The effect of lipid emulsion pretreatment on plasma concentrations and pharmacodynamics of ropivacaine after epidural administration in adults

Abstract

Objective To determine whether there is a change of ropivacaine plasma concentration and analgesia efficacy associated to the pretreatment of lipid emulsion (LE) during epidural anesthesia in adults undergoing lower limb operations.Method Twenty-nine adult patients aged 18 to 65 years,ASA Ⅰ-Ⅱ,scheduled for elective lower limb operations under epidural anesthesia,were invited to participate in the study.The patients were randomized into three groups:control group(NS group,n=11),medium and long chain fat emulsion group(MLE group,n=8) and long chain fat emulsion group(LLE group,n=10).Three groups of patients were pretreated with 0.9 ％ saline,20 ％ LLE or 20 ％ MLE,at 2 ml·kg-1·h-1 for 30 min via left upper limb vein.2 mg/kg (including the test dose) of ropivacaine was injected through the epidural catheter.Hemodynamic parameters were recorded.Sensory block and the degree of motor block was determined.Ropivacaine plasma concentrations were measured from artery plasma samples at 1,5,10,15,30,45,60,90,120 min after total ropivacaine was given.Results No significant differences were observed between groups in onset time of sensory and motor block,time to maximum spread of sensory block,the segments of spinal nerve block,persistent time of sensory and motor block.The plasma ropivacaine concentration among all groups had no significant differences at each time.Conclusions Pretreatment of LLE and MLE had no effect on plasma concentration and pharmacodynamics of ropivacaine during epidural anesthesia in adults undergoing lower limb operations. Key words: Lipid emulsion; Local anesthetic,ropivacaine; Pharmacodynamics; Plasma concentration; Intraspinal anesthesia, Epidural