Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-08-02
2003-04-29
Nguyen, Anhtuan T. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
Reexamination Certificate
active
06554809
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates generally to the field of epidural needles and methods of using the same.
2. Background Art
In general there are two methods for administering epidural anesthesia. The first is by means of a straight epidural needle connected at its proximal end to a syringe or other source of liquid anesthesia. The second is by means of a curved-tip epidural needle used to introduce an epidural catheter into the epidural space, which ranges on the order of 2-7 mm in width.
Straight epidural needles employed in the former procedure do not require the passage of a catheter. They typically have a straight distal end and a gauge size on the order of 21-22 gauge (iso-9626). Curved-tip epidural needles, through which a catheter is introduced, of necessity are somewhat larger, having a gauge size typically on the order of 17-18 gauge (iso-9626).
Curved-tip epidural needles, used for introducing a catheter into the epidural space, possess a curved tip so that the distal end of the catheter can curve upward for proper placement within the epidural space, rather than perpendicularly abutting the dura matter, the delicate membrane lying over the arachnoid and pia matter covering the spinal cord.
The epidural needles of the curved type currently in use are of two kinds: (1) those curved to have an inclined surface on the order of 7° from the longitudinal axis (known as“Tuohy” epidural needles); and (2) those curved to have an inclined surface on the order of 12° from the longitudinal axis (known as “Husted” epidural needles.)
Whether the procedure is of the type wherein the anesthesia is introduced through a syringe attached to the epidural needle or of the type where the anesthesia is introduced through a catheter, great care must be taken to avoid puncturing the dura mater and thus permitting spinal fluid to leak out.
In a typical procedure, a local anasthetic may first be given to minimize pain and discomfort from the epidural needle. With the stylet in the needle, the needle is slowly and carefully inserted until it abuts the ligamentum flavum, at which time the anesthesiologist senses an increase of resistance to further insertion. At this time, the stylet is removed from the needle and a“loss of resistance” syringe is attached to the luer fitting of the needle hub. By slowly advancing the needle and syringe while simultaneously applying pressure to the syringe piston, the ligamentum flavum is penetrated and the needle is advanced into the epidural space where loss of resistance to the syringe piston is confirmed.
At this point, the syringe is removed and the epidural catheter is inserted through the needle until the distal end of the catheter exits the curved tip of the needle and is inserted the desired distance into the epidural space.
The proximal end of the catheter is then placed in fluid communication with a source of the anesthetic drug to be introduced. Typically, this is done by securing the proximal end of the catheter within the distal end of an adapter and securing a syringe containing the anesthetic drug to the proximal end of the adapter.
U.S. Pat. No. 4,141,365 discloses a tissue stimulation apparatus for positive positioning of an electrode-bearing lead proximous to tissue which is to be stimulated electrically, the invention particularly includes a body penetration and insertion assembly which carries an elongated flexible strip of physiologically inert plastic material having at least one electrode positioned thereon into contacting relation with said tissue. The insertion assembly comprises a hollow needle having a slot formed longitudinally along the length of one wall thereof, the slot allowing transverse removal of the flexible lead from the needle after proper positioning of the lead and after removal of the needle from the body. The slotted assembly allows use of a flexible electrode lead having electrical connections at the external end thereof which are too large to pass through the hollow needle. U.S. Pat. No. 4,141,365 is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,721,506 discloses an epidural needle and method of use involving a needle shaft having a first end and a second end with an axial channel extending therebetween. The first end of the needle shaft includes an inclined surface and a rounded and blunted point. The second end of the needle includes an attachment means. A solid rod having an inclined surface and a rounded and blunted point is receivable into the axial channel of the needle shaft. When the solid rod is positioned within the axial channel of the needle shaft, the point of the solid rod and the needle together form a unitary tip having an inclined portion and a blunted portion. The blunted portion forms an end face disposed at an angle of about 80 to 100 degrees relative a longitudinal axis of the needle. The unitary tip avoids nicking, piercing, severing, or perforating the veins, arteries, nerves and dura of the patient in traversing the spinal ligaments and in entering a space proximate the dura matter of a spinal cord of a patient to provide liquid communication with the space when the solid rod is withdrawn from the axial channel of the needle. U.S. Pat. No. 4,721,506 is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,808,157 discloses a needle that is a multi-lumen needle and preferably a dual-lumen epidural-spinal needle. The needle is provided with a hub, which allows for attachment of a syringe to one or more of the lumina, or alternatively the attachment of an adapter to which a syringe can be attached. Preferably the lumina have different cross sectional areas. The smaller of the lumina should be of sufficient size to allow a spinal needle, guide wire, or microcatheter to be inserted through the lumen. The larger of the two lumina should preferably be of sufficient size to allow an epidural catheter, spinal needle or guide wire to be introduced. The needle of the present invention has applications of regional anesthesia, chronic and post operative pain management, cricothyroid puncture, intracerebroventricular puncture and, access and drainage of concealed fluid collections within the body. U.S. Pat. No. 4,808,157 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,425,717 discloses a system for administering epidural anesthesia utilizing an epidural catheter permanently secured at its proximal end to an adapter for putting the catheter in fluid communication with a source of liquid anesthesia. The system employs a splinable needle for inserting the catheter into the peridural space. U.S. Pat. No. 5,425,717 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,573,519 discloses an elongated, hollow spinal needle that is less prone to causing postdural puncture headache by having a modified, pencil-like point with a rounded shoulder at the juncture between the modified, pencil-like point and the body of the spinal needle. A side port is formed in the hollow needle at a position adjacent the rounded shoulder. The leading edge of the side port is located not more than 1.5 times the external diameter of the hollow needle from the tip of the pencil-like point to reduce the bending moment between the tip and the side port. The cross sectional area of the side port is configured to be equal to or incrementally larger than the cross sectional area of the lumen of the hollow needle. U.S. Pat. No. 5,573,519 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,628,734 discloses various embodiments of spinal needles, each having a curvature, that are used in a method of administering a spinal anesthetic while preventing the development of post dural puncture headache. U.S. Pat. No. 5,628,734 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,843,048 discloses an epidural needle through which an epidural catheter may be threaded for administering liquid anesthesia into the epidural space, the needle having a curved distal end, the tip of the needle distal to the opening in the
Lam Ann Y
Nguyen Anhtuan T.
Rosenthal & Osha L.L.P.
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