[Single-dose spinal anesthesia with a mixture of isobaric bupivacaine 0.5% and hyperbaric mepivacaine 4%].
BACKGROUND
Single-dose spinal anaesthesia with hyperbaric local anaesthetic provides profound analgesia and motor blockade and allows exact assessment of the analgesic level. The present prospective, randomised study compares a mixture of plain 0.5% bupivacaine and hyperbaric 4% mepivacaine with hyperbaric 0.5% bupivacaine with regard to onset time of analgesia and duration of the sensory and motor blockade.


METHODS
One hundred and twenty-two orthopaedic patients (69 m/53 f, aged 20-91 years) scheduled for elective lower limb surgery under spinal anaesthesia were randomly allocated to one of two groups. In group 1, 67 patients received a 1:1 mixture of plain 0.5% bupivacaine and hyperbaric 4% mepivacaine (density: 1,015 kg/m3, 37 degrees C). In group 2, 55 patients received hyperbaric 0.5% bupivacaine (density: 1,021). The lumbar puncture was performed between L3 and L5 using a 26 G Quincke needle through a 20 G introducer with the patients either in the sitting or lateral position. The local anaesthetic was administered with an injection speed of 1 ml per 5 s. Patients with a body height < 160 cm received 2.0 ml, those 160-180 cm 3.0 ml, and those > 180 cm 4.0 ml. The level of analgesia was registered every minute by pin-prick until the maximal analgesic level was reached. The time of regression of analgesia to the level of T 12 and regression of the motor block to Bromage scale 3 was registered. The data were analysed using Student's t-test with P < 0.05 considered as significant.


RESULTS
Demographic data did not differ between groups. In group 1, the onset time of analgesia was faster than in group 2 (8 +/- 3 vs. 14 +/- 5 min, P < 0.001). While in group 1 the onset time of analgesia was faster in patients injected sitting compared to those in the lateral position (p < 0.05), there was no position-related difference in group 2. The groups also did not differ with respect to the maximal level of analgesia and the duration of sensory and motor blockade.


CONCLUSIONS
The local anaesthetic mixture may be preferred to hyperbaric 0.5% bupivacaine in patients requiring a fast onset of analgesia associated with a 2-3 h duration of sensory and motor block.
Eckert
S
S
Abteilung für Anästhesiologie, Universitäts-Krankenhaus Eppendorf, Hamburg.
Standl
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000008:administration & dosage; D001842:Bone and Bones / Q000601:surgery; D002045:Bupivacaine / Q000008:administration & dosage; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage; D008875:Middle Aged; D009994:Osmolar Concentration; D011446:Prospective Studies; D013997:Time Factors
D000779:Anesthetics, Local; D008619:Mepivacaine; D002045:Bupivacaine