"External or internal cooling techniques can be used to initiate cooling within minutes to hours". The two main randomized and positive studies dealing with the efficiency of hypothermia after cardiac arrest have used external cooling systems. However, several animal studies documented the importance of initiating hypothermia as soon as possible after cardiac arrest. Intravascular cooling enables more rapid induction of hypothermia compared with external cooling method after brain injury. Although several human studies have also documented that intravascular cooling provides more precise control of core temperature than external methods and although an endovascular method has been used safely in pilot studies in those experiencing hypothermia after cardiac arrest, the superiority of such a cooling on the prognosis after cardiac arrest remains unknown, as well as its cost efficiency.