My lecturer cites Boron and Boulpaep's Medical Physiology (2nd edition) for the following claims:

  • the total $\ce{CO2}$ content of arterial blood is $26.4$ mmol/L or $48\%$ v/v (not sure if these numbers convert)
  • including $90\%$ as bicarbonate, $5\%$ as dissolved gas and 5% as carbamino compounds (specifically carbaminohaemoglobin)
  • the arterial partial pressure of $\ce{CO2}$ is $40$mmHg

How does one get from the arterial partial pressure value to determining these proportions and figures?

What I've tried: Henry solubility constant for $\ce{CO2}$ in water, equilibrium constants for the hydration of $\ce{CO2}$, ionisation of carbonic acid, assumed carbaminohaemoglobin formation went to completion and only consumed $\ce{CO2(aq)}$. Still don't seem to completely match my lecturer's figures.


1 Answer 1


Even when Douglas equation has been criticized is the best approach I know to calculate CO2 content. You can calculate plasma CO2 content and total blood CO2 content

Douglas 1988 (DOI: 10.1152/jappl.1988.65.1.473)

  • 3
    $\begingroup$ It's great to have the DOI to a reference, but can you summarize its contents? Otherwise, this doesn't answer the question. $\endgroup$ Commented Jan 17, 2018 at 14:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.