Deep hypothermic circulatory arrest (DHCA) is a surgical technique that involves cooling the body of the patient and stopping blood circulation. It is used in cardiac surgery to allow operation on the aortic arch and in neurosurgery to repair some brain aneurysms.The procedure requires keeping the patient in a state of hibernation at 12–18 °C with no breathing, heartbeat, or brain activity for up to one hour. Blood is drained from the body to eliminate blood pressure.