title: [Isobaric and hyperbaric local anesthetic used in spinal anesthesia].
abstract: OBJECTIVE
  To reveal the advantages and disadvantages of the application of isobaric and hyperbaric local anesthetic in spinal anesthesia so as to provide reference for clinical practice.
  
  
  METHODS
  One hundred and sixty ASA patients (physical status I - II) undergoing lower abdominal surgery within 3 hours under spinal anesthesia (using CSEA technique via spinal needle in epidural needle) were allocated to 2 groups with 80 cases each. In lateral decubitus, patients randomly received a subarachnoid injection of 3.0 mL (15 mg) isobaric (Group I) or hyperbaric (Group H) bupivacaine and then turned supine. Hemodynamic changes and patients' responses were perioperatively observed. After subarachnoid injection, we recorded the time of onset and motor block, the peak sensory blocked level, the time of regression of 2 dermatomes, the time of the first administration of analgesics for a significant pain of the incision, the time of the regression of motor block to modified Bromage scale 2, and the time of recuperating the function of urination.
  
  
  RESULTS
  Both isobaric and hyperbaric 0.5% bupivacaine solutions in a volume of 3.0 mL provided effective sensory and motor block for the operations. The time of onset and complete motor block were similar in the two groups. Compared with Group I, the time of peak sensory block in Group H was shorter, the peak sensory block level was higher (more maximal dermatomes of blocked sensory nerves), the time of regression of sensory and motor block were shorter, the time of recuperating the function of urination was longer, and the incidence of feeling sick, nausea, vomiting and hypotension was higher.
  
  
  CONCLUSIONS
  Isobaric solution is superior to hyperbaric solution in spinal anesthesia.
authors.affiliation: Department of Anesthesia, Xiangya Hospital, Central South University, Changsha 410008, China. lilime00@126.com
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Qu-Lian
authors.initials: QL
authors.lastname: Guo
authors.forename: Jian-Qin
authors.initials: JQ
authors.lastname: Yan
mesh_terms: D000368:Aged; D000775:Anesthesia, Spinal / Q000379:methods*; D000779:Anesthetics, Local; D002045:Bupivacaine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D019999:Pharmaceutical Solutions; D012677:Sensation
chemical_list: D000779:Anesthetics, Local; D019999:Pharmaceutical Solutions; D002045:Bupivacaine