Norepinephrine added to fluids protects against blood loss, study finds
THURSDAY, Sept. 27 (HealthDay News) -- The drug norepinephrine may come to the rescue of trauma victims suffering from heavy blood loss and shock, a French study in rats suggests.
"This is the first scientific study showing the benefits of using norepinephrine in hemorrhagic shock," said study author Dr. Marie-Pierre Poloujadoff, an emergency physician at one of the University of Paris' hospitals.
Uncontrolled bleeding is a "huge problem" for human victims of gunshot wounds, automobile accidents and other traumatic injuries, Poloujadoff said. A steep drop in blood volume can quickly lead to hemorrhagic shock.
Once the victim is in surgery, the surgeon will be able to control the shock. However, "the problem is what to do between the accident and surgery," Poloujadoff said. Long delays can be fatal, she said.
In cases involving major blood loss, physicians try and supply the body with fluids so that the heart will keep pumping and blood pressure won't drop too low, she added. But if there is too much fluid, that can actually speed bleeding, decrease coagulation or dilute the blood so it doesn't adequately carry oxygen to the brain.
To control the balance between getting fluids but not too much, emergency physicians may use "vasoconstrictors" -- drugs that narrow blood vessels. The vasoconstrictor norepinephrine is often used in emergency rooms because it's effective against toxic shock.
The unavailability in France of vassopressin, a vasoconstrictor used in the United States, led to the idea of testing norepinephrine, Poloujadoff said.
The animal study involved four groups of 10 rats. Each group received a different dose of norepinephrine, which was used in rats showing normal blood pressure or low blood pressure. The animals were experimented on while under anesthesia.
The researchers sought to replicate emergency room situations resembling those of human patients who might be cared for after copious bleeding linked to head injury.
At specific doses, norepinephrine combined with standard resuscitation fluids significantly boosted the rats' odds of survival, the French team found.
Poloujadoff said she hopes these results will provide scientific justification to begin clinical research in human on the use of norepinephrine in these scenarios.
The study was published in the October issue of Anesthesiology.
But until more studies are done, the impact of the French results may be limited, said Dr. Philip Levin, chief of anesthesia and director of perioperative services at Santa Monica UCLA Medical Center and Orthopedic Hospital.
"If I read this in one of my journals, it would sound interesting, but I'd wait until we get human studies and larger studies before I'd change my habits," he said.
Another expert agreed.
Dr. Ron M. Walls, a professor of medicine at Harvard Medical School, said that the use of norepinephrine might have some benefit but that, "first we need to know a lot more and have more studies before we could consider this in humans."
Ideas about fluid resuscitation in humans have changed over the last 10 years, he said. Current theory involves the use of fluid to keep vital organs perfused, rather than trying to use enough fluid to restore normal blood pressure, said Walls, who is also chairman of emergency medicine at Brigham and Women's Hospital, in Boston.
"You don't want to constrict the blood vessels more, you want to perfuse the blood," he said.
However, Walls believes the norephinephrine idea might merit further study, especially from the perspective of trying to keep trauma victims alive until they can reach a hospital.
"There's so much blood loss from trauma around the world from both combat and non-combat situations," he said. "If you thought of this in Cleveland, it might not make so much difference, but if you're looking at a victim of a bus accident in sub-Saharan Africa, it might make more of a difference."
There's more on treating bleeding at the National Library of Medicine.
SOURCES: Marie-Pierre Poloujadoff, M.D., M.S., emergency medicine physician, Hopital Avicenne, Paris, France; Philip Levin, M.D., chief, anesthesia and medical director, perioperative services, Santa Monica UCLA Medical Center and Orthopedic Hospital; Ron M. Walls, M.D., chairman, emergency medicine, Brigham and Women's Hospital, and professor, medicine, Harvard Medical School, Boston; October 2007 Anesthesiology
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