Over-the-needle versus microcatheter-through-needle technique for continuous spinal anesthesia: a preliminary study.

BACKGROUND AND OBJECTIVES

A new catheter-over-needle design (Spinocath, B. Braun) has been developed to minimize problems and complications of continuous spinal anesthesia with microcatheters, which include difficult catheter insertion, failure of insertion, breakage, inadequate anesthesia, postdural puncture headache, and, rarely, development of cauda equina syndrome.

METHODS

A comparative evaluation of this new catheter (22-gauge Spinocath) to the microcatheter (28-gauge Portex) was performed to study the problems of insertion, complications, quality of anesthesia, and postoperative analgesia in a prospective, randomized manner. Patients were allocated to two groups of 10 each: catheter-over-the-needle group (group I) and microcatheter-through-the needle (group II). Postoperative protocol consisted of an infusion of 0.125% isobaric bupivacaine delivered with a syringe infusion pump for 24 hours.

RESULTS

The two groups were comparable in relation to age, sex, type of surgery, median height of the block, and the time taken for catheter insertion and surgery. Spontaneous backflow of cerebrospinal fluid (CSF) through the catheter with the needle in position was possible only in the spinocath group (8/10 cases). Initial introduction of the catheter into the subarachnoid space (8 vs 3: chi-square = 5.05; P = .03) and threading of the catheter were easier (8 vs 3 cases: chi-square = 5.05; P = .03) in group I. Aspiration of CSF was easy in group I in all ( 10 vs 2: chi-square = 13.33; P = .004). Complications such as resistance to drug injection, kinking (P < .05), inadequate anesthesia, and supplementation with general anesthesia were seen only in group II. Postoperative pain relief was comparable in both groups (P > .05). Both groups were comparable hemodynamically in the intra- and postoperative periods.

CONCLUSIONS

Insertion, maintenance, and clinical effects were better achieved with the catheter-over-the needle design compared to the microcatheter. These preliminary findings need to be confirmed by a larger study.