title: Sevoflurane requirements to suppress responses to transcutaneous electrical stimulation during epidural anesthesia with 0.5% and 1% lidocaine.
abstract: We sought to determine general anesthetic requirements to suppress skin vasomotor reflex (SVmR) and pupillary dilation (PD) in response to transcutaneous electrical stimulation (TES) during combined epidural-general anesthesia. Thirty-five patients undergoing lower abdominal surgery were randomly divided into 2 groups to epidurally receive 0.5% (Group 1) or 1% lidocaine (Group 2) with sevoflurane anesthesia. A bolus injection of either lidocaine was followed by the infusion of the same solution, and the central dermatomal level of loss of cold sensation (C) was determined. After the induction of general anesthesia with 5% sevoflurane and 67% nitrous oxide, nitrous oxide was discontinued, and sevoflurane concentration was decreased. TES was given at both site C and site three dermatomal segments (U) cephalad to C to determine the end-tidal sevoflurane concentration required to suppress SVmR and PD. End-tidal sevoflurane concentration that suppressed both responses was larger in Group 1 than in Group 2 at both sites and was larger at site U than at site C in both groups. We conclude that sevoflurane requirements to suppress SVmR and PD in response to TES during combined epidural-general anesthesia are different depending on the concentration of lidocaine and the site where surgical stimulation is applied.
  
  
  CONCLUSIONS
  We evaluated sevoflurane requirements to suppress skin vasomotor reflex and pupillary dilation in response to a transcutaneous electrical stimulation at the surgical site during combined epidural-general anesthesia. Our results indicate that when epidural anesthesia is combined, general anesthetic requirements decrease depending on the lidocaine concentration for epidural anesthesia and the site where surgical stimulation is applied.
mesh_terms: D000328:Adult; D000767:Anesthesia, Epidural; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000097:blood; D000779:Anesthetics, Local / Q000097:blood; D003080:Cold Temperature; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000097:blood; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage / Q000097:blood; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011680:Pupil / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D000077149:Sevoflurane; D012867:Skin / Q000098:blood supply
chemical_list: D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008738:Methyl Ethers; D000077149:Sevoflurane; D008012:Lidocaine