title: Low dose hyperbaric bupivacaine for unilateral spinal anaesthesia.
abstract: OBJECTIVE
  To evaluate the effects of hyperbaric bupivacaine concentration in producing unilateral spinal anaesthesia.
  
  
  METHODS
  With Ethical Committee approval and written consent, 60 patients undergoing lower limb surgery were placed in the lateral position with the side to be operated on dependent. After dural puncture (25-gauge Whitacre spinal needle), the needle hole was turned toward the dependent side and patients were randomly assigned to receive 8 mg of either 0.5% (Group0.5%, n = 30) or 1% (Group1%, n = 30) hyperbaric bupivacaine. The lateral position was maintained for 15 min, while a blinded observer recorded loss of pinprick sensation and degree of motor block on both sides until two segment regression of sensory level on the dependent side.
  
  
  RESULTS
  At the end of the 15 min lateral position spinal anaesthesia was more frequently unilateral in Group0.5% (80%) than in Group1% (53%)(P < 0.05). However, 30 min after patients were turned supine, unilateral spinal anaesthesia decreased to 60% of cases in Group0.5% and 40% of cases in Group1% (P = NS). The maximum sensory level on the dependent side [T10(L1-T2) in Group0.5% and T8 (T12-T3) in Group1%], time to reach it [20 (5-30) min in Group0.5% and 25 (10-35) min in Group1%], and time to two segment regression of sensory level [80 (30-135) min in Group0.5% and 75 (20-135) min in Group1%] were similar in both groups.
  
  
  CONCLUSIONS
  Highly concentrated solutions of hyperbaric bupivacaine are not advantageous in obtaining a unilateral spinal anaesthesia, when a small anaesthetic dose is injected slowly through a Whitacre spinal needle.
authors.affiliation: University of Milan, Department of Anaesthesiology and Intensive Care, IRCCS H San Raffaele, Italy. casati.andrea@hsr.it
authors.forename: A
authors.initials: A
authors.lastname: Casati
authors.forename: G
authors.initials: G
authors.lastname: Fanelli
authors.forename: G
authors.initials: G
authors.lastname: Cappelleri
authors.forename: B
authors.initials: B
authors.lastname: Borghi
authors.forename: V
authors.initials: V
authors.lastname: Cedrati
authors.forename: G
authors.initials: G
authors.lastname: Torri
mesh_terms: D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal / Q000295:instrumentation / Q000379:methods; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000737:chemistry; D002045:Bupivacaine / Q000008:administration & dosage* / Q000737:chemistry; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007866:Leg / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000187:drug effects; D009339:Needles; D009407:Nerve Block; D011187:Posture; D011312:Pressure; D012677:Sensation / Q000187:drug effects; D016683:Supine Position
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine