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October 1, 1998

Open-Heart Surgery Risks Reduced by Use of Blood Filters

Annals of Thoracic Surgery Study Shows Leukocyte Reduction Improves Patient Outcomes While Decreasing Costs and Length of Hospital Stay

Atlanta, GA -- A new study of open-heart surgery patients found that filtering leukocytes (white blood cells) from blood reduces the risks associated with this life-saving surgery and improves patient outcomes. The results of a prospective randomized study of 400 open-heart surgery patients, published in the current, (September), issue of the Annals of Thoracic Surgery, found that filtering blood also significantly decreases the length of hospital stay and costs.

"One of the greatest problems with open-heart surgery is inflammatory injury," said John Parker Gott, MD, Associate Professor of Surgery, Emory University School of Medicine, and Chief, Cardiac Surgery, Crawford Long Hospital and the study's lead investigator. Inflammatory injury occurs when the patient's own blood, after circulating through the cardiopulmonary bypass (CPB) circuit (also known as the heart-lung machine) is returned to the patient. This inflammatory response causes cell damage and diminished organ function leading to increased morbidity and a longer recovery time with an increase in both length of hospital stay and costs.

"The study was designed to improve the safety of this surgery. We know that white blood cells can be injurious to the patient during an open heart operation," said Dr. Gott. "The procedure we found to be most associated with a good outcome in the majority of people was filtration of the white blood cells from all blood products that are transfused including the patient's own blood."

The study found a significant decrease (20%) in length of hospital stay (5.4 days versus 6.8 days) and a significant decrease in mean patient charges ($33,000 versus $39,000) for a majority of patients when leukocyte reduction filters were used.

"We found there can be a $3,000 to $6,000 savings in hospitalization costs per patient with leukocyte filtration. If we multiply that by the approximately 300,000 patients who undergo cardiopulmonary bypass each year in the United States, you can imagine the great savings in healthcare costs," Dr. Gott added.

Study Design

The study compared the current standard of practice with each of three procedures believed to prevent inflammation and subsequent injury. These procedures were the current standard plus aprotinin (an anti-inflammatory drug also used to reduce blood loss), the current standard plus leukocyte filtration, and the current standard with internal surfaces of components of the heart-lung machine coated with heparin (HEP).

At study entry, patients were stratified into one of three risk groups: low risk (defined as an anticipated mortality risk of less than 5%) medium risk (between 5 and 15%) high risk (greater than 15%)

Over 70% of study patients were stratified in the low risk group. This group represents a majority of all patients who undergo open-heart surgery in the U.S. each year.

The patients who received the greatest benefit from leukocyte filtration were those stratified pre-operatively as low risk. For patients stratified as high risk (about 8 percent of study patients), the aprotinin treatment had a significant reduction in length of stay (7.4 days versus 8.2 days) and a significant mean reduction in patient charges ($49,000 versus $55,000). No significant effects for any of the three procedures were found in the medium risk group (12% of study patients).

"The study's findings have demonstrated that we can make open-heart surgery even safer, and save money at the same time," said Dr. Gott, "These findings also led to a change in the way we practice here. We have incorporated leukocyte reduction of all transfused blood products for all open-heart surgery patients across all risk strata. In addition, for those patients stratified as low risk - who are the majority of open-heart surgery patients - we also filter their own blood."

Experts Concur on Benefits of Leukocyte Reduction

In a discussion of the study between leading cardiac surgeons that was published as an addendum to the article, Bradley Allen, MD, Assistant Professor of Surgery, Division of Cardiothoracic Surgery, University of Illinois at Chicago Medical Center, noted that the results are similar to his findings in pediatric patients undergoing cardiac surgery. This study of 28 infants (4 days to 37 months of age), published in the December 1997 issue of the Annals of Thoracic Surgery, demonstrated that leukocyte filtration reduced the formation of oxygen-free radicals, which can cause cell damage, during cardiopulmonary bypass.

This decrease in free radical production improved post-operative heart and lung function. Based on these findings, Dr. Allen stated that his institution has used leukocyte filtration for the last one and a half years in all pediatric patients with excellent results. He believes leukocyte filtration should be a routine part of pediatric heart surgery as it helps minimize the injury caused by cardiopulmonary bypass.

Emory Hospitals include Emory University Hospital, a 587-bed hospital located on the Emory University campus in northeast Atlanta, and Crawford Long Hospital, Emory's 583-bed, community-based hospital in midtown. Emory Hospitals are components of EMORY HEALTHCARE, which also includes The Emory Clinic and its 18 health centers throughout greater metropolitan Atlanta, Emory-Adventist Hospital in Smyrna, The Emory Children's Center, and Wesley Woods Center.

For more general information on The Robert W. Woodruff Health Sciences Center, call Health Sciences Communication's Office at 404-727-5686, or send e-mail to hsnews@emory.edu.