The first heat wave of the season is already scorching the US Southwest with high temperatures, and firefighters in Phoenix Arizona, America's hottest city, are employing a new tactic in hopes of saving more lives in the county, where 645 people died from the heat last year, Medical Xpress reported. Starting this season, the Phoenix Fire Department is immersing heat stroke victims in ice on their way to area hospitals. This medical method, known as cold water immersion, is familiar to marathon runners and military personnel and was recently adopted by Phoenix hospitals as a basic protocol, according to Fire Department Capt. John Prato. The method can significantly lower body temperature in minutes, he said. “Just last week we had a critical patient who we were able to bring back to life before he even walked through the emergency room doors,” Prato said. - It's our goal to improve patient survival rates." Human-sized bags designed to help heat stroke patients have become standard equipment on all Phoenix Fire Department vehicles. It's one of the measures the city has taken this year as temperatures and casualties have steadily risen. Phoenix is keeping two cooling stations open overnight for the first time this season. Meanwhile, forecasters are predicting +43.3 degrees Celsius in Phoenix and Las Vegas in the coming days.