Acid-Base

Christina Barkauskas, Talal Dahhan, Anne Reihman.

 

This is one of the difficult but most important topics in critical care medicine. It is not easy to approach the first time, but once you get the hang of it, it’s a fun problem solving exercise.  This webpage has three elements:

  • 1.  Lecture by Dr. Barkauskas, involving linked files
  • 2.  The webpage itself
  • 3.  A great talk by Anne Reihman

 

1.   Please take a look at the power point presentation by Dr. Barkauskas:
LINK TO POWERPOINT SLIDES

 

2.  Once you are done reviewing the slides, consider reading the review article referenced below. It goes over the physiology behind below rules and how to explain using them on a clinical basis.

 

Integration of Acid–Base and Electrolyte Disorders, by Julian L. Seifter, M.D., N Engl J Med 2014; 371:1821-1831.

 

Key points to remember:

* Compensation Equations for Acid Base Disorders:

acid1

Adapted from: Adrogue et al, J Am Soc Nephrol 21: 920–923, 2010.

Approach to metablic acidosis specifically

acid2

* To find out mixed disorders, looking at the Acid-base nomogram might help:

acid3

 

General Rules to help with Acid-Base work-ups:

  • Calculate Anion Gap (AG) = Na – (Cl + HCO3). Use measured not corrected Na.
  • Expected AG = Serum Albumin x 2.5.
  • If AG is elevated, there is a metablic acidosis process.
  • Once AG is elevated, calculate delta AG/ delta HCO3:
  • If the ratio = 1-2, this indicates pure AG metabloic acidosis process, proceed with compensation calculation as above.
  • If the ratio is less than 1, this indicates metablic and non-metabolic acidosis processes.
  • If the ratio is more than 2, this indicates metabolic acidosis and metabolic alkalosis processes.

 

3. Lecture by Anne Reihman:   link to talk