Intraoperative Blood Loss Under Standard Versus Low Pneumoperitoneum Pressure During Laparoscopic Liver Resection.

After signing the informed consent patients will be randomized into 2 groups. Randomization will be conducted by investigators via drawing a sealed envelope with computer-generated intervention code at the Department just before patient transfer to the operating theatre. There will be two study arms with 1:1 fashion

For both trial arms additional routine elements of perioperative anesthesia care will be defined:

• low central vein pressure, aimed for 5 ± 2 mmHg with restrictive fluid therapy
• ventilation in a volume-controlled mode without intraoperative high positive end-expiratory pressure (PEEP)
• invasive arterial blood pressure monitoring with maintaining mean arterial pressure ≥ 60 mmHg
• maintaining hemoglobin concentration > 8g/dl
• maintaining normothermia and normoglycemia
• maintaining oxygenation >94%, in case of hypercapnia with respiratory acidosis, the respiratory rate and tidal volume will be stepwise increased

The surgeon will be blinded to the study arm and level of pneumoperitoneum pressure.

The blood loss during liver parenchyma transection and total procedure blood loss will be reported based on the amount of sucked outside intraperitoneal fluids after liver transection and after procedure without volume inserted for intraperitoneal irrigation. The estimated blood loss will be measured in milliliters. Patients who are converted to open surgery are excluded from the analysis of the primary end-point.

During the procedure, the surgeon will be asked regularly to rate the quality of operating space in accordance to the Leiden Surgical Rating Scale. In case of inadequate operating space, pneumoperitoneum pressure may be increased by 2 mmHg (with maximum of 16 mmHg in arm 1. and 12 mmHg in arm 2.). Intraoperative adverse events will be assessed in accordance to ClassIntra classification. Quality of recovery (QoR) will be measured on postoperative day 1, 3 and 5 with patient reported QoR-40 questionnaire, 30-day postoperative complication rate will be assessed in accordance to Clavien-Dindo classification. Length of hospital stay will be counted from the date of surgery to the discharge day. All patients will be followed up by researchers who are blinded to the intraoperative grouping.

Inclusion criteria

• Patients scheduled to perform elective laparoscopic major liver resection
• Age of 18 years or older
• Signed informed consent

Exclusion criteria

• Severe cardiopulmonary disease
• Severe renal disease
• Liver cirrhosis
• Emergency surgery
• Pregnancy
• Patient's refusal of participation