The Effect Of Femoral Nerve Block On Oxygen Consumption Of Patients Under General Ansthesia During Knee Surgery

OBJECTIVE: The aim of this study is to observe the effects of femoral nerve block on oxygen consumption of patients under general anesthesia during knee surgery.METHODS: Sixty patients,scheduled for knee surgery enrolled in this study.After the induction of general anesthesia,LMA was inserted and the patients were given 50% oxygen.Desflurane was maintained at 1.0MAC minimal inhalation.Thirty patients were randomly assigned to receive a FNB with 10 ml 0.375% bupivacaine followed by general anesthesia;patients in control group received only general anesthesia.The end-tidal carbon dioxide pressure was maintained between35-45 mm Hg by mechanical ventilation with volume controlled ventilation.BP,HR,Sp O2,NIBP,PETCO2,VO2,VCO2,RQ were recorded15 minutes after intubation(T0)and incision(T1).RESULTS:The two groups had no statistical difference in heart rate and VCO2.The FNB group had lower blood pressures before and during surgery.In control group,VO2 increased significantly 15 min after surgical incision(P<0.05),from(186.6±37.91)to(194.2±38.31)ml/min.The VO2 in FNB group had no significant change after skin incision,from(185.9±39.13)to(188.1±37.67)ml/min.CONCLUSIONS: Femoral nerve block can reduce VO2 of patients undergoing knee surgery during general anesthesia.