title: Neuromuscular effect of dexmedetomidine on sevoflurane: an open-label, dose-escalation clinical trial.
abstract: BACKGROUND
  Sevoﬂurane presents reliable central neuromuscular effects. However, little knowledge is available regarding the interaction between sevoflurane and demedetomidine. We evaluated the neuromuscular effect of dexmedetomidine on sevoflurane in patients with normal neuromuscular transmission and calculated the 50% effective concentration (EC50).
  
  
  METHODS
  One-hundred and forty-four ASA grade I~II patients with normal neuromuscular transmission, aged 20~60 years old, undergoing lower limbs surgery were enrolled in this open-label, dose-escalation clinical trial. Patients were randomly assigned into 12 groups. Each patient received intravenous 0, 0.5, or 1.0 μg/kg dexmedetomidine 15 min after inhaling 0.7, 1.0, 1.4, or 2.0 MAC sevoﬂurane. Neuromuscular monitoring was recorded from the adductor pollicis muscle by using acceleromyography with train-of-four (TOF) stimulation of the ulnar nerve (2 Hz every 20 s). TOF ratio was recorded before inhaling sevoﬂurane, 15 min after keeping constant at target MAC of sevoﬂurane, 30 min after receiving target dose of dexmedetomidine, and 15 min after sevoﬂurane washing out.
  
  
  RESULTS
  Sevoﬂurane produced a concentration-dependent decrease in TOF ratio. Mean TOF ratio in 0.7, 1.0, 1.4, and 2.0 MAC groups was 97.9%, 94.9%, 84.7%, and 77.2%, respectively. Neuromuscular EC50 of sevoﬂurane was 1.31 MAC (95% CI: 1.236~1.388 MAC). Intravenous 0.5 and 1.0 μg/kg dexmedetomidine decreased 3.1% (EC50: 1.27 MAC [95% CI: 1.206~1.327 MAC]) and 10.7% (EC50: 1.17 MAC [95% CI: 1.122~1.217 MAC]) of neuromuscular EC50, respectively.
  
  
  CONCLUSIONS
  Sevoﬂurane has a concentration-dependent central neuromuscular effect in patients with normal neuromuscular transmission. Intravenous dexmedetomidine dose-dependently decreases the neuromuscular EC50 of sevoﬂurane.
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Hui-Hua
authors.initials: HH
authors.lastname: Ke
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Huang-Hui
authors.initials: HH
authors.lastname: Wu
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital Affiliated to Fujian Medical University, Fuzhou, China.
authors.forename: Jin-Rong
authors.initials: JR
authors.lastname: Xiao
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Xiu-Zhu
authors.initials: XZ
authors.lastname: Su
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital Affiliated to Anhui Medical University, Hefei, China.
authors.forename: Wan-Jing
authors.initials: WJ
authors.lastname: Zheng
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital Affiliated to Fujian Medical University, Fuzhou, China.
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Cai
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China.
authors.forename: Xiao-Zhi
authors.initials: XZ
authors.lastname: Wu
authors.affiliation: Department of Emergency, Xijing Hospital, the Fourth Military Medical University, Xi'an, China.
authors.forename: Yu-Tong
authors.initials: YT
authors.lastname: Wang
authors.affiliation: Department of Anesthesiology, Fuzhou General Hospital, Fuzhou, China - cgzssq2000@sina.com.|Department of Anesthesiology, Fuzhou General Hospital Affiliated to Fujian Medical University, Fuzhou, China.|Department of Anesthesiology, Fuzhou General Hospital Affiliated to Anhui Medical University, Hefei, China.
authors.forename: Guo-Zhong
authors.initials: GZ
authors.lastname: Chen
mesh_terms: D000328:Adult; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D020927:Dexmedetomidine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009469:Neuromuscular Junction / Q000187:drug effects*; D061886:Neuromuscular Monitoring; D000077149:Sevoflurane / Q000494:pharmacology*
chemical_list: D018712:Analgesics, Non-Narcotic; D018685:Anesthetics, Inhalation; D000077149:Sevoflurane; D020927:Dexmedetomidine