This study will investigate the effects two levels of positive end expiratory pressure (peep) on the incidence of pulmonary complications in patients undergoing coronary artery bypass surgery. After obtaining ethics committee approval, the study on 90 patients in the 30-80 age range who are candidates for coronary artery bypass surgery in Khorramabad Heart Hospital of Shahid Madani will be done. By consecutive non-probability sampling, patients will be randomly divided into two groups: control (n = 45) and intervention (n = 45). Meanwhile, the two groups are equal in age, sex, smoking history. and off-pump or on-pump. Inclusion criteria in the study are: 1- patients who are in the 30-80 age range. 2- Lack of ejection fraction (EF) less than 30% in preoperative angiography tab. 3- No history of chronic obstructive airway disease (COPD). 4-No previous history of open heart surgery. 5- No history of broken ribs and a chest tube investments. 6- Their operation is not urgent. 7- The level of consciousness (GCS) of patients is equivalent to fifteen.
Exclusion criteria are : 1- Time of aortic clamping more than 100 minutes. 2- Time of heart - lung bypass more than 120 minutes. 3- Use of intra aortic balloon pump during and after surjery. 4- In case a patient needs ventilation protocol out of our research protocol should be excluded. 5- If a Sick has to be transferred to the operating room (OR) again. 6- If the patient is in intubation over 24 hours.
Patients who are in control group from admission in the Intensive Care Unit to tracheal extubation time will receive a PEEP of 5 cm H2O. However, patients in intervention group, if their hemodynamic status is not impaired, they will receive for 4 hours an average of PEEP of 10 cm H2O and until extubation, PEEP of 10 cm H2O will receive. Then the two groups will be compared in terms of the incidence of atelectasis, pneumonia, pneumothorax, tracheal extubation time , chest drainage bottles and changes of parameters Pao2/Fio2, o2-sat and Paco2.