As a paramedic, Peter Carlson is used to racing to people's homes. But on his way to see 86-year-old Erika Bruvelis recently, he stopped for coffee and parked outside her Minneapolis house for several minutes—reluctant to arrive too early. In this case, no one had called 911, and with any luck, no one would go to the hospital. Carlson, 28, is one in the first wave of "community paramedics" in Minnesota and the nation. Instead of responding to emergencies, his job is to try to prevent them.