The Effectiveness And Safty Of Local Infiltration With Ropivacaine In Different Concentration For Patients Undergoing Laparoscopic Cholecystectomy

Background:Preemptive analgesia is the process of initiating an analgesic regimen before the onset of noxious stimuli with the goal of limiting the cas-cade of neurobiologic events that ultimately lead to increase in pain. Infiltration ropivacaine before skin incision may be effective in improving postoperative pain in LC patients, but the optimal ropivacaine dose and its safety profile is still lack of evidence.Aim:To investigate the effect of pain relief and the systemic plasma concentration after infiltration of different doses of ropivacaine at port sites before incision, in order to decide the clinically optimal ropivacaine dose.Methods: 60patients undergoing laparoscopic cholecystectomy (LC) were randomly assigned to receive local infiltration of ropivacaine with a concentration of0.75%(group H),0.5%(group M),0.2%(group L) or saline solution(group C) at5-10min before incision, using the same technique and delivering the same volume (20ml) for all four groups. Plasma concentrations of ropivacaine were studied30min after infiltration. Postoperative pain were assessed with NRS when the patients leaving the PACU and4,6,8,24h after infiltration. The frequency of analgesics use was also recorded.Results:The group H and M did not differ significantly in term of plasma ropivacaine concentration, but the group L experienced significantly (p<0.01) lower concentration than the group H and M.There were significant difference among group C and group H, M, L in term of NRS. There was no difference between the three groups in terms of pain at rest or at cough through out the observed time periods, neither the frequency of analgesics use. Regression analysis study predicts to avoid reach the toxicity plasma level of ropivacaine; the dose of ropivacaine should not exceed5.62mg/kg.Conclusions:Infiltration ropivacaine at port site can effectively reduce the pain after LC,20ml of ropivacaine at concentration of0.75%,0.5%or0.2%result in similar NRS and analgesics demand. In order to avoid reaching the toxicity level of ropivacaine, the dose of ropivacaine should not exceed5.62mg/kg. Though ropivacaine plasma concentration may not exceed toxic threshold, high concentration (0.75%) ropivacaine infiltration is not recommended.