Effects Of Volume Controlled Ventilation And Pressure Controlled Ventilation With Low Level Positive End Expiratory Pressure On Respiratory Mechanics And Pulmonary Oxygenation During Gynecologic Laparoscopic Surgery

Objective: To identify and compare the effects of volume controlled ventilation（VCV） and pressure controlled ventilation （PCV） with low level positive end expiratorypressure （PEEP） on respiratory mechanics and pulmonary oxygenation duringgynecologic laparoscopic surgery, and finding appropriate intra-operative breathingmanagement pattern.Methods: Forty ASA class I or II patients aged20⁶0yr weighing45⁶5kgundergoing gynecological laparoscopic surgery（estimated pneumoperitoneum time1²h）,were randomly divided into V group and P group（n=20）.Before CO₂pneumoperitoneum, two groups both use volume control ventilation, keep PETCO₂（38±2） mmHg by adjusting the tidal volume and respiratory rate. After CO₂pneumoperitoneum begining, a PEEP of5cm H2O was applied to all the patients,VCV+PEEP ventilation mode was used in V group, allowing PETCO₂moderatelyelevated in （43±2） mmHg, and PCV+PEEP ventilation mode was used in P group,keeping PETCO₂in （43±2） mmHg.Intraoperative maintained by target controlledinfusion（TCI） of propofol concentration effect room3μg/ml, and remifentanyl10²0μg.kg^-1.h^-1, maintaining entropy index at40⁶0.In the end of pneumoperitoneum,PETCO₂was adujusted to below40mmHg in the two groups.Take Arterial blood forblood gas analysis,and moniter PetCO₂,tidal volume,the airway peak pressure value（Ppeak）,airway pressure platform （Pplat）, chest lung compliance （Compl）, thencalculate the oxygenation index （OI）, respiratory index （RI）, alveolar-arterial oxygenpartial pressure difference （PA-aDO₂）, within intrapulmonary shunt （Qs/Qt） at fourcertain intervals: in5minutes after endotracheal intubation（T₁）,15minutes afterpneumoperitoneum（T₂）,45minutes after pneumoperitoneum （T₃）,10minutes afterpneumoperitoneum （T₄）.Results: Compared with T₁, Ppeak and Pplat were significantly elevated at T₂and T₃in all patiens,and those of V group were more higher than P group; after CO₂pneumoperitoneum, the lung compliance obviously decreased, while PaO₂, PaCO₂, PA-aDO₂, Qs/Qt and RI significantly increased （P<0.05）, the above variations weremore obvious in V group than those in P group at T₃（P<0.05）. Patients in both groupshad no significant difference at arterial blood pH value of each point （P>0.05）.Conclusion: PCV+PEEP ventilation mode have more advantages than VCV+PEEPventilation on improving lung of respiratory function and oxygenation, witch is asuperior breath management scheme for patients with laparoscopic surgery.