Calculation of whole blood CO2 content

Area of Science:

• Physiology
• Biochemistry

Background:

• Existing methods for calculating whole blood CO2 content from plasma CO2, blood pH, hemoglobin, and O2 saturation produce inconsistent results.
• Accurate measurement of blood CO2 is crucial for understanding respiratory and metabolic states.

Purpose of the Study:

• To reevaluate the constants in fundamental equations relating blood CO2 content to plasma CO2 content.
• To develop a more accurate calculation for whole blood CO2 content.

Main Methods:

• An iterative computer technique was employed to derive new constants.
• Data from nine healthy male subjects at rest and during exercise were used for empirical derivation.
• Constants were derived from fundamental equations relating blood CO2 content to plasma CO2 content.

Main Results:

• A new calculation was derived that demonstrated a good fit to the experimental data (difference 0.02 +/- 1.19 ml/100 ml, r = 0.98).
• The derived formula for blood CO2 content (CCO2) is presented, incorporating plasma CO2 content (pCCO2), blood pH, O2 saturation (SO2), plasma CO2 solubility coefficient (s), and apparent pK'.

Conclusions:

• The reevaluated constants and derived calculation improve the accuracy of determining whole blood CO2 content.
• This refined method offers a more reliable approach for assessing CO2 levels in physiological studies.