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MHz Transducer (mhz + transducer)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

A comparison of ultrasound-guided supraclavicular and infraclavicular blocks for upper extremity surgery

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2009
Z. J. KOSCIELNIAK-NIELSEN
Background: Ultrasound (US)-guided supraclavicular or infraclavicular blocks are commonly used for upper extremity surgery. The aims of this randomized study were to compare the block performance and onset times, effectiveness, incidence of adverse events and patient's acceptance of US-guided supraclavicular or infraclavicular blocks. We hypothesized that the supraclavicular approach, being more superficial and easier to visualize using a 10 MHz transducer, will produce a faster and a more extensive sensory block. Methods: One hundred and twenty patients were randomized to two equal groups: supraclavicular (S) and infraclavicular (I). Each patient received a mixture containing equal volumes of ropivacaine 7.5 mg/ml and mepivacaine 20 mg/ml with adrenaline 5 ,g/ml, 0.5 ml/kg body weight (minimum 30 ml, maximum 50 ml). The sensory score (anaesthesia , 2 points, analgesia , 1 point and pain , 0 point) of the seven terminal nerves was assessed every 10 min. Patients were declared ready for surgery when they had an effective surgical block , anaesthesia or analgesia of the five nerves below the elbow. Thirty minutes after the block, the unblocked nerves were supplemented. The block performance and latency times, surgical effectiveness, adverse events and patient's acceptance were recorded. Results: Significantly more patients in the I group were ready for surgery 20 and 30 min after the block. The mean block performance time was 5.7 min in the S group and 5.0 min in the I group (NS). Block effectiveness was superior in the I group: 93% vs. 78% in the S group (P=0.017). The S group patients had a significantly poorer block of the median and ulnar nerves, but a better block of the axillary nerve. Sensory scores at 10, 20 and 30 min were not significantly different. Thirty-two patients in the S group vs. nine patients in the I group experienced transient adverse events (P<0.0001). Patients' acceptance of the block was similar in both groups. Conclusions: Infraclavicular block had a faster onset, better surgical effectiveness and fewer adverse events. Block performance time and patients' acceptance of the procedure were similar in both groups. [source]

Imaging of the Calf Vocal Fold With High-Frequency Ultrasound,

THE LARYNGOSCOPE, Issue 10 2008
Conor J. Walsh MSME
Abstract Objectives/Hypothesis: High-frequency ultrasound imaging offers the potential for assisting in the diagnosis and treatment of vocal fold pathology if it allows aspects of vocal fold microstructure to be visualized noninvasively. The objective of this study was to assess the ability of high-frequency ultrasound to image vocal fold anatomy and injected biomaterials. Study Design: The vocal folds of two excised calf larynges were imaged ex vivo and compared with corresponding histological sections. Methods: High-frequency ultrasound imaging was performed under saline submersion using 40 and 50 MHz transducers, and corresponding cryostat cross-sections were stained with H&E, Trichome, and Verhoeff's Van Gieson stains. Results: The epithelial surface, lamina propria, and underlying muscle were easily identified with the high-frequency ultrasound as verified with histological sections representing each imaged region. The arytenoid cartilage vocal process can also be clearly distinguished from the surrounding tissue, as can the full extent of injected biomaterials within the superficial lamina propria. Useful ultrasound resolution was obtained to depths of at least 10 mm within the tissue with the 40 MHz transducer. Conclusions: This preliminary study demonstrates the capability of high-frequency ultrasound to image the layered anatomy of the calf vocal fold and to discern materials injected into the superficial lamina propria, indicating that this technology holds a strong potential for use in phonosurgery. [source]

Ultrasonographic Morphometric Measurements of Digital Flexor Tendons and Ligaments of the Palmar Metacarpal Region in Haflinger Horses

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2010
S. Boehart
With 2 figures and 3 tables Summary The aim of the study was to determine morphometric values of the superficial and deep digital flexor tendon, the inferior check ligament and the suspensory ligament in the palmar metacarpal region of sound Haflinger horses using ultrasonography and to assess the influence of different factors on them. The findings were compared with the literature. A total of 30 sound Haflinger mares aged 4,20 years were used. Transverse ultrasound images were obtained with an 8,10 linear MHz transducer and the cross-sectional area, the circumference and the dorsopalmar and lateromedial width were determined for each structure at six regions of interest (ROI) in both forelimbs. The coefficient of variation was <3%. The structures were compared between each other and the values of each structure at the ROIs. Age, height at the withers, body mass index, diameter of the Os metacarpale III and the circumference of the mid-metacarpal region showed significant influences on some of the parameters. Reference values for the tendons and ligaments in the palmar metacarpal region in sound Haflinger mares were obtained and the influence of different factors was tested. Description of the dimensional relationship between the structures and comparison of the data with the literature provide knowledge required for adequate veterinary care. [source]