The backgroud of this study was not well discussed.

Volume controlled ventilation(VCV) is a most common used ventilation mode during general anesthesia. But VCV can cause high airway peak pressure when patient under steep Trendelenberg position with pneumoperitoneum. Autoflow-VCV can reduce airway peak pressure and improve dynamic compliance. We will compare parameters(arterial blood gas analysis, airway compliance, etc) when each group applied VCV and autoflow-VCV during RALP.

Robot assisted laparoscopic radical prostatectomy(RALP) has been used to treatment of prostate cancer since 2001. RALP offers some advantage such as reduced blood loss, sparing nerves, less postoperative pain. However, RALP require steep Trendelenberg position with pneumoperitoneum. It can cause increased airway peak pressure and unwanted hemodynamic effect under conventional volume controlled ventilation(VCV). Autoflow-VCV use decelerating flow, can reduce airway peak pressure and improve dynamic compliance.

We will compare parameters(arterial blood gas analysis, airway compliance, etc) when each group applied VCV and autoflow-VCV during RALP.

Inclusion Criteria:

• Adult (age 19-65)
• American Society of Anesthesiology Classification I-III

Exclusion Criteria:

• cardiovascular disease, cerebrovascular disease, pulmonary disease
• over BMI 30