OBJECTIVES: Comparative study of the continuous and intermittent blood gas monitoring technology. METHODS: We divided into two groups the randomly selected sample from the scope of patients come through open-heart operation assisted with extracorporeal support at the University of Pécs: therapeutic (continuous blood gas monitoring/CDI-500) and control (intermittent sampling) group. After the retrospective data collection we carry out the analysis with (prevalence) frequency and confidence interval calculation and Khi square test. RESULTS: The following accompanying diseases occurred significantly higher rate in the therapeutic group: AMI (p=0.007), kidney disease (p=0.009), chronic pulmonary disease (p=0.001), and the aggregation of the accompanying diseases showed also significantly high degree (p=0.001). The long interval operations occurred significantly higher rate (p=0.036) in the therapeutic group, and the times of the aorta clinch (p=0.025) and the perfusion (p=0.001) was also significantly longer. Despite of that during the perfusion in a significantly more cases remained the rates in the normal range concerning to the therapeutic group (pH: p<0.001; BE: p<0.001; pCO2:p<0.001), and the prevalence of the restart of the heart showed also significantly higher rate (p=0.005). CONCLUSIONS: The continuous blood gas analyses assure reliable and the postoperative recovery assisted ECC circulation support. This assists considerably for keeping the parameters in the physiological limits even in the higher rate of the incidences of complex operations and accompanying diseases. This could contribute to lower incidence of side effects, preventing the causeless elevation of the postoperative hospital charges.