| 摘要 |
A catheter used to measure chemical parameters, in particular to be inserted into biological tissue, fluids or the like, comprising a feed duct running longitudinally through the catheter to its outer end for the purpose of feeding a liquid, further a return duct running through the catheter to return the liquid and a partly permeable tubular membrane at the end of the catheter and enclosing the flow path between the end of the feed duct and the return duct. This catheter is characterized in that the feed duct (26) substantially coaxially encloses the return duct (4), or vice-versa, in that the tubular membrane (16) forms at least in the vicinity of the catheter end an inner wall (10) of the radially external return duct or the radially external feed duct (26), that the feed duct (26) and the return duct (4) communicate with each other at the catheter end by at least one radial aperture (24) and in that spacers are provided which brace the inner wall (10) of the radially external tubular part (12) and/or of the tubular membrane (16) against the external wall (6) of the inner tubular part (2).The catheter can be manufactured in simple and economical manner and makes possible a small diameter and small dead space and allows measurement without substantial time-delay at a high measurement level. |
