The Alveolar–arterial gradient (A-aO2, or A–a gradient), is a measure of the difference between the alveolar concentration (A) and the arterial (a) partial pressure of oxygen. It seems an useful and interesting parameter in the topic of pulmonary imbibition, but I failed to find published research in last years.
Can you help me?
Dear Marco,
I think You could find what You are looking in the Researchgate' pages of Gattinoni and Pesenti or Pelosi. They are the Italian University Professors that were studying this "item" since '80 years. Moreover i'll look in my records if i can find something of useful. Kind personal Regards. GFV
Alveolo arterial gradient equation is used in many calculators available on the Net, but unfortunately, they never referenced…
MeasuredAaG = (FIO2 * (pAtm - pH2O)) - (pCO2 / RespQuot) + (pCO2 * FIO2 * (1 - RespQuot) / RespQuot) – paO2
OR PAO2 = (FiO2 * (760 - 47)) - (PaCO2 / 0.8)
A-a gradient = PAO2 - PaO2
You may found the answer on the papers by Cole RB J Appl Physiol 1967 22: 685-93. This study is not available, despite an INSERM Code. The first page is available in PDF, the others are not available, but the equations are listed in the methods section. Idem for a paper published in Acta Physiol Scandinavia 1966 67:1, 10-20.
You may have a look at Guyton and Hall textbook of medical physiology 12 edition available on the net, Chapter 39. Of course a good overview with results of interest, but the equation is not reported…
Hi Guido,
thank you for the suggestion. I often read and listen Gattinoni, but I never found A-a gradient. I have to re-check his works looking for the "gradient". Please if you will find it in your records I would like to have the link.
marco
Dear François
exhaustive answer !! hence I'm going to think that contemporany papers on this topic there not exist, but i have to take a look at Guyton's textbook.
Unfortunately I have not access to Guyton's textbook for free.
here you have the Guyton and Hall Free , all the book!
[PDF]Guyton and Hall Textbook of Medical Physiology - University ...
www.umc.edu/.../Medicine/.../Physiology.../Textbook...
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John E. Hall, Ph.D. Arthur C. Guyton ... TWELFTH EDITION. Page 2. vii. Preface. The first edition of the Textbook of Medical Physiology ... of Medical Physiology were written entirely by Dr. Guyton, ..... and Dilution: “Free Water” and Osmolar.
Hi Francois
thanks for your aim. Unfortunately the link doesn't run. Please if you have the pdf of full text you could sent me by email. You already have my mail ID.
marco
Check out John West's lectures on U-Tube. As you may know John wrote the most widely used primer on Respiratory Physiology -"The Essentials" and made videos of up to 50 of his lectures at UCSD for anyone to download via U-Tube.
Of course there is always the handbook of Physiology (older version) or its successor "Comprehensive Physiology" if you want to dig deeper.
Much of the research was done in the 1940s and 1950s
I have attached an early article
Hi Robert,
what a great paper ! what a shame it is historical one !!
What I am looking for it is a blood gas analysis parameter linked to interdialytic weight gain in hemodialysis patients. In my experience, and "of course", in incoming pulmonary edema A-a O2 gradient rises up to 50 mmHg, but I am looking for early gas derangement. Can You suggest me what to look for ?
marco
Sorry for the delay. Perhaps you have already answered the question. Anyway, the most recent article (2014) I found on the gradient AA O2 is in French and is attached. See if it can be useful.
Dear Francesco,
Many thanks for the paper. I take it just a quick look.
I have not yet the answer to my question. However within the french paper there are some interesting points to read carefully.
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