Author: Chase Doyle
While numerous methods have been used to decrease red blood cell transfusions, a technique employed by military surgeons on the battlefield may be the most effective one, according to a retrospective study of cardiac surgery patients.
Intraoperative autologous donation (IAD), the reinfusion of a patient’s own blood recovered during surgery, is associated with a significant reduction in allogeneic transfusions. The removal of more than 900 mL of IAD appeared to decrease total trans fusion by 28.6%, the study authors reported.
“Our major takeaway from this research is that autologous blood donation in large amounts is very feasible in cardiac surgery patients,” said Reney A. Henderson, MD, a cardiothoracic fellow in the Department of Anesthesiology at the University of Maryland School of Medicine, in Baltimore. “We also cooperated with perfusionists to have them do retrograde autologous priming, which is priming of the cardiopulmonary bypass circuit with a patient’s own blood, in order to decrease hemodilution.”
For this retrospective study, Dr. Henderson and his colleagues analyzed patients who presented for aortic valve replacement (AVR), coronary artery bypass graft (CABG), or AVR with CABG between January and September 2017. Although the quantity of IAD and hemodynamic management during IAD was at the discretion of the anesthesiologist, researchers selected patients for analysis who had more than 900 mL of IAD. Patients with the following characteristics were excluded from the study: age over 80 years or under 40 years, body mass index greater than 45 kg/m2, cardiopulmonary bypass longer than four hours, hematocrit less than 27%, and platelet count less than 100,000/mcL. Once the patient was in the ICU, transfusion was regulated per institutional protocol, the authors noted.
Transfusion Rates Nearly Halved
As Dr. Henderson reported at the 2018 annual meeting of the Society of Cardiovascular Anesthesiologists (abstract 19), 84 autologous patients were propensity matched to 84 patients who did not receive IAD. Findings showed that 38 propensity-matched non-IAD patients compared with 21 IAD patients received transfusion (45% and 25%, respectively; P=0.006) (Table). Based on these findings, IAD appears to decrease transfusion by 20%, Dr. Henderson said.
|Table. Variables by Whether Patient Received Autologous Blood|
|Variable||Autologous (n=84)||Not Autologous (n=84)|
|Any transfusion||21 (25%)||38 (45%)|
|12-hour chest tube output (mL)||362.5±290.8||402.2±330.2|
“We are always looking out for the safety of the patient, so by maintaining euvolemia and supplementing alpha-adrenergic medications, we can maximize the effects of autologous blood returned after the cardiopulmonary bypass,” Dr. Henderson explained.
Although patients with an ejection fraction lower than 30% were removed from analysis, these patients may ultimately benefit from IAD, Dr. Henderson noted. In addition, researchers are still looking for an explanation as to why transfusions of allogeneic blood products were reduced across the board.
“We’re analyzing coagulation studies to see if there’s a difference in coagulation profiles before these patients go on bypass, while they’re on bypass, and then when we give them their autologous blood back, to see if there are any overlaps with patients who don’t undergo IAD,” Dr. Henderson said.
Transfusion Alternatives Needed
As Dr. Henderson reported, cardiac surgery accounts for 15% to 20% of the national blood supply used, with more than half of cardiac surgery patients requiring transfusions. Even though the transfusions undoubtedly save lives, there are complications associated with the procedure.
“Blood transfusions can be harmful to patients, increasing the risk of infection, renal failure and hospital length of stay,” said Dr. Henderson, who noted that two units of packed red blood cells impose a twofold additive risk for adverse events and death.
Although many methods, including cell salvaging and preoperative erythropoietin and autologous donation, have been used to decrease rates of transfusion, said Dr. Henderson, IAD is easily performed and provides a source of whole blood that has been protected from the deleterious effects of cardiopulmonary bypass. Nevertheless, studies so far have shown mixed results regarding its benefits, the authors noted.
In an interview with Anesthesiology News, Jacques Neelankavil, MD, an anesthesiologist at the Ronald Reagan UCLA Medical Center, in Los Angeles, noted that transfusion for cardiac surgery is an important area to tackle for the triple aim of medicine: patient satisfaction, cost and patient outcome.
“We know that transfusion of red blood cells and coagulation factors may be deleterious to patients; however, anemia and coagulopathy must be managed in the perioperative period to provide safe patient care,” said Dr. Neelankavil, who was not involved in the study. “This study highlights a possible solution to a vexing clinical dilemma: How can we reduce blood transfusions following cardiac surgery? Autologous blood collection has been done for a long time, and it has proven to be relatively safe. We have an extensive history with autologous blood collection in our Jehovah’s Witness population in cardiac surgery, but we have usually reserved the autologous donation to approximately one unit of whole blood.”
This study may be an important proof of concept in high-volume autologous blood collection, Dr. Neelankavil said. The next steps in follow-up studies, he continued, would be to see if high-volume autologous blood collection is applicable to a wide variety of cardiac surgical cases.
“It would also be interesting to examine if transfusions in the intensive care [unit] following autologous blood collection were similar to non-autologous blood collection patients,” Dr. Neelankavil said. “Hopefully, the results of the study will be confirmed with larger studies.”