From University of North Carolina School of Medicine
Method to restart the heart after traumatic injury and bleeding caused it to stop may help save lives now almost certainly lost
CHAPEL HILL -Very few survive a traumatic injury that causes cardiac arrest after profound blood loss. Massive hemorrhage means loss of life-sustaining oxygen to the heart and brain. Blood pressure drops, the heart stops beating, the brain dies.
But according to new research at the University of North Carolina at Chapel Hill, this picture may someday prove less dismal. A method for delivering an oxygen-carrying fluid to resuscitate the heart after cardiac arrest may help save trauma victims by buying valuable time to allow surgeons to repair the damage.
A report of the still-experimental procedure is published in the November issue of Critical Care Medicine.
Researchers led by James E. Manning, M.D., associate professor of emergency medicine at UNC-CH School of Medicine, describe selective aortic arch perfusion (SAAP), as a potentially effective way to pump an oxygen-carrying fluid into the aorta, the large artery that arches from the heart and distributes blood to the body. The fluid is HBOC-201, a hemoglobin-based oxygen carrier developed by Biopure Corporation, Cambridge, Massachusetts.
"This procedure involves taking a specialized balloon catheter developed here at UNC and advancing it though the femoral artery and into to the chest, into the aorta," Manning explained. "When the balloon is inflated and the oxygenated fluid pumped in, the upper part of the body is selected for perfusion. It's about the fastest way to relatively isolate the heart and the brain and perfuse it with an oxygenating solution."
In previous animal experiments with SAAP, the researchers had focused on cardiac arrest associated with heart rhythm disturbance tied to sudden death. Manning said it later became evident that people who were dying from hemorrhage - who go into cardiac arrest from bleeding, such as might happen after traumatic injury - might benefit from this perfusion technique.
"Cardiac arrest due to blood loss, hemorrhage, especially after blunt trauma, has an almost 100 percent mortality. When there's cardiac arrest from severe injury, many surgeons consider resuscitation" futile," he said. "If you can keep somebody like this alive, you may be able to get them to an operating room, stop the bleeding and repair the damage."
The new study involved a pig model of liver injury and severe bleeding. The subsequent blood pressure drop caused the animals' hearts to stop beating. Six others were treated with SAAP plus BioPure's HBOC-201. These were compared to a control group of six animals where SAAP was used with a saline solution, which has very limited oxygen-carrying capacity.
Spontaneous heartbeat with sustained aortic blood pressure occurred only in those animals that received the HBOC-201 oxygen-carrying solution. Manning said more animal studies are needed that would further demonstrate the procedure's benefits for emergency trauma patients. These could be followed by a clinical trial in the emergency setting.
As to its military applications, the UNC emergency medicine physician said SAAP with an oxygen-carrying solution could be administered in a field medical unit and, if made portable, may even be administered at the point of traumatic injury. "Often when someone has a severe injury and bleeding, they exsanguinate and die before they can get to a medical facility or surgeon. And if we can keep them alive long enough to transport them to an operating room, the bleeding can be surgically controlled, they can be resuscitated, stabilized, and hopefully survive," Manning said.
"I think the combination of selected aortic arch perfusion technique with this hemoglobin-based oxygen carrier is effective therapy for cardiac arrest. We've shown it in the laboratory setting for both non-traumatic and traumatic cardiac arrest," he added. "And if we refine and improve this technique and show it is robust in further studies, it could prove very beneficial in human cardiac arrest."
UNC study co-authors with Manning were Drs. Laurence M. Katz and Christopher C. Baker. Also from UNC were Neil Batson, B.S. and Shane L. McCurdy, B.S. From Biopure Corp. were Drs. L. Bruce Pearce and Maria S. Gawryl.
The research was supported, in part, by Biopure Corporation, Cambridge, MA.
Media note: Contact Dr. Manning at 919-966-5933; firstname.lastname@example.org. School of Medicine contact, Les Lang, 919-843-9687; email@example.com