Effexts Of Pressure-controlled Ventilation On Ventilation Function And Pressure Of Carbon Dioxide During The Procedure Of Gynecological Laparoscopic Operation

Objective To compare the effects of pneumoperitoneum at different ventilation parameters of pressure-controlled ventilation(PCV) on ventilation function and pressure of carbon dioxide(CO₂) in patients undergoing gynecological laparoscopic operation.Methods Forty-five ASA I or II, 20～60 years old, weighted 45～65kg patients, who were accepted total intravenous anesthesia undergoing elective gynecological laparoscopic operation(surgical procedures of relatively long duration two hours), were randomly divided into three groups(A B C, n=15). They were managed by pressure-controlled ventilation with airway pressure at 10cmH2O and ventilation frequency at 14 times per minute pre-pneumoperitoneum and after reversal of pneumoperitoneum. After the establishment of pneumoperitoneum ventilation parameters of groups A B C, that is airway pressure and ventilation frequency, were adjusted as 18, 16, 14cmH2O and 12, 14, 16 times per minute. The maintenance of anesthesia was depended on target-controlled infusion(TCI) of propofol and constant infusion(CI) of remifentanil. Artery blood gas analysis was measured at four certain intervals: pre-pneumoperitoneum(T1), 30 minutes (T2) and 60minutes(T3) after the establishment of pneumoperitoneum, 5 minutes(T4) after reversal of pneumoperitoneum. At the same time the follow variables were recorded or calculated: tidal volume(VT), minute ventilation(MV), lung-thorax compliance(Compl), end tidal carbon dioxide partial pressure(PetCO₂) and Pa-etCO₂ gradient. Results: Intraclass: Compared with pre-pneumoperitoneum and after reversal of pneumoperitoneum, ventilation volume, Compl and the value of pH were lower and CO₂ pressure was much higher during pneumoperitoneum. Compared with pre-pneumoperitoneum, ventilation volume and Compl were stable, while CO₂ pressure was higher and the value of pH was lower after reversal of pneumoperitoneum. During pneumoperitoneum, ventilation volume and the value of pH were stable, while Compl kept on decreasing and CO₂ pressure was increasing over time. Pa-etCO₂ gradient: there were not significant differences between pre-pneumoperitoneum and after the establishment of pneumoperitoneum, while it began to increase after reversal of pneumoperitoneum. That was there was a good correlation between PetCO₂ and PaCO₂, but the relationship became worse after reversal of pneumoperitoneum.Interclass: Pre-pneumoperitoneum: there were not significant differences among three groups in each monitored item. During pneumoperitoneum: tidal volume: group A>group B>group C, Compl: group A2 pressure: group A and B2 gradient. After reversal of pneumoperitoneum: CO₂ pressure and Pa-etCO₂ gradient: group A and B2.