Between December 2011 and October 2014, 113 OHCA patients were included. We observed a significant difference in asystole and VF as initial rhythm between NSc and NSnc, respectively (P = 0.035 and P = 0.001). In both groups of NS, duration of ALS was significant longer compared with the two S groups (P = 0.001 in both comparisons). We observed no significant difference in first measured rSO2, mean rSO2 until 1 minute before ROSC and increase in rSO2 until 1 minute before ROSC (respectively P = 0.123, P = 0.501, P = 0.265) between Sc and Snc. However, when we compare the nonsurvivors of cardiac with noncardiac origin, we observed a significant difference in mean rSO2 until 1 minute before ROSC, 35% (27 to 44) in the NSc group and 27 (21 to 34) in the NSnc group (P = 0.026). First measured rSO2 was 24.5% (13 to 34) in the NSc group and 14 (4 to 28) in the NSnc group (P = 0.069) trending to be significantly different. No significant difference was observed in increase until 1 minute before ROSC between both groups of NS (P = 0.920). Significant differences was observed in mean rSO2 until 1 minute before ROSC and increase in rSO2 between Snc and NSnc (P = 0.033; P < 0.001) and between Sc and NSc (P = 0.001; P < 0.001).