Rate of injection through whitacre needles affects distribution of spinal anaesthesia.
A prospective, randomized, double-blind study was performed to investigate whether altering the rate of injection of local anaesthetic through a Whitacre needle had any effect on the spinal block achieved. Twenty patients scheduled for elective urological surgery under spinal anaesthesia received an injection of 3 ml of 0.5% plain bupivacaine either by hand (fast) over 10 s (18 ml min(-1)) or by infusion pump (slow) over 3 min (1 ml min(-1)). All patients were in the sitting position both during insertion of the spinal needle and for 3 min after the start of spinal injection, and they then changed to the supine position. The slow injection group achieved peak sensory block earlier, after a median interval of 20 (95% confidence interval 12.5-30) min vs 30 (22.5-45) min (P<0.05) for the fast group. The level of peak sensory block was similar: T3.5 (T2-T4.5) vs T4 (T1.5-T6.5). The time to lowest mean arterial pressure occurred earlier in the slow group, at 10 (8 to 18) vs 20 (15-31) min (P<0.05). Duration of the motor block was shorter in the slow group: 180 (152-242) vs 270 (225-300). We conclude that a slow spinal injection of plain bupivacaine results in a block of more rapid onset and recovery.
Anderson
L
L
Department of Anaesthesia, Western Infirmary, Glasgow, UK.
Walker
J
J
Brydon
C
C
Serpell
M G
MG
D000368:Aged; D000369:Aged, 80 and over; D000775:Anesthesia, Spinal / Q000295:instrumentation*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000494:pharmacology; D002045:Bupivacaine / Q000008:administration & dosage* / Q000494:pharmacology; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000187:drug effects; D009339:Needles; D011446:Prospective Studies; D012677:Sensation / Q000187:drug effects; D013520:Urologic Surgical Procedures
D000779:Anesthetics, Local; D002045:Bupivacaine