title: The timing of administration of intravenous dexmedetomidine during lower limb surgery: a randomized controlled trial.
abstract: Dexmedetomidine, a selective alpha-2 agonist, has sedative, analgesic, and anxiolytic effects without respiratory depression. Dexmedetomidine can cause a biphasic cardiovascular response, and induce transient hypertension. Hypotension is a common complication of spinal anesthesia. Decreasing anxiety of patients before procedure is important for high quality of procedure. This study aimed to compare the incidence of hypotension and patients' anxiety and comfort levels when dexmedetomidine was intravenously administered before and after spinal anesthesia.
  
  
  
  Seventy-four patients with American Society of Anesthesiologists physical status classification I or II were randomly allocated into two groups. Spinal anesthesia was performed using 12 mg of 0.5% heavy bupivacaine. In Group A, 1 μg/kg of dexmedetomidine was intravenously administered for 10 min, followed by the maintenance infusion of dexmedetomidine 0.2 μg/kg/hr after 5 min of intrathecal bupivacaine injection. Patients in Group B received same dose of dexmedetomidine by intravenous administration before 5 min of intrathecal bupivacaine injection. Perioperative vital signs, anxiety (using the Spielberger's State-Trait Anxiety Inventory) and comfort (using the numerical rating scale) were evaluated.
  
  
  
  The incidence of hypotension was significantly lower in Group A (16.1%) than in Group B (48.4%) during infusion of dexmedetomidine (p = 0.01). The need for treatment of hypotension is higher in Group B than Group A (p = 0.02). The incidence of bradycardia and desaturation did not significantly differ between the two groups. There were no statistically significant differences regarding the patients' anxiety and comfort.
  
  
  
  Hypotension is more frequently occurred, and the treatment of hypotension is more needed in Group B. The intravenously administration of dexmedetomidine before spinal anesthesia has no advantages in hemodynamic status and patients' comfort compared to that after spinal anesthesia during lower limb surgery.
  
  
  
  ClinicalTrials.gov number, NCT02155010 . Retrospectively registered on May 22, 2014.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Eunsu
authors.initials: E
authors.lastname: Kang
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea. tedy3333@naver.com.
authors.forename: Ki Hwa
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Cheju Halla General Hospital, 65, Doryeong-ro, Jeju-si, Jeju-do, 63127, Korea.
authors.forename: Sang Yoon
authors.initials: SY
authors.lastname: Jeon
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Kyu Won
authors.initials: KW
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Myoung Jin
authors.initials: MJ
authors.lastname: Ko
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Hyojoong
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Yong Han
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University 1435, Jwa-dong, Haeundae-gu, Busan, 612-862, Korea.
authors.forename: Jae-Wook
authors.initials: JW
authors.lastname: Jung
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000775:Anesthesia, Spinal / Q000009:adverse effects / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage; D002045:Bupivacaine / Q000008:administration & dosage; D020927:Dexmedetomidine / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007022:Hypotension / Q000453:epidemiology*; D015994:Incidence; D007278:Injections, Spinal; D035002:Lower Extremity / Q000601:surgery; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine; D002045:Bupivacaine
keywords: Dexmedetomidine; Hypotension; Spinal anesthesia