ANH Preserves Platelet Count and Function Regardless of Storage Method and Time

Across the United States, transfusions are standard in cardiac operating rooms, but at Nationwide Children’s Hospital, a practice geared toward limiting blood transfusion has been established and finely honed. According to a recent study from The Heart Center at Nationwide Children’s, more than 60 percent of patients receive no donor blood products during their entire perioperative period.

While there are clear benefits to blood transfusion in many clinical situations, trying to limit the number of blood transfusions has many advantages.

In addition to lowering the rates of viral and bacterial infections, and reducing the rate of morbidity and length of intensive care unit and hospital stay, “Using blood is also expensive. About 14.5 million units of packed red blood cells are used for transfusions in the U.S. annually, at a cost, the American Red Cross estimates, of $10 billion,” says Aymen Naguib, MD, director of Cardiac Anesthesia in The Heart Center and the Department of Anesthesiology and Pain Management at Nationwide Children’s.

“Many studies have shown an association between blood transfusion and increased morbidity and mortality,” says Dr. Naguib, who is also a clinical associate professor of Anesthesiology at the Ohio State University College of Medicine.

Over more than a decade, The Heart Center at Nationwide Children’s has developed a comprehensive protocol to achieve the goal of a transfusion-free pediatric cardiac surgery and a culture of blood conservation. From preoperative medications to stimulate red blood cell production for some patients to reduced sizes of cardiopulmonary bypass (CPB) circuits, the approach considers every aspect of the surgery.

One of the key intraoperative components is acute normovolemic hemodilution (ANH). In a recent prospective study published in Pediatric Anesthesia, a team at The Heart Center examined this technique, which aims to preserve platelet count and function that could be affected during CPB.

“Platelets are often damaged by contact with the CPB machine and tubing, resulting in heightened inflammatory factors and reduced clotting ability for the patient,” explains Todd Ratliff, CCP, a team perfusionist. “The purpose of ANH is to save some of the patient’s own blood, with preserved platelet function, to give back after bypass.”

Intraoperatively, the goal in a blood conservation culture is to limit the administration of crystalloids, especially in the pre-CPB period.  “With traditional acute ANH, when you take blood out, you replace it with alternative fluids,” says Ratliff. When trying to achieve a bloodless surgery, however, “We don’t routinely do that. If we give fluids back to the patient, we hemodilute the patient, which at the end may defeat the whole goal of preventing transfusion.”

Fifty patients who underwent cardiac surgery on CPB were included in the recent study. Platelet counts and function testing showed no loss or degradation, even after more than four hours of storage. Additionally, there was no difference in platelet count or function between collecting and storing this blood in a syringe or a bag.

“The protocol has been shown to be safe, effective and repeatable, but we’re constantly trying to refine and verify the work we do,” says Roby Sebastian, MD, an anesthesiologist in The Heart Center and a study author.

ANH is used in most cardiac surgeries at Nationwide Children’s. With ANH, based on the child’s weight, hematocrit, type of surgery and other factors, 10-20 percent of the patient’s blood volume is removed.

The team at The Heart Center has developed guidelines for the use of ANH, and they continue to refine and validate the approach through research. “One of the main questions we still need to answer is how to identify the amount of ANH that is just right for each patient,” Dr. Naguib says. The team is now planning such a study.

Reference:

Sebastian R, Ratliff T, Winch PD, Tumin D, Gomez D, Tobias J, Galantowicz M, Naguib A. Revisiting acute normovolemic hemodilution (ANH) and blood transfusion during pediatric cardiac surgery: a prospective observational study. Pediatric Anesthesia.2016 Oct 13. [Epub ahead of print]