Acid-Base

http://www.acidbase.org

Anion gap correction for hypoalbuminemia:  2.5 meq/l for every 1g/dl decline in albumin

Venous blood gas agrees with arterial blood gas (pH, bicarbonate, lactate, base excess, and carbon dioxide pressure (Pco2)) within 95% CI:

1. Middleton P, Kelly AM. Brown J, et al: Agreement between arterial and central venous values for pH, bicarbonate, base excess, and lactate.  Emerg Med J  2006; 23(8):622-4.

2. Malatesha G, Singh NK, Bharija A, et al: Comparison of arterial and venous pH, bicarbonate, Pco2 and Po2 in initial emergency department assessment.  Emerg Med J  2007; 24(8):569-71.

3. Kelly AM: The case for venous rather than arterial blood gases in diabetic ketoacidosis.  Emerg Med Australas  2006; 18:64.

From LifeInTheFastLane:

• • When you look at a gas either draw this little grid or visualise it with your mind’s eye:

• • For instance, if PaCO2 is 50 mmHg, that’s an increase of 10 mmHg from normal (PaCO2 40 mmHg). Thus in acute metabolic compensation the HCO3 should increase by 1 mmol/L from normal (HCO3 25 mmol/L) to 26 mmol/L, and in chronic compensation it should increase by 4 mmol/L from normal to 29 mmol/L.

  • Using the 4 square grid helps you remember which numbers correspond to what (acute comes before chronic, left before right), and whether they go up (top row) or down (bottom row).