This is Part V of the EMCrit Acid-Base Talks. If you haven't listened to the initial series, you may be better off starting there:

* Part I lays out the background of the quantitative approach

* Part II puts it in mathematical terms to allow calculation of acid base status

* Part III takes you through some real world examples

* Part IV discusses the Acid-Base Effects of IV Fluids

* Part V is this one, down with the Bicarb

* Part VI ok, bicarb is not all bad

The Acid Base Series

EMCrit Podcast 44 – Acid Base: Part IEMCrit Podcast 45 – Acid Base: Part IIEMCrit Podcast 46 – Acid Base: Part IIIEMCrit Podcast 50 – Acid Base Part IV – Choose the Solution Based on the ProblemPodcast 96 – Acid Base in the Critically Ill – Part V – Enough with the Bicarb AlreadyPodcast 97 – Acid-Base VI – Chloride-Free SodiumEMCrit Podcast – Acid Base Ep. 7 – Bicarb Updates, Quantitative Approach, and Prof. David Story

Acid-Base Sheet

EMCrit Acid-Base Sheet

Today's topic comes from a debate I have been having with Steve Smith of the amazing EKG Blog. The main thrust of the debate started with this question...

Does Bicarb Fix pH if You Can't Increase Minute Ventilation?

 

When you can adjust PaCO2 to maintain a certain value (i.e. you increase minute ventilation), bicarb will raise pH as evidenced by this animal study (Crit Care Med 1996; 24:827-834). However, if you can't blow off the CO2 then the effects on pH will not be there (J Pediatr 1977;91(2):287).

In this study, NaBicarb did not correct the pH, while CarbiCarb did (Carbicarb: an effective substitute for NaHCO3 for the treatment of acidosis. (Surgery 102:835–839).

This review article recommends against bicarb for permissive hypercapnia (Intensive Care Med (2004) 30:347–356).

This study furthers the idea that NaBicarb is not all that great in closed systems (J Pediatr 1972;80(4):671) and then this discussion explores all of the biochemical reasons why administering bicarbonate as a rapid push in a closed system is a bad idea (J Pediatr. 1972 Apr;80(4):681-2.).

Here is a quote from another review article (Anesthesiology 1990;72(6):1064):

The key concept in the equation [above] is that pH is not related to the absolute value of either bicarbonate concentration nor PCo2, but rather to their ratio.

When exogenous bicarbonate is administered during acidemia,