Regional-Anaesthesie
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Regional-Anaesthesie · Mar 1990
[The effect of the Tuohy cannula on the positioning of an epidural catheter. A radiologic analysis of the location of 175 peridural catheters].
The aim of this study was to determine at which lumbar spinal level the tips of different epidural catheters may be located following insertion through cranially directed Tuohy needles. Previous studies varied with respect to materials and methods and may have left the false impression that different types of catheters are necessary or actually more advantageous for particular needs. ⋯ In a clinically controlled study based on the Tuohy principle of inserting catheters through a needle with a Huber point, different epidural catheter models were inserted into the lumbar epidural space and their locating radiologically documented. It was shown that 52% of the epidural catheters that had been advanced 5 cm into the lumbar epidural space through a cephaled-directed Tuohy needle did not reach the intended spinal level cranial to the puncture site. The results are similar to those of earlier studies, which were not systematic and involved a variety of methods and materials. One reason for the unreliable ascension of the catheter tips may be the many structures within the epidural space which may dislodge and divert the catheters during advancement. In addition, it has sometimes been observed that a change in the patient's position may cause a spinous process cranial to the puncture site to exert pressure and traction on the catheter, partially dislodging it. It must thus be concluded that the use of a Tuohy needle cannot guarantee cranial ascension of an epidural catheter in the lumbar epidural region.
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Four cases of unilateral spread of epidural anesthesia are presented. All were documented by X-ray epidurography. In two patients the catheter had passed immediately into one of the intervertebral foramina so that the local anesthetic had almost totally been injected into the paravertebral space. ⋯ This article discusses the fact that strands of the dorsomedian connective tissue band of the lumbar epidural space can cause catheters to coil up, be diverted, and not infrequently be directed into the next intervertebral foramen. These strands sometimes form a dense membrane, which together with the plica mediana of the dura mater prevent symmetrical spreading of epidurally injected fluids. When informing a patient about epidural anesthesia, the anesthesiologist should mention that anatomical variations in the epidural space can cause epidural anesthesia to spread unilaterally.
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Regional-Anaesthesie · Mar 1990
Case Reports[Complications of the postoperative use of lumbar epidural catheters in place for surgery].
Two cases of secondary subarachnoidal dislocation of lumbar epidural catheters are reported. The first catheter was placed, tested, and injected with 20 ml local anesthetic in order to achieve intraoperative anesthesia up to the T4 level. ⋯ Use of this catheter for postoperative analgesia led to total spinal anesthesia in spite of negative aspiration and test dose prior to injection of 7 ml local anesthetic. Implications of these two cases concerning placement procedures and monitoring during reuse of catheters placed some time before are discussed.