 Management of cardiac arrest is complicated by the lack of a readily available tool identifying individuals who are likely to be successfully resuscitated. S100 beta is a protein that originates in the astroglial cells of the brain, and NSE Neuron Specific Enolase is another protein that originates in the neurons themselves. In the laboratory, the concentration of these proteins correlate with evidence of brain damage after head trauma, stroke and exposure to low levels of oxygen. The concentration of these proteins in the blood of human survivors of cardiopulmonary resuscitation in humans is much higher than in patients who were resuscitated but did not survive. However, it is still unclear whether survivors from cardiopulmonary resuscitation have higher levels of these proteins in their blood if they survive with neurological injury secondary to the arrest and resuscitation. 