Effect of carbon dioxide pneumoperitoneum on pharmacodynamics of rocuronium administered by closed-loop muscle relaxation injection system

Abstract

Objective To investigate the effect of carbon dioxide pneumoperitoneum on pharmacodynamics of rocuronium(ROC)in gynecological laparoscopic surgery.Methods Patients of ASA Ⅰ-Ⅱscheduled for elective gynecological laparoscopic surgery(Group L,n=29)or open gynecological surgery(Group C,n=29)were given total intravenous anesthesia(TIVA)with propofol and remifentanil.All patients initially received ROC 0.6mg·kg-1 by 1.8μg·kg-1·min-1 through closed-loop muscle relaxation injection system.ROC(30μg·kg-1·min-1)was given to maintain muscle relaxation when T1 reached 15%of control.The onset time of ROC(T1down to 0%),the first time of ROC injection(T1reach 15%),recovery index of muscle relaxation(T1increase from 25% to 75%),frequency of ROC injection and injection dosage per unit time were recorded.The hemodynamic parameters including heart rate(HR),mean arterial pressure(MAP),cardiac output(CO),PaCO2,pH and depth of anesthesia(bispectral index,BIS)were also recorded before intubation(P0),after intubation(P1),5min after pneumoperitoneum(P2),30 min after pneumoperitoneum(P3),1hafter pneumoperitoneum(P4),the end of pneumoperitoneum(P5)and time of removal of intubation(P6).Results The first time of ROC injection in group L was significantly longer than that in group C([42.1±10.7]min vs[27.7±9.5]min,P0.01),and the recovery index of muscle relaxation in group L was significantly longer than that in group C([13.8±6.0]min vs[9.6±3.9]min,P0.01).The total dosage per unit time of ROC in group L was significantly less than that in group C([5.4±0.8]μg·kg-1·min-1 vs[6.3±0.5]μg·kg-1·min-1,P0.05).The frequency of ROC injection in group L was significantly less than that in group C([2.1±1.0]per hour vs[2.8 ±0.9]per hour,P0.05).Hemodynamically,CO in group L was found significantly lower than that in group C during P2-P4(P0.01).Conclusion The duration and recovery time of ROC in patients undergoing laparoscopic surgery under carbon dioxide pneumoperitoneum are prolonged,and smaller dosage is required compared to opengynecological surgery,which is likely due to the lower CO caused by carbon dioxide pneumoperitoneum.