pH CO2 HCO3
Arterial Blood Gas Values
to ABG Analysis
I used Swearingen's handbook (1990) to base the results of this
calculator. The book makes the distinction between acute and chronic
disorders based on symptoms from identical ABGs. This calculator only
differentiates between acute (pH abnormal) and compensated (pH normal).
Compensation can be seen when both the PCO2 and HCO3 rise or fall together to
maintain a normal pH. Part compensation occurs when the PCO2 and HCO3 rise
or fall together but the pH remains abnormal. This indicates a
compensatory mechanism attempted to restore a normal pH. I have not put
exact limits into the calculator. For example, it will perceive
respiratory acidosis as any pH < 7.35 and any CO2 > 45 (i.e. a pH of 1 and
CO2 of 1000). These results do not naturally occur.
It's possible to have more than one disorder influencing blood gas
values. For example ABG's with an alkalemic pH may exhibit respiratory
acidosis and metabolic alkalosis. These disorders are termed complex
acid-base or mixed disorders.
*This table is able to classify most clinical blood gas values but not
all. In cases where blood gas values do not fall into any of the above
classifications, an answer "unable to determine" will appear when using the
interpreter. For example a pH of 7.428, pCO2 43.6, and a HCO3 of 29.1 do
not match any of the classifications (I found these results in someone's
chart). While the pH and pCO2 are normal, the HCO3 is abnormally high.