The Associated Press reported this week that there is growing concern about blood stored for transfusions.
When we cut our finger, we see blood as a simple red liquid. It was perhaps that view that prompted doctors centuries ago to believe that blood that leaked out of one patient could simply be replaced by blood from another patient.
Such is not the belief of doctors today. There is a growing school of thought among the best doctors today that transfusing blood is as fraught with complications as transplanting organs.
What doctors in the 1700's couldn't have known is that blood is a complex mix of red blood cells, white blood cells, platelets, plasma, and a myriad other small constituents. Likely you've heard blood being referred to as "type A," "type B, or "type O." These distinctions refer to antigens in the blood, and so far researchers have discovered 29 different "types." The antigens essentially make each person's blood unique; they do not play well with others. Mismatched blood was the reason for the death of nearly all early tranfusion patients. Even with all the technology available today, it is estimated that about one in 12,000 units of blood transfused in the United States is given to the wrong person.
Your body creates red blood cells at the astonishing rate of 2 million to 3 million per second! That's an amazing little factoid, but it makes you think: if your bone marrow is creating 2 million cells per second, it is doing so because 2 million blood cells are dying per second. Since a unit of blood, stored, waiting to be transfused, is about one tenth of a person's whole blood supply, that means that one tenth of that figure, about 200,000 red blood cells, are dying each second. If blood is stored for just one hour, that's 72,000,000 dead cells. I'm not feeling real great about 72,000,000 dead anything being pumped into my body. What's the number of dead cells after a day? A week? How long before they begin to putrify?
White blood cells come in many varieties. Some of them live for a year, but some die every 36 hours. So a unit of stored blood has millions of dead white cells in it also. Other blood constituents, such as antibodies and hormones, also begin to break down and die in stored blood.
In the normal course of things, these broken down and decaying blood constituents are filtered out by your liver and kidneys, and passed out of your body in your feces and urine. When a unit of blood is drawn from someone, some of this pre-feces-pre-urine material was on it's way to the donor's kidneys and liver, and got sidetracked into the IV needle, to be stored for someone's transfusion. If you're like me, you may be struggling to come to grips with how you would feel about having this quart of rotting material routed into your arteries. I think the word you're looking for is "eeeew."
But there's more. While blood is rushing around in your bloodstream, the motion generates a chemical called nitric oxide. Nitric oxide is vital to your blood's ability to carry oxygen. It helps dilate your smallest blood vessels to allow blood to squeeze through. If blood can't get to the smallest passageways, it can't offload it's oxygen. And transporting oxygen to your cells is kind of the whole point of transfusing blood.
However, when blood is removed from a donor and sits still in a storage bag, it no longer generates nitric oxide, and it immediately begins losing whatever nitric oxide it contains. Some tests indicate that stored blood has lost most of it's nitric oxide - hence most of it's oxygen-carrying capacity - within three hours of being removed from a donor. Three hours!
For these and other reasons, many doctors are taking a long, hard look at blood transfusions. Several studies have shown that patients that are treated without blood transfusions have shorter stays in the hospital, and fewer post-operative problems.
For example, it was reported this week that Dr Jimmy Chow of St. Luke's Medical Center in Phoenix has developed a micro-invasive hip replacement procedure. Hip replacement is typically a bloody operation, but Chow claims that with his method the patient loses no more than 200 cc's - about 6 ounces - of blood.
Next time you read a story that uses the expression "life saving blood transfusion," you might want to forward this article to the writer of that story.
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