Study identifies ideal plasma ratio for blood transfusions in trauma patients

What is the best mixture of blood in transfusions? This study answers the question.

Many patients arrive at the University of Maryland's Shock Trauma Center bleeding profusely, their lives depending largely on whether doctors can stop the hemorrhaging and replace the lost blood.

But doctors at trauma units around the country use different blood mixtures when performing transfusions on patients because it has been unclear whether one combination worked better than another. No one had studied the issue extensively.

The results of a multi-hospital study released Tuesday in the Journal of the American Medical Association provide some clarity that researchers hope will lead to new protocols and save lives.

Funded by the Army, which hopes to apply its lessons to help wounded soldiers on the battlefield, this study examined what mix of blood plasma to platelets to red blood cells hospitals should use when transfusing blood into patients with severe injuries.

The hope now is that trauma units will use the research to adopt uniform standards, said Dr. John Holcomb, the study's principal investigator, a retired Army surgeon and director of the Division of Acute Care Surgery at the University of Texas Health Science Center at Houston Medical School.

"We hope it will solidify the practice for those already using it and help to implement guidelines at institutions," Holcomb said. "We hope that it will establish more protocols."

The study employed a novel, and controversial, way to gain the consent of patients and research subjects who usually were unable to give individual consent because they were so badly injured. Already Shock Trauma, pointing to the study's success, plans to use the method — known as community consultation — to conduct research in other areas.

For this study, Shock Trauma researchers reached out to people through newspaper and radio advertisements directing them to a website about the research. They also went to community meetings, churches and events. People not wanting to participate were told to wear a particular armband.

Critics say there is no way to inform enough of the community about a study and that people should have the choice whether to participate in trials that could harm or kill them even if the chances are small.

One ethics expert said community consultation is the only way to study issues in emergency medicine.

"If you require consent for all clinical studies you end up getting into a Catch-22 where you can never systematically learn about anything in an emergency setting," said Nancy Kass, deputy director of bioethics and public health at the Johns Hopkins Berman Institute of Bioethics. "A person having a heart attack cannot give consent."

Kass added that as part of community consultation, doctors must ask family members, if they are on hand, for consent on behalf of a patient. They also must tell a patient they are part of a study after they regain consciousness.

About 40 patients at the Maryland's Shock Trauma were part of the study. The center had no one opt out, said Dr. Thomas Scalea, the center's physician-in-chief and director of the University of Maryland School of Medicine's trauma program. He agreed there was no other way to do the trial.

"There is no better way to learn than good prospective clinical trials," Scalea said.

To conduct the study, one group of patients received a unit of plasma and one of platelets for every unit of red blood cells, while another group received one unit of plasma and one of platelets for every two units of red blood cells.

Red blood cells transport oxygen from the lungs, and are prescribed often to replace lost blood. Platelets help blood to clot. Plasma carries blood proteins that also aid in the clotting process.

The research pivoted around how much plasma to use in blood transfusions because some studies have linked it to increased risk of acute lung injury, or respiratory distress after the transfusion. The lung disorder is one of the more common causes of transfusion-related deaths and, at the very least, lands most patients on a ventilator. Yet its use has become more common, and many doctors argue it saves lives.

The study of 680 severely injured patients found that those who received a mix of one unit of red blood cells, one unit of platelets and one unit of plasma were more likely to have their bleeding stopped and less likely to die from blood loss.

There also were not the complications from plasma that previous studies found.

The study led by Holcomb was randomized, the gold standard of research. It looked at patients in real time, and randomly gave them one or the other of the treatments.

The researchers now also have developed a database of nearly 700 patients and have started other studies using the same pool of data looking at brain injuries, complications in trauma patients and other subjects.

"We collected a lot of data and now we have 55 more questions," Scalea said. "We celebrated the results for about a day and half and now we have to get back to work."

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