Saturday, July 2, 2011

Ambulance Diversion Kills People? Maybe?

This article got a ton of press - but it tries to take far too simple an approach to far too complicated an issue.  I've done research like this, where you use zip code centroids and calculated distances to nearest hospitals, and it's just one way a blind man describes an elephant.

These authors look retrospectively at all the acute MIs in four California counties, then looked at hospital daily diversion logs for each day from each of those hospitals - and tried to merge them together to prove that if your nearest hospital was on diversion for a lot of the day you had your acute MI, you had worse outcomes.

Their final analysis says, basically, there's a 3-5% difference in 30-day, 90-day, and 1-year mortality if your nearest hospital is on diversion >12 hours in a day vs. if your nearest hospital is on diversion <6 hours per day.  The between 6-12 hour diversion cohort performed identically to the <6 hour per day cohort.  So, I don't know exactly what to make of this.  Their 95% CI almost crosses zero.  Something magical happens at 12 hours that changes your acute MI mortality risk.  So, yes, what the authors are trying to prove is probably true - but this article's data mining and massage can only hypothesize the association, and doesn't prove anything.

"Association Between Ambulance Diversion and Survival Among Patients With Acute Myocardial Infarction."
http://www.ncbi.nlm.nih.gov/pubmed/21666277

Friday, July 1, 2011

Algorithmic Approach To Detect Sepsis Fails

I was asked to blog about this little article - since it lies at the intersection of Emergency Medicine and informatics.

So, that feeling you get when you look at a patient who is obviously ill?  Computers don't have that yet.  These folks tried to encapsulate that feeling of "sick" vs. "not sick" into the criteria for severe sepsis, which includes SIRS and hypotension.  The hope was that an algorithmic approach that automatically recognized the vital sign and physiologic criteria for SIRS would trigger reminders to clinicians that would spark them to initiate certain quality care processes sooner.

Out of 33,460 patients processed by the system, 398 triggered the system.  Less than half (46%) of those were true positives.  To follow that up, they tried to evaluate their system for sensitivity and specificity by pulling 1 week's worth of data (1,386 patients) for closer review - and they found the system generated 6 false positives, 7 true positives, and 4 false negatives.  And those numbers speak for themselves.

Looking back at their four quality measures, they all showed a trend towards improvement - unfortunately three of their four quality measures don't even have a theoretical connection to improved outcomes.  Chest x-ray, blood cultures, and measuring a serum lactate are all clinically relevant in certain situations, but they are all diagnostic and management decisions independent of "quality".  Antibiotic administration, however, is part of EGDT for sepsis (for what it's worth), and that trended towards improvement (OR 2.8, CI 0.9 to 8.6).  

But the final killer?  "In approximately half of patients electronically detected, patients had been detected by caregivers earlier".  So, clinicians were receiving automated pages suggesting they might consider an infectious cause to hypotension, probably while already placing central lines for septic shock.

Great concept - but automated systems just don't yet have robust, rapid, high-quality inputs like those a clinician gets just by walking in the room.  But, EM physicians in busy departments overlook things - and a well-designed system might in the future help catch some of those misses.

"Prospective Trial of Real-Time Electronic Surveillance to Expedite Early Care of Severe Sepsis."

Wednesday, June 29, 2011

Time To Let ABCD2 Die

The problem - the most difficult clinical situations are the ones where we need a handy decision tool - and the hardest to come up with an effective one.  Syncope rules, PE prediction rules, ACS prediction rules, and now TIA evaluation.

The most important number to come out of this paper is probably 1.8% - the number of patients with a TIA who went on to have a stroke in the next seven days.  That's 38 out of their 2056 patients enrolled.  The next number is 2.7%, which is the 56 patients who had another TIA within 7 days.  So somehow a rule has to magically pick out that tiny proportion of patients who are going to have bad outcomes without excessively testing the remaining supermajority.

Nearly everyone had a CT of the head, nearly everyone had an EKG, very few (15% with an ABCD2 score ≤ 5 and 22.% with a score > 5) had consultation with a neurologist, and even fewer were admitted.  The specificity for stroke within 7 days with a score >2 - the AHA definition of "high risk" - is only 12.5%.  Not only that, but there was significant disagreement between enrolling physicians and the study center regarding the correct ABCD2 score for a patient.

So, in the end, ABCD2 is difficult to apply and only minimally useful.  You're going to miss half the strokes at 7 days if you apply it in a situation where the specificity is >50% - so, sure, a sky-high score tells you they're in trouble, but that still doesn't help you discharge the majority of your TIAs safely for outpatient follow-up.

"Prospective validation of the ABCD2 score for patients in the emergency department with transient ischemic attack."
www.ncbi.nlm.nih.gov/pubmed/21646462

Tuesday, June 28, 2011

Surfactant for Hydrocarbon Aspiration

I've seen surfactant administered for alveolar collapse following near-drowning, but this is a case report regarding surfactant use in severe pneumonitis after low viscosity/low volatility lamp oil.  Less than 1mL of similar aspirated hydrocarbons may result in significant lung injury.  In their specific case they administered 80 mL/m2 of surfactant intratracheally as rescue therapy when their patient continued to become hypoxemic despite recruitment maneuvers on mechanical ventilation.

Definitely something to keep in mind depending on the pathophysiology of the lung injury.

"Early administration of intratracheal surfactant (Calfactant) after hydrocarbon aspiration."
http://www.ncbi.nlm.nih.gov/pubmed/21624880

Monday, June 27, 2011

Kids Are Too Fat For The Broselow Tape Now

Now that increasing numbers of children are overweight and obese (up to 36% of 10 to 17 year olds now), 53% of this pediatric sample from West Virginia fell out of the Broselow tape estimate based on height.  Of these, 77.1% of the incorrect weights were greater than that predicted by the Broselow.

It is West Virginia - not the healthiest state in the U.S. - but any hospital that serves a predominantly disadvantaged population may have similar results, and should realize that they may be under dosing their medications.  The authors suggest only a couple alternative strategies, but I think we're probably just best off using clinical judgement as to whether the tape is accurate in each individual clinical situation.

"Is the Broselow tape a reliable indicator for use in all pediatric trauma patients?"
http://www.ncbi.nlm.nih.gov/pubmed/21629149

Sunday, June 26, 2011

The Mortality Burden of Homelessness

Anyone working in the Emergency Department knows that homelessness and psychiatric disorders go hand-in-hand - and that also goes psychiatric disorders and substance abuse.  This study confirms what we already know about the prevalence of these issues in the homeless population.

The most interesting number I read out of it was that the life expectancy of a homeless male aged 15-24 years was 38.7, and 47.4 for similarly aged homeless females - compared to life expectancies of 60.3 and 64.8 in their general population.  It makes me wonder how much of that life expectancy difference is just the homelessness, or whether it's the psychiatric and substance abuse disorders - I would probably say most of that difference is made up with the substance abuse.

"Psychiatric disorders and mortality among people in homeless shelters in Denmark: a nationwide register-based cohort study."
http://www.ncbi.nlm.nih.gov/pubmed/21676456