Effects of concentration and volume of 2-chloroprocaine on epidural anesthesia in volunteers.
BACKGROUND
Effect of local anesthetic concentration and volume on the spread and density of epidural anesthesia is unclear. This study was performed to delineate effects of a threefold difference in concentration and volume of 2-chloroprocaine on epidural anesthesia.


METHODS
Twelve healthy volunteers underwent lumbar epidural anesthesia with 300 mg of 2-chloroprocaine as a 3% (10 ml) and a 1% (30 ml) solution in a randomized, double-blind, balanced, crossover fashion. Sensory block was assessed with pinprick, touch (calibrated plastic filament), cold, and electrical stimulation. Motor block was assessed at the quadriceps and gastrocnemius muscles with isometric force dynamometry. Differences between solutions were assessed with repeated measures analysis of variance followed by post hoc testing.


RESULTS
The number of dermatomes blocked to pinprick, touch, and cold was significantly greater with the 1% concentration (2 dermatomes greater than the 3% concentration on average, P < 0.05). Similar intensity of sensory block to electrical stimulation developed at the hip and knee and was unaffected by concentration of 2-chloroprocaine. Similar intensity of motor block developed at the quadriceps with both concentrations.


CONCLUSIONS
Intensity of sensory and motor block from epidural anesthesia with 2-chloroprocaine appears to depend primarily on total milligram dose.
Liu
S S
SS
Department of Anesthesiology, Virginia Mason Medical Center, University of Washington, Seattle 98111, USA.
Ware
P D
PD
Rajendran
S
S
D000328:Adult; D000767:Anesthesia, Epidural / Q000379:methods*; D000779:Anesthetics, Local; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D011343:Procaine / Q000031:analogs & derivatives*
D000779:Anesthetics, Local; D011343:Procaine; C004616:chloroprocaine