INTRATHECAL LOCAL-ANESTHETIC DISTRIBUTION WITH THE NEW SPINOCATH CATHETER

Background and Objectives. Microcatheters have been linked in some cas es to the development of cauda equina syndrome, which may be further t raced to the maldistribution of the local anesthetic. A long injection time via the microcatheters contributes to the inadequate mixing. Wit h the new Spinocath catheter, considerably shorter injection times can be achieved due to larger internal size. This study examined whether this leads to more homogeneous intrathecal distribution without causin g greater trauma to the dura. Methods. In an in vitro model of the spi nal canal, the distribution of hyperbaric and isobaric 0.5% bupivacain e (2.5 mL) as well as 5% lidocaine (2.5 mL) was examined after injecti on via the 28-gauge CoSpan catheter (Kendall, Healthcare, Mansfield, M A), the 22-gauge Spinocath catheter (Braun, Melsungen, Germany), and a 29-gauge Quincke needle (Becton Dickinson, Rutherford, NJ). The local anesthetic concentration in the vertebral interspaces T12-L1 to L5-S1 was measured via gas chromatography 3 and 10 minutes after injection. Ln addition, the morphologic puncture characteristics of human dura w ere examined with the halftone electron microscope, after puncture wit h the catheters and needle. Results. After injection through the 28-ga uge CoSpan catheter, caudal segments of the spinal canal showed peak c oncentrations up to a maximum of 1,147 mu g/mL bupivacaine or 8.5 mg/m L lidocaine with hyperbaric solutions, which did not decrease over the 10 minutes of measurement. After injection through the Spinocath cath eter, there was a homogeneous distribution with data peaks of approxim ately 350 mu g/mL bupivacaine or 4.2 mg/mL lidocaine similar to the da ta found after injection through the spinal needle. Conclusions. The n ew Spinocath catheter allows a better mixing of the local anesthetic w ith the cerebrospinal fluid. Because of significantly shortened inject ion times, hyperbaric solutions also show a more homogeneous distribut ion. Although the Spinocath catheter has a larger inner diameter than the other microcatheters, it appeared to cause less trauma to the dura .