Blood Q&A with Dr. Eldad Hod
November 19, 2014 – CAF periodically receives questions from patients on a wide range of topics related to thalassemia and its treatment. We have shared a few of these questions relating to blood issues with Eldad A. Hod, MD, of Columbia University/New York-Presbyterian. We thank Dr. Hod for sharing his expertise with us and with the thalassemia community.
CAF: Can you talk about the potency of donated blood and how that changes as the blood ages? In other words, what is the difference in potency between newly donated blood and blood that is 20 days old or 30 days old or 42 days old?
Dr. Hod: The FDA currently allows donated blood to be stored in a refrigerator for up to 42 days prior to transfusion. Whether transfusion of older blood is harmful is still very controversial and there are a number of studies currently being performed; unfortunately, none of these studies are in patients with thalassemia. However, it is well accepted that red cells are damaged during prolonged refrigerator storage and these damaged red cells are destroyed faster than fresh blood. Thus, transfusion of older red cells will result in a need for another transfusion sooner leading to an increased number of transfusions in the long run.
What can I do to ensure that I get “fresh” units when I am transfused?
There is no study in patients with thalassemia to suggest that fresher units of blood are beneficial. Thus, there are no practice guidelines to suggest that fresher units should be used and the blood bank can release units up to 42 days old by FDA criteria. Furthermore, in the grand scheme of things, if you get a fresher unit, then under the current system, someone else will get an older unit. Since we do not know who will benefit most from receiving fresh blood, who should get the fresher blood is a difficult ethical question. You can certainly try to ask your physician to try to get you fresher units and/or advocate for a clinical study to test whether this is a beneficial practice for treating thalassemia, but remember, older blood is still better than no blood.
What kind of safeguards are in place in the U.S. to prevent transmission of Babesia, Chagas disease and ebola via blood transfusion? Are there tests for these, or is it reliant on blood donor screening? Does washed blood eliminate the possibility of contracting these (and other infections) via transfusion?
Currently, the blood supply is tested for HIV, Hepatitis B, Hepatitis C, human T-cell lymphotropic virus (HTLV), syphilis, West Nile Virus, and Chagas disease. There is no FDA-approved test for Babesia; however, studies are underway to determine how best to test for Babesia in the blood supply. Furthermore, the blood supply is not screened for Ebola, but travelers to the parts of Africa with Ebola would be deferred from donation by the donor questionnaire. Finally, washing blood will not eliminate the possibility of contracting these infections via transfusion. The washing procedure might also damage the red cells leading to a less than optimal transfusion.
What is the state of synthetic blood development, and does it seem likely that this will one day create blood that can be used for red blood cell transfusions for thalassemia patients?
There are no approved blood substitutes on the market due to the toxicity associated with their infusion. It is unlikely that a blood substitute would be available in the near future. Furthermore, to the extent that the blood substitutes utilize iron to carry oxygen, it is unclear how this will have a beneficial impact on the iron overload associated with transfusion.
If someone is a blood donor, what type of donation is more advantageous for thalassemia patients?
Depending on your blood type and the state of the blood supply, it may be more advantageous to donate whole blood or double red cells. If you are willing to do either, a donor specialist at the blood drive will be able to better help you decide which donation to make.
What’s the proper length of time that a unit of red blood cells should be transfused? Does that time vary based on age? What happens if it is transfused too quickly?
The main concern if blood is transfused too quickly is that the heart will be overwhelmed with too much blood volume (an entity called transfusion-associated circulatory overload). In general, the blood should be given as tolerated over approximately 1.5 to 3 hours, but may be given more slowly in patients with heart disease at the doctor’s discretion.