Within all the surgical specialties, major surgeries are performed whenever possible, as minimally invasive procedures to reduce blood loss, reduce pain and discomfort after surgery, avoid major scars, provide a faster recovery and thus shorter hospital stay. Such minimally invasive procedures in urinary tract surgeries are often performed as laparoscopic or robotic surgeries where CO2 (carbon dioxide) is insufflated into the abdominal cavity to create a working space for the surgeon's instruments. That high pressure created in the abdominal cavity (pneumoperitoneum) to create a workspace for the surgeon start a series of physiological changes in the heart, lung and kidney.

Today, most laparoscopic, and robotic operations are performed with pneumoperitoneum of approximately 12-15 mm Hg, despite the fact that international guidelines recommend the use of the lowest intra-abdominal pressure (IAP) possible allowing adequate exposure of the operative field rather than using a routine pressure level.

Investigator will conduct a randomized double-blind study involving 120 patients (2 groups of 60). The first group will be operated with standard pressure in the abdominal cavity 12-15 mm Hg (high IAP), patients in the second group will be operated on with a reduced pressure of ≈ 7 mmHg (low IAP).

Investigator would like to assess the practical feasibility of operating under low IAP. Quality of recovery of patients in relation to both physical and mental status, and post-operative use of pain killer will be also investigated using a validated questionnaire . Finally, Invistigator will examine the impact of IAP on post-operative renal function, and risk of kidney injury.

Hypothesis is carrying out laparoscopic/robotic surgeries under low IAP can optimize the post-operative quality of recovery, decrease pain and use of pain killer, improve post-operative renal function, and decrease risk for kidney injury. On the other hand low IAP can risk overview for surgeon, make workspace smaller and raise risk of bleeding.

A total of 120 patients between the ages of 18 and 80 years who were scheduled for elective robotic radical nephrectomy/ prostatectomy will included in the study. This is randomized controlled double-blind clinical trial.

A standard anesthesia protocol will be used in both groups. Bladder catheter inserted by the OP-nurse. After ports installment under IAP of 7 mm Hg, the surgeon leaves the operation field and sits at a surgical console. The ground nurse opens the sealed letter which indicated the pressure for operation (electronic randomization was previously performed by investigator using https://www.graphpad.com/quickcalcs/index.cfm) The required IAP sets by the ground nurse before the surgery started. Assistants are not blinded in the study, but the surgeon is. Intra-abdominal pressure will be maintained at 7 mmHg in Group Low IAP and at 12 mmHg in Group High IAP throughout the surgery. If under operation the surgeon required to raise the IAP because of bad views, or bleeding, he/she can always ask the ground nurse to raise the pressure by 2- or 3-mm Hg at a time until surgeon obtain the preferred view. This involved both groups. Patient will not be excluded from study if pressure increased, but the duration of raised IAP will be registered.

During the operation, the surgical working space will be evaluated by surgeon using an adopted version of SRS (Surgical rating scale). 1st time during mobilization of bowel, 2nd time during renal vascular dissection, and last time when surgeon remove the kidney and set it in the Endobag.

All patients asked to register their 24-hour urine production before the operation day. Intra-operative urine output will be also registered. 10 ml urine will be collected 3 times in order to investigate the risk of Acute Kidney Injury (AKI) by kidney injury biomarker (u-NGAL, og KIM-1). Pre-operatively during urinary catheter placement, 2-hour post-operatively, and 24 hours after operation. Urine samples collected and stored in -80 C for later analyses.

Investigator will test the quality of recovery using a validated Quality of recovery-15 (QoR-15) questionnaire before the surgery and at day 1,3,14,30 post-op.

Inclusion Criteria:

• Patients diagnosed with kidney/prostate cancer at the department of Urology, Aalborg University Hospital, who are offered radical nephrectomy/prostatectomy.
• Speaks and understands Danish

Exclusion Criteria:

• Patient diagnosed with kidney cancer but can be treated with partial nephrectomy.
• Patients with severe to end stage chronic kidney disease (CKD stage 4-5)
• Inability to understand or comply with instructions.

Withdrawal Criteria:

• Inability to complete the surgery without raising the pneumoperitoneum for low pneumoperitoneum arm.
• Complications that require re-operation which can change the quality of recovery of primary operation.