In current double-blinded randomized clinical trial, 80 women candidate to undergo laparoscopic gynecological surgery, aged between 18 and 60 years old with ASA class I physical status will be enrolled and patient with systemic and psychotic disorders will be excluded. Maintenance of general anesthesia will be done via midazolam, remifentanil, propofol and atracurium. Positive pressure ventilation (PPV) with volume controlled ventilation (VCV) will be applied as follows, tidal volume of 8-10 ml per minute, respiratory rate of 12 per minute and 1 to 2 rate of inhalation and exhalation. Patients will be randomly assigned to study groups, considering positive end-expiratory pressure (PEEP) rate: case group (PEEP, n=40) in association with PPV will receive low PEEP with pressure of 5 cmHg and control group (zero end-expiratory pressure (ZEEP) ,n=40) will receive PPV without PEEP. Hemodynamic variables including heart rate, systolic and diastolic blood pressure, mean arterial pressure and arterial oxygen saturation will be measured before induction of anesthesia, immediately after induction, at 5th,10th, 20th, 30th, 60th minutes and at the end of operation. In addition, surgery duration, anesthesia duration, duration of pneumoperitoneum, administered intravenous fluid volume, volume of blood loss, urine output and dysrhythmia incidence with regard to its type, will be recorded. An anesthesiologist will manage the anesthesia and monitor the patients, however second anesthesiologist who will be blinded to patients study group, will record the study variables.