Iwe have a project looking at leukoreduction effects in equine whole blood stored over 5 weeks in CPDA-1. Oxygen tensions are ~200-225 mmHg by week 2 in leukoreduced bags, slowly increase from 60 to ~100 in non0leukoreduced bags. CO2 increases to ~80 mmHg in lekoreduced and stays there by week 1, increase is to about 120 mmHg in non-leukoreduced. I am trying to sort out why?
Dr. Wilkins,
Is this data compatible with "RBC storage lesion?" Is this typical of changes associated with loss of 2,3-DPG from RBC? I have not read much about the plastic bags contributing to the changes in RBC over time. I am sure there must be, however perhaps increased Oxygen tension in LR blood is associated with reduced oxygen consumption by the nucleated cells?
Hi Jeffery,This is exactly what we are looking at, differenced between leukoreduced and non-leukoreduced blood over 5 weeks of storage at 4C. We think your response is part of the answer but how does teh oxygen tension get above atmospheric in the LR bags and stays below atmospheric in the non-LR bags?
:-)
Any thoughts greatly appreciated, we cannot see this described anywhere.....going through older literature now but the 'breathable' plastics were introduced in the las 2 decades in support of the platelet demands for O2...they are stored warm not cold.
Pam
We have exactly same finding of high O2 above atmospheric in LR units in all kinds of additive solutions. Because we have leukoreduced as standard since 2001 I have no idea if these values were different before leukoreduction. The lower O2 and higher CO2 in Non-LR should be the results of metabolism by leukocytes. The standard blood bags, usually PVC-DEHP, allow gasses to pass the foil, and you see always an increase in O2 and a decrease in CO2 as soon as the metabolizing cells are removed or not longer active. The breathable bags for platelets were developed to increase the exchange, but this does not mean that before there was no gas-exchange. How values can be above atmospheric I also don't understand, this might have to do with the analytical method used, which is developed for clinical samples and not for stored blood.
Thank you, I am glad we are not alone! Do you have any references?
sorry, we try to avoid boring results in our published studies, and as it was always the same trend we never reported this as far as I could check in my publications.
Thank you.....I guess we will take the 'publish the boring results' route as I cannot find it anywhere! I really do appreciate your help.
Hi Pam, very curious. What is the pH? Is it possible there are still some metabolically active cells even after LR? One possible explanation (would require quantitation with Hb properties to be plausible) would be severe metabolic acidosis -- release of CO2 --- Bohr effect to drive up PO2. For that to work, the bags would have to be fairly impermeable. O2 and CO2 permeation constants vary at least two orders of magnitude amongst different plastics (high for silicones and rubbery polymers, very low for perfluorocarbons and more stiff, higher crystalline microstructure polymers) and usually considered proprietary information by the manufacturers. For our gases for the MIGET infusions, the only reliable way to tell is direct measurement. I would start with saline and then fill the gas space with nitrogen and follow PO2 over time.
One other potentially very important factor is temperature. If the bag is O2 permeable and stored at 4C in air it will equilibrate to 150 PO2 at 4C. Then when warmed, the PO2 would exceed 150 until the excess diffuses back out of the bag. Warming increases CO2 also, but hard to imagine values up to the 80s if the bag was very permeable and could get rid of CO2 when surrounded by air. Cheers.
Hi Jim! pH is a bit acid, and progressively more so with time. In LR blood slight increase in PCO2 with thime, big increases with non-LR blood over time. O2 vewry different between LR and non-LR blood, more than 250 mmHg in LR blood by end of week one. Thank you for the suggestion re: nitrogen in bag. :-)
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