Sunday, November 16, 2014

Ostrich Pseudoaxioms

An old essay I wrote, publishing it again:

"The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what's true." - Carl Sagan
In his existential exploration of earth's place in the universe, Carl Sagan came to the conclusion that truths about this universe and about our existence within it seemed to constantly contradict human explanations for it.  The human explanations for the cosmos have been fathomed since the beginning of language and perhaps even earlier, as the elementary human brain started its pondering of the skies.  In all of philosophical and religious history, the questions of why we are here were confronted by spiritual leaders, thinkers, and scientists of the time.  To conceivable each one of these theories and to almost every individual's concept of the truth of the physical world, we can confidently disregard as rubbish.
These theories whether personally derived or institutionally propagated, flow freely throughout time and are believed as if they were as true as knowing red is red. Ask one of the devout 68 million Catholics in the world when Earth was created and their answer is my proof of this.  Or, had you asked a Spaniard in the age prior to Galileo whether the sun was the center of the planetary system, you would have been met with swift censorship.  This of course would have come under the indictment given to any copernican theory of heliocentrism at the time which was that it was "false and contrary to scripture".  Human beings emotional, spiritual and philosophical brain regions are a complicated smattering of neurons that seem to resist and deny hard evidence at every opportunity.  Maybe there are some psychological or neurological explanations of this, of which I am ignorant of.  Whatever it is, it is quite clear that people stick to their guns once a decision is made.  This is particularly true when the circumstance being pondered is of a vast and overarching concept of life and its place in the universe.  However, this emotionally driven stagnation of truth exists in other aspects of human cognition.  An example I would like to discuss is that of the resistance by intelligent, learned, and honest people in the medical field whom try desperately to "hold deeply held prejudices", and to "determine truth by preference."  
In a book by Dr. David Newman, Hippocrates' Shadow, the young and hard-headed emergency physician points out endless examples of what he calls, "Ostrich Pseudoaxioms."  Imagine a fabled, yet clear and extremely simplified example: for decades physicians are taught the practice of treating heart attacks acutely with potion #5.  This practice has gone on for years without extensive study, but cases where patients lives were saved were reported in the literature and then this practice continued to be taught as the treatment.  Then suddenly, 5 major institutions across the world study potion # 5's efficacy as a treatment in randomized controlled clinical trials, the gold standard of medical proof.  Each of these studies shows that firstly, there is NO benefit to potion # 5 during heart attack when compared to a sugar pill and secondly, there were a few deaths that were convincingly due to the administration of potion #5.  Most people with average intellect would imagine the practice of giving potion #5 would stop immediately, right?  Nope, those silly doctors keep on giving it!  Well, they say, its still "in the guidelines." There are countless potion #5's that are given in medicine as we speak. Are you taking one?
 This is a dumbed down scenario of a complicated situation, but represents actual patterns of physician behavior.  The administration of potion #5 becomes a "pseudoaxiom" or a false-self-evident truth.  These are believed truths, falsely taught and proliferated by medical institutions who knowingly deny the evidence that contradicts their "truthiness" (thanks Colbert).  Physicians awareness of the evidence, but quiet denial or hiding from this contradictory data, allows these propagations to become what is known quite eloquently as Ostrich Pseudoaxioms.  Doctors are shoving their heads in the sand to avoid grappling with the acceptance of uncomfortable orcounterintuitive evidence that distorts their own hard-wired concept of what the truth is.
Maybe you always thought doctors were smart enough to make the leap into the counterintuitive, if it was proven by the science they so diligently claim to worship. Perhaps, it was always convenient to think that physicians have no deeply held intellectual prejudices, and that the proof was in the pudding.  But in the end, just as Dr. Sagan pointed out to us long ago, and as Dr. Newman begrudgingly demonstrated in his passionate expose of the medical world:
Physicians also like to have their preferences determine what truth is.

Monday, November 10, 2014

Keep in Mind: Pitalls of POCUS #1

This is a new series focusing on important pitfalls in using POCUS. Sometimes the most important knowledge of using a specialized skill set or tool is a robust understanding of the possible pitfalls including common false positives or negatives.

The case report here from JEM brings up a great point we often overlook. Be weary of a patient with prolonged or high volume resuscitation prior to performing a FAST exam. Transudative 3rd spacing within the peritoneum is common and can lead to a false positive FAST.  Both blood (fresh, unclotted) and transudate (or ascites which could be pre-existing) appear dark, hypo echoic. 

Now ... the case is clearly a devastatingly sick girl, who was persistently hypotensive so its hard to argue against taking her to the OR after a positive repeat FAST. However, in the setting of a poor neurologic exam, and an echo later revealing a poor ejection fraction (10%) one may have hesitated to take her to the OR even with positive FAST given the understanding of POCUS pitfalls in conjunction with other clinical information and the risks of operating on a profoundly ill patient. 

Keep in Mind #1: FAST pitfalls. False positives after high volume fluid resuscitation. Therefore, get a good, thorough prehospital resuscitation history and ensure a detailed transfer of care if you are sending a patient from your facility to a trauma center, or if you'll be the one accepting.

Recurrent Chest Pain: Are these people crazy?

Interesting article in BMJ on mental condition of patients with recurrent chest pain with no evidence of CAD on angiography.

These people have higher baseline anxiety and are 120% more likely to suffer somatoform disorder. They are also (no shock here) hypochondriacs.

Check out the article here

Saturday, September 13, 2014

POCUS-FOCUS #1: Recognizing Hypertrophic Cardiomyopathy

Welcome to the first of what I hope will be a continuing series of concise monthly videos or e- learning material FOCUSed on POCUS (Point-Of-Care-UltraSound). The intention of the series is to draw attention to supplemental or more advanced uses for POCUS, interesting cases, important EM Ultrasound literature, online resouces (FOAM), and other fun EM Ultrasound tidbits.

The first POCUS-FOCUS topic will be:
Differentiating Hypertrophic Cardiomyopathy (HCM) from both hypertensive heart disease (HHD) AND Athletic heart.

I will keep this simple and focused on scanning techniques that most EM-trained docs should be able to perform, while avoiding much the more difficult and advanced methods.
HCM: A genetic protein mutation leading to inappropriate LV muscular thickness (anywhere) but more often septal leading to obstruction of the LVOT (left ventricular outflow tract) and often malignant dysrhythmia.

Our job in the ED: Risk stratifying and screening appropriate patients with concerning clinical and/or family history for HCM. Our job is NOT TO DIAGNOSE HCM. We should simply search for evidence that this may be the underlying etiology of the presenting complaint which could alter our disposition or management.

What you should do?: Perform focused cardiac ultrasound (FoCUS). Most importantly the Parasternal Long Axis and the Parasternal Short Axis ; if desired use M-mode which will ensure more accurate phase (end-diastole). Measure the LV thickness at end diastole at various different locations.

PSSA: Measure Base, Mid, and Apical LV Thickness _________________________________________________________________

PSLA (with M-mode): Measure LV thickness @ the trough (end diastole) -Septal wall AND posterior wall (yellow) measurements (then calculate ratio)

What measurements should worry you?

Guidelines differ however it appears widely accepted that LV thickness in ANY myocardial segment >15mm is concerning for HCM. Also, septal to posterior (s/p) wall thickness ratio > 1.3 (in normotensive) and > 1.5 (in hypertensive patients) is considered highly suspicious for HCM
Hypertensive hearts MAY also have larger septal thickness compared to posterior. They are not always concentrically hypertrophic as is classically taught. Athlete hearts are often much less thick than both HHD and HCM.
Here are some tables with important measurements, these are the some of the values from which the guidelines have been derived:

Bonus (more advanced US technique/interpretation): There are no pathognomonic findings on echo for HCM, given that hypertension can give profound LV thickness, even asymmetric septal thickness. However, there is a finding called SAM (systolic anterior motion) which is anterior motion of the anterior leaflet of the mitral valve toward the septum just after systole begins (which is why HCM becomes obstructive – particularly in hypovolemia/Valsalva/etc). See the table above which reveals that no normal or hypertensive patients demonstrated SAM and 36/47 HCM patients did. This finding is very specific, but not so sensitive, for HCM.
You can see this as an EM doc at the bedside ... I PROMISE. Just watch the LVOT (left ventricular outflow tract) –particularly the anterior mitral leaflet- in these parasternal long axis (PSLA) clips of NORMAL patients and HCM patients.

Sheikh N. The electrocardiographic phenotype in athletes with hypertrophic cardiomyopathy: implications for pre-participation cardiovascular evaluation using electrocardiography. Heart. 2014 Jun;100 Suppl 3:A51
Bart et al. Measurement of Left Ventricular Wall Thickness and Mass by Echocardiography. Circulation. 1972;45:602-611
Williams, et al. Echocardiography in hypertrophic cardiomyopathy diagnosis, prognosis, and role in management. Eur J Echocardiogr (2009) 10 (8):iii9-iii14. (
Doi, et al. Echocardiographic differentiation of hypertensive heart disease and hypertrophic cardiomyopathy. Br Heart J 1980;44:395-400 doi: 10.1136/hrt.44.4.395
Lang, R. M., et al. (2005). "Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology." J Am Soc Echocardiogr 18(12): 1440-1463. 

Saturday, January 4, 2014

Sux in Head Injury

The confirmation Ive been looking for!

US Diagnosis of Intraperitoneal Air

Very cool, from this study. Id be curious if this reverb artifact exists without significant free fluid?

This demonstrated free intraperitoneal fluid in Morison’s pouch (Video Clip S1). Upon attempting views of the pelvis, distinct hyperechoic foci with reverberation artifacts were visualized within the free fluid, suggesting associated free intraperitoneal air (Video Clip S2).