The incidence of postoperative pulmonary complications in elderly patients undergoing upper abdominal laparoscopic surgery remains high, and the lung protective mechanical ventilation strategy aims to reduce the incidence of lung injury caused by ventilators. PEEP, as an important protective ventilation strategy, maintains end expiratory alveolar volume to improve intraoperative oxygenation and pulmonary respiratory mechanics, and plays a protective role in the lungs; Personalized PEEP is the most beneficial, especially for elderly patients. However, there is currently no ideal way to achieve precise and personalized regulation of PEEP. This project aims to target and control intraoperative mechanical ventilation to drive pressure, personalize PEEP titration, and conduct a randomized controlled study on perioperative changes in pulmonary oxygenation function and pulmonary complications in elderly patients undergoing upper abdominal laparoscopy.

Inclusion Criteria:

• ASA<III、 general anesthesia, 60-80 years, BMI<30kg/m2, pneumoperitoneum time>0.5h, laparoscopic surgery on the upper abdomen (stomach, liver, gallbladder)

Exclusion Criteria:

• Severe anemia (Hb<60g/L), OSA, severe COPD (FEV1<30% pre), asthma, bronchiectasis, preoperative pulmonary infection, respiratory failure, thoracic deformity, postoperative return to ICU, heart function grade III-IV, severe liver and kidney dysfunction (Child B or C, dialysis), intraoperative bleeding greater than 30% of blood volume.

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