Cardiac surgery consumes a large proportion of all available blood products – up to half of patients undergoing cardiac procedures receive blood transfusion, and this figure exceeds 70 percent in pediatrics. Yet evidence is mounting that blood transfusion may not be as safe as once thought. Literature reviews uncover links between blood transfusions and an array of adverse clinical outcomes. Consensus is growing that blood transfusion is often performed too frequently and unnecessarily.
To promote better practices, the International Board of Blood Management and American Society of Extracorporeal Technology has established a certification program for Patient Blood Management Specialists (PBMSs). Isaac Chinnappan, M.S., a senior cardiopulmonary perfusionist specializing in pediatric perfusion at Monroe Carell Jr. Children’s Hospital, was one of the first 15 perfusionists in the country to obtain the PBMS certification.
“The more blood products you must use, the more complications there are post-operatively.”
“The first focus in our pediatric population is how we can minimize blood utilization. The more blood products you must use, the more complications there are post-operatively. This certification helps us to analyze the clinical scenario and to transfuse the exact quantity of blood products needed to get the maximum clinical benefit,” Chinnappan said.
Safer Practices Through Blood Management
Advocates for change argue that with adequate training, data collection and analysis, and accurate assessment of anemia risk and comorbidities, clinicians can safely utilize blood transfusion less frequently. Restrictive blood transfusion practices have been shown to produce better clinical outcomes with minimal post-operative morbidity compared to more liberal blood use. One review of controlled trials showed restrictive blood practices reduced red blood cell transfusions by 39 percent while not increasing adverse events.
Until recently, it was common practice to use blood transfusion to keep hemoglobin at 10 g/dL and hematocrit at 30 percent. This “10/30 rule” was based on anecdotal evidence. However, the preponderance of evidence does not support such liberal blood use. Blood transfusions are often performed to prevent ischemia by increasing global oxygen delivery (DO2), thereby preventing global oxygen consumption (VO2) from dropping. Yet, studies show that increasing DO2 and arterial oxygen content via blood transfusion usually does not improve VO2 or significantly prevent ischemia, Chinnappan says.
Moreover, a dose-response relationship shows that blood transfusions result in increased mortality, mechanical ventilator time and length of stay, higher rates of multisystem organ failure, and increased postoperative infection.
According to Chinnappan, PBMSs and other perfusionists concerned about these potential negative outcomes of excessive transfusion can safely adopt more restrictive practices. These can include preoperative blood conservation by autologous priming techniques, miniaturized cardiopulmonary bypass (CPB) circuits with reduced priming volume (mini-circuits), normovolemic hemodilution, or salvage of blood from the CPB circuit and modified ultrafiltration – all of which preserve perioperative red blood cell volume and reduce hemodilution. In the case of volume expansion and anemia, agents that stimulate the production of red blood cells can often be used in lieu of blood transfusion.
The Transformative Potential of the PBMS
Through the PBMS certification, Chinnappan and like-minded perfusionists are better able to effectively utilize blood management standards to improve patient outcomes. “By getting my certification, I can bring a patient blood management program to our pediatric hospital that gives us standardized, better guidelines to our clinical practice about how much blood we use for our pediatric patient population.”
“Blood conservation is a key to shorter hospital stay and better outcomes overall.”
The benefits are becoming well-appreciated by surgical leaders. “Blood conservation is a key to shorter hospital stay and better outcomes overall,” said David Bichell, M.D., William S. Stoney Jr. Professor of Cardiac and Thoracic Surgery and chief of pediatric cardiac surgery at Vanderbilt.