Development of Ultrasound Transducer for Guidance of Regional Anesthesia

• Main Authors: Ya-Cheng Chang, 張雅程
• Other Authors: Yin Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/44722914542295912224

碩士 === 國立陽明大學 === 醫學工程研究所 === 100 === Regional anesthesia including spinal anesthesia and epidural anesthesia for surgery, obstetrics and perioperative pain have been used frequently. In clinic, the current anesthetic process is carried out by the rule of thumb, and this ’blind’ process easily causes the damage of spinous bone by the insertion needle. The purpose of this study is to develop a novel ultrasound probe integrated with the needle for the guidance of regional anesthesia. The ultrasound probe consisted of a PZT-5H ceramic with a central hole, a matching layer, and backing layer. The design of central hole was for the needle in/out. Before and during the needle insertion, the path between spinous processes can be identified by comparing the ultrasound echo signals from the bone tissue and non-bone tissues. Typically, the echo from the spinous process is stronger much than that from the gap between spinous processes. A prototype of 2-MHz ultrasound probe with a bandwidth of 46% and a pulse width of 2.98 μs was developed in-house. Compared with the initial design, the variations of center frequency, bandwidth, and pulse width was 5.3%, 20.3%, and 34.9%, respectively. The errors are caused by inconsistent material properties, fabrication and measurement errors. A phantom and ex vivo porcine lumbar experiments were performed. The experimental results showed that the L3, spinal nerve between L3/L4, L4, spinal nerve between L4/L5, and L5 of the human-mimic lumbar model were identified by the echo signals detected by the self-developed probe even though the insertion angle of the needle was 5o, 10o, or 15o. In the ex vivo porcine lumbar experiments, the skin, fat layer, ligament, and spinous bone were positioned by the ultrasound probe, and further the gap between spinous processes was identified. The ultrasound transducer technology specific for the guidance of the anesthesia has been established in this study and the feasibility of avoiding needle-insertion bone damage under the ultrasound guidance has also been verified through a series of in vitro experiments.