Optimization of PEEP During Laparoscopic Surgery

Lung-protective ventilation (LPV) during general anesthesia can trigger the development of early postoperative pulmonary complication (PPC) and ventilator associated lung injury. One of the proven components of the LPV is low tidal volume (TV). Data on the positive end-expiratory pressure (PEEP) parameters adjustment in laparoscopic surgery, as well as the effects on the respiratory biomechanics, lung tissue and respiratory muscles damage are limited and not clear.

The objective of the study is to evaluate the ability of the esophageal pressure (Pes) based controlled personalized PEEP adjustment, to improve the biomechanics of the respiratory system and oxygenation due to laparoscopic cholecystectomy.

During laparoscopic surgery pressure on alveoli increases, due to in the conditions of pneumoperitoneum, muscle relaxation, the patient's position on the operating table, excess body weight and other factors. As the consequence, the alveoli collapse due to negative transpulmonary pressure. The personalized PEEP adjustment for each particular patient during laparoscopic surgery can help to avoid the adverse effects on biomechanical parameters of the respiratory system, the early PPC incidence and improve overall patients' recovery.

The objective of the study is to evaluate the ability of the esophageal pressure (Pes) based controlled personalized PEEP adjustment, to improve the biomechanics of the respiratory system and oxygenation due to laparoscopic cholecystectomy.

Investigators will measure if PEEP adjustment according to the pressure indicators in the lower third of the esophagus Pes (intervention group) versus PEEP constantly set at 5 cmH2O (control group) gives better outcomes and prevent the early PPC incidence in hospitals.

After the induction, intubation and insertion of the esophageal balloon catheter, TV for patients both groups is set to 6 ml / kg BMI: for men (50+0.91\* (height-152.4), for women (45+0.91\* (height-152.4); minute ventilation (MV) to ensure the level of PetCO2 - 30-35 mmHg, respiratory rate (RR) 15-25/min (maximum up to 35/min).

Gas exchange parameters including partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in arterial blood will be measured before the induction (T0), after 1 hour after surgery (T5) and after 24 hours after surgery (T6), then will calculate PAO2/FiO2 respectively.

FiO2, oxygen saturation (SpO2), hemodynamic parameters including blood pressure (BP), heart rate (HR) will be recorded in all point of the study.

Following respiratory mechanics will be measured: plateau pressure (Pplat), PEEP, driving pressure (DP), Pes during inspiration and expiration, volumetric capnometry (VCO2), end-tidal carbon dioxide tension (PetCO2).

Respiratory system compliance (Cstat, Cl, Ccw), end-expiratory lung volume (EELV) will calculated after intubation (T1), after PEEP set according to the patient's group allocation PEEP Pes and PEEP 5 (T2), after initiating pneumoperitoneum (T3) and placing the patient in the reverse Trendelenburg position (T4).

This is a randomized controlled study in the operating room of the University hospitals.

Eligibility Criteria:
Inclusion Criteria:

* Patients undergoing laparoscopic surgery with mechanical lung ventilation American Society of Anesthesiologists Classification (ASA) I-III

Exclusion Criteria:

* pregnancy
* age less than 18 or more than 70 years
* patients ASA \> III
* life-threatening heart rhythm abnormalities and/or systolic blood pressure \< 80 mmHg despite norepinephrine at a dose \> 2 μg/kg/min
* primary lung diseases (e.g. interstitial lung diseases, lung emphysema) or tumor metastases in the lungs
* chronic decompensated diseases with extrapulmonary organ dysfunction (tumor progression, liver cirrhosis, congestive heart failure)
* Glasgow coma score \< 14
* upper airways obstruction