Blood loss is a leading cause of death for people critically injured, yet most emergency responders to the scene of a car crash or other trauma can do little more than try and stem the flow of blood and rush to a hospital. State Medevac helicopters recently began carrying whole blood for transfusions in the field, and Howard County Department of Fire & Rescue Services announced Thursday that it has become the first local jurisdiction in the state to carry whole blood on some of its emergency trucks, hoping to improve more people’s chances of survival.