[The reduction in the local anesthetic dose required for a caudal epidural block in infants and children using a Teflon cannula].

We investigated the spread of mepivacaine mixed with a radio-opaque substance in caudal epidural anesthesia for hernioplasty in 37 patients aged from 3 months to 5 years. All patients were placed in the left lateral position. Conventional caudal epidural anesthesia was performed on one group of patients (Group C) using a 23 gauge needle (25 mm in length). This new method was also performed on another group (Group N) using a 23 gauge Teflon cannula (63 mm in length), which was introduced as close to the S1 segment as possible. The volume for 9 segmental anesthesia (7.0 +/- 2.3 ml) was determined by following Takino's formula: Volume (ml.segmental-1) = 0.067 x [body weight (kg)] + 0.06. The amount was injected from the S1 in Group N patients, and the cephalad spread of the anesthetic reached Th12.8 +/- 0.8 on left side, and L1.1 +/- 0.7 on right side. When the volume for 13 segmental anesthesia (11.5 +/- 2.8 ml) was injected in Group C patients, the cephalad spread of the anesthetic reached Th12.6 +/- 1.2 on the left side, and Th12.5 +/- 1.1 on the right side. In conclusion, we detected no significant difference between Group C and Group N in the cephalad spread of the anesthetic. The required dose of local anesthetic for caudal epidural anesthesia using the Teflon cannula was about two-third the volume of that used for the conventional local anesthetic method.