title: Emulsified halothane produces long-term epidural anesthetic effect: a study in rabbits.
abstract: Previous studies have demonstrated that volatile anesthetics could produce local anesthesia. Emulsified isoflurane at 8% has been reported to produce epidural anesthetic effect in rabbits. This study was designed to investigate the long-term epidural anesthetic effect of emulsified halothane in rabbits. In this study, 40 healthy adult rabbits (weighting 2.0-2.5 kg) with an epidural catheter were randomly divided into 4 groups (n=10/group), receiving epidural administration of 1% lidocaine (lido group), 8% emulsified isoflurane 1ml (8% E-iso group), 8% emulsified halothane (8% E-Halo group) and 12% emulsified halothane (12% E-Halo group). After administration, sensory and motor functions as well as consciousness state were assessed until 60 minutes after sensory and motor function returned to its baseline or at least for 180 min. After epidural anesthesia, all the rabbits were continuously observed for 7 days and sacrificed for pathological evaluations. As a result, all the four study solutions produced typical epidural anesthesia. Onset times of sensory and motor function blockade were similar among the four groups (P>0.05). Duration of sensory blockade in 12% E-Halo group (83±13 min) was significantly longer than other groups: 51±12 min in 8% E-Halo group (P<0.01), 57±8 min in 8% E-iso group (P<0.01) and 47±9 min in lido group (P<0.01). Duration of sensory blockade in 8% E-iso group is longer than lido group (P<0.05). Duration of motor blockade in 12% E-Halo group (81±12 min) was also significantly longer than other groups: 40±8 min in 8% E-Halo group (P<0.01), 37±3 min in 8% E-iso group (P<0.01), 37±6 min in lido group (P<0.01). Normal consciousness was found in the rabbits from 8% E-Halo, 8% E-iso and lido groups while there were four rabbits in 12% E-Halo group (4/10) showed a light sedation. For all the rabbits, no pathological injury was found. The present study demonstrates that emulsified halothane produces reversible concentration-dependent epidural anesthesia and at 12% (v/v), emulsified halothane could produce long-term anesthesia without pathological injury.
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China ; State Key Laboratory of Biotherapy, Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Fengshan
authors.initials: F
authors.lastname: Li
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Daqing
authors.initials: D
authors.lastname: Liao
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China ; Department of Anesthesiology, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Department of Anesthesiology, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Guo
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China ; Department of Anesthesiology, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Yi
authors.affiliation: Laboratory of Anesthesia and Critical Care Medicine, Translational Neuroscience Center, West China Hospital of Sichuan University Chengdu, Sichuan, P. R. China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhou
mesh_terms: D000767:Anesthesia, Epidural / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D002626:Chemistry, Pharmaceutical; D003243:Consciousness / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry; D006221:Halothane / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D007530:Isoflurane / Q000494:pharmacology; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D010743:Phospholipids / Q000737:chemistry; D011817:Rabbits; D013024:Soybean Oil / Q000737:chemistry; D013997:Time Factors
chemical_list: D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D004337:Drug Carriers; D004655:Emulsions; D010743:Phospholipids; C545823:soybean oil, phospholipid emulsion; D013024:Soybean Oil; D008012:Lidocaine; D007530:Isoflurane; D006221:Halothane
keywords: Emulsified halothane; emulsified isoflurane; epidural anesthesia; rabbits