricular TPA for intraventricular hemorrhage - I wouldn't call it counter-intuitive, but I would certainly call it unusual.

This is a small placebo-controlled, randomized, blinded, prospective trial enrolling 48 patients with intraventricular hemorrhage requiring placement of an intraventricular catheter for CSF drainage.  They were testing the theory that low-dose TPA would assist in clot breakdown, thus speeding recovery.  There are probably not significant differences between groups - although the placebo group was oddly mostly women.  Also fascinatingly, the predicted mortality of each group was ~74% - and ended up being 23% in the placebo group and 19% in the TPA group.  Serious adverse events including 61% in the TPA group and 36% in the TPA group.  Due to the small sample size of the cohort, none of these differences reached statistical significance.

Unfortunately, the screaming major flaw in this study is that they do not truly have a control group - a true control would be standard care without the use of placebo administration through the intraventricular catheter.  Their rate of ventriculitis (8% and 9%) is higher than the typically expected rate for intraventricular catheter placement (probably below 5%), and is consistent with prior studies that showed increased incidence of ventriculitis when the catheter is used for administration of drugs or irrigation.  So, the safety profile and minimal outcome trend in favor of the TPA group can't truly be evaluated because it isn't being compared to the current standard of care, which is leaving the catheter alone for drainage only.

The authors conclude these results support further evaluation - which is already ongoing in the CLEAR III trial - and that the treatment met their pre-defined safety profile cut-offs.  Unfortunately, yet again, propagating their skew on the data is motivated by financial interests - Johns Hopkins has applied for a use patent and Genentech is behind the rtPA licensing and funding.  

"Low-Dose Recombinant Tissue-Type Plasminogen Activator Enhances Clot Resolution in Brain Hemorrhage"

Sunday, November 13, 2011

Big Pharma Is Behind The Money Hemorrhage

This is a research letter from the Archives of Internal Medicine that received a good deal of press recently, examining exactly where in the health system we were wasting money.

They focused on the ambulatory setting, used the NAMCS/NHAMCS database, and evaluated for the activities identified in the "Good Stewardship Working Group" identified by consensus to be low-yield and unnecessary.  They considered this to include antibiotics for afebrile/non-strep pharyngitis, routine EKGs, CT and MRI for uncomplicated low back pain, DEXA scans for young women, etc.  And they found - and this is where the big story comes in - $6.7 billion in these consensus not-recommended activities.

Fortunately for our Internal Medicine and Family Medicine colleagues, they actually weren't ordering a lot of unnecessary tests - $175 million for low back pain and $527 million for DEXA are a lot of money, but still a drop in the bucket.  The majority of the unnecessary activities, $5.8 billion of the total $6.7 billion, was writing for a brand-name statin (atorvastatin or rosuvastatin) instead of one of the generics.

Certainly just the tip of the iceberg.  Drug reps are more than earning their salaries, apparently.

"'Top 5' Lists Top $5 Billion"
http://www.ncbi.nlm.nih.gov/pubmed/21965814

Saturday, November 12, 2011

When Parents Refuse a Septic Workup

This is a brief commentary and discussion regarding the implications of parental refusal of hospitalization and evaluation of a potentially septic neonate.  It is absolutely an issue we all hope to never face, but probably will at some point in our careers.

Two pediatricians offer differing opinions on the extent to which social work and child protective services need be involved, raising such issues as the threshold percentage for likelihood of serious bacterial infection/bacteremia should be for "imminent harm" to the child, and the perceived benefits of therapy.  No specific answers are gleaned from the article, but it is worth reading and thinking through the discussions you would have in a similar situation.

"When Parents Refuse a Septic Workup for a Newborn"
www.ncbi.nlm.nih.gov/pubmed/22025599

Thursday, November 10, 2011

Ethanol - Miracle Drug (For Stroke)

From China, in Stroke, an animal model (poor rats, as usual) of MCA ischemia, collagenase-induced ICH, and post-TPA ICH.  Rats received either 0.5 mg/kg, 1.0 mg/kg, or 1.5 mg/kg ethanol after two hours of MCA occlusion.  Performance on various foot, balance, and parallel behavioral testing significantly favored the ethanol treatment group with initial and sustained reduction in errors as compared to the no-treatment group.

No difference was found between groups in induced ICH volume, and in their (small) series, no increase in ICH after TPA administration.  A transient increase in expression of hypoxia-inducible factor 1-alpha favoring ethanol was seen at 3 hours after reperfusion, gone by 24 hours.

I cannot wait to see the day where we give IV ethanol for acute stroke.

"Beer, the cause and solution to all the world's problems."

"Neuroprotective Effect of Acute Ethanol Administration in a Rat With Transient Cerebral Ischemia"

Wednesday, November 9, 2011

Computers - Probably Better Doctors for UTI

Uncomplicated urinary tract infections are probably one of the diagnoses that Emergency Physicians handle the worst - if they come to the ER, they're likely to get some sort drawn-out testing, whereas, if they went to their regular physician or called the nurse hotline, there would be antibiotics waiting for them at the pharmacy before they finished talking.

This is a prospective study in which patients with possible UTI were referred to a triage kiosk to complete a standardized computer questionnaire.  624 patients with possible UTI interacted with the kiosk - and unfortunately, only 103 qualified for the study by having enough features of typical, low-risk illness.  Patients were then randomized to protocolized antibiotic prescription as reviewed by a triage physician or usual care.

The good news - the kiosk saved a lot of time (89 minutes vs. 146 minutes).  The bad news - there were only 41 patients  followed-up in the intervention group and 26 followed-up in the control group, so we end up with only a tiny number of patients in each arm.  The kiosk group received more antibiotics for negative urine cultures than the control group (93% vs. 67%), so there is some additional element of harm secondary to antibiotic exposure - and, with a limited protocol, there are potential misses - and this study isn't large enough to identify them.

But, really, uncomplicated, typical UTI symptoms in women shouldn't be rocket science - and you shouldn't necessarily be doing any testing.  I would say the computer is a better physician - except, it would be absolutely simple for a physician to simply narrow their approach to match the efficiency of the kiosk with, in theory, some added skill.

"A Randomized Trial of Computer Kiosk–expedited Management of Cystitis in the Emergency Department"

Tuesday, November 8, 2011

Conflict of Interest in TPA Literature

Another tiny bit of self-promotion - a new publication published today.  Stems essentially from a literature review I did after clawing through ECASS-III and noting that 12 of the 14 investigators were paid, sponsored, or employed by the manufacturers of alteplase - which muddied my estimation of the reliability of the conclusions.  Turns out, ECASS-III wasn't the only one....

"Pharmaceutical Sponsorship Bias Influences Thrombolytic Literature in Acute Ischemic Stroke"

Monday, November 7, 2011

Resident Productivity Does Not Predict ABEM Scores

Simple, single-institution study of 11 years of resident in-service scores, patients-per-hour, and ABEM qualifying examination scores - and, as previously shown, only PGY-3 in-service examination scores predicted ABEM oral and written examination scores.

Simulated oral board examination scores did not correlate with ABEM oral examination scores, and the relative number of patients-per-hour had no significant correlations between any testing.

I would say that bears out my observational experience - doing more has no bearing on whether you might be doing more incorrectly.

"Outcome Measures for Emergency Medicine Residency Graduates: Do Measures of Academic and Clinical Performance During Residency Training Correlate With American Board of Emergency Medicine Test Performance?"
www.ncbi.nlm.nih.gov/pubmed/21999560

Good luck to everyone taking their ABEM exam today!

Sunday, November 6, 2011

CTA Contrast Probably Increases ICH With TPA

...although the authors of this study draw the opposite conclusion.

In an effort to decrease the administration of TPA to stroke mimics and TIAs, some institutions are moving to the use of CT angiographic and perfusion studies after the initial non-contrast scan.  Previous studies have suggested an association between iodinated contrast administration and ICH after TPA.

These authors beg to differ.  In their study cohort, they retrospectively evaluate 319 patients receiving TPA for acute stroke, 69 of whom receive contrast and 243 who do not.  Depending on whether the ECASS or SITS-MOST definition of symptomatic ICH is used:
 ECASS - 4 of 69 (5.8%) with contrast, 12 of 243 (4.9%) without contrast
 SITS-MOST: 3 of 69 (4.4%) with contrast, 9 of 243 (3.7%) without contrast

...and that small absolute difference does not reach statistical significance because their numbers are so small.  This does not prevent the authors from stating "we found no association of either IV contrast administration or contrast dose with SICH in our series of patients treated with IV rtPA."  They're not wrong - but they barely address how underpowered their study is, or how every baseline characteristic (age, stroke severity, comorbid conditions) favored their contrast group, yet they still trended towards increased ICH.

Does the author of every TPA article live in a distortion field that blinds them to reasonable consideration of safety issues and study limitations?

"Iodinated Contrast Media and Cerebral Hemorrhage After Intravenous Thrombolysis"
http://stroke.ahajournals.org/content/42/8/2170.short?rss=1

Friday, November 4, 2011

Predicting Deterioration After Admission

This is a decidedly unsexy topic that I guarantee your Medical Director or QI committee cares about a lot.  Particularly where I work, we occasionally have a prolonged boarding event, the patient isn't reassessed in a certain time frame, the patient is transported out of the ED - and they arrive on the floor or step-down and Rapid Response is called for an unanticipated escalation in care.

This is apparently a bigger deal in the United Kingdom, because it is recommended by their government hospital body to employ a risk-stratification system to predict patient deterioration.  These two articles discuss the derivation in the UK and the validation in Canada of the "ViEWS" score, which is named in part by from their electronic health record that stores their physiologic data.  The general gist of the system is that the authors of the first article derived a score incorporating pulse, respiratory rate, temperature, systolic BP, O2 saturation, whether patient was on oxygen, and a measure of CNS alertness.  They then compare it do several other scoring systems and amazingly enough, the scoring system they derive - using the system from the company the authors' wives work for and in which they own shares of stock - works better than the other systems.

An abbreviated version of this is put into validation at a Canadian hospital that does not use any of the equipment, or have any financial conflict of interests.  They found equally good results - which, in summation they give as four risk-stratification groups:
 - < 3 points: 65% of all patients, only 0.02% died within 48 hrs.
 - 3-6 points: 28% of all patients, 0.41% died within 48 hrs.
 - 7-10 points: 6% of all patients, 3% died within 48 hrs.
 - >11 points: 0.7% of all patients, 13.8% died within 48 hrs.

So, yes, we all can probably look at the patients scoring >11 and know they're sick without a scoring system.  However, this might be a model to look at with nursing staff to help change the parameters for floor beds or to reassess which patients can be downgraded in order to free up more intensive resources upstairs.  Just don't necessarily buy the product being hawked by the original authors.

"ViEWS—Towards a national early warning score for detecting adult inpatient deterioration."
www.ncbi.nlm.nih.gov/pubmed/20637974

"Validation of an abbreviated VitalpacTM Early Warning Score (ViEWS) in 75,419 consecutive admissions to a Canadian Regional Hospital"
www.ncbi.nlm.nih.gov/pubmed/21907689

Thursday, November 3, 2011

Medication Errors During Resuscitation

According to previous literature from 2002, up to 19% of medication doses are administered in error to hospitalized patients.  Presumably, we've improved.

Apparently, we haven't.  This is a prospective observational study by pharmacists in Pittsburgh who observed the inpatient Medical Emergency Team in operation - which in this instance, was a physician-led team with "full" critical care capabilities, as opposed to their non-physician Rapid Response Team.  They observed medication administration during 50 of these calls and found that there were 1.6 errors per medication administration.  Yes, they really observed more than one error per dose - but 66% of those issues involved aseptic technique.  Subtracting those, they observed an error merely every other dose.  46% were prescribing errors, 28% administration technique, 14% mislabeling, 10% preparation, and 2% improper doses.  The authors eventually conclude that 14% of the total non-aseptic errors were truly harmful, not just "errors".

Despite the small sample size, I think it's a fair assessment that "medical emergency" situations can be chaotic and error-prone - and we still have a ways to go to implement systemic changes to prevent errors.

In the end, the pharmacists' solution is - more pharmacists.  Hmmm....

"Medication Errors During Medical Emergencies in a Large, Tertiary Care, Academic Medical Center"
www.ncbi.nlm.nih.gov/pubmed/22001000

Tuesday, November 1, 2011

Dabigatran Worsens/Does Not Worsen Bleeding

Stroke and Circulation are both Journals under the umbrella of the American Heart Association.  So, when they publish articles that come to contrasting conclusions, I find that entertaining.

Both of these articles are mouse models of bleeding on dagibatran, C57BL/6 or CD-1 mice.  Sadly, they are frighteningly complex in their adjustments and statistical analyses - which means it defeats my ability to concisely summarize the findings and methods.

In short, one of these articles looks at intracranial hemorrhage after collagenase injection for mice receiving several different doses of oral dabigatran, and compare it to controls, warfarin, lepirudin, fondaparinux, and heparin.  It appears, and the author's final conclusion is, that dabigatran is the least harmful of all anticoagulants - about halfway between controls and the other anticoagulants.  They also shoot the mice with lasers in another portion of the study, and dabigatran "wins" that as well.

The other article looks at trying to reverse dabigatran - which, if you recall the human study I posted a few weeks back, was not successful in humans.  However, human trials were all surrogate markers of bleeding as measured by laboratory measurements of clotting.  What entertains me is, in contrast to the other study, these authors have no trouble inducing bleeding and significant ICH formation with dabigatran.  In any event, once the mice were adequately bleeding, the authors compared prothrombin concentrate complexes (specifically, Beriplex), FFP, and FVIIa for treatment of ICH 30 minutes after induced injury with collagenase.  Happily, PCCs, in a dose-dependent manner, attenuated the induced ICH, while the others failed.

So, perhaps this "novel, reversible" anticoagulant has a treatment option for life-threatening bleeding.  Human confirmation, at least case reports, needed.

"Anticoagulation With the Oral Direct Thrombin Inhibitor Dabigatran Does Not Enlarge Hematoma Volume in Experimental Intracerebral Hemorrhage"
http://circ.ahajournals.org/content/early/2011/09/11/CIRCULATIONAHA.111.035972.abstract

"Hemostatic Therapy in Experimental Intracerebral Hemorrhage Associated With the Direct Thrombin Inhibitor Dabigatran"

Monday, October 31, 2011

Sodium Polystyrene Sulfonate For Lithium Toxicity

This one is for @drsamko, thanks to his tweet yesterday.  


The most recent of 19 articles in pubmed for the search "sodium polystyrene sulfonate lithium", a retrospective cohort review looking at the use of SPS in the treatment of lithium toxicity.  Given that lithium and potassium are similarly charged cations, multiple animal studies evaluated its use in lithium overdose, but only case reports in humans.  These authors reviewed 9 years of cases at their institutions, two hospitals in Montreal, Canada, for the effect on lithium serum half-life between patients prescribed SPS vs. patients who were not prescribed SPS.


They only looked at chronic overdoses admitted for management - 90 patients, 72 chronic, 48 had data points to properly evaluate the half-life.  36 received "standard treatment" and 12 were prescribed SPS.  The authors don't well-describe the standard treatment group, and don't indicate whether any received hemodialysis - but I get the impression the treatment for chronic toxicity only employs HD on rare occasions of renal failure.  Of the 12 that received SPS, most simply received IV hydration and observation in addition to SPS - and one received hemodialysis due to renal failure.  Half-life of lithium in the controls was 43 hours compared to 20.5 hours in the SPS-receiving group.


SPS isn't totally benign - there was mild hypokalemia in half their treatment population - and in rare cases it causes intestinal necrosis.  And, considering chronic lithium toxicity generally has a benign course, you could go either way.  You can certainly argue that decreased hospital length-of-stay is a significant financial and health benefit and justify giving it, though, so it's worth knowing about.


"Successful treatment of lithium toxicity with sodium polystyrene sulfonate: a retrospective cohort study"
www.ncbi.nlm.nih.gov/pubmed/19842945

Saturday, October 29, 2011

Novel Ischemia Prediction from CCTA

One of the arguments against CCTA is that it only describes coronary anatomy - and has no demonstrated clinical predictive value regarding whether the observed lesions are flow-limiting or potentially related to anginal symptoms.  This study develops a computational fluid dynamics model that attempts to predict flow through coronary stenoses seen on CCTA.

Korea, Latvia, and California come together to evaluate 103 patients in a multicenter trial in which patients with suspected CAD underwent CCTA, invasive coronary angiography, and fractional flow reserve measurement.  They used only 256 and 64-slice scanners for CCTA, and CAD was quantified as none, mild (0-49%), moderate (50-70%), and severe (>70%).  Patients then underwent invasive coronary angiography where ischemia-related flow-limitation was defined as a fractional flow reserve of < 0.80.  The study group then developed a method of deriving the FFR from CCTA data, and compared it to the actual measurements from invasive coronary angiography using the same threshold value.

The conclusions from this article depend what takeaways you're looking for.  On one hand, the FFR-CT method was pretty decent - 87.9% sensitive and 82.2% specific regarding their definition of ischemia-causing lesions.  The other real takeaway is that CCTA has abysmal performance at the threshold typically used in the CCTA studies of >50% stenosis.  Their calculated +LR for CCTA stenoses >50% was only 1.51 in the setting of a specificity of 39.6%.  To me, another nail in the coffin showing CCTA is the d-Dimer of CAD, leading to a ton of unnecessary testing.

Considering it took them 5(!) hours to generate the FFR-CT measurement based on Newtonian fluid and Navier-Stokes equations on a parallel supercomputer, I don't think we'll be seeing this anytime soon - but hope is out there for the future.

"Cardiac Imaging Diagnosis of Ischemia-Causing Coronary Stenoses by Noninvasive Fractional Flow Reserve Computed From Coronary Computed Tomographic Angiograms"
http://www.theheart.org/article/1299631.do

Friday, October 28, 2011

Soft Drinks & Youth Aggression

This is not an EM article - but it was too bizarre to pass up.  Apparently, the use of soft drinks and junk food is a validated legal strategy for justifying homicide (e.g., the 'Twinkie Defense') - and this study finds an association to support it.

2,725 Boston high-school students surveyed regarding non-diet soft drink use and violence towards peers, dates, children, or firearm use.  Attempting to control for other factors, they eventually find statistically significant associations between youths who drink >5 cans of soft drinks in a week and increased alcohol use, increased tobacco use, as well as all categories of violence.  In fact, with all four categories of violence, the incidence of each increased in a dose-dependent manner with soft drink consumption.

This is, of course, an observed association, not necessarily a causal relationship, although the authors speculate on how sugars and caffeine might incite aggression.  If you are the parent of a high-school student, it isn't necessarily going to prevent violence to deny them access to non-diet soft drinks - but, if your high-school student is a heavy soft drink consumer, look out!

"The ‘Twinkie Defense’: the relationship between carbonated non-diet soft drinks and violence perpetration among Boston high school students."
http://injuryprevention.bmj.com/content/early/2011/10/14/injuryprev-2011-040117.abstract

Wednesday, October 26, 2011

Do/Don't Scan the Trauma Patient

In a study attempting to build consensus, they discovered philosophical differences between the trauma team and the emergency physician.

This is a prospective observational study in which 701 blunt trauma activations at LAC-USC were enrolled, with the EP and the trauma team each giving an opinion on which CT studies were necessary.  The authors then reviewed which scans were obtained, sorted out the scans that were undesired by one or both physicians, and determined whether any injuries would be missed.

Bafflingly, 7% of the 2,804 scans obtained during the study period were deemed unnecessary by both the emergency physician and the trauma attending - yet were still performed.  The remaining 794 undesired scans were desired by the trauma team but not the emergency physician.  Their question - would anything of significance been missed if the scans had been more selectively ordered?

The answer is - yes and no.  The trauma surgeon authors state yes, and justify that by saying that many of the abnormalities missed on CT required closer monitoring - just because none of the missed injuries deteriorated during the study period does not mean they were not significant.  The emergency physician authors point to a 56% reduction in pan-scanning, the benefits of radiation and cost reductions, and hang their hats on the fact that none of the hypothetically missed injuries changed management.

So, who is right?  Both, and neither, of course.  Emergency physicians and trauma teams should work on developing evidence-based clinical decision rules to support selective scanning in blunt trauma - and then try this study again to see if they can generate results they can agree on.

Definitely a fun read.

As far as medical literature goes, of course.

"Selective Use of Computed Tomography Compared With Routine Whole Body Imaging in Patients With Blunt Trauma."
www.ncbi.nlm.nih.gov/pubmed/21890237

Tuesday, October 25, 2011

ECMO For Influenza

Not many institutions in the U.S. are set up for ECMO in adults, particularly in the Emergency Department, but there are several small datasets out there indicating it should be a significant part of our arsenal for selected patients.  This is a review of ECMO's use in H1N1 influenza-associated ARDS in England during the "Swine Flu" pandemic.

The authors retrospectively reviewed 80 patients with H1N1 from prospectively collected cohort data, all of whom required critical care for ARDS and were referred for ECMO in the United Kingdom.  Through some data calisthenics, these 80 patients were compared to matching subgroups of patients out of 1,756 in the H1N1 critical care cohort.  Of the 80 patients referred for ECMO, only 69 actually received it.  However, when compared to these 80 patients in an intention-to-treat analysis, there was a significant survival advantage associated with referral to ECMO - approximately 24% mortality in the ECMO-referral group compared to 46-52% in the matched controls, depending on which method they used to identify matched controls.

Not a big stretch to interpret this as a positive treatment association for ECMO in H1N1-associated ARDS.  But, I'd still get your flu shot.

"Referral to an Extracorporeal Membrane Oxygenation Center and Mortality Among Patients With Severe 2009 Influenza A(H1N1)"

Sunday, October 23, 2011

EMS Blood Pressures Aren't Unreliable

Ever since a trauma patient billed as normotensive with stable vital signs rolled off the elevator with CPR in progress having "just lost pulses", I've been somewhat skeptical of my prehospital report, including vital signs.  This study, at least, supports a position that, barring untruthfulness, EMS providers vital signs are usually not clinically significantly different than vital signs obtained on arrival to the Emergency Department - even if observed techniques for EMS providers weren't perfect.

The first phase study looked at 100 patients arriving in the Emergency Department.  BP measurements were obtained within 5 minutes of arrival, and compared to the reported measurement from EMS.  There was approximately a 17mmHg +/- spread to the systolic pressures measured by EMS compared to the first BP in the Emergency Department.

The second phase of the study had observers riding with EMS and documenting the technique at which they used to find vital signs - and then having the research assistants performing the same measurement in the field as well.    In this phase, EMS providers systolic pressure was only a 10.1mmgHg +/- spread away from the research assistant - despite having ideal technique deficiencies and a terminal digit preference for numbers ending in zero.

The article concludes that EMS providers measurements had poor agreement with subsequent measurements, and that the differences were clinically significant.  However, based on the distribution of error in their Bland-Altman plots, I disagree that assessment, as most of the variability occurred throughout a range of inconsequential systolic pressures between 120 and 170.  They unfortunately had very few patients with clinically important hypo- or hypertension, so the question really remains unanswered whether EMS measurements at the clinically important extremes are reliable.

I do find it rather entertaining that their methods included a "specially trained research assistant" to measure blood pressure, referred to in the title as an "expert".  You can be an "expert" in anything nowadays, apparently.

"Agreement between emergency medical services and expert blood pressure measurements."
www.ncbi.nlm.nih.gov/pubmed/21982624