When Kelly assists the woman who is passed out during the party after taking an unnamed pill while drinking, he finds she has a rapid heart rate as well as having a high temperature. To reverse the effects of the drug combination, he asks for a large bowl of ice water. By dunking her forehead repeatedly in the cold water, the mammalian diving reflex is triggered. This reflex does three things: slow the heart rate/break out of the ventricular tachycardia; shunt blood to the body's core; and slows overall metabolism. It's seen in seals and other diving mammals but humans exhibit the same reflex and it's quite an effective out of hospital emergency measure, especially when breaking a run of tachycardia which can in rare situations be fatal.