Laparoscopic cholecystectomy is accepted as gold standard in the management of cholelithiasis. Although laparoscopic procedures have many advantages,intra-abdominal CO2 insufflation can cause decreased lung volumes and compliance, increased airway resistance and impaired ventilation-perfusion ratio. In this study, investigators aim to investigate effects of intra-operative PEEP treatment at 3 distinct levels on respiratory dynamics and elimination time of volatile anesthetic agent.

In the study, 75 ASA I-II patients aged 30-65 years will be randomized into 3 groups to receive 0 cmH2O PEEP (Group-1), 5 cmH2O PEEP (Group-2) and 8 cmH2O PEEP (Group-3) in PVC mode. In all patients underwent general anesthesia; hemodynamic parameters, Ppeak, Pplateau, compliance values as well as Fisevo/Fexpsevo ratio at 1 MAC and times from 1 MAC to 0.3 and 0.1 MAC will be recorded. In addition, preoperative and postoperative pulmonary function tests will be compared in all patients.

Inclusion Criteria:

• ASA (American Society of Anesthesiologists) I-II
• BMI of 25-30
• patients scheduled to elective laparoscopic cholecystectomy.

Exclusion Criteria:

• Patients with ASA III, IV, V risk,
• Patients with comorbid diseases that may increase intra-abdominal pressure or pulmonary hypertension,
• Patients with renal and hepatic failure,
• Patients with pregnancy and
• Patients using bronchodilator or steroid were excluded.

patients who will undergo for elective laparoscopic cholecystectomy