If kidney stones cannot be dissolved by drugs, the favoured procedure is lithotripsy. Lithotripsy works by focusing thousands of shock waves onto the kidney stones in an effort to break them into pieces small enough to urinate out of the body or be dissolved by drugs.
However, it is difficult to discover exactly when the treatment has succeeded in breaking the stone and patients frequently have to experience more shocks than necessary, or be sent home when an insufficient number of shocks have been delivered to break the stone.
The new 'Smart stethoscope' has been developed by a team from the University's Faculty of Engineering and the Environment in collaboration with Guy's and St Thomas' Foundation Trust (GSTT).
The 'Smart stethoscope' is placed on a patient's skin as they undergo shock wave treatment for kidney stones and assesses whether the treatment is working. It listens to the echoes, which reverberate around the body after each shock wave hits the stone. The device is now being used clinically at the London hospitals.
Professor Tim Leighton says: "It is an imperfect analogy, but consider a railwayman walking along the length of a train, hitting the metal wheels with a hammer, If the wheel rings nicely, he knows that it's not cracked. If the wheel is cracked, it gives a duller sound. We are looking for the stone to go from being intact at the start of treatment – when it will give a nice ring "tick" sound – to being fragmented at the end of the treatment, when it will give a duller "tock" sound."
Doctor Fiammetta Fedele said: "Professor Leighton's CFD predictions of the acoustic signals emitted when bubbles collapse against kidney stones during SWL led to a £5,000 passive acoustic sensor. When placed on the patient's skin this sensor diagnoses successful SWL treatments – with 94.7 per cent accuracy in clinical trials, compared to the 36.8 per cent achieved by clinicians with the current state-of-the-art equipment suite. An accurate diagnostic is needed to conform with the 2004 'The NHS improvement Plan: putting people at the heart of public services' of reducing the 'patient pathway', because currently 30-50 per cent of SWL patients require re-treatment and an unknown are overdosed."
COMPAMED.de; Source: University of Southampton