Few early prognostic indicators are currently available for patients' families and clinicians following out of hospital cardiac arrest (OHCA), and blood biomarkers may be of prognostic value in these cases. Brain tissue is highly dependent upon aerobic respiration, and oxygen deprivation result in irreversible neuronal cell injury. Peptides released into the blood by injured neuronal cells can be measured to estimate degree of injury, and potentially predict long term neurological outcome.