Perioperative airway resistance and lung function are evaluated perioperatively in patients, who undergo surgical procedures in different postures and with or without gas insufflation into the peritoneal cavity.

Lung function, upper and lower airway resistance measurements are performed in patients in prone horizontal or head tilted down (40°) position. Half of the patients with head down position will have surgery in laparoscopic technique (including gas insufflation to achieve a pneumoperitoneum). Measurements are performed on the day prior to surgery, on the morning of surgery, 30 - 45 minutes, 2 hours, and 24 hours after extubation.

Inclusion Criteria:

• Patients older than 18 years of age.
• Patients with normal lung function with respect to age, gender and weight. -Patients scheduled for Prostatectomies, robotic Prostatectomies, and open hemicolectomies.

Exclusion Criteria:

• Patients younger than 18 years.
• Patients with pathological lung function.
• Patients with with major cardiac disease.

20 patients scheduled for "robotic" prostatectomies 20 patients scheduled for open prostatectomies 20 patients scheduled for open hemicolectomies