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 contin uous spinal anesthesia with microcatheters, which include difficult cathete r insertion, failure of insertion, breakage, inadequate anesthesia, postdur al puncture headache, and, rarely, development of cauda equina syndrome. Me thods. A comparative evaluation of this new catheter (22-gauge Spinocath) t o the microcatheter (28-gauge Porter) was performed to study the problems o f insertion, complications, quality of anesthesia, and postoperative analge sia in a prospective, randomized manner. Patients were allocated to two gro ups of 10 each: catheter-over-the-needle group (group I) and microcatheter- through-the needle (group II). Postoperative protocol consisted of an infus ion of 0.125% isobaric bupivacaine delivered with a syringe infusion pump, fnr 24 hours. Results. The two groups were comparable in relation to age, s ex, type of surgery, median height of the block, and the lime taken for cat heter insertion and surgery. Spontaneous backflow of cerebrospinal fluid (C SF) through the catheter with the needle in position was possible only in t he 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 o f the catheter were easier (8 vs 3 cases: chi-square = 5.05; P = .03) in gr oup 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, kinki ng (P < .05), inadequate anesthesia, and supplementation with general anest hesia were seen only in group II. Postoperative pain relief was comparable in both groups (P > .05). Both groups were comparable hemodynamically in th e intra- and postoperative periods. Conclusions. Insertion, maintenance, an d clinical effects were better achieved with the catheter-over-the needle d esign compared to the microcatheter. These preliminary findings need to be confirmed by a larger study.