Tuohy needle

As an epidural needle ( epidural, Periduralnadel or cannula ) cannulas are referred to this are, due to their special shape to puncture the epidural space ( epidural space ) and by the injection of anesthetics and / or the introduction of an epidural catheter an epidural (synonym: peridural ) to cause. The now almost exclusively used variant is the Tuohy needle (after Edward Tuohy, American anesthesiologist, 1908-1959 ). There are modified versions that allow simultaneous spinal anesthesia ( Combined Spinal and epidural anesthesia ).

Development and construction

After August Bier had in 1899 described the first clinical application of spinal anesthesia, the French radiologist Jean- Anthanase Sicard published the first report of a puncture of the epidural space, which he had performed at the level of the sacrum to relieve chronic pain in this area.

One-time injections into the epidural space at the level of the lumbar spine have been documented in 1921 by the Spaniards Fidel Pagés and 1933 by the Italian Archile Mario Dogliotti ( 1897-1966 ). Continuous blockades were carried out by the Romanian gynecologist Eugene Aburel (1931 ) and the American Robert A. Hingson (from 1942). They used for this purpose just spinal needles by Barker, with whom the insertion of a catheter ( thin initially urinary catheters were used for this purpose ) was impractical and difficult, with correspondingly low success rates of the procedure.

Edward Tuohy, a former military doctor and anesthesiologist at the Mayo Clinic, developed in the 1940s which was later named after him puncture needle. Key changes were the curved tip of the needle and a stylet which prevented carryover of skin cells. Due to the bending of the cannula has now succeeded in bringing the inserted catheter in spinal cord parallel arrangement, what the success rates increased. Tuohy this principle, however, did not think themselves out, but took over the invention of the dentist Ralph L. Huber ( 1890-1953 ). This had developed the curved cannula tip to reduce the pain on injection into blood vessels and tissue trauma (now Port needles have a similar tip). Tuohy was Huber ignored in the description of its modified needle, which is criticized today. He also did not recognize the opportunity to contribute to the cannula a pain catheter into the epidural space, but was rather interested in a continuous anesthesia in the spinal space. The epidural administration was popularized only by the Cuban anesthesiologists Cuban Manuel Martinez Curbelo.

It later made ​​multiple further modifications of the Tuohy needle, inter alia, by Charles E. Flowers, Robert Hustead, OB Crawford, Jess Weiss and Jürgen sprat. They had, among other things, to reduce a better practicality and less tissue trauma to target the high rate of postpunktionellem headache that brings an accidental puncture of the Spinalraumes with it.

Application

The epidural anesthesia is performed sitting or in the lateral position under sterile conditions. The choice of the level of the puncture site on the patient's spine is primarily dependent on the purpose ( lumbar spine in obstetrics, height of the thoracic spine with interferences of the chest or abdominal cavity ). After disinfection, and local anesthesia of the skin, the Tuohy needle is inserted into the back of the patient between the two spinous processes of the spine. The needle penetrates the band structures of the spine and reaches after passing the epidural space. During the procedure is applied with a syringe continuous printing; after reaching the epidural space can be easily inject fluid or air in contrast to the bands, so this is identifiable (loss - of-resistance or loss of resistance method). Through the cannula then anesthetics (usually local anesthetics, opioids) inject and where appropriate to introduce an epidural catheter, active ingredients can be administered repeatedly or continuously over the. This is introduced by the curvature of the needle parallel to the spinal cord, usually in the direction of the head ( cranial).

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