title: A Coaxial Dual-element Focused Ultrasound Probe for Guidance of Epidural Catheterization: An Experimental Study.
abstract: Ultrasound guidance for epidural block has improved clinical blind-trial problems but the design of present ultrasonic probes poses operating difficulty of ultrasound-guided catheterization, increasing the failure rate. The purpose of this study was to develop a novel ultrasonic probe to avoid needle contact with vertebral bone during epidural catheterization. The probe has a central circular passage for needle insertion. Two focused annular transducers are deployed around the passage for on-axis guidance. A 17-gauge insulated Tuohy needle containing the self-developed fiber-optic-modified stylet was inserted into the back of the anesthetized pig, in the lumbar region under the guidance of our ultrasonic probe. The inner transducer of the probe detected the shallow echo signals of the peak-peak amplitude of 2.8 V over L3 at the depth of 2.4 cm, and the amplitude was decreased to 0.8 V directly over the L3 to L4 interspace. The outer transducer could detect the echoes from the deeper bone at the depth of 4.5 cm, which did not appear for the inner transducer. The operator tilted the probe slightly in left-right and cranial-caudal directions until the echoes at the depth of 4.5 cm disappeared, and the epidural needle was inserted through the central passage of the probe. The needle was advanced and stopped when the epidural space was identified by optical technique. The needle passed without bone contact. Designs of the hollow probe for needle pass and dual transducers with different focal lengths for detection of shallow and deep vertebrae may benefit operation, bone/nonbone identification, and cost.
authors.affiliation: 1 Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Guo-Chung
authors.initials: GC
authors.lastname: Dong
authors.affiliation: 1 Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Chiu
authors.affiliation: 2 Department of Anesthesiology, Taipei Veterans General Hospital, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chien-Kun
authors.initials: CK
authors.lastname: Ting
authors.affiliation: 1 Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Jia-Ruei
authors.initials: JR
authors.lastname: Hsu
authors.affiliation: 3 Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Huang
authors.affiliation: 4 Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yin
authors.initials: Y
authors.lastname: Chang
authors.affiliation: 1 Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: Gin-Shin
authors.initials: GS
authors.lastname: Chen
mesh_terms: D000818:Animals; D002404:Catheterization / Q000379:methods*; D004824:Epidural Space; D023421:Models, Animal; D013552:Swine; D018084:Ultrasonography, Interventional / Q000295:instrumentation* / Q000379:methods*
keywords: animal study; epidural anesthesia; labor pain relief; lumbar catheter insertion; ultrasound probe