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

Commonly the pressure of about 14 mmHg is applied during laparoscopic liver resection (LLR) with moderate neuromuscular blockade. Lowering the pneumoperitoneum pressure combined with deep neuromuscular blockade may sustain optimal operating space with providing better short-term postoperative results. It has been proved in randomized controlled trials in colorectal or bariatric patients, however there is lack of similar data for laparoscopic liver resection. Doubts about lowering the pneumoperitoneum pressure too hasty are supported by apprehension of worse bleeding control during liver parenchyma transection and its impact on postoperative results.

The aim of the trial is to assess the impact of standard (14 mmHg; arm 1) versus low (10 mmHg; arm 2) pneumoperitoneum pressure on intraoperative blood loss, what will be the primary outcome. As secondary endpoints following outcomes will be measured: quality of operating space, intraoperative adverse events, quality of recovery, postoperative renal function, 30-day postoperative complications rate, length of hospital stay. The investigators assume that lower pneumoperitoneum provides non-inferior blood loss control during laparoscopic liver resection with better postoperative results.

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.

Eligibility Criteria:
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