The absence of N20 of the somatosensory evoked potentials (SEP) is recommended as a valuable predictor of poor neurologic outcome in post-cardiac arrest patients. However, interpretation of N20 is affected by the background noise levels. Reliable analysis of N20 is limited with high noise levels and artifacts. Moreover, presence of N20 does not guarantee good neurologic outcome. P30 is a positive deflection of N20 occurring on 25-35 msec. According to our pilot study, N20 without following P30 is related with poor outcome, while N20 followed by P30 is highly related with good outcome. P30 is evident even when the N20 is ambiguous in patients with good outcome. We hypothesized that the negative-positive deflection of N20-P30 components is more valuable predictor than the N20 alone. In this observational study, we will identify whether presence of P30 checked on 24 and 72 hours after cardiac arrest predicts neurologic outcome more accurately than the presence of N20 alone.