title: Plasma lidocaine concentrations during continuous thoracic epidural anesthesia after clonidine premedication in children.
abstract: There is no report concerning oral clonidine's effects on epidural lidocaine in children. Therefore, we performed a study to assess the concentrations of plasma lidocaine and its major metabolite (monoethylglycinexylidide [MEGX]) in children receiving continuous thoracic epidural anesthesia after oral clonidine premedication. Ten pediatric patients, aged 1-9 yr, were randomly allocated to the Control or Clonidine 4 microg/kg group (n = 5 each). Anesthesia was induced and maintained with sevoflurane in oxygen and air (FIO2 40%). Epidural puncture and tubing were carefully performed at the Th11-12 intervertebral space. An initial dose of 1% lidocaine (5 mg/kg) was injected through a catheter into the epidural space, followed by 2.5 mg x kg(-1) x h(-1). Plasma concentrations of lidocaine and MEGX were measured at 15 min, 30 min, and every 60 min for 4 h after the initiation of continuous epidural injection. The concentrations of lidocaine and MEGX were measured using high-pressure liquid chromatography with ultraviolet detection. Hemodynamic variables were similar between members of the Control and Clonidine groups during anesthesia. The Clonidine group showed significantly smaller lidocaine concentrations (p < 0.05) and the concentration of MEGX tended to be smaller in the plasma of the Clonidine group for the initial 4 h after the initiation of epidural infusion. In conclusion, oral clonidine preanesthetic medication at a dose of 4 microg/kg decreases plasma lidocaine concentration in children.
  
  
  CONCLUSIONS
  Oral clonidine decreases the plasma lidocaine concentration in children. Our finding may have clinical implications in patients receiving continuous epidural anesthesia. Additionally, perhaps an additional margin of safety regarding lidocaine toxicity is gained through the use of oral clonidine in children who will receive epidural lidocaine.
authors.affiliation: Department of Anesthesiology, University of Tsukuba, Tsukuba-shi, Ibaraki-ken, Japan. inomatas@md.tsukuba.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Inomata
authors.forename: E
authors.initials: E
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Miyabe
authors.forename: Y
authors.initials: Y
authors.lastname: Kakiuchi
authors.forename: A
authors.initials: A
authors.lastname: Nagashima
authors.forename: Y
authors.initials: Y
authors.lastname: Yamasaki
authors.forename: S
authors.initials: S
authors.lastname: Nakayama
authors.forename: Y
authors.initials: Y
authors.lastname: Baba
authors.forename: H
authors.initials: H
authors.lastname: Toyooka
authors.forename: K
authors.initials: K
authors.lastname: Okuyama
authors.forename: Y
authors.initials: Y
authors.lastname: Kohda
mesh_terms: D000284:Administration, Oral; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology; D000767:Anesthesia, Epidural; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology*; D004347:Drug Interactions; D006801:Humans; D007223:Infant; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000097:blood*; D008297:Male; D008738:Methyl Ethers; D011229:Preanesthetic Medication; D000077149:Sevoflurane; D013904:Thoracic Vertebrae; D013520:Urologic Surgical Procedures
chemical_list: D000316:Adrenergic alpha-Agonists; D000700:Analgesics; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008738:Methyl Ethers; D000077149:Sevoflurane; D008012:Lidocaine; C001173:monoethylglycinexylidide; D003000:Clonidine