A blood transfusion practice previously studied only in patients with severe traumatic injuries has been widely adopted by hospitals for surgical patients without traumatic injuries, according to a new study published in JAMA Surgery journal by researchers at Harvard Medical School and Massachusetts General Hospital.

However, this practice has not been shown to benefit nontrauma patients, and the new study suggests that it may even be harmful to some, an observation that indicates the need for more research.

“The strategy of giving patients requiring massive transfusion greater amounts of fresh frozen plasma relative to the amount of red blood cells has spilled over from trauma patients into unstudied patient populations,” said study leader Daniel Dante Yeh, HMS assistant professor of surgery in the Division of Trauma, Emergency Surgery and Surgical Critical Care in the Mass General Department of Surgery. “This may have important consequences, since our results suggest that certain populations may be harmed by this practice.”

Massive blood transfusions – defined as transfusing at least 10 units of red blood cells within 24 hours – are given to patients experiencing severe blood loss, often in response to traumatic injuries but also in the context of procedures like cardiovascular surgery or liver transplantation and even in some nonsurgical patients. Massive transfusion can include adjustments of the ratios of components – including fresh frozen plasma (FFP), platelets and red blood cells (RBCs) – with the goal of improving outcomes.

The strategy of giving a higher proportion of plasma is based on the belief that maintaining the balance of coagulation factors carried in plasma would reduce the overall amount of bleeding, requiring lower amounts of red blood cells and improving survival. While not new, the concept has gained interest in recent years following reports from military surgeons that administering a higher ratio of FFP to RBCs may have improved the survival of soldiers with serious injuries. Similar reports from civilian trauma centers have led to broad adoption of what is called ratio–based resuscitation for trauma patients requiring massive transfusion.

The research team—including physicians from both the trauma service and the blood transfusion service—embarked on the current study in response to the observation that high–ratio transfusion was increasingly being used in massive transfusions given to non–trauma patients, a practice not previously studied in this population. To determine how common that had become and to test the hypothesis that higher ratios of FFP to RBCs were associated with improved survival of nontrauma patients, the investigators analyzed data covering all massive transfusions administered at Mass General from 2009 to 2012.

Of the 865 massive transfusions administered during the four–year period, 767 were given to nontrauma patients – most often to control bleeding during nonemergency surgery. Overall, the ratios of FFP to RBCs given to patients who did or did not survive were almost identical. Dividing patients into three groups – those receiving high, medium and low FFP to RBC ratio transfusions – revealed no difference in 30–day mortality between groups, including for trauma patients. However, among general surgery and medical service patients those receiving high–ratio transfusions had a higher mortality rate than those receiving low–ratio transfusions, while the opposite was found among vascular surgery patients.