Spinal anesthesia with tetracaine in 0.75% glucose: influence of the vertebral interspace used for injection.
OBJECTIVE
The anesthetic behavior and hemodynamic consequences of spinal anesthesia with marginally hyperbaric tetracaine containing a low concentration of glucose injected at two different interspaces were examined and compared with those of conventionally hyperbaric solution.


METHODS
One-hundred twenty ASA Physical Status I or II patients scheduled for elective surgery to the lower limb were sequentially assigned to one of three equal groups to receive spinal anesthesia: Group 1 received 0.5% tetracaine in 0.75% glucose with 0.125% phenylephrine at the L2-L3 interspace; group 2 0.5% tetracaine in 0.75% glucose with 0.125% phenylephrine at the L3-L4 interspace; group 3 0.5% tetracaine in 7.5% glucose with 0.125% phenylephrine at the L3-L4 interspace. Neural block was assessed in a double-blinded manner by cold, pinprick, and touch sensation, and a modified Bromage scale after the injection of the study drug.


RESULTS
Injection at the L2-L3 interspace produced significantly higher spread of analgesia [median T7 (10th, 90th percentiles T10, T4)] than injection at L3-L4 interspace [T10 (L1, T5)] when using the solution in 0.75% glucose. There were no significant differences in peak dermatomal levels between groups 1 and 3, but the number of patients who required ephedrine for the treatment of hypotension was larger in group 3.


CONCLUSIONS
A marginally hyperbaric tetracaine solution injected at the L2-L3 interspace with the patient in the lateral position produced greater extent of cephalad spread than that at the L3-L4 interspace. When compared to a conventionally hyperbaric tetracaine solution injected at the L3-L4 interspace, the marginally hyperbaric solution injected at the L2-L3 interspace caused less hemodynamic variability despite similar levels of maximum sensory block.
Sakura
S
S
Department of Anesthesiology, Shimane Medical University, Izumo City, Japan.
Sumi
M
M
Morimoto
N
N
Yamamori
Y
Y
Saito
Y
Y
D000775:Anesthesia, Spinal / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007278:Injections, Spinal; D008297:Male; D008875:Middle Aged; D012996:Solutions; D013748:Tetracaine / Q000008:administration & dosage*
D000779:Anesthetics, Local; D012996:Solutions; D013748:Tetracaine; D005947:Glucose