[Fluid distribution and catheter position in the peridural space in postoperative and cancer pain therapy. A radiological study].

A radiological study was made in 33 patients of the position of the epidural catheter and the spread of the contrast medium Metrizamide (Amipaque) when used in volumes of 10, 15 and 20 ml. The puncture at the interspinal space L2/L3 and L3/L4 allows the safe inclusion of eight peridural segments in all cases, whereas puncture of the upper regions of the spine results in a less predictable effect with spread of the injected fluid to higher spinal segments. A larger volume of contrast medium of 15 ml allows the safe inclusion of a larger number of spinal segments. Abnormal presentation, areas of fluid loss and the distribution of the analgesics or local anaesthetics injected may be detected early, which allows correction or adaptation of decisions concerning the fluid volume or the concentration of analgesics such as morphine.