Friday, November 16, 2012

Don't ß-Blockade Cocaine Chest Pain

Or, specifically, ignore this evidence that says you can.

There may be some mythology to the hypothesis that non-selective ß-receptor blockade is contraindicated in the setting of cocaine chest pain.  After all, the supporting evidence consists only of small, laboratory case series – and other outcomes-oriented data suggests ß-blockade is cardioprotective, as we already know.  However, this study is a perfect example of inappropriately extending a conclusion from retrospective data.

These authors identified 378 patients from retrospective chart review, selecting patients with chief complaints of chest pain and positive toxicology tests for cocaine.  Unfortunately, urine toxicology tests for cocaine stay positive for days following the initial episode of cocaine use.  Therefore, there is no way from these chart review methods to reliably differentiate the acuity of the cocaine intoxication.  

This is important because a major flaw in retrospective reviews, such as this, is a confounding selection bias.  If all cocaine chest pain patients are not created equal – the neurohormonal effects of cocaine last on the minutes to hours while their drug tests are positive for days – then providers may be selecting patients for beta blocker use/non-use based on acuity information this review cannot detect.  If providers are excluding patients from beta-blockers based on the acuity of their intoxication – as many sensible providers might – and only using beta-blockers in non-acute presentations, then this study may not include any of the population of interest.

The authors' statement of "We have found that BB use in the acute management of cocaine-associated chest pain did not increase the incidence of MI" cannot be defended as accurate, as it is based on indefensible assumptions.

"Safety of β-blockers in the acute management of cocaine-associated chest pain"
http://www.ncbi.nlm.nih.gov/pubmed/23122421

Wednesday, November 14, 2012

The Hazards of Love

"Sexual activity is mechanically dangerous, potentially infectious and stressful for the cardiovascular system."

Indeed!

According to this retrospective review of 11 years of electronic health records from University Hospital Bern, Switzerland, they identified 445 patients seeking emergency care secondary to sexual intercourse.  The majority of emergency department visits were secondary to suspected infectious etiologies (62%), but neurologic complaints, trauma, and cardiovascular incidents comprised the remaining portion.  

The trauma portion probably speaks for itself without need for additional detail.  There was one myocardial infarction and one aortic dissection.  Among the "various complaints", two patients were diagnosed with "eczema".  However, among the neurologic emergencies, there were 12 cases of subarachnoid hemorrhage and 11 cases of – ah – "transient global amnesia".

All things being equal, at least, sexual activity was only associated with 0.1% of emergency department visits – hardly the most dangerous of potential choices of recreation.

"Sexual activity-related emergency department admissions: eleven years of experience at a Swiss university hospital" 
http://www.ncbi.nlm.nih.gov/pubmed/23100321

Monday, November 12, 2012

Viral Testing in Children With Fever

This study attempts to address the question we've been asking ourselves since the dawn of antibiotics – does this child with a fever have a viral infection, or a bacterial infection?  Of course, in reality, we should be asking a more complicated question – does this child have a viral infection, or a bacterial infection for which the increased likelihood of positive outcome with antibiotics outweighs the harms of the antibiotics?  But, I digress.

One hypothesis that is bandied about in literature and practice is, if rapid viral testing were available in the Emergency Department, perhaps a positive viral test result would reduce the likelihood of antibiotic usage.  These folks from Washington University performed viral PCR for a host of common viruses on 75 children with fever without a source, 15 children with probable bacterial infections, and 115 afebrile children presenting for outpatient surgery.  The authors note the patients with bacterial infections were less likely to test positive for a virus – and suggest prospective trials might describe a strategy in which viral testing decreased antibiotic use.

In their cohort, 55% of children aged 2 to 12 months and 39% of those aged 13 to 24 months with no obvious source for fever received antibiotics.  This is irresponsible lunacy.  However, a much faster, cheaper way to decrease antibiotic use is:  to simply return from the abyss of antibiotic overuse to a land of rational practice.  

After all, 40% of the bacterial infections and 35% of the outpatient surgical patients tested positive for a virus – clearly indicating the presence of a virus has limited association with acute viral illness or absence of an acute bacterial infection.  More tests are not the answer – at least, certainly not this battery of PCR tests.

"Detection of Viruses in Young Children With Fever Without an Apparent Source"
http://www.ncbi.nlm.nih.gov/pubmed/23129086