Blood gas: Aa gradient and also… Would venous do?

21 Jan

Hi everyone,

Last week our ED registrars hosted a really good day of education for their colleagues in the surrounding hospitals. I was asked to give a workshop on blood gas. During the MNSHA masterclass I enjoyed the discussion about arterial versus venous, and decided to share that with our colleagues-to-be. Just for starters, hope I made some of them curious enough to search for details. But I started with the alveolar gas equation, to explain how we can assess if the lungs are properly transferring oxygen into the blood. I have put my slides on our website so you can use them.

Gr. Laura

PPP Blood gasses


2 Responses to “Blood gas: Aa gradient and also… Would venous do?”

  1. Egon Zwets January 23, 2013 at 15:52 #

    Hi Laura, great presentation….In my mind nobody calculates the Aa-gradiënt, but the pulmonolgists often admit a patiënt because of a low paO2, even when they’re not that sick (or they want a D-dimer!). Learning the Aa-gradiënt maybe can change that.

    1 question: recently we had somebody with a bad venous blood gas and the arteriel one was normal. They said it was because of the long time it takes from taking the sample till the time the sample is in the lab….Do you know anything about this???

  2. Rahul Goswami (@Rahul_Goswami_) January 23, 2013 at 20:08 #

    If the heparin is not mixed well, it can skew the results. My lab says oxidisation of the blood occurs if not capped well and left standing or gas bubble.
    Otherwise, it is our experience that there is no major difference and we only do art gases for hypoxia or ventilated patients. Depends on what you are measuring – the “lung” or the “cell”?

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