Q: What is Delta-Delta? I tried to look it up in three textbooks including a monograph on Acid Base balance but no joy. The closest I got was a brief reference to "delta anion gap/delta bicarbonate" yet the units on the ABGPro do not seem to follow such calculation.

A: If you go to Help on the Menu, it will explain what Delta-Delta is, but to summarize, Delta-Delta measures the bicarbonate level that existed prior to the anion gap acidosis. There are different conventions used (such as change in AG divided by change in Bicarb - which then you use a ratio to evaluate if there was a pre-existing acid-base disorder), but they are all computing the same thing. My references are also listed in the Help section of ABG Pro.