Saturday, January 7, 2012

Specious Ideas: CO2 is bad for you and acidosis is a killer too

Here's some bad acid and CO2
Certain biases in the way we think in medicine are so pervasive and so misleading that I'm going to make a special section on this blog for them:  The Specious Ideas Series.  We'll begin with my favorite, the approach to hypercarbia (high CO2) and acidosis (low pH) both in and out of the ICU.

Patients with serious illness often have derangements in PaCO2 (arterial partial pressure of CO2; hereinafter abberviated CO2) and pH.  But it does not necessarily follow that patients are experiencing physiological stress because of CO2 and pH, and it likewise does not follow that actions to normalize these values will make patients better.  Indeed, such actions are often not only a distraction and a waste of time, but they can also be harmful.

Wednesday, January 4, 2012

When the elderly need a protection order against warfarin-wielding physicians

This is a tree.  If you want to see the forest, back up.
(Added 1/11/12 - This post was prescient:  See this article in today's NYT: Interactive Tools to Assess the Likelihood of Death which reviews this JAMA article: Prognostic Indices for Older Adults; here is the Prognosis Website - In my opinion, it's too complicated to be useful, but it's a start.)

Ever since I was in medical school, I have been hearing the tired old refrain about how warfarin for stroke prevention in atrial fibrillation is underutilized in just about everybody, especially the elderly.  Well, if you want to see uber-high rates of warfarin underutilization, you need look no further than trials of stroke prevention such as the original SPAF trial (Ezekowitz, NEJM, 1992), where more than 93% of screened patients were excluded from the trial and not given warfarin!  There's an interesting contradiction.  Moreover, it is likely that warfarin is not as underutilized as has been stated because of inadequate data on appropriate exclusion criteria (see Srivastava, Thrombosis Journal, 2008).