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Brown: Atlas of Regional Anesthesia, 3rd ed., Copyright © 2006 Saunders, An Imprint of Elsevier
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NEEDLES, CATHETERS, AND SYRINGES

Effective regional anesthesia requires comprehensive knowledge by the anesthesiologist of both local anesthetics and the equipment (i.e., the needles, syringes, and catheters that allow the anesthetic to be injected into the desired area). During the early years, regional anesthesia found many variations in the methods to join needle to syringe. Around the turn of the century, Carl Schneider developed the first all-glass syringe for Hermann Wolfing-Luer. Luer is credited with the innovation of a simple conical tip for easy exchange of needle to syringe, but the “Luer-lock” found in use on most syringes today is thought to have been designed by Dickenson about 1925. The Luer fitting became virtually universal, and both the Luer slip tip and the Luer-Lok were standardized in 1955.

In almost all disposable and reusable needles used for regional anesthesia, the bevel is cut on three planes. The design theoretically creates less tissue laceration and discomfort than the earlier styles did, and it limits tissue coring. Many needles that are to be used for deep injection during regional block incorporate a security bead in the shaft so the needle can be easily retrieved on the rare occasions when the needle hub separates from the needle shaft. Figure 1-6 contrasts a short, beveled, 22-gauge security bead needle with a 22-gauge “hypodermic” needle. Traditional teaching holds that the short-beveled needle is less traumatic to neural structures. There is little clinical evidence that this is so, and experimental data about whether sharp or blunt needle tips minimize nerve injury are equivocal.

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Figure 1-6  Frontal, oblique, and lateral views of regional block needles. A, Blunt-beveled, 25-gauge axillary block needle. B, Long-beveled, 25-gauge (“hypodermic”) block needle. C, Ultrasonography “imaging” needle. D, Short-beveled, 22-gauge regional block needle.  (A–D From Brown DL. Regional Anesthesia and Analgesia. Philadelphia, W.B. Saunders, 1996. By permission of the Mayo Foundation.)



Figure 1-7 is a collage of spinal needles. The key to their successful use is to find the size and bevel tip that allows one to cannulate the subarachnoid space easily without causing repeated unrecognized puncture. For equivalent needle size, rounded needle tips that spread the dural fibers are associated with a lesser incidence of headache than are those that cut fibers. The past interest in very-small-gauge spinal catheters to reduce the incidence of spinal headache, with controllability of a continuous technique, faded during the controversy over lidocaine neurotoxicity.

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Figure 1-7  Frontal, oblique, and lateral views of common spinal needles. A, Sprotte needle. B, Whitacre needle. C, Greene needle. D, Quincke needle.  (A–D From Brown DL: Regional Anesthesia and Analgesia. Philadelphia, W.B. Saunders, 1996. By permission of the Mayo Foundation.)



Figure 1-8 depicts epidural needles. Needle tip design is often mandated by the decision of whether to use a catheter with the epidural technique. Figure 1-9 shows two catheters available for either subarachnoid or epidural use. Although each has advantages and disadvantages, a single-end-hole catheter appears to provide the highest level of certainty of catheter tip location at the time of injection, whereas a multiple side-hole catheter may be preferred for continuous analgesia techniques.

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Figure 1-8  Frontal, oblique, and lateral views of common epidural needles. A, Crawford needle. B, Tuohy needle. The inset shows a winged hub assembly common to winged needles. C, Hustead needle. D, Curved, 18-gauge epidural needle. E, Whitacre, 27-gauge spinal needle.  (A–E From Brown DL. Regional Anesthesia and Analgesia. Philadelphia, W.B. Saunders, 1996. By permission of the Mayo Foundation.)



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Figure 1-9  Epidural catheter designs. A, Single distal orifice. B, Closed tip with multiple side orifices.  (A and B From Brown DL. Regional Anesthesia and Analgesia. Philadelphia, W.B. Saunders, 1996. By permission of the Mayo Foundation.)



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