Lung Protective Ventilation Strategies

Forty obese patients who underwent robotic bariatric surgery in our hospital were selected and randomly divided into a lung-protective ventilation strategy group (Group P) and a control group (Group C). The volume-controlled mode was used to assist ventilation, and the inspiratory/expiratory ratio (I: E) was 1:2. Tidal volume (VT) was set according to the Predicted body weight (PBW) throughout the whole procedure, and in group C, VT was 9 ml /kg without Positive end-expiratory pressure (PEEP), and the inhaled oxygen concentration (Fraction of oxygen) was 0.5 ml /kg, while the inspiratory oxygen concentration (Fraction of oxygen) was 0.5 ml /kg. Group C: VT 9ml /kg, no Positive end-expiratory pressure (PEEP), Fraction of inspiration O2 (FiO2) of 60%; Group P: the ventilation mode was the same as that of Group C from tracheal intubation to the beginning of pneumoperitoneum for 10 minutes, and after 10 minutes of pneumoperitoneum, the ventilation mode was the same as that of Group C. After the pneumoperitoneum for 10 minutes, the ventilation mode was VT 7ml/kg, PEEP 6cmH2O, FiO2 of 40%, and the plateau pressure was maintained at <30cmH2O. In both groups, the intraoperative gas flow was 2L/min, and SpO2 was maintained at ≥95%; if it could not be maintained, the oxygenation function of the patients could be improved by adjusting the ventilation parameters and strategies; meanwhile, the respiratory rate (RR) was adjusted to maintain the End-tidal carbon dioxide partial pressure (PETCO2) at ≥30%, and the end-tidal carbon dioxide partial pressure (PETCO2) was maintained at ≥30%, and the end-tidal carbon dioxide partial pressure (PETCO2) was maintained at ≥30%. The respiratory mechanical parameters: tidal volume, RR, airway peak pressure (PPeak), plateau pressure (PPeak), and plateau pressure (PPeak) were recorded at 5 minutes after tracheal intubation (T0), 10 minutes after the start of the pneumoperitoneum (T1), 60 minutes (T2), 120 minutes (T3), and 10 minutes after the pneumoperitoneum was closed (T4). pressure (PPeak), and plateau pressure (PPlate), and calculate the dynamic lung compliance; arterial blood was drawn at T0, T1, T2, T3, and T4, respectively, and the arterial partial pressure of oxygen (PaO2) and the arterial partial pressure of carbon dioxide (Arterial CO2) were measured. The arterial partial pressure of oxygen (PaO2) and arterial carbon dioxide pressure (PaCO2) were measured, and the oxygenation index (OI) was calculated.

Inclusion criteria

Obese patients with ASA grade Ⅰ ~ Ⅲ No obvious abnormality in preoperative lung function and blood gas analysis results Undergoing robotic bariatric surgery

Exclusion criteria

Had been mechanically ventilated 2 weeks before surgery Thoracic deformity Neuromuscular disease Significant abnormalities in vital organ function Combined pneumothorax or pulmonary herniation Participating in other clinical intervention trials or refusing general anesthesia with tracheal intubation Emergency surgery