I was intrigued by a news story all over the wires today and yesterday – that blood transfusions may do more harm than good. Over 4.5 million Americans receive blood transfusions for one reason or another each year in the US. Two new studies have been published in the Proceedings of the National Academy of Sciences, suggesting that blood can get “stale” much sooner than we think. Although we’ve known for a while that blood transfusions should be given only when critically needed, this news is interesting in that it may explain why blood transfusions are not a panacea.
Blood contains nitric oxide – a gas that is used as a signaling molecule in humans. It can trigger the relaxation of blood vessel walls, which is important in getting blood flow and oxygen to areas of the body that need it. Nitric oxide exists in small amounts in the bloodstream, but it can evaporate rapidly once outside the body (such as in a transfusion bag). So the question is: how critical is it to have nitric oxide dissolved in the blood given via transfusion?
The Red Cross keeps blood for up to 42 days after it is donated (though nitric oxide depletion may occur within hours) and will continue to do so until it is clearly shown that the expiration dates should be shortened. Further research is underway to test whether or not infusing nitric oxide back into blood is a viable option to improve its ability to oxygenate the recipient. It’s not easy to do this, since nitric oxide is a very tricky gas that can become a free radical or an acid in the presence of certain oxygen species. So the exact proportion of nitric oxide is critical – a little does just the right thing, but too much can be harmful or even fatal – which is probably why we haven’t tested this in humans yet, only dogs.
Still, many have high hopes for adding nitric oxide to the blood supply – Dr. Jonathan Stamler of Duke University appears to have applied for more than 50 nitric oxide associated patents and, not surprisingly, is taking the lead on various research studies, including the two new ones mentioned in my first paragraph.
My personal take on this? Blood transfusions are a serious treatment that can save lives, but should not be given willy nilly to “boost” people’s hematocrits. I’ve witnessed physicians giving their patients an extra unit of blood “just to perk them up a bit” prior to discharge from the hospital. That behavior is not safe or appropriate. So before you undergo a blood transfusion, make sure you really need one. Until we figure out how to replace nitric oxide safely in the blood supply, the life-saving potential benefits of a transfusion must outweigh the risks of stroke and heart attack from nitric oxide-depleted blood.This post originally appeared on Dr. Val’s blog at RevolutionHealth.com.