This study will investigate the distribution of gas during mechanical ventilation in patients undergoing robot assisted laparoscopic prostatectomy. The gas distribution of ventilation are monitored and data extracted using electric impedance tomography in different respiratory rates.

Mechanical ventilation during anaesthesia and intensive care often results in an uneven gas distribution of ventilation. Patients anaesthetized for laparoscopic surgery and patients positioned i a Trendelenburg position is particularly at risk.

A less harmful mode of ventilation could possible lead to a more optimal ventilation with avoidance of ventilator induced lung injuries. The project will investigate if volume controlled ventilation with a higher respiratory frequency can be used in this purpose.

The researchers intend to investigate patients, without previously known lung disease, undergoing robot-assisted laparoscopic prostatectomy. After the patients have given informed consent, they will be included in the project. The distribution of ventilation will be monitored with electric impedance tomography (EIT). Once the patients have been anaesthetized, positioned with the head down and the surgical procedure have been started with insufflation of carbon dioxide we will start our test.

The investigators will perform three episodes of standardized ventilation with the respiratory rate (RR) of 20, 40 and 60. With a higher RR the tidal volume will be reduced tom maintain a constant inhaled minute volume. Data will be collected from the EIT-equipment, the anaesthesia machine and the monitoring system.

Inclusion Criteria:

• Patients planned for robot-assisted laparoscopic prostatectomy
• > 18 years
• Consent to take part in the study

Exclusion Criteria:

• Impaired cognitive function
• Previously known lung disease
• Insufficient skills in Swedish language to understand information about the study