CONTROL OF CATHETER POSITION AND DISTRIBU TION OF CONTRAST-MEDIUM IN ROUTINE POSTOPERATIVE EPIDURAL CATHETER ANALGESIA

In the last few years epidural analgesia with bupivacaine and/or opioi ds has become an important technique in the therapy of postoperative p ain. Using bupivacaine only 2-20% of the patients are treated without sufficient success. To ascertain and evaluate the underlying reasons f or this, we prospectively investigated 51 patients routinely, and 6 pa tients with an insufficient analgetic effect from a group of 212 patie nts, by means of epidurography. All patients were treated mainly with bupivacaine. The observed and documented radiographic data were compar ed with the individual analgetic results. Methods. All investigations were performed within 24 h after placing the catheters. The contrast a gent was injected under radiographic guidance in two different positio ns, and the end of the distribution was documented in the anterior-pos terior ray path. In group 1 (n = 26) the catheter position and the dis tribution of the contrast medium with 3.0 ml iopamidol were documented . In group II (n=25) the catheter position was documented in the same way, but the distribution was documented for the stepwise-injected con trast medium (3.0 ml + 2.0 ml + 3.0 ml). As a result of these findings we changed our epidural catheter placement concept in the following p atients (group III, n = 212), and performed radiographic examinations in patients with a therapy failure only (group IIIa, n = 6). Instead o f placing the catheter postoperatively mostly lumbal in a lateral posi tion, we now placed them preoperatively, in the sitting position, as n ear as possible to the centre of the segments to be treated. Results. Only 27 patients demonstrated an ideal catheter position and a typical contrast medium distribution. Three of these patients still could not be treated successfully. In 12 patients the spread of the contrast me dium was inhomogeneous, and in 5 patients the contrast medium was foun d on one side of the epidural space only. Half of these 17 patients n = 9 needed supplementary therapy. Surprisingly, 4 of 8 patients with a paraepidural catheter position were treated with success. Discussion. Effective bupivacaine therapy by epidural catheter injections constit utes no striking evidence for a correct epidural catheter position. If the catheter lies in the epidural space, the actual therapeutic effec t of bupivacaine therapy is determined mainly by the distribution of t he substance. The epidural position of the catheter - central or later al in the epidural space - seems, however, not to be particularly impo rtant. If high-quality analgesia is to be achieved with bupivacaine al one, or in combination with an opioid, the catheter should usually be placed near to, or better into the centre of the segments to be treate d. The results demonstrate that in the case of failure of epidural cat heter therapy, epidurographic examinations are very helpful in ascerta ining and evaluating the underlying reasons for this failure and in co ming to a logical decision for changing the concept.