Monday, May 21, 2012

Plain C-Spine Radiography in Children

In adults, the use of plain radiography has largely been replaced in the U.S. by computed tomography over concerns regarding missed injuries - and some literature even argues that, given the right clinical circumstances, even a normal CT scan is inadequate.  But, in children, the harms of radiation exposure are greater, so pediatrics has been more hesitant to move to CT as the first imaging study of the cervical spine in blunt trauma.

Unfortunately, this retrospective PECARN study of children with cervical spine injuries isn't as helpful as one would hope.  The authors identified 204 children, 58 of whom were aged less than 7 years, who sustained a CSI and had plain radiographs of the cervical spine performed.  Of these patients, 127 patients had a definite injury on plain radiography.  41 additional patients had "possible" abnormalities.  Then, 20 films were judged to be inadequate by technique.  And, finally, there were 18 adequate radiographs with normal findings who subsequently had a CSI identified.  The overall sensitivity, then, was 90% (CI 85-94%) - which compares very similarly to the sensitivity in adults from the 34,000 patients in the NEXUS study.

The authors note that most missed injuries fell into two general categories: they were either subtle and non-morbid, or the patients were altered/intubated/focal neurologic findings.  It is probably still reasonable to start with screening plain-film radiography and use clinical judgment to determine when CT may be necessary, but if you're looking for airtight evidence to guide your decision-making, CSI in children is too rare to generate that sort of data.
"Utility of Plain Radiographs in Detecting Traumatic Injuries of the Cervical Spine in Children"

Saturday, May 19, 2012

Azithromycin - Not Guilty of Murder

The FDA has announced it is reviewing the safety of azithromycin in lieu of a recent NEJM article documenting an association between azithromycin and cardiovascular death.  In theory, azithromycin has been implicated in QT-prolongation and pro-arrhythmic effects, leading to torsades de pointes and polymorphic ventricular tachycardia.  The authors of this study therefore hypothesized an association between azithromycin use and cardiovascular death.

This is a retrospective study of computerized data generated from the Tennessee Medicaid program between 1992 and 2006, linking deaths to any concurrent antibiotic prescriptions.  The authors data-mined for a cohort aged 30 to 74 years of age, had no "life threatening non-cardiovascular illness", did not abuse drugs, and did not reside in a nursing home.  They compared azithromycin prescriptions to non-prescription controls, as well as amoxicillin, ciprofloxacin, and levofloxacin cohorts.  And, after a little statistical maneuvering, they report a death rate of 85.2 per 1,000,000 courses of antibiotics with azithromycin, which compares to a death rate of 29.8 with no antibiotic and 31.5 with amoxicillin.

So, for every ~20,000 prescriptions of azithromycin written, there is one additional death from cardiovascular causes.  This is another one of those cases where the severity of the absolute difference doesn't quite match the relative difference - it is likely any efficacy difference between a macrolide and a second-line agent results in greater morbidity than the magnitude of effect found in this study.

Then, azithromycin is frequently prescribed for upper and lower respiratory tract infections - conditions that, in the absence of other specific signs, might be non-infectious cardiovascular disease misdiagnosed as having an infectious etiology.  In their non-propensity matched cohorts, 50% more azithromycin prescriptions were written for respiratory symptoms than amoxicillin.  The propensity matching in their statistical analysis attempts to account for this, but 30% of their azithromycin prescriptions had no documented indication - which I think means there's likely a hidden statistical difference in underlying pathophysiology secondary to unknown indications.

Finally, this runs contrary to a 2005 article "Azithromycin for the Secondary Prevention of Coronary Events" published in NEJM - at one point, it was theorized that azithromycin would be protective for coronary events.  For 4,000 patients who took azithromycin weekly for a year, there was no difference in cardiovascular outcomes as compared to placebo (CI -13% to +13% relative risk reduction).

There are lots of reasons not to prescribe azithromycin, but this study isn't the one that should change your practice.

"Azithromycin and the Risk of Cardiovascular Death"

Thursday, May 17, 2012

The Papermate Flexgrip Cricothyroidotomy

Emergency Medicine has more than a little MacGyver instinct to it - and one of the semi-urban legend aspects of EM is the ability to perform a cricothyroidotomy as a life-saving measure in any situation.  The most commonly described version is performed using simple, commonly available tools - any sort of cutting blade and a hollow tube, such as a hollow pen.

Several studies have approached feasibility by describing the flow dynamics of various pens, but this is the first study to evaluate the procedural feasibility of bystander cric.  This is an observational, cadaveric study using non-EM junior physicians and medical students in which they used a 26-blade scalpel and a Papermate ballpoint pen of 8.9mm external diameter to attempt an "off-the-cuff" cric.  The 9 participants attempting 14 procedures were successful 8 times, although complications were frequent, including vascular and muscular/cartilaginous injuries.

Whether this is externally valid to the living, or to patient-oriented outcomes of effective ventilation, I'm not so certain - but, then again, if the alternative is 100% mortality via no possible ventilation, it's a fun study to see.

"Observational cadaveric study of emergency bystander cricothyroidotomy with a ballpoint pen by untrained junior doctors and medical students"

Tuesday, May 15, 2012

Reducing ED Overcrowding Reduces Mortality

In Western Australia, in 2008, a mandate was undertaken in which Emergency Departments were to implement processes requiring patients to be discharged or admitted within four hours of presentation.  These rules phased in through 2009 in the tertiary hospitals, and then in 2010 in the secondary hospitals.

Of course, with an arbitrary mandate to simply "work faster," the concerns were that this would have adverse effects on mortality.  Rather, the overall mortality of patients admitted through the Emergency Department tended to decrease during this time period.  Each of the hospitals spent less time of ED diversion ("access block") as well.

The article doesn't mention specifically what process changes were implemented, but it does allude to and likely understates the resistance met while making ED overcrowding a problem for the entire hospital.  Authors report that shifting patients out of the Emergency Department led to a greater proportion of the initial investigations being performed on the inpatient wards, leading to some professional stress.

Regardless, this article seems to suggest that it is feasible, in a culture accepting of change in practice pattern, to decrease the amount of time patients spend in the Emergency Department.  It also seems to demonstrate it is, at least, potentially safe.  That being said, it would be quite a feat to accomplish something similar here in the U.S., given the various warring incentives at work in our highly dysfunctional system.

Emergency department overcrowding, mortality and the 4-hour rule in Western Australia"

Sunday, May 13, 2012

Codeine, Potentially Unpredictably Lethal

Frequently used in the pediatric population, codeine is a narcotic analgesic in prodrug form.  In the body, codeine is metabolized to morphine through the CYP2D6 pathway.  In the general population, it is estimated that approximate 10% of codeine undergoes conversion to morphine.

We're generally familiar with the concept that a certain percentage of the population is ineffective at metabolizing codeine, and therefore receives no additional analgesic effect.  However, the flip side, as these authors report, is a CYP2D6 genotype of over-metabolizers.  In this case series, the over-metabolism of codeine in three post-surgical children likely resulted in supra-therapeutic conversion to morphine, leading to respiratory arrest.

The short summary - when possible, avoid medications that are unpredictably metabolized - such as codeine.

"More Codeine Fatalities After Tonsillectomy in North American Children"

Friday, May 11, 2012

Suprapubic Tap Should Be Used for Urinalysis in Children?

"Ideally, SPA should be used for microbiological assessment of urine in young children," states the abstract conclusion for this article from Australia.

Looking retrospectively at urine samples from 599 children with an average age of 7 months, these authors conclude that suprapubic aspiration is superior to all other methods of obtaining urine samples for contamination rates.  Contamination rates were 46% with bag urine, 26% for clean catch, 12% for catheterization, and 1% for suprapubic aspiration.

We generally rely on catheterized urine samples in our Emergency Departments - and we even have difficulty convincing some parents that this is required, let alone a suprapubic aspiration.  In fact, I'm rather surprised they had 84 patients (14%) in their cohort receiving suprapubic aspiration, considering I have never seen it performed.

While I have no issue with their conclusion from a microbiologic accuracy standpoint, I'm not so sure such an invasive and painful procedure has a place in routine practice.

"Contamination rates of different urine collection methods for the diagnosis of urinary tract infections in young children: An observational cohort study."

Wednesday, May 9, 2012

A Chest Pain Disposition Decision Instrument

This article has three things I like - information graphics, informed patients, and an attempt to reduce low-yield chest pain admissions.  Unfortunately, in the end, I'm not sure about the strategy.

This is a prospective study in which the authors developed an information graphic attempting to illustrate the outcome risks for low-risk chest pain presentations.  They use this information graphic as the intervention in their study population to help educate patients regarding the decision whether to be observed in the hospital with potential provocative stress testing, or whether they would like to be discharged from the Emergency Department to follow-up for an outpatient provocative test.  They were attempting to show that use of this decision aid would lead to increased patient knowledge and satisfaction, as well as reduce observation admissions for low-risk chest pain.

The good news: it definitely works.  Patients reported increased knowledge, most were happy with the decision instrument, and a significantly increased proportion elected to be discharged from the Emergency Department - 58% of the decision aid group wanted to stay vs. 77% of the "usual care" arm wanted to stay.

My only problem: this study truly exposes the invalidity of our current management of chest pain.  If these patients are low-risk and they're judged safe enough for the outpatient strategy in this study – why are any of them being offered admission?  Of course, it's probably because they don't have timely follow-up, and AHA guidelines dictate stress testing urgently following the index visit.  But, truly, in an ideal world, few (if any) of these low-risk patients – such as the one who ruled in by enzymes – should be offered admission.

But, other than that, I'm all for information graphics and patient education techniques to include them in a shared decision-making process!

"The Chest Pain Choice Decision Aid : A Randomized Trial"

Monday, May 7, 2012

Outpatient Management of PE - With ERCast

Hosted by the mellifluous Rob Orman, we discuss a couple recent articles regarding the outpatient management of low-morbidity pulmonary emboli.  Short summary:  overdiagnosis of pulmonary emboli of uncertain clinical significance notwithstanding, the key to managing physiologically intact patients with pulmonary emboli is close follow-up to minimize the length of time patients are subject to dual anticoagulation.

Listen at:  ERCast - Pulmonary Embolus Outpatient Treatment

The Legend of the Therapeutic Arterial Line

As many Emergency Physicians can probably attest, one of the curious practices of critical care is to catheterize every potential organ system - as though the presence of these catheters in some way improves outcomes.  And, the theory is - the non-invasive numbers are not accurate enough upon which to base treatment options.

So, this is a simple study performed in an intensive care unit in which patients with arterial blood pressure monitoring receive non-invasive measurements at the arm, ankle, and thigh (not everyone in the ICU will have an accessible arm).  And, essentially, the results show - even in the critically ill, even on vasopressors - that the mean arterial pressure in the arm is probably a accurate measurement, with a mean bias of 3.4 mmHg.  The systolic and diastolic numbers, as well as the ankle and thigh values, were not quite as precise or accurate.

For the Emergency Department, it probably tells you it's OK to do what you probably already do - critically ill patients get arterial lines only if there is a luxury of time available.  Someone else with half an hour to spare can poke around fruitlessly in the radial wrist before surrendering to the femoral....

"Noninvasive monitoring of blood pressure in the critically ill: Reliability according to the cuff site (arm, thigh, or ankle)"

Saturday, May 5, 2012

Rational Clinical Examination: GI Bleeding

This series of articles, "The Rational Clinical Examination" in JAMA is by far one of my favorite approaches to medicine.  They ask simple clinical questions, and they do literature searches to find evidence to apply.  Additionally, the form in which they distill the evidence tends to be likelihood ratios - a far more useful statistical construct in estimating how a particular finding contributes to ruling-in or ruling-out disease.

This most recent literature review covers gastrointestinal bleeding - and it covers a few worthwhile points.  Most encouragingly, the authors are exceedingly skeptical about the utility of NG tube placement - reasonable positive LR for UGIB, but, as the authors note, a suspected source is usually well-established prior to NG tube placement.  Additionally, they note that the NG lavage does not tend to influence final patient-oriented outcomes - and lean towards not recommending its use.  Secondly, they also cover the Blatchford and Rockall scores, which are decision instruments that might have value in helping triage patients for outpatient management.

"Does This Patient Have a Severe Upper Gastrointestinal Bleed?"

Thursday, May 3, 2012

How Medical Students Choose Residencies

Turns out, it's only mildly earthshaking - for some students, location is more important.  For other students, the program "fit" is more important.

The article goes on to evaluate whether there are specific factors that residency directors can influence in terms of attracting the right candidates and, obviously, none of the location-based factors are easily influenced by program leadership.  The top location-based factor was simply the attractiveness of a particular geographic location, with proximity to family being the next most important factor.

Drilling into the features of individual programs that residency directors can modify, it seems as though candidates base their decision mostly on "gut feeling" - coming down to how well they clicked during the interview session or when meeting with current residents.  After "fit" characteristics, then factors such as curriculum, length of program, and reputation came into play.  Relatively unimportant features were compensation, program size, and websites/social media run by a program.

Unfortunately, the article does not delve into what specific program characteristics residents were looking for - presumably 3-year programs were preferred to 4-year, and one of the popular curriculum questions during visits is regarding the presence of "floor" months.  However, it is an interesting overview of how candidates self-report the importance of their ranking influences.

"Factors That Influence Medical Student Selection of an Emergency Medicine Residency Program: Implications for Training Programs"

Tuesday, May 1, 2012

"Consequences" of Conflict of Interest Disclosure

As if physicians are children, and truths must be hidden from them, three consultants of the healthcare industry have published a commentary in JAMA regarding the possible adverse effects of conflict of interest disclosure. 

They provide cautionary justification for their belief that physicians who have conflicts of interest will overstate or exaggerate their results.  They believe this will happen either as a compensatory mechanism to overcome any skepticism created their reported COI, or because physicians will use their disclosure as an excuse to provide biased results "because the [audience] has been warned."  They also feel that disclosures of conflicts of interests to patients might make them anxious, which would impact the therapeutic relationship built on trust.  And, finally, they believe that all this hullabaloo about disclosure distracts from the real COI issues associated with fee-for-service and other financial arrangements that should be prioritized for reform.  I tend to think these are narrow, paternalistic arguments that downplay the critical importance of transparency.

Additionally, given a ten citation limit, they cite their own prior articles six times.  I'm not sure if this is an effective strategy to build trust in their evidence or the legitimacy of their message.

But it got them in JAMA.

"The Unintended Consequences of Conflict of Interest Disclosure"

Sunday, April 29, 2012

Hopping To Rule Out Appendicitis

The "Best Evidence Topic" reports from the Manchester Royal Infirmary are published in the Journal of Emergency Medicine.  Overall, they are meant to summarize evidence regarding more practical, clinical applications.  One of the recent summaries focuses on appendicitis, and whether eliciting pain during coughing, percussion, or hopping is useful in ruling in or out disease.

For this topic, they summarize a few articles - mostly following a prospective derivation study in which hopping/percussion/coughing was 93% sensitive and 100% specific for appendicitis.  Unfortunately, the test performance didn't quite hold up - sensitivity ranging from 72% to 89%, depending on age group, and highly variable specificities.

So, unfortunately, somewhat like the "hamburger test," you won't be able to base the entirety of your clinical disposition on this, but it's not an irrelevant input into your general clinical gestalt.

"BET 1: Is abdominal pain when asked to hop suggestive of appendicitis in children?"

Friday, April 27, 2012

Lactate Clearance and ScvO2 Goals in Sepsis

Early goal-directed sepsis care is successful - but no one can say precisely what makes it successful.  Hawthorne effect?  Early antibiotics appear to have uncertain association with better outcomes.  Is it the blood?  Is it meeting the central venous oxygenation goal of >70%?

Other studies have shown equivalency in outcomes while performing serial lactic acid measurements, and this is another study in the same vein.  203 patients form the analysis cohort, in which 93 received management decisions based on lactate clearance and 110 which received management decisions based on the ScvO2.  All included patients had both values measured simultaneously, but were blinded to the opposition.

And, this is another study where the two measures are different but similar - which is probably why the analysis is so convoluted.  Of the 203 enrolled, 175 either fortuitously or by design met the ScvO2 goal, while 178 met the lactate clearance goal.  Meeting the ScvO2 goal led to a death rate of 21% and meeting the lactate clearance goal led to a death rate of 17%.  There was no difference in therapeutic interventions between the ScvO2 goal group and the lactate clearance group.

However, if you met the lactate clearance without meeting the ScvO2 goal, you had an 8% (2/25) mortality, while the ScvO2 group that didn't clear lactate had a 41% mortality (9/22).  Unfortunately, there were a number of baseline differences between the groups, and it's hard to draw any conclusions or hypotheses from this finding.  It's also clear they didn't identify any specific interventions that improved survival in their cohort - and, more appropriately, simply observed that poor lactate clearance simply portends a worse outcome, without any specific recommendation on how to address it.

"Prognostic Value and Agreement of Achieving Lactate Clearance or Central Venous Oxygen Saturation Goals During Early Sepsis Resuscitation"

Wednesday, April 25, 2012

Most Severe Mechanism Children Don't Need Head CTs

The PECARN group has published a set of criteria that identify children at very low risk for significant traumatic injury.  This is publicly available and an excellent decision instrument to enhance your clinical judgement.  But, the problem is, with excellent sensitivity, the specificity is weak - such that a great number of patients who fail to meet low-risk criteria will still have good outcomes.

So, this is a follow-on study attempting to determine whether the severe mechanism portion of the decision instrument was predictive of significant TBI, or whether scans could be avoided if mechanism was the only positive feature in their decision instrument.  And, yes, a severe injury mechanism in isolation - at least in the 35% of their cohort who received a head CT - had only a 0.3% chance of significant injury in age <2 years and 0.6% chance of significant injury in age >2 years.  Severe injury mechanisms associated with additional PECARN criteria, however, had 4% and 6% incidence of TBI, depending on age.

Probably the most important aspect of these numbers is they allow for a better discussion of risks with parents and families.  While 1 in 150 or 1 in 300 sound like pretty good odds, when you practice long enough, those odds will catch up with you.  Even with severe mechanism and additional features, 19 of 20 CTs will be negative - you can still make a reasonable case for observation rather than knee-jerk scanning.

"Prevalence of Clinically Important Traumatic Brain Injuries in Children With Minor Blunt Head Trauma and Isolated Severe Injury Mechanisms"

Monday, April 23, 2012

Mobile Stroke Units - Probably Not Helpful

Door to needle times too long?  Well, take the needle to the patient, then.

This is an interesting idea that, unfortunately, probably isn't a good idea.  They loaded a CT scanner, a stroke physician, a paramedic, and a mobile laboratory into a truck, and sent it out to meet acute stroke patients in the field.  The primary endpoint of the study - alarm to thrombolysis time - was great, with a mean time from alarm to therapy decision of 35 minutes.

The authors are very excited about the concept - as they feel the accelerated time scale in terms of acute stroke thrombolysis represents a paradigm shift in management.  Unfortunately, the patient-oriented outcomes - which were not part of the primary endpoint - don't support their enthusiasm.

All their safety and therapeutic outcomes are underpowered, but, out of their 47 intervention patients and 53 control (in-hospital thrombolysis) patients, 12 vs. 6 were treated stroke mimics and 3 vs. 0 were dead within 7 days.  Comorbidities and stroke severity should have favored the intervention group, so, these outcomes are surprising.  But, it is underpowered, so more data is needed.

"Diagnosis and treatment of patients with stroke in a mobile stroke unit versus in hospital: a randomised controlled trial."