Background and Objectives. The use of micro-bore spinal catheters for catheter spinal anesthesia (CSA) has been associated with untoward neurologic events. Eleven cases of Cauda Equina syndrome have been reported after CSA was performed using smaller catheters and in which large amounts of hyperbaric lidocaine (5% in glucose) were infused. To evaluate if smaller catheters necessitate larger amounts of hyperbaric lidocaine to successfully achieve surgical anesthesia, the use of this agent in both macro-and micro-bore catheters for 12 months was reviewed.

Methods. Only those CSA that used hyperbaric lidocaine as the sole anesthetic were analyzed. Patient characteristics, initial and total dosing of lidocaine, and the type and duration of surgical procedures were evaluated. Available records were reviewed to ascertain the occurrence of newonset neurologic deficits.

Results. Out of a total of 134 CSA cases, 95 were performed using hyperbaric lidocaine alone. Forty-four of these cases were performed with micro-bore and 51 with macro-bore catheters. There were no significant differences noted in patient characteristics or dosing requirements when comparing the two groups. One patient developed an isolated L5 motor root dysfunction that was felt not to have resulted from his (micro-catheter) CSA.

Conclusions. This review failed to support the hypothesis that catheter size necessitates different doses of hyperbaric lidocaine. Further, the results suggest that a much lower dose than those used for single shot spinal anesthesia can be used with CSA, to further improve the safety of the technique.