Embargoed until Friday, November 7th, 1997
Contact:
Bob Schwadron, 212/468-3616
Debra Bloom, 404/686-8191
Study Shows New Approaches Significantly Improve Outcomes
of Open-Heart Surgery
Life-Saving Surgery Can Be Improved
With a Decrease in Hospital Stay and Costs
Atlanta, November 7, 1997 -- A new study has found that filtering leukocytes (white blood cells) out of transfused blood and blood that passes through a heart-lung machine during cardiac surgery resulted in significantly decreased length of stay and therefore, cost of care, for a majority of patients. The results of a prospective, randomized study in 400 open-heart surgery adult patients were presented today at the annual meeting of the Southern Thoracic Surgical Association by John Parker Gott, MD, Associate Professor of Surgery, Emory University School of Medicine, and Chief, Cardiac Surgery, Crawford Long Hospital.
"Although there has been progress in the area of minimally invasive cardiac surgery, a majority of patients still require cardiopulmonary bypass (CPB) with a heart-lung machine," explained Dr. Gott. "One of the greatest problems associated with the heart-lung machine is inflammatory injury. This injury is a whole body response which occurs when the patient's own blood, after circulating through the heart-lung machine, is restored to the patient causing cell damage resulting in diminished organ function."
"The results of our study demonstrate that we can provide the majority of patients who undergo CPB an added level of protection," Dr. Gott said. "By reducing inflammation with leukocyte filtration, we can improve patient outcome significantly and cost effectively, making this important life-saving procedure even better."
Pulmonary and myocardial dysfunction increases post-surgical interventions including greater requirement for potent drugs, longer patient time on a ventilator leading to protracted length of stay in the intensive care unit (ICU) all at significantly increased costs.
"The use of a heart-lung machine is a necessary evil in most open-heart operations," said Dr. Gott. "As physicians, we want to prevent or minimize the deleterious effects associated with extracorporeal circulation."
Filtration Decreases Hospital Stay and Costs
The study was designed to compare three procedures to prevent inflammation and the subsequent reperfusion injury. The approaches studied compared a current standard of practice with either the standard plus aprotinin (an anti-inflammatory drug also used to reduce blood loss), the standard plus leukocyte filtration (filters that reduce leukocytes, mediators of inflammation, from transfused blood products and patients' own white blood cells circulating in the heart-lung machine), and the standard of practice with internal surfaces of components of the heart-lung machine coated with heparin (HEP) in an effort to mimic the natural lining of blood vessels and thereby prevent inflammation. Length of hospital stay and hospital charges were selected as end points of the study because they have been found to correlate with post-operative complications in open-heart surgery.
For a subset of the patient group where leukocyte filtration was used, there was a significant decrease in hospital stay of 20 percent (5.4 days versus 6.8 days) and a significant decrease in mean hospital costs ($33,000 versus $39,000) compared to standard practice. The patients who received the greatest benefit from leukocyte filtration were those stratified pre-operatively as low-risk (anticipated mortality < 5%), which were a majority (approximately 80%) of patients studied, and also represent the majority of patients who undergo open-heart surgery each year.
For patients stratified as high risk (anticipated mortality > 15%), the aprotinin treatment group had a significant reduction in length of stay (7.4 days versus 8.2 days) and a significant mean reduction in costs ($49,000 versus $55,000). This high risk group comprised approximately 8% of the patients studied. No significant effects for any of the approaches were found in the medium risk group (anticipated mortality 5-15%), which comprised the remaining 12% of the patients studied.
The Role of Leukocytes in Inflammation with CPB
Although most clinicians consider autologous (or one's own) blood as safe blood, this is not the case for patients who undergo open-heart surgery with CPB. The patient's own blood is directed out of their body through the extracorporeal circuit (CPB circuit), called the heart-lung machine. When the patient's own blood is diverted to the CPB circuit, the blood is exposed to foreign surfaces. As a result, neutrophils, the most prevalent leukocytes in the circulation, become activated.
Neutrophils contain potentially destructive chemicals known as oxygen free radicals and proteolytic enzymes which are damaging to organs. Activated neutrophils also plug the capillaries in the organs, blocking blood flow. This process can injure vital organs increasing patient risk.
"There has been increasing evidence that leukocytes are an important factor in many post-operative complications, not just where the patient's own blood is used but also in operations where donor blood is used," Dr. Gott explained.
Preventing Injury in Infants Undergoing Open-Heart Surgery Bradley Allen, MD, Assistant Professor of Surgery, Division of Cardiothoracic Surgery, the University of Illinois at Chicago Medical Center, identified similar benefits of leukocyte filtration in infants undergoing cardiac surgery. In a study of 24 infants (4 days to 37 months of age), who underwent open-heart surgery requiring cardiopulmonary bypass, it was found that the production of oxygen free radicals was significantly reduced when the leukocytes were filtered from the blood. The oxygen free radicals (superoxide anions) that are released by activated leukocytes are associated with the cell destruction that can injure the heart and lungs.
Dr. Allen and his colleagues commented that reduction of oxygen free radicals were consistent with their clinical and experimental observations of improved lung function allowing for decreased use of potent drugs and decreased time on the ventilator for the infants.
"Any opportunity to minimize this injury provides more than clinical and cost benefits," stated Dr. Allen. "It also enables us to get the infants back together with their parents sooner helping to alleviate the psychological trauma associated with cardiac surgery."
According to the American Heart Association, there are more than one-quarter million procedures with CPB conducted in the US annually.
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Emory Hospitals, comprised of Emory University and Crawford Long hospitals are adult tertiary care hospitals in Atlanta, Georgia. Emory University Hospital is a 587-bed facility located in northwest Atlanta on the Emory University Campus. Crawford Long Hospital is a 583-bed community-based facility located in Midtown Atlanta. Both hospitals are staffed by members of the Emory Clinic who are faculty members of Emory University School of Medicine. The hospitals are known for their work in cardiology, organ transplantation, orthopaedics, obstetrics, plastic/reconstructive surgery, urology and neurology. The Emory Hospitals are part of EMORY HEALTHCARE, a network of medical services that offers patients the newest knowledge and most advanced technologies and innovations through its ties to Emory University.
Editors note: Dr. Gott and Dr. Allen are available for interviews. Please contact Bob Schwadron (212/468-3616), Caroline Almeida (212/468-3413) or Debra Bloom (404/686-8191) to schedule an interview. Additionally, B-roll including discussions with Dr. Gott and Dr. Allen, open-heart surgical procedures on adult and infant, infant on ventilator and in ICU is available on: Friday, November 7, 1997 at 10.00am-10.30am ET on C_BAND: GALAXY (C) 4/TRANSPONDER 14/AUDIO 6.2 & 6.8 and at 1.00pm-1.30pm ET on C_BAND: GALAXY 9/TRANSPONDER 1/AUDIO 6.2 & 6.8.
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