Comparison of technical and block characteristics of different combined spinal and epidural anesthesia techniques

Background and Objectives: The combined spinal and epidural (CSE) technique can reduce or eliminate some of the disadvantages of spinal and epidural a nesthesia, while still preserving their advantages. CSE anesthesia is now c ommonly performed with a single-segment needle-through-needle technique; ho wever, this technique involves some controversies about needle handling and the risk of catheter migration. To avoid some of these potential problems, special CSE sets have been produced. Ln the present study, 2 of these sets were compared with the traditional double-segment technique. Methods: Ninety patients undergoing orthopedic surgery of the lower extremi ty were randomly allocated into 3 groups of equal size: Group 1, CSE set wi th an interlocking device between the spinal and epidural needle; group 2, CSE set with a "backeye" at the epidural needle curve for the passage of th e spinal needle; group 3, double-segment technique. All epidural needles we re 18-gauge, and spinal needles were 27-gauge with a pencil-point tip. In g roups 1 and 2, the puncture was performed at the L3-4 interspace, and in gr oup 3 the epidural catheter was first inserted at the L2-3 interspace follo wed by spinal puncture one interspace lower. Hyperbaric 0.5% bupivacaine, 2 mt, was used for the spinal block, and 4 mt of 2% lidocaine with epinephri ne through the epidural catheter was used as a lest dose. The block perform ance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Postoperatively, a bolus of epidural morphine 2 to 4 mg was used for the control of postoperative pain. All patients were interv iewed on the Ist and the 7th postoperative days. Afterwards, the needles an d catheters were examined by microscopy. Results: The frequency of the successful CSE block was higher in groups 3 ( 100%) and 2 (90%) than in group 1 (63%) (P < .05). The mean duration of suc cessful block performance, as well as the median level of analgesia, were s imilar in all the groups. One case of epidural catheter migration intrathec ally was observed (group 1). Postoperative nausea and vomiting occurred in 23% of patients, and the incidence of postdural puncture headache was 2.2%. The incidence of backache at the puncture site was similar in the groups. Microscopy showed 6 distorted spinal needle tips tall in group 1), but no m aterial damage to the epidural catheters. Conclusions: The use of the CSE sets does not seem to save time compared wi th the double-segment technique. Technical problems, unsuccessful CSE block , and damaged spinal needle tip were noted relatively often with the interl ocking CSE set. Anesthetic characteristics in the successful blocks were si milar with the different techniques.