Graeme McLeod

Technical failure still occurs in 25% of epidural blocks and in 7% of regional techniques. Regional blocks are conducted using ultrasound, although epidural block remains a blind technique dependant on operator skill. Ultrasound scanning is restricted to identification of the mid-line and measurement of distance to the epidural space. For both epidural and regional block, resolution of tissue targets and needle tips is hampered by increasing depth. For example tissue resolution using 5MHz to 10MHz transducers varies between 600mm and 300mm due to attenuation of acoustic energy. Needle visibility is further impaired by increasing needle angle and out-of-plane needle alignment, even using echogenic or textured needles.

The objective of my research is to develop new needle technologies that improve both image presentation and operator interpretation of ultrasound images particularly in the obese population where skin landmarks are difficult to feel and palpation much more prone to error.

Visible vibrating needle project We have invented an ultrasound actuator that vibrates needles between 14g and 25g at 20,000 Hertz, patent No. GB 1304798.0, 2013. The licensing agreement for this technology was sold to Active Needle technologies, Buckinghamshire, UK by the University of Dundee in December 2015. Vibration shows needles in colour using doppler ultrasound, is less likely to deflect and, using the reverse peizo-electric effect, measures needle tip force, electrical impedance and resonant frequency in real-time.

Ultrasound at Tip of Needle Project The logical key innovative step in future ultrasound technology is to narrow the distance between the ultrasound transducer and anatomical region of interest by building a needle incorporating ultrasound elements at its tip. The advantage of such a device would be two-fold: not only would energy be attenuated less because the distance between transducer and target was considerably reduced, but close proximity would necessitate the use of transducers with much higher frequencies with shorter focal points, and by inference much higher resolution and better discrimination between tissue not just out with but also within nerves. I am a member of multi-disciplinary, multi-centre research group consisting of clinicians and engineers from the Universities of Dundee, Edinburgh, Glasgow, Heriot-Watt and Birmingham. My PhD student, Anu Chandra, is funded by a Br J Anaesth/RCoA grant

Impact

Patents
EP2747664A1, WO2013030556A1 CA2847015A1 Bi-array ultrasound probe. 2014. Inventors: S Cochran, R Habershaw, J Marsh, G Corner, G McLeod. Licensing sold to Zonare, Palo Alto by
University of Dundee

GB 1304798.0, 2013. Visible vibrating needle. Inventors: M Sadiq, Z Huang, S Cochran, G Corner, G McLeod. Licensing agreement to Active Needle Technologies, Chesham, Buckinghamshire

Mastery learning of UGRA on the Thiel soft embalmed simulator using eye tracking metrics
Mastery learning is a new paradigm for medical education used to gain maximum learning outcomes when teaching simulator based technical skills. We conducted a study sponsored by Optomize, a spin-out psychology company of the University of Strathclyde, Glasgow. Using eye tracking technology we generated learning response curves for each trainee; identified crucial time periods before and during needle intervention; retention of competency after 4 months and differences between trainees and experts.