[@Aisling] The father shook his head. "15 minutes is way too quick. There are people who have been revived for five hours, and they survived it without any severe brain damage. And brain damage doesn't always start after such a short time. Usually, it starts after three minutes without any circulation, but depending on your body temperature, that time span can increase to up to thirty mintues. As I said, Vladi was cold, and CPR keeps the blood circulating at rates of about 33 per cent of its normal rate. That's why CPR is so important: Not because it makes the heart beat - it doesn't in most cases - but because it prevents brain damage."