Effects of PEEP on Parameters of Tissue Perfusion in Patients Post Cardiac Surgery

This is a prospective, randomized study and will be performed on patients who accept coronary artery bypass grafting with cardiopulmonary bypass, the conscious openness to participate in the study. Age, sex, body mass index (BMI), smoking habits, diagnosis, additional diseases, drugs used, surgery, intervention, peroperative supportive treatments, left ventricular ejection fraction, post operative blood and cardiopulmonary bypass (CPB) time (min), cross clamp time (min), duration of operation, postoperative extubation period, intensive care day of hospitalization, day of hospitalization will be recorded.The study was planned in 3 groups. Group G5 (control group: no changes will be made to the value of PEEP). Group G10 \[after 30 minutes of admission (time 0) the PEEP will be raised to 10 cmH2O (time1) for 30 minutes and then returned to 5 cmH2O (time 2)\]. Group G15 \[after 30 minutes of admission (time 0) the PEEP will be raised to 15 cmH2O (time 1) for 30 minutes and then returned to 5 cm H2O (time 2)\]. At each time of protocol (0, 1 and 2) will be collected: arterial blood gas measurements (partial pressure of arterial oxygen \[PaO2\] and partial pressure of carbon dioxide (\[PaCO2\]), the ratio between the partial oxygen pressure, inspired oxygen fraction (PaO2/FiO2) and pH. Also, will be performed parameters of tissue perfusion: central venous oxygen saturation (\[SVO2\]), arterial blood lactate, venoarterial CO2 difference (\[Dif VA CO2\]) and vital signs. In all other respects, treatment will follow the standard of care.