title: Comparison of plain and hyperbaric solutions of ropivacaine for spinal anaesthesia.
abstract: BACKGROUND
  Preliminary work has shown that ropivacaine provides spinal anaesthesia of shorter duration than bupivacaine, and may be of particular use in the day-case setting. However, there are few data comparing the actions of plain and hyperbaric solutions of this drug.
  
  
  METHODS
  Forty ASA grade I-II patients undergoing elective perineal surgery under spinal anaesthesia were randomized to receive 3 ml ropivacaine 5 mg ml(-1), either in plain solution or with glucose 50 mg ml(-1). The extent and duration of sensory and motor block, pulse rate, blood pressure, and time to mobilization were recorded.
  
  
  RESULTS
  Two patients (one per group) were withdrawn because of total block failure. There were significant differences in median time to onset of sensory block at T10 (plain 10 min; hyperbaric 5 min; P<0.01), median maximum extent (plain T8; hyperbaric T4; P<0.05), and median duration of sensory block at T10 (plain 25 min; hyperbaric 115 min; P<0.001). However, median times to complete regression of both sensory (270 vs 240 min; P<0.05) and motor (180 vs 120 min; P<0.001) block were longer in the plain group. Patients therefore mobilized sooner in the hyperbaric group (218 [n=16] vs 286 min [n=17]; P<0.01). All the hyperbaric blocks were adequate for surgery, but three patients receiving plain ropivacaine required general anaesthesia.
  
  
  CONCLUSIONS
  Addition of glucose 50 mg ml(-1) to ropivacaine 5 mg ml(-1) increases the speed of onset, block reliability, duration of useful block for perineal surgery, and speed of recovery. Plain solutions are less reliable for surgery above a dermatomal level of L1.
authors.affiliation: University Department of Anaesthesia, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
authors.forename: P D W
authors.initials: PD
authors.lastname: Fettes
authors.forename: G
authors.initials: G
authors.lastname: Hocking
authors.forename: M K
authors.initials: MK
authors.lastname: Peterson
authors.forename: J F
authors.initials: JF
authors.lastname: Luck
authors.forename: J A W
authors.initials: JA
authors.lastname: Wildsmith
mesh_terms: D000328:Adult; D000368:Aged; D000577:Amides / Q000008:administration & dosage* / Q000737:chemistry; D000762:Anesthesia Recovery Period; D000775:Anesthesia, Spinal / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000737:chemistry; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D005947:Glucose; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects; D010502:Perineum / Q000601:surgery; D000077212:Ropivacaine; D012677:Sensation / Q000187:drug effects; D013046:Specific Gravity
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D005947:Glucose