The goal of this clinical trial is to compare two kind of trocar in patients undergoing complex robot-assisted partial nephrectomy. The main question it intends to answer is whether the use of valveless trocars can significantly reduce carbon dioxide absorption.

In the literature there are studies on the benefit of valveless trocars in robotic surgery. There are no studies on the potential effects even in complex kidney surgery. Through this randomized study we want to investigate whether the ability to clear CO2 is better using valveless trocars

Inclusion Criteria:

• asa status 1-3
• surgical classification RENAL or PADUA score >9

Exclusion Criteria:

• BMI>30