Donated blood deteriorates in storage so that it no longer carries oxygen efficiently. After transfusion, it can take 48 hrs to become fully reactivated.Donated blood may initially reduce the oxygen-carrying efficiency of thepatient’s own blood. The longer the blood is stored, the greater the risk. Our objective is to investigate a technology that promises to reduce, or reverse, deterioration in storage. The major benefits in extending the activelife of donated blood are: • the risk to the patient is reduced and • an extended shelf-life reduces wastage. The novel technology passes blood over a membrane impervious to blood, but through which gases can pass. In this way, the concentrations of gases in theblood can be accurately controlled.