Evolution Based Medicine: A Philosophical Framework for Understanding Why Things Don't Work

An afternoon session at the ATS meeting this year about "de-adoption" of therapies which have been shown to be ineffective was very thought provoking and the contrasts between it and the morning session on ARDS are nothing less than ironic.   As I described in the prior post about the baby in the bathwater, physicians seem to have a hard time de-adopting therapies.  Ask your colleagues at the next division conference if you should abandon hypothermia after cardiac arrest and rather just treat fever based on the TTM trial and the recent pediatric trial, and see what the response is.  Or, suggest that hyperglycemia (at any level in non-diabetic patients) in the ICU be observed rather than treated.  Or float the idea to your surgical colleagues that antibiotics be curtailed after four days in complicated intraabdominal infection, and see how quickly you are ushered out of the SICU.  Tell your dietition that you're going to begin intentionally underfeeding patients, or not feeding them at all and see what s/he say(s).  Propose that you discard sepsis resuscitation bundles, etc.  We have a hard time de-adopting.  We want to take what we have learned about physiology and pharmacology and apply it, to usurp control of and modify biological processes that we think we understand. We (especially in critical care) are interventionists at heart.

The irony occurred at ATS because in the morning session, we were told that there is incontrovertible (uncontroverted may have been a better word) evidence for the efficacy of prone positioning in ARDS (interestingly, one of the only putative therapies for ARDS that the ARDSnet investigators never trialed), and it was strongly suggested that we begin using esophageal manometry to titrate PEEP in ARDS.  So, in the morning, we are admonished to adopt, and in the afternoon we are chided to de-adopt a host of therapies.  Is this the inevitable cycle in critical care and medical therapeutics?  A headlong rush to adopt, then an uphill battle to de-adopt?

Goldilocks Meets Walter White in the ICU: Finding the Temperature (for Sepsis and Meningitis) that's Just Right

In the Point/Counterpoint  section of the October issue of Chest, two pairs of authors spar over whether fever should be controlled in sepsis by either pharmacological or external means.  Readers of this blog may recall this post wherein I critically appraised the Schortgen article on external cooling in septic shock that was in AJRCCM last year.  Apparently that article made a more favorable impression on some practitioners than it did on me, as the proponents of cooling in the Chest piece hang their hats on this article (and their ability to apply physiological principles to medical therapeutics).  (My gripes with the Schortgen study were many, including a primary endpoint that was of little value, cherrypicking the timing of the secondary mortality endpoint, and the lack of any biological precedent for manipulation of body temperature improving mortality in any disease.)

Reading the Point and Counterpoint piece (in addition to an online first article in JAMA describing a trial of induced hypothermia in severe bacterial meningitis - more on that later) allowed me to synthesize some ideas about the epistemology (and psychology) of medical evidence and its evaluation that I have been tossing about in my head for a while.  Both the proponent pair and the opponent pair of authors give some background physiological reasoning as to why fever may be, by turns, beneficial and detrimental in sepsis.  The difference, and I think this is typical, is that the proponents of fever reduction:  a.) seem much more smitten by their presumed understanding of the underlying physiology of sepsis and the febrile response; b.) focus more on minutiae of that physiology; c.) fail to temper their faith in application of physiological principles with the empirical data; and d.) grope for subtle signals in the empirical data that appear to rescue the sinking hypothesis.