SAN DIEGO -- A life-saving solution may have helped save the lives of some critically injured San Diegans.

For nearly a year now, paramedics have been testing a blood substitute that is compatible with all blood types.

A traumatic injury can result in serious blood loss, a loss that even paramedics can't control.

"Unfortunately there is not a lot we can do for the patients, espeically if they have internal bleeding. We cannot stop the bleeding," said Devin Price, an American Medical Response paramedic.

Paramedics use a saline solution to keep blood pressure up until the victim reaches the hospital. But often it isn't enough.

Now paramedics have a new way to temporarily replace lost blood for critiically injured patients out in the field. It's a blood substitute being studied at the University of California, San Diego, Medical Center.

"We believe that having a solution that can carry oxygen ... may be better than getting salt water in the field," said UCSD trauma surgeon David Hoyt.

Polyheme can deliver oxygen and boost blood volume before a patient reaches the hospital.

Paramedics have used Polyheme on more than a dozen trauma patients in the past year, with encouraging results.

Polyheme doesn't carry the risks of blood. It is filtered and considered safe.

Researchers will compare the survival rates of patients who receive the blood substitute to those getting the saline solution.

The results will be sent to the Food and Drug Administration for review.