Transfusion of blood stored for more than 14 days increases mortality among cardiac surgical patients

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March 20, 2008 By Vijayalakshmi Kunadian MBBS MD MRCP [1]

Cleveland: Researchers have demonstrated that administration of blood that has been stored for more than 14 days during cardiac surgery is associated with increased in-hospital and long term mortality.

Advances in technology in recent years have made blood transfusion a safe procedure in terms of reduction in transmission of infectious disease through blood products. Although there is reduction in infectious diseases, previous studies among patients who have sustained trauma and critically ill patients suggest that blood transfusion is associated with increased mortality, shock severity and sepsis.

During cardiac surgery, nearly half of the patient population receive blood transfusion (around 1-2 units on an average). A number of factors impact the outcome following cardiac surgeries. In the recent issue of the New England Journal of Medicine, Koch and colleagues from the Cleveland clinic determined if administration of blood older than 14 days is associated with worse outcomes following cardiac surgery.

This study consisted of over 6000 patients who had undergone coronary artery bypass surgery, valve surgery or both from 30 June 1998 to 30 January 2006 in the Cleveland clinic. Patients were divided into two groups:

  • Group 1: Those that received blood which was stored for 14 days or less (median 11 days) and
  • Group 2: Those that received blood which was stored for more than 14 days (median 20 days).

Patients in group 1 (n=2872) received a total of 8 802 units of blood and those in group 2 (n=3130) received a total of 10 782 units of blood.

This study demonstrated that there was an increase in:

  • In-hospital mortality (2.8% vs. 1.7%, p=0.004),
  • Intubation duration >72 hours (9.7% vs. 5.6%, p<0.001),
  • Renal failure (2.7% vs. 1.6%, p=0.003),
  • Sepsis or septicemia (4% vs. 2.8%, p=0.01) among patients in group 2 compared to those in group 1.

The composite complications were also significantly high among those who received blood older than 14 days (25.9% vs. 22.4%, p=0.001). At one year, patients in group 2 had an increase in mortality compared to those is group 1 (11% vs. 7.4%, p<0.001). This finding remained significant despite correcting for confounding factors including blood group.

Although the Food and Drug Administration allows storage of red blood cells up to 42 days, this study demonstrates the detrimental outcomes associated with the use of old blood among cardiac surgical patients. A number of potential reasons have been speculated for this association including loss of viability and red cell function as a result of progressive structural and functional changes when blood is stored for a long period of time.

Given the association of increased mortality with old blood, this study reiterates the importance of examining the need for blood transfusion during cardiac surgery. Whether reuse of shed blood during surgery and the use of blood substitutes would improve outcomes following cardiac surgery is not clear.