Research project: Invention outperforms clinicians monitoring kidney treatment in patients

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A sensor for monitoring the successful of kidney stone destruction using shockwaves has now been used in the treatment of over 200 patients.

Project Overview

Part 1 (November 2004)

Research produces the 'Smart stethoscope' to diagnose the efficacy of kidney therapy

Part 2: (October 2008)

Successful clinical trials for Smart Stethoscope merit national award

Part 3 (December 2012)

Hundreds of patients benefit from LithocheckTM (the device produced from the "smart stethoscope").

What is it? The ‘smart stethoscope' (now marketed as Lithocheck ^TM ) consists of a probe that looks like the end of a stethoscope (two - one red and one blue - are pictured below). They are placed on the patient's abdomen. Instead of going into a doctor's ears (as with a normal stethoscope) the cables lead to a screen (shown on the right) which automatically makes a diagnosis.

What is it trying to diagnose? The ‘smart stethoscope’ determines when a surgeon has been successful at breaking up kidney stones (see the picture on the right) during ‘Shock Wave Therapy’ (SWT). This treatment involves sending around 3000 shocks, at a rate of about one per second, into the human body to try to break up the stone.

Why do the doctors need it? The problem is, X rays before and after SWT are not accurate at showing whether the stone has broken up (see the picture below). As a result, 30%-50% of patients need retreatment (they are sent home with the stones unbroken and need to return, taking up extra theatre time) and an unknown number are overexposed (because the stone broke up well before the 3000th shock, but no-one knew). Overexposure can lead to serious side effects.

How does it work? The sensors are placed on the patient’s abdominal area (see picture to the right), and listen to the echoes that bounce around the body when a clinician fires each of the 3000 shocks into the body. If the shock misses the stone, there is little echo – it is similar to if a railwayman tries to work out if a wheel is cracked by hitting it with a hammer. If he misses the wheel, he hears no sound (see picture, below right). In the same way the sensor can tell the doctor that the shock is missing the stone, perhaps because the patient moved after the first aiming was done.

However if the railwayman hits the wheel, he can tell from the sound whether the wheel is cracked or not (see picture below). In the same way the echoes from the shock wave as it bounces off the stone can tell the ‘smart stethoscope’ if it is breaking up. Click on the 'useful downloads' link (top right of the page) to listen to a sound file (entitled 'Ineffective and effective shock'). This file plays the sounds of two echoes, the first being from a shock that was not effective at breaking the stone, followed immediately afterwards by one that was (as recorded by the 'smart stethoscope'). You can hear now different they sound.

How was it invented? In the early 1990s, Tim Leighton (Uni Southampton) and Andy Coleman (Guys and St Thomas’ Health Trust) collaborated in preliminary experiments which showed that the sound generated during SWL contains information that might be useful for diagnosis.

It took another 17 years (only 4 of which were funded, via EPSRC) to develop the device and get it through clinical trials. The collaboration had extended to include Precision Acoustics Limited. The clinical trials showed that the ‘smart stethoscope’ (costing around £5000) correctly predicted successful treatments 94.7% of the time, compared to 36.8% scored by clinician in theatre using the best currently-available equipment (costing around £1,000,000).

For more information on bubble acoustics click here .

Awards

The Smart Stethoscope won the 2008 ‘Medical & Healthcare' award by ‘The Engineer' (click here for details). It was also finalist for 2009 Unico National Business Impact award and an NHS Innovations award.

For details of clinical trials (the most important paper to read on this study), click on:

Leighton, T.G., Fedele, F., Coleman, A., McCarthy, C.,Ryves, S., Hurrell, A., De Stefano, A. and White, P.R. (2008) A passive acoustic device for real-time monitoring the efficacy of shockwave lithotripsy treatment, Ultrasound in Medicine and Biology, 34(10), 1651-1665

To get to the clinical trial stage, the experimental and hospital tests had to be backed up by careful computer simulations, which are detailed in the papers below (which can be obtained by clicking on the author list):

Leighton, T.G., Turangan, C.K., Jamaluddin, A.R., Ball, G.J. and White, P.R. (2013) Prediction of far-field acoustic emissions from cavitation clouds during shock wave lithotripsy for development of a clinical device, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 469 (2150), 21pp

Jamaluddin, A.R., Ball, G.J., Turangan, C.K. and Leighton, T.G. (2011) The collapse of single bubbles and calculations of the far-field acoustic emissions for cavitation induced by shock wave lithotripsy, Journal of Fluid Mechanics, 677, 305-341

Turangan, C.K., Jamaluddin, A.R., Ball, G.J. and Leighton, T.G. (2008) Free-Lagrange simulations of the expansion and jetting collapse of air bubbles in water, Journal of Fluid Mechanics, 598, 1-25

Leighton, T.G., Fedele, F., Coleman, A., McCarthy, C., Jamaluddin, A.R., Turangan, C.K., Ball, G., Ryves, S., Hurrell, A., De Stefano, A. and White, P.R. (2008) The development of a passive acoustic device for monitoring the effectiveness of shockwave lithotripsy in real time, Hydroacoustics, 11, 159-180

Leighton, T.G. (2004) From seas to surgeries, from babbling brooks to baby scans: The acoustics of gas bubbles in liquids, Invited Review Article for International Journal of Modern Physics B, 18(25), 3267-314

Ball, G.J., Howell, B.P., Leighton, T.G. and Schofield, M.J. (2000) Shock-induced collapse of a cylindrical air cavity in water: A Free-Lagrange simulation, Shock Waves, 10, 265-276

For details of the early experiments, click on:

Coleman, A.J., Whitlock, M., Leighton, T.G. and Saunders, J.E. (1993) The spatial distribution of cavitation induced acoustic emission, sonoluminescence and cell lysis in the field of a shock wave lithotriptor, Physics in Medicine and Biology, 38, 1545-1560

119 Coleman, A.J., Choi, M.J., Saunders, J.E. and Leighton, T.G. (1992) Acoustic emission and sonoluminescence due to cavitation at the beam focus of an electrohydraulic shock wave lithotripter, Ultrasound in Medicine and Biology, 18, 267-281

Webs, blogs and press material on this story:

From 2012: 'Smart Stethoscope' used on hundreds of patients

AlphaGalileo Foundation (12 December 2012) web and pdf

Daily Me (12 December 2012) web and pdf
Engineering and the Environment (Southampton) (12 December 2012) web and pdf
GizMag (14 December 2012) web and pdf
Lukmachara (12 December 2012) web and pdf
MediMoon (12 December 2012) web and pdf
Mukiakitta (12 December 2012) web and pdf
Research Blogging (12 December 2012) web and pdf
Say People (12 December 2012) web and pdf
Science Business (13 December 2012) web and pdf
Science Daily (12 December 2012) web and pdf
Telecare Aware (18 December 2012) web and pdf

From 2008: Successful clinical trials for Smart Stethoscope merit national award

E Library (November 1 2008): web (or pdf if web inaccessible)
Life Sciences (University of Southampton) (October 29 2008): web (or pdf if web inaccessible)
News Release Southampton University(October 29 2008): web (or pdf if web inaccessible)
Science Photo Library (October 29 2008): web (or pdf if web inaccessible)
The Engineer (web) (October 29 2008): web (or pdf if web inaccessible, with fuller article here )
Unico Business awards (May 21 2009) web (or pdf if web inaccessible)
University of Southampton Business News(November 1 2008): web (or pdf if web inaccessible)