Blood transfusions increase the risk of complications and reduce survival rates. Recent research is revealing that almost immediately after it is donated, blood begins to loose its ability to transfer oxygen from the red cells into the tissues of the patient. When patients receive stored blood, their chances of heart attack, heart failure, stroke and death increase in proportion to the length of time the blood has been stored.
Nitric oxide in red blood cells is critical to the delivery of oxygen to tissues. It is nitric oxide that keeps blood vessels open. Several recent studies have shown that the nitric oxide in red blood cells begins to break down almost immediately after the donated cells leave the body of the donor. It doesn't matter how much oxygen is carried by red blood cells. Without sufficient amounts of nitric oxide, this oxygen cannot reach the tissues. When the blood vessels cannot open because of insufficient nitric oxide, tissues go without oxygen. The result can be fatal.
Recent Studies and results
In a study reported in the March 20, 2008
New England Journal of Medicine, researchers tested the hypothesis that serious complications and mortality after cardiac surgery are increased when transfused red cells are stored for more than 2 weeks. Data was examined from patients given red cell transfusions during coronary-artery bypass grafting, heart-valve surgery, or both between June 30, 1998 and January 30, 2006. A total of 2,872 patients received 8,802 units of blood that had been stored for 14 days or less ("newer blood") and 3,130 patients received 10,782 units of blood that had been stored for more than 14 days ("older blood"). The median duration of storage was 11 days for newer blood and 20 days for older blood.
Researchers found that patients who were given older units had higher rates of in-hospital mortality (2.8% vs. 1.7%, P=0.003), incubation beyond 72 hours (7% vs. 5.6%, P=0.001). kidney failure (2.7% vs.1.6%, P=0.003), and sepsis or septicemia (4.0% vs. 2.8%, P=0.01). A composite of complications was more common in patients given older blood (25.9% vs. 22.4%, P=0.001). Older blood was associated with an increase in the risk-adjusted rate of the composite outcomes (P=0.03). At one year, mortality was significantly less in the patients given newer blood (7.4% vs. 11.0% P<0.001).
Researchers concluded that in patients undergoing cardiac surgery, transfusion of red cells that had been stored for more than 2 weeks was associated with a significant increased risk of postoperative complications as well as reduced short-term and long-term survival.
In another study, at the University of Bristol and the Bristol Heart Institute in the U.K., reported by the American Heart Association in
Circulation, research was aimed at quantifying associations of transfusion with clinical outcomes and cost in patients having cardiac surgery.
Researchers examined clinical, hematology, and blood transfusion databases linked with the UK population register. Additional hematocrit information was obtained from intensive care unit charts. Respiratory, wound infections or septicemia, and heart attack, stoke, and renal impairment or failure were pre-specified as co-primary end points. Secondary outcomes were resource use, cost, and survival. Associations were estimated with an adjusted regression model. All adult patients having cardiac surgery over an eight year period with key exposure and outcome data were included in the study.
Researchers concluded that patients receiving a red blood cell transfusion were three times more likely to experience complications from lack of oxygen to key organs, such as heart attack or stroke. At any time after their operations, transfused patients were less likely to have been discharged from the hospital, and were more likely to have died. Red blood cell transfusions were also associated with increase length of hospital stay, increased early and late mortality, and higher hospital costs.
A study at Duke university in 2004 found that heart patients who receive a blood transfusion to treat blood loss or anemia were twice as likely to die during their first 30 days of hospitalization. They were also more than three times as likely to suffer a heart attack within 30 days, when compared to those who did not receive a transfusion.
This study was based on a retrospective analysis of the treatments received by more than 24,000 patients who had experienced an acute coronary syndrome.
Conclusions
There are times when transfusion may be necessary, such as when a patient has undergone massive blood loss. However, it is apparent that many physicians often rush to order a transfusion when it may not be needed, simply based on the patient having low numbers on a blood test. The body can generally respond to lower blood levels by producing more red blood cells. This is how a donor replaces the blood he has donated. These study results suggest that this readiness to transfuse needs to be examined.
When transfusion is indicated, the age of the blood should be a consideration in light of the study results, even if it is your own blood that has been banked for use in your surgery. Current practice is to store blood for transfusion for up to six weeks. Yet this research indicates that positive outcomes are associated with transfusions of fresh blood. Treating stored red blood cells with a solution of nitric oxide results in restoration of most of the ability of the red cells to provide oxygen to tissues. As the first study indicates, stored blood becomes deficient in nitric oxide, limiting its ability to transport oxygen to the tissues of the body. Yet stored blood is not routinely treated with nitric oxide before it is administered in most hospitals.
The ability to screen donated blood for HIV and other infections has lead to an understanding among people that blood for transfusion is safe. People accept transfusion when it is bought up, because they assume it is a safe procedure. These studies indicate otherwise. As these findings become more widely known, empowered patients may begin to question the need and appropriateness of transfusion except in the most dire of circumstances. The empowered patient may even begin to question the need for the surgery that is being recommended, and view it, as also indicated, in only the most dire circumstances.
Sources:
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http://cardiology.jwatch.org/cgi/co...)
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http://content.nejm.org/cgi/content...)
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http://circ.ahajournals.org/cgi/con...)
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http://www.dukemednews.duke.edu/new...)
