Extracorporeal shock wave lithotripsy is currently preferred for patients with kidney and ureteral stones. The principle of extracorporeal shock wave lithotripsy is a treatment method that uses shock waves to generate compressive stress at the interface of two propagation media with different acoustic impedance between tissues and stones, causing stones to gradually peel off and break from the surface, breaking large stones that cannot be discharged on their own into pieces that can be discharged on their own and then discharged through the urinary tract with urine. Currently used extracorporeal shock wave lithotripters have X-ray or ultrasound positioning devices, which are positioned by moving the patient.
The propagation characteristics of shock waves are close to those of sound waves, and the acoustic impedance of various different media varies greatly due to their different densities. The acoustic impedance of water is much greater than that of air, so shock waves in water are almost completely reflected at the interface of water and air. Human tissue contains more water, acoustic impedance is close to water, so the shock wave in water into the body almost no reflection, less energy loss, which is why the body needs to be completely immersed in water or the use of water bladder as a propagation medium, so as to reduce energy loss, but also to avoid the shock wave through the human body and air interface damage to the human body.
Since the acoustic impedance of stones is 5-10 times that of water, the shock wave will also be reflected at the interface between the tissue and the stones, and the stress caused by the difference in acoustic impedance will cause the stones to break up.
Since the introduction of the first extracorporeal lithotripter by Dornier in Germany in the early 1980s, millions of cases have been treated by extracorporeal lithotripsy at home and abroad, and it has become the preferred method for the treatment of urolithiasis.
This technology is safe and reliable because of its accurate stone localization and reasonable treatment energy release, which not only ensures the lithotripsy effect, but also achieves the maximum human protection.
Indications.
1.No narrowing of the urinary tract below the stone;
2.The affected kidney is functional;
3.Single pelvic calyx stone with a diameter of 2cm or less;
4.Surgical residual or postoperative recurrent kidney stones;
5. Infected kidney stones need to be controlled after infection.
ESWL can also be considered in the following cases.
1. Stones of more than 3 cm but with a loose texture, such as small antler stones;
2. Multiple and relatively concentrated kidney stones;
3. Kidney stones with hunchback, spinal curvature deformity or difficult surgery.
Contraindications.
1.Stenosis in the urinary tract below the stone;
2, the kidney is not functional;
3. Excessive body size, the distance from the body surface to the stone is greater than the distance from the semi-ellipsoid to the second focus;
4, intra-diverticular stones and narrow neck opening;
5.Patients with organic lesions or poor function of heart, liver, lung and kidney;
6.It is difficult to adhere to the body position of ESWL.