Masui. The Japanese journal of anesthesiology
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Ultrasound-guided techniques for peripheral nerve blocks are gaining popularity in the community of anesthesiology. This technique has many clinical benefits for regional anesthesia in the field of clinical anesthesia. These are; 1. short time for procedures; 2. peripheral nerves, blocking needles and surrounding structures around the nerves are easily recognized, and; 3. the decreased incidence of complications with insertion of the needles. The knowledge, basic considerations and some techniques of ultrasound-guided peripheral nerve blocks are described in the following articles.
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Ultrasound-guided peripheral nerve block has been gaining popularity in the community of anesthesiologists. Despite its well-known clinical benefits, inconsistent success in block has been one of the major limita- tions of conventional peripheral nerve block. Recent development in ultrasound technology enables us to see nerves, needles and surrounding structures in real-time. ⋯ In this article, we introduce some evidences that support the clinical benefits of ultrasound-guided peripheral nerve block, including performance time, quality, onset and duration of sensory blockade, cost analysis and patient satisfaction. However, ultrasound-guidance may be even more dangerous without appropriate imaging of target nerve and surrounding structures, accurate localization of needle tip and assessment of local anesthetic spread around the target nerve. These problems will be solved by future guidelines, teaching program and further advancement in ultrasound technology.
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Epidural block is performed with surface landmark guidance and loss of resistance technique. Ultrasound visualization of the spinal column and surrounding structures gives additional anatomical information, which could make the block easier and safer. ⋯ The dura mater is identified as an echogenic structure inside the spinal canal. Prepuncture ultrasound examination offers useful information for epidural block such as puncture point and depth as well as angle to the epidural space.
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Ultrasonographic guidance has been introduced as an aid to nerve localization, for brachial plexus blockade in the interscalene and infraclavicular regions. Ultrasound-guided interscalene approach and infraclavicular approach were established as an excellent method to provide good analgesia during surgery and relieve post-surgical pain after shoulder or upper arm surgery and forearm or hand surgery respectively. Single shot injection and continuous catheter approach in both nerve blocks were described together with clinical key points based on the ultrasound images.
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The ultrasound waves (> 20 kHz) are high-frequency sound waves that are not audible to the human ear. As the ultrasound waves move through body tissues of different acoustic impedances, they are attenuated, reflected, or scattered. Reflected waves are transformed back into an electrical signal that is processed by the ultrasound machine to generate an image on the screen. ⋯ The recent advance of ultrasonography has provided close-sectional images of the body in real time. Ultrasound imaging has been useful to visualize neural anatomical structures and the surrounding structures, and navigate the needle toward the target nerves. This review introduces the theories and practices of ultrasonography for the peripheral nerve blocks.