Comparison of three catheter sets for continuous spinal anesthesia in patients undergoing total hip or knee arthroplasty

Background and Objectives: Continuous spinal anesthesia (CSA) with microcat heters may be complicated because of technical problems. Ln elderly patient s, some of the problems may be solved by using thicker catheters. A recent invention, involving a catheter-over-needle system, may prevent leakage of cerebrospinal fluid (CSF) and may also improve the prediction of the intrat hecal position of the catheter tip. Methods: This study included 90 patients undergoing primary hip or knee rep lacement, randomly allocated into 3 groups, with 30 patients in each group: Group EC, a 24-gauge epidural catheter through a 19-gauge Tuohy needle; gr oup MC, a 28-gauge microcatheter through a 22-gauge spinal needle; group SC , a 22-gauge spinal catheter over a 27-gauge spinal needle through an epidu rally placed 18-gauge Crawford needle. All subarachnoid catheterizations we re performed with the patient in the lateral position and the initial spina l block dose was 2 mL of plain 0.5% bupivacaine. Increments of 0.5 mt were administered when required. The block performance characteristics were reco rded, and the level of analgesia was studied in a blinded fashion. Catheter function during the postoperative infusion was assessed. Afterwards the ne edles and catheters were examined by microscopy. Results: The: frequency of the successful catheterization was higher in the EC and MC groups (90% in each) than in the SC group (63%) (P < .05). The m ean duration of the successful catheterizations, as well as the median leve l of analgesia, were similar in the groups. The postoperative infusion had to be stopped in 3, 1, and 1 patients in groups EC, MC, and SC, respectivel y, because of a technical reason. No neurologic sequelae occurred in this s tudy. Microscopy showed 4 distorted spinal needle tips (2 each with MC and SC) and minor material damage of the SC catheters when hone had been met du ring block performance. Conclusions: Placement of the SC catheters was unsuccessful to a high degre e, and bone contact produced distortion of the tip of some of these cathete rs. Otherwise, the quality associated with catheterization time, anesthetic distribution, and catheter function was similar with the 3 catheters.