新采集血液不适宜立即使用

In a finding that runs counter to commonly held beliefs about fresh being better, a clinical trial published October 8 by the Journal of the American Medical Association shows that acutely（剧烈地） ill premature babies who received fresher blood did not fare better than those who received the current standard of care. There was no difference between the two approaches with respect to major organ injury, mortality and infection. "Before now, most of the literature on the subject suggested that fresh red blood cells are better," says lead author Dr. Dean Fergusson, who heads up the Clinical Epidemiology（流行病学） Program at the Ottawa Hospital Research Institute and is an associate professor at the University of Ottawa. "However, the effect of fresher blood on clinical outcomes had never been examined using a randomized clinical trial in human patients, which is considered the gold standard in medical science. Now it has, and we found the standards currently in place are no different for this highly vulnerable population of pre-term infants than a policy and system that would favour fresh blood."

Previous observational studies of patient outcomes used already existing clinical data, which is problematic for a number of key reasons. Determining the average age of blood and its impact for those transfused more than once is very difficult because the age of red blood cells used in each transfusion could range dramatically within the acceptable shelf life of 42 days.

Called the ARIPI Randomized Trial, which stands for Age of Red Blood Cells in Premature Infants, this study involved 377 babies weighing less than 1,250 grams and requiring red blood cell transfusions. Randomly, they either received blood that had been stored a week or less, or received the current standard of practice used by blood banks. It turned out that there was no difference in outcome between the two groups.

"Over the years, the number of retrospective（回顾的） studies showing possible harm from older blood has created pressure to change the management of the blood supply to provide fresher transfusion products," says Dr. Dana Devine, Vice President, Medical, Scientific & Research Affairs of Canadian Blood Services. "This is a huge undertaking that would require many more donations than we currently have and greatly increase the cost of operating the blood system.

"To have this particular human clinical trial saying otherwise is important because it is the first such study using the highest level of evidence, the randomized controlled trial, and it was done in a very vulnerable patient population."