useful files to download:

several calculators
and a presentation

The late Peter Lloyd of Hawke's Bay Hospital, Hastings, NZ wrote an excellent spreadsheet calculator based on the Stewart approach. Ross Freebairn, the Medical Director for Intensive Care Services at that hospital, having consulted Peter's mother, gave us permission to make this calculator available for download:
Acid-Base Calculator V10.8.
Together with Ross Freebairn he wrote an article with many detailed examples describing how to use the calculator. This article is available for download, too:
Using Quantitative Acid-Base Analysis in the ICU.

related reading:
an obituary about Peter Lloyd
obviously a fascinating person!

Somewhat less sophisticated is my own little calculator, but it offers an integrated gamblegramme:
(it works best with OpenOffice, but is workable with Excel, too.)
a small acid-base calculator, OpenOffice version.
a small acid-base calculator, MS Excel version.

A very unique spreadsheet has been written by Dr. Helmut Schröck, Zentrum für Biomedizin und Medizintechnik Mannheim.
It is, to my knowledge, the only freestanding calculator allowing you to calculate the pH value of a solution based on the solution's composition (i.e. the value of the independent variables: SID, Atot and PCO2):
Helmut Schröck's pH calculator
(You must allow the programme to use macros, though). The programme is best used with a manual - this is available in German and in English:
Helmut Schröck's manual in German
Helmut Schröck's manual in English

There is a java-based downloadable programme available on http://www.anaesthetist.com:
(authored chiefly by Lara Hopley and Jo van Schalkwyk)
With the help of their programmes, you can make clear graphs showing the effects of the three independent variables on the acidity of a solution.

BUT beware: you will have to use the correct measurement units, mostly, but not exclusively, SI- based ones.
this is notoriously difficult for medical people based in many non-Scandinavian European countries and the USA! Try and get some help from websites informing about unit conversion, like http://www.globalrph.com, SI unit conversion ("Three nations have not officially adopted the International System of Units as their primary or sole system of measurement: Liberia, Myanmar and the United States.", wikipedia, accessed 20090228.)

If anyone has the time, enthusiasm and knowledge to make the spreadsheets compatible with different units, we would be glad to receive your help!

write to us

A gifted young Egyptian colleague wrote a presentation about the different approaches to acid-base analysis:

Mohamad Atef Radwan's acid-base presentation