A new study conducted by researchers at the Cleveland Clinic suggest that the amount of time donated blood is stored can substantially affect patients receiving transfusions during heart surgery. Those patients receiving red blood cells stored over two weeks died at a higher rate, experienced more incidents of kidney failure, and suffered more potentially dangerous infections than those receiving newer blood. While the findings aren’t expected to force immediate changes in blood bank processes—such as those at the American Red Cross, which handles about 40% of the country’s blood supply—officials say the issue needs to be studied.
The question of whether older blood is harmful has also been the subject of several studies in recent years, with mixed results. “This paper addresses an ongoing debate in the field, and although provocative in findings and conclusions, it does not provide a definitive answer,” said Richard Benjamin, chief medical officer for the national office of the Red Cross. “I would tell patients facing cardiac surgery that, of the many risks they face from their underlying health issues caused by their disease, this is not the one they should be preoccupied about.” The study revealed that the in-hospital death rate following surgery was 2.8% for the older blood group, compared with 1.7% for the newer blood group. A year following surgery, the survival rate in the old-blood group was 89%, compared with 92.6% in the new-blood group. Patients receiving older blood were also more likely to need prolonged ventilator support—9.7%, compared with 5.6%—and suffered multiple organ failures three times more than those receiving new blood. Researchers estimate restricting blood storage time to under two weeks would prevent one death a year for every 28 patients.
The Food and Drug Administration (FDA) allows blood to be stored for as long as 42 days. Because the median storage time for red blood cells nationally is 15 days, this means about half of the country’s supply falls into the older range of stored blood. “Blood banks need to explore changing their inventory-management practices,” says Colleen Koch, a cardiac-surgery anesthesiologist at the Cleveland Clinic and lead author of the study. The researchers say their study is the largest to date and better-managed variables that could influence the results.
The standard inventory practice among blood banks is known as first in, first out so that older blood is used first. Koch says one alternative is to distribute newer blood first; however, other experts say there may not be enough supply for that strategy. Koch says the clinic is in the early stages of a 2,000-patient randomized clinical trial comparing outcomes with transfusions using older and newer blood.
Researchers aren’t sure why older blood may be bad for patients, but they do know that the red cells undergo physical and chemical changes during storage that may affect their function and viability post surgery. The findings should urge doctors to be “more conservative with how they approach blood transfusion,” says Koch. For instance, anemic patients can take iron supplements before surgery to minimize red-blood-cell transfusions.