Dornier kidney stone smashers
The Dornier kidney stone shatterer was the first device for the contactless crushing of urinary stones with the help of bundled shock waves from outside the body ( extracorporeal shock wave lithotripsy ), which was developed by Immenstaader Dornier System GmbH ( Dornier ) from around 1970.
The procedure was first used on humans in 1980 at the Großhadern Clinic in Munich . The method was a revolution in the previously common surgical removal of urinary stones.
prehistory
The shock wave technology was a spin-off from a development work on the all-weather suitability of the Lockheed F-104 Starfighter . The Starfighter could fly up to Mach 2, but only in dry weather or above the clouds, which earned it the name “fair weather aircraft”. As soon as rain hit the leading edges of the wings during supersonic flight, not only did the surface of the metal erode, but the surrounding material structure was also damaged. The explanation was found in the shock wave that the raindrop triggers when it hits the metal at supersonic speed.
In order to generate these shock waves in the laboratory and to test erosion-resistant materials, two rotating arms were built whose outer ends carried the material samples. The first was operated outdoors at atmospheric pressure close to Mach 1. Operation under atmospheric pressure generated intense noise. The second was operated in an evacuable container at a pressure of approx. 10 mbar and reached a peripheral speed of up to 3 Mach. Operation at this low pressure required less drive power and it was no longer as loud. This test stand was in operation for more than 30 years; it was dismantled around 2005.
Alternatively, a shock wave generator was developed based on the principle of electrohydraulically generated shock waves . An ignition element, which consists of two electrodes, is ignited in the water with a high voltage current from a previously charged capacitor, so that the surrounding liquid at the electrodes is suddenly heated. A gas and plasma bubble forms , which releases pressure into the surrounding liquid. The resulting pressure wave propagates as a shock wave at the speed of sound of the medium. It does not move water, but transports energy. The shock wave generated in this way is bundled, focused and aligned in a reflector . The number and intensity of the shock waves could be controlled and precisely aligned with the sample. Dornier had this shock wave generator patented.
Device development
The use of shock waves to smash kidney and gallstones and other mineral accumulations in the human body was obvious. The human body with 73% water content can transmit the shock wave, albeit somewhat weakened. Various kidney stones had been successfully smashed in the laboratory. After investigations on anesthetized pigs, Dornier built a prototype for extracorporeal shock wave lithotripsy (from the Greek λίθος “stone” and τρίβειν “rub”) on humans, which went into series production in 1983 with a few modifications.
The HM2 ("Human Model 2") device at the time consisted of a type of bathtub with the shock wave generator embedded in the bottom. The patient was brought into the tub on a special couch. The water in the tub conducted the shock waves from the generator into the patient's body. Two X-ray devices were used to locate the stone, the central rays of which crossed in the focus of the shock wave generator and allowed the three-dimensional location of the stone. To prevent cardiac arrhythmias , the sequence of shock waves was synchronized with the patient's pulse. From 1983 to 1986, Dornier exported 122 copies of the successor model, the HM3 , at a unit price of around four million DM (2.05 million euros). Some of these devices are still in use in 2008. Production was relocated from Immenstaad to Germering near Munich at the end of 1985 .
Dornier called the device "kidney stone shatterer", it was later renamed "lithotripter" in scientific publications. There are now a large number of lithotripters for various applications and - after Dornier's patent protection has expired - also from various manufacturers. The patient no longer lies in a tub during treatment, but the generator, surrounded by water, focuses the shock wave on the kidney stone via a rubber membrane attached to the body. The modern devices today automatically record the position of the stone and correct the position of the patient. Ultrasound devices and no longer X-ray devices also take over the three-dimensional alignment of the focus of the shock waves. Today (2008) there are over 5000 lithotriptors in use around the world with over a million treatments per year.
In 1983 Dornier System GmbH received the German Business Innovation Prize for the development of the kidney stone breaker. One of the first series devices (HM3) is exhibited in the Dornier Museum in Friedrichshafen, the prototype is now in the Deutsches Museum in Bonn .
Dornier turned the product into a business area. In 1985 it became an independent company, is now called Dornier MedTech GmbH and is located in Weßling near Munich.
literature
- Dornier brochure concepts, technologies, systems , published by Dornier GmbH, 1990
Web links
Individual evidence
- ↑ https://www.researchgate.net/publication/6247277_Extracorporeal_shockwave_lithotripsy_ESWL_Chronology_of_the_development F. Eisenberger, Ch. Chaussy, B. Forssmann: Extrakorporale Shockwellenlithotripsie (ESWL) Chronology of a development in: Der . 1015, 2007, page 10. accessed on Jan. 30, 2019