Minimally invasive techniques in liver surgery gain popularity as they facilitate postoperative recovery while achieving comparable oncologic outcomes to the open approach. No consensus on the application of pneumoperitoneum pressure in minimal invasive liver resections (MILR) has been reached yet, as prospective clinical studies are scarce. The positive pressure of the CO2 pneumoperitoneum reduces intraoperative blood loss during MILR alongside the development of new transection devices and advancements in inflow control. Low-pressure pneumoperitoneum on the other hand has been shown to decrease postoperative pain scores and analgesic consumption in comparison to standard pneumoperitoneum, and international guidelines recommend the application of "the lowest intra-abdominal pressure allowing adequate exposure of the operative field rather than a routine pressure". Nevertheless, evidence for the application of low-pressure pneumoperitoneum is only moderate to low, requiring additional studies to better define its safety. To address this oxymoron, the investigators conduct a randomized non-inferiority trial to investigate the effect of low in comparison to high-pressure pneumoperitoneum during the transection phase of major MILR on intraoperative blood loss while also evaluating the risk of embolic complications.

Inclusion Criteria:

• age equal or older than 18 years and
• capacity of consent and
• planned elective conventional laparoscopic or da Vinci-assisted major liver resection or resections near the liver hilum or the hepatic venous vasculature. Major liver resections are defined as the resection of 3 liver segments or more (right and left partial hepatectomies, extended right and left hepatectomies, liver resections of 3 or more segments). Right posterior sectionectomies and mesohepatectomies of ≥2 liver segments are considered resections in proximity to the liver hilum or hepatic venous vasculature.

Exclusion Criteria:

• the participation in another trial with interference of intervention and outcome of this study,
• being a woman who is pregnant or breast-feeding or planning to become pregnant,
• American Society of Anesthesiologists (AS) score >3,
• language barrier,
• any contraindication to a minimal invasive surgical approach or intolerance to pneumoperitoneum
• a patent foramen ovale (PFO) or any other structural cardiac defect that facilitates paradoxical gas embolisms,
• diagnosis of neuromuscular disease, heart failure NYHA > class II or chronic obstructive pulmonary disease (COPD)
• being on oral anticoagulation therapy other than Aspirin 100mg daily or any other condition known to increase the risk of bleeding.

Upon reasonable request, the data generated by the current research that supports our future article, would be made available as soon as possible, wherever legally and ethically possible.