Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1994-11-10
1997-03-18
Rimell, Sam
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604158, A61M 500
Patent
active
056117787
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of surgical instruments comprising a needle and an associated catheter capable of sliding inside the needle, in particular for performing epidural anesthesia.
Epidural anesthesia is a technique that is widespread at present, and as shown in FIG. 1 it consists in putting a catheter C into place in the epidural space P of a patient in order to inject an anesthetic by means of a needle A which is provided at its distal end 5 with a tapering chamfer tip, also known as a Tuohy needle.
To perform epidural anesthesia, the anesthetist generally begins by inserting the needle A in the back of the patient until the distal end 5 of the needle penetrates into the epidural space P, then the catheter C is inserted via the proximal opening 10 of the needle until it penetrates into the epidural space P via the distal end 5 of the needle.
In order to avoid trauma to this sensitive region of the patient, it is important to avoid pushing the needle in too deep, and thus to know the length of needle that has been inserted into the back of the patient. To do this, a Tuohy needle A of the prior art is generally provided, as shown in FIG. 2, with marks 15 that are spaced apart axially uniformly along its length, thereby enabling the anesthetist to deduce by calculating the length of needle that has been inserted into the back of the patient, i.e. by knowing the total number of marks on the needle and by subtracting therefrom the number of marks that remain visible after the needle has been inserted.
It is also important to know the length of catheter that has been inserted into the epidural space, and the catheter C is generally provided for this purpose with identical marks uniformly spaced axially along its length. To discover the length of catheter extending in the epidural space P, the anesthetist generally counts the number of marks on the catheter C that go in through the proximal opening 10 of the needle as the catheter is being pushed into the needle and after it has left the chamfer thereof, which the anesthetist can feel easily since it becomes more difficult to urge the catheter into the needle once the end of the catheter has gone beyond the distal end of the needle. Thereafter, the Tuohy needle A is withdrawn while the catheter is left in place in the epidural space in order to inject an anesthetic solution therein.
The anesthetist encounters several difficulties that occur during the various steps of performing epidural anesthesia as described above.
Firstly, to know the lengths of needle and of catheter inserted into the back of the patient, the surgeon must note or remember the total numbers of graduations carried by the needle and by the catheter, and must subtract therefrom the numbers of graduations that remain visible after insertion of the needle or of the catheter, and this is not easily done in the context of a surgical operation.
Also, when the needle is being extracted, the catheter tends to be entrained with the needle because of friction, and it then becomes difficult to establish with accuracy the length of catheter that remains in the epidural space after the needle has been withdrawn, which problem is illustrated diagrammatically in FIG. 3.
Finally, since the catheter may remain in place for several hours, there is a danger of it moving during this period and it is important to know its position accurately before any further injection of anesthetic.
The present invention provides a surgical instrument comprising a needle and an associated catheter suitable for sliding inside a needle, in particular for performing epidural anesthesia, remedying the main difficulties described above.
This surgical instrument is characterized in that the catheter is provided with a set of main axial marks suitable, when the catheter is inserted in the needle, for coinciding with an index mark defined on the needle, to indicate merely by reading and without performing any calculation, the length of catheter extending beyond the distal end of the needle, and is provided with a s
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Rimell Sam
Vygon
LandOfFree
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