New York City paramedics have begun treating cardiac arrest patients with hypothermia therapy in ambulances.

The procedure involves administering cold intravenous liquids, reducing the body temperature to 32 degrees Celsius for 24 hours. It helps stop damage to muscle and tissue and preserves neurological functions.

Mayor Michael Bloomberg said the procedure has been proven to slow the effects of cardiac arrest on the body.

Other cities have already been using it for years.

In New York City, some city hospitals have been performing hypothermia therapy for several years, and as of last year, more than 40 do it. The city's paramedics began doing it in ambulances Sunday.