Early Transfusion of Packed Red Blood Cells to Be Predictor of ARDS in Trauma Patients

Newswise — A study published in the February issue of Anesthesiology offers compelling evidence that adult trauma patients transfused with packed red blood cells (PRBCs) early in their treatment have a greater chance of developing the acute respiratory distress syndrome (ARDS).

The study may help to improve strategies that anesthesiologists and critical care personnel use to treat this vulnerable patient population.

"Our study showed that transfusion of PRBCs is an independent predictor of ARDS in adult trauma patients," said John D. Lang, M.D., from the Department of Anesthesiology at the University of Washington and VA Puget Sound Healthcare System, Seattle. "And our findings suggest that a conservative transfusion strategy that decreases PRBC exposure " even by one unit " may be warranted to reduce the risk of ARDS in these injured patients."

It is one of the largest studies of its kind to date, involving 14,070 patients from the National Study on Costs and Outcomes after Trauma and leaders in injury research from the Harborview Injury Prevention and Research Center. Its findings could be critically important to medical workers who are often forced to balance the benefits and risks of blood product transfusions for injured patients.

Blood transfusions are vital for the treatment of critically ill patients by replacing lost blood volume, correcting the body's blood clotting ability and improving oxygen delivery. Adverse events associated with blood product administration include allergic reaction, infection transmission, administration of mismatched blood and development of ARDS.

ARDS is a serious lung disease that disrupts the normal breathing process and usually occurs in conjunction with traumatic medical conditions.

In a companion editorial in Anesthesiology, Marc Moss, M.D., from the University of Colorado at Denver and Health Sciences Center, lauded Dr. Lang's study for establishing a relationship between the amount of blood transfused and the risk of developing ARDS.

"Previous studies have suggested that a safe threshold for the number of transfused units of blood may exist," said Dr. Moss. "In this study, a dose-dependent association between the number of transfused units and the development of ARDS was exhibited. It is likely that with each biologically active unit of blood product, there is a unique interaction with the host that determines the probability of causing lung injury. Given these risks, should we adopt a more restrictive transfusion strategy in those critically ill patients with preexisting risk factors such as trauma?"

Dr. Lang seems to think so.

"Injury is the fifth leading cause of death in patients over 18 years of age, and PRBCs are the most commonly transfused blood products in the hospital," said Dr. Lang. "Our main findings are that early PRBC transfusion of more than five units during the first 24 hours of hospital admission predicted ARDS and that each unit of PRBCs transfused early after admission increased the risk of ARDS by 6 percent, indicating that each unit of blood administered carries a particular risk to the patient. Exercising prudence in transfusing trauma patients should be urged."

Dr. Lang's study is also the first to report an independent association between transfusion of fresh frozen plasma (as opposed to PRBCs) and the development of ARDS in trauma patients, said Dr. Moss. "While a restrictive strategy of PRBC transfusion may only decrease exposure by a few units, a restrictive strategy in the use of fresh frozen plasma has the potential to prevent large exposure to blood products."

These findings point to fresh frozen plasma as an emerging and possibly predominant risk factor for the development of transfusion-related ARDS, said Dr. Moss.

Both Dr. Lang and Dr. Moss indicate that further clinical trials will be necessary before Dr. Lang's findings can be confirmed and applied to widespread practice.

Anesthesiologists: Physicians providing the lifeline of modern medicine. Founded in 1905, the American Society of Anesthesiologists is an educational, research and scientific association with 43,000 members organized to raise and maintain the standards of the medical practice of anesthesiology and improve the care of the patient.

For more information visit the ASA Web site at www.asahq.org.