The Impact Of Carbon Dioxide Pneumoperitoneum On Monitoring Depth Of Anesthesia During Retroperitoneoscopy Operation

Background: According to the recent clinical trials, the application of carbon dioxide(CO2) pneumoperitoneum during retroperitoneoscopy surgery affected the stability ofrespiratory and circulatory function, but information regarding the influence of carbondioxide gas pneumoperitoneum on the monitor of anesthetic depth remains scanty.The objectives of this prospective study were to investigate the effects of carbondioxide gas pneumoperitoneum during retroperitoneoscopy surgery on the monitor ofanesthetic depth.Methods: One hundred and ten consecutive patients undergoing selectiveretroperitoneoscopy surgery with carbon dioxide gas pneumoperitoneum wererandomly allocated to hypercapnia group (n=42), in which PETCO2was controlledbetween45mmHg and55mmHg; and control group (n=47), in which PETCO2wascontrolled under40mmHg. Anaesthesia with inhalational anesthetia agents wasmaintained at the level of1.1MAC or propofol at the level of3.5ug/ml. During theretroperitoneoscopy surgery, we recorded the data of Narcotrend Index (NI), PETCO2,blood pressure, heart rate, peak airway pressure, airway resistance and lungcompliance value at induction, intubation, posed operation position, the beginning ofpneumoperitoneum and every5minutes until the end of operation.The third group (n=20), including twenty selective conventional nephrectomypatients with sevoflurane, was as the control of above-mentioned hypercapnia groupand control group.Results: The baseline clinical features among three groups had no significantdifferences. Compared with control group, NI value was significantly higher inhypercapnia group from25minutes to60minutes after pneumoperitoneum among the patients with sevoflurane (P<0.01), deflurane (P<0.01), aswell as propofol (P<0.01).NI value from25minutes to60minutes after pneumoperitoneum were significantlyhigher than whose at5minutes after pneumoperitoneum in hypercapnia group withsevoflurane or desflurane or propofol. Compared with conventional nephrectomygroup, NI value in the hypercapnia group was significantly increased (P<0.05). Butthere is no significant difference between conventional nephrectomy group andcontrol group on NI value (P>0.05).Conclusions:1. The value of Narcotrend monitoring.can be increased by accumulation of CO2during retroperitoneoscopy surgery2. Hypercapnia could increase the Narcotrend Index, which was misunderstanded tobe light anaesthesia.