If you’re injured in an accident and need blood, you may become part of a medical experiment – without your knowledge or consent.

A number of hospitals nationwide are testing a new artificial substitute for blood called PolyHeme to treat severely injured and bleeding patients. The substance, which is derived from human hemoglobin, is designed to carry oxygen like blood and to replace blood in emergency situations where a transfusion is not available.

Denver Health, formerly known as Denver General Hospital, is one of the hospitals taking part in the test. In a statement, the hospital said patients who qualify would either receive infusions of PolyHeme or of saline solution, which is the current standard treatment. 

The infusions would begin at the scene of the injury or in the ambulance, and continue for 12 hours after the patient arrives at the hospital. 

“This study could potentially lead to a change in the initial treatment of critically injured and bleeding patients that may result in improved survival,” Dr. Ernest E. Moore, chief of surgery and trauma services at Denver Health, said. 

However, the lack of patient consent in the study has created some controversy. The Denver hospital said many of the patients, because of their injuries, might not be able to make a decision on whether to take part. However, scientists involved in the study have provided a way for people to avoid taking part.

People who don’t want to take part can call the study coordinator in Denver, Jeffrey Long, to obtain a wristband that will alert emergency workers not to administer the blood substitute. Long can be reached at (303) 436-7906. Other hospitals, and the company producing PolyHeme, are offering the wristbands as well.

The study includes 20 hospitals. Other medical facilities taking part in the study, according to The Associated Press, include:

• University of Texas Medical School in Houston;
• Loyola University Medical Center in Maywood, IL;
• Mayo Clinic in Rochester, MN; and
• Regional Medical Center in Memphis, TN.

Northfield Laboratories of Evanston, IL, which makes PolyHeme, would not tell the news service the names of the other hospitals that are taking part.

The company said PolyHeme is designed to carry oxygen like real blood. It also is designed to avoid side effects associated with other blood substitutes, to have a longer shelf-life than real blood and to cut the risk of transmitting diseases such as HIV or hepatitis through a transfusion.

A number of groups that advocate for patients’ rights told The AP they object to the study, however, pointing to studies or earlier blood substitutes that led to the deaths of some people taking part.