Brain damage after cardiac arrest results from an interruption of the supply of oxygen-rich blood to the brain, reports Mayo Clinic. Additionally, the blood trapped in the brain becomes stale and collects free radical oxygen molecules, acids and other toxins, adds About.com. Victims of cardiac arrest usually become unconscious within 20 seconds, and brain activity ceases within three to four minutes.
Because interrupted blood flow affects the brain so quickly, it is important for victims of cardiac arrest to receive hands-on CPR as soon as possible to flush out the toxins and supply the brain with fresh oxygen and nutrients, advises About.com. Most people who survive cardiac arrest suffer from a degree of brain damage, and some fall into a vegetative state, explains the American Heart Association. Their prognosis depends on their ethnicity, age and poor health conditions that they may have had prior to cardiac arrest. Other factors include how soon CPR or defibrillation occur and the expertise of the person administering the CPR or defibrillation. Following cardiac arrest, some patients suffer strokes, which further impair brain function.
Sometimes doctors perform therapeutic hypothermia after cardiac arrest to cool body temperature and prevent brain damage, points out Drugs.com. The procedure involves IV administration of cool liquids or the application of ice packs or special cooling blankets. The treatment is not always effective and carries a number of risks.