THE ULTRASOUND-GUIDED MIDDLE INTERSCALENE BLOCK
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Sonography may be useful when the subclavian artery pulse is absent;
however it can be used when all the reference points are present.
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The procedure is as follows: after having drawn the angle and its bisectings-line (or the straight line when the pulse can be felt)... |
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... we apply a linear probe to the posterior edge of the medial half of the clavicle... |
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... and slide it slowly in a lateral direction... |
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... at a certain point the subclavian artery will appear on the screen as a pulsating “black hole” and just lateral to this we can see the “circular crowns” (nervous tissue surrounded by the epinevrium) of the brachial plexus components, cut transversely by the U.S. beam. |
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Since the presence of the probe and the clavicle together hamper the insertion of the needle, according to the safe direction described in our technique... |
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...we rotate the probe about 45° degrees, in a clockwise direction on the right side and anti (counter) clockwise on the left, while observing the artery on the screen. |
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The sonographic image will essentially remain the same, but by rotating the probe we will see the bisecting-line or the straight-line needed to direct the needle, as described in our technique, and we will have enough space for its insertion “out- of- plane”. |
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To have an in-plane insertion the probe is applied on the line laterally tangent to the subclavian artery pulse or on the bisecting line of the angle if the subclavian artery pulse is absent. |
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Thus, the image shown by the ultrasound will completely differ and the elements of the brachial plexus, longitudinally cut, can be seen between the anterior and middle scalene muscles.
The arterial tube, cut along its syphone by the probe, will be seen as a hypoechogenic oblonged oval surrounded by a more or less hyperoechogenic wall, proportional to the arteriosclerosis degree. |
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The same image with color-dopler effect |
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Here we can see the images of the combined method: NEUROSTIMULATION + U.S. GUIDE |
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This picture shows the black hole of the subclavian artery and, close to it, the brachial plexus components transversely cut. |
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After having evoked the required twitch with a 0.3 mA current, we may notice the typical expansion of the anaesthetic fluid within the neurovascular bundle covered by a cloak, by a mantel of anesthetic solution. |
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AND NOW SOME INTERESTING OPINIONS
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M.J. Fredickson MD
From the Department of Anesthesiology, Faculty of Medical and Health Sciences, the University of Auckland, New Zealand.
This sentence makes us wonder if with U.S. there are sometimes problems. The images are not always clear enough, also in the hands of an expert. |
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Brian Sites MD
From the Departments of Anesthesiology and Orthopedic Surgery, Dartmounth Medical School, Lebanon New Hampshire.
The
paper is one of the clearest theoretical pubblications about U.S. management |
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Alain Borgeat, Professor and Chief-of-staff, Department of Anesthesia, Balgrist University Hospital, Zurich, Switzerland |
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S 43 Admir Hadzic, Professor of Clinical Anesthesiology Columbia University of Physicians and Surgeons, Director New York School of Regional Anesthesia.
Author of the most complete and thorough textbook of Regional Anesthesia, published in the 2007. |
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To sum up:
We have not to work in function of the probe, but the probe must work in function of the applied technique, checking the right direction of the needle and the expansion of the anaesthetic fluid when the required twitch is obtained.
Ultrasound gives us anatomical images and dynamic effects which arouse enthusiasm, but
we must not think to have found the solution to every problem.
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