What Is Extracorporeal Shock Wave Lithotripsy?

Extracorporeal shock wave lithotripsy (ESWL) is the use of extracorporeal lithotripters to generate shock waves, which are focused on the stones after being focused by the machine. After multiple releases of energy, the stones in the body are crushed and eliminated with the urine. Since the first extracorporeal lithotripsy of Dornier in Germany in the early 1980s, extracorporeal lithotripsy treatment abroad has reached millions of cases, and it has become the routine method of choice for the treatment of urolithiasis.

Liang Lili	(Deputy Chief Physician)	Department of Urology, Peking University First Hospital
Guo Xiaojian	(Associate Researcher)	Department of Urology, Peking University First Hospital

Chinese name: Extracorporeal shock wave lithotripsy

Foreign name: ESWL

Overview of extracorporeal shock wave lithotripsy

In July 1982, Academician Guo Yinglu of Peking University First Hospital and Professor Wang Dezhao of the Institute of Acoustics of the Chinese Academy of Sciences jointly studied ESWL technology. At the end of the year, the experiment of crushing kidney stone specimens in vitro was completed and a shock wave focused lithotripsy for experiment was made. Device. The experimental results were summarized and published in early 1983. Later, the effects of ESWL lithotripsy on kidney tissue and large animal lithotripsy experiments were completed, which laid the foundation for clinical application. In 1984, Peking University Institute of Urology and Institute of Acoustics, Chinese Academy of Sciences developed China's first lithotripsy prototype. In that year, ESWL technology was successfully applied to the treatment of kidney stones. In March 1987, Academician Guo Yinglu and others first proposed the use of prone position ESWL for the treatment of middle and lower ureteral and bladder stones, which was successfully accepted by the world's urological community. After the practice of a large number of clinical cases, the effect is very satisfactory, not only expanding the indications of ESWL, but also greatly improving the curative effect of lithotripsy.

China has accumulated nearly 20 years of experience in treatment. The stone positioning system of this technology is accurate and correct, and the therapeutic energy release is appropriate and reasonable. It not only guarantees the effect of lithotripsy, but also achieves the maximum degree of human protection. It has the advantages of safety, reliability, painlessness, outstanding lithotripsy effect and immediate effect of stone formation.

Basic principles of extracorporeal shock wave lithotripsy

The basic principle of shock wave generation (hydraulic electricity) is to form a high-energy-density high-temperature, high-pressure plasma zone on the discharge channel through high voltage, large current, and instantaneous discharge, which quickly converts electrical energy into thermal energy, light energy, force energy, and sound. Yes, the discharge channel expands sharply during the discharge process, forming a pressure pulse in the aqueous medium, that is, a shock wave. In addition to hydroelectric shock wave sources, there are also shock wave sources such as electromagnetic wave sources and piezoelectric crystal wave sources.

Generally speaking, all stone crushers are composed of the most basic two parts, namely the shock wave source capable of crushing stones and the precise positioning system for stones. The shock wave source is the core of the stone crusher. Shock wave sources are further divided into hydroelectric shock wave sources and electromagnetic shock wave sources. Hydroelectric model: The advantages are that the technology is quite mature, and the effect is safe and reliable; due to the wear of the electrode tip, the focus is easy to drift, so every patient in the clinic needs a new electrode to ensure the lithotripsy effect. The disadvantage is that the electrodes are changed frequently.

Electromagnetic wave source model: The electromagnetic model generates a shock wave from a pulsed magnetic field generated by an electromagnetic coil. The advantages are low noise, no need to replace the electrode, the discharge is basically stable, and the focus is not easy to shift. The disadvantages are lower focus pressure and higher recombination rate.

After more than 20 years of clinical experience accumulation and summary, the effect of lithotripsy of hydroelectric shock wave source is better than other shock wave sources.

Extracorporeal shock wave lithotripsy positioning system

The positioning of ESWL is the process of using relevant equipment to determine the position of stones in the human body and accurately move the stones to the focal spot area of the shock wave. The positioning system is one of the key factors for the success of extracorporeal lithotripsy. At present, most lithotripters use X-ray surveillance systems or B-ultrasound systems for positioning. These two methods have their own characteristics and complement each other.

Extracorporeal shock wave lithotripsy positioning system type

1. X-ray positioning and B-ultrasound positioning: These two methods have their own advantages and disadvantages, which can complement each other. The lithotripter with joint positioning has both X-ray and B-ultrasonic positioning systems, and has the advantages of the above two methods. Regardless of positive or negative stones, kidney and ureteral stones can be located, and the stone dynamics and its crushing process can be monitored in real time, so the level of lithotripsy treatment can be improved. However, the cost of the dual positioning system lithotripter will be much higher.

2. X-ray positioning model: Because the majority of patients with urolithiasis are positive stones (more than 95%), this model is an insurance type lithotripsy machine for stone positioning, which is convenient and simple to locate. . In the case where the B ultrasound cannot locate, the X-ray positioning system can play a role to help accurately locate the lithotripsy, and can track the lithotripsy effect during the lithotripsy process to determine the doctor's judgment and formulate an intraoperative treatment plan. Because the X-rays have strict radioactive requirements for hospital lithotripsy, its cost is higher than other lithotripsy models. Currently the only internationally recognized gold standard lithotripter -------- DORNIER HM3 X-ray positioning lithotripter.

3. B-ultrasonic positioning models: B-ultrasonic positioning stone crushers are divided into B-ultrasonic upper and lower positioning. B-ultrasonic upper positioning is relatively easier to operate than lower positioning. The upper positioning can be freely operated. Changing the patient's position to achieve the positioning purpose, the C-arm positioning lithotripter B ultrasound probe is as convenient as holding it in the hands of the operating physician. B-ultrasonic positioning lithotripsy is difficult to locate the middle and lower ureteral stones, and it is time consuming. In particular, kidney stones that are too large should be used with caution. Once the stones break and fall into the ureter, they should be replaced by other methods or go to the X-positioned lithotripter to find stones for lithotripsy treatment. Its model is simple and low cost. It does not have high requirements for the installation of lithotripsy rooms. Generally, it is more convenient and economical to use in small hospitals.

Preparation of extracorporeal shock wave lithotripsy

Evaluation of extracorporeal shock wave lithotripsy

Before the operation, a comprehensive physical examination should be done according to the specific conditions of the patient. Laboratory-assisted examinations are also essential, mainly including routine blood and urine tests; platelet counts and blood clotting times; related tests; liver and kidney function tests; electrocardiogram tests, and so on.

Examination of extracorporeal shock wave lithotripsy urinary system

Don't rush the lithotripsy until you know the whole urinary system.

1. Abdominal plain film (KUB) More than 95% of urinary tract stones are positive stones, so for patients suspected of having urinary stones, KUB examination should be the first choice, economical and convenient. Its advantage is that it can comprehensively understand the location, size, number and density of stones; at the same time, it can understand whether the spine and pelvis are deformed or other abnormalities, which is helpful for positioning during treatment.

2. Routine pyelography (IVU) routine application. Urography can help determine the exact location of the stone, and at the same time understand kidney function, and whether there is obstruction below the stone.

3. The biggest advantage of B-ultrasound is that there is no X-ray radiation damage, which helps to judge the degree of hydronephrosis in the kidney. However, the detection rate of small stones in the middle and lower ureters is low.

4. CT examination In patients who have not done IVU, CT and plain scan can be selected to make a clear diagnosis.

5. Kidney map examination is mainly to understand the effect of dividing kidney function on lithotripsy.

Extracorporeal shock wave lithotripsy preparation

1. Eliminate the nervousness of the patient. Fasting was started in the morning on the day of treatment.

2. Intestinal preparation For low-density, especially stones in the middle and lower ureters, laxatives are taken orally 1 day before treatment to reduce intestinal gas accumulation and stool.

3. Antibiotics combined with urinary tract infection, or infectious stones, antibiotics 1 day before surgery.

4. The day before treatment should take a bath to remove the oil on the surface of the skin to facilitate the entry of shock waves and reduce losses.

Extracorporeal shock wave lithotripsy contraindications and indications

In a broad sense, urinary tract stones can be treated with extracorporeal shock wave lithotripsy, except for organic obstructions distal to the stones. However, in clinical practice, the following considerations should be made when selecting patients.

Extracorporeal shock wave lithotripsy

1. Lithotripsy should not be used for systemic bleeding disorders to avoid severe hematuria caused by lithotripsy.

2. Cerebrovascular diseases, such as severe hypertension, cerebral hemorrhage, heart failure, heart rhythm disorders, and pulmonary dysfunction that have occurred within the past six months should not be lithotripsy.

3 The active period of infectious diseases, such as active hepatitis, bacterial dysentery, and atypical pneumonia, should not be lithotripsy.

4 For uncontrolled diabetes, control blood sugar before lithotripsy to prevent uncontrollable severe urinary tract infection after lithotripsy.

5. Pregnant women, especially those with stones in the lower ureter, should not be lithotripsy to avoid adverse effects of X-rays or shock waves on the fetus.

6, women's menstrual period should not be lithotripsy.

7, patients with pacemakers are still contraindications to lithotripsy.

8. Patients with epilepsy and rickets are relatively contraindicated.

Extracorporeal shock wave lithotripsy urinary system

There is an organic obstruction in the urinary tract below the stones, and lithotripsy should not be performed before the obstruction is resolved.

1. Renal function. For those with renal insufficiency, the causes of renal insufficiency should be distinguished and treated separately. Urinary tract obstruction caused by ureteral stones should be actively lithotripsy to remove the obstruction as soon as possible.

2. Urinary tract infection should not be lithotripsy during acute urinary tract inflammation, and effective antibiotics should be used to control the infection before lithotripsy. ^[1-4]

Extracorporeal shock wave lithotripsy before and during surgery and anesthesia

With the improvement of lithotripsy, especially the application of low-energy lithotripsy in the clinic, the pain has been greatly reduced when the shock wave enters the human body, and the pain is very slight when treating renal pelvis and bladder stones. No anesthesia is required except for anaesthesia. Patients who are particularly nervous before surgery can achieve a satisfactory analgesic effect by intramuscular injection of 50 mg orally with a tablet of painkillers half an hour before surgery. For preschool children, general anesthesia is used for gravel.

Follow-up after extracorporeal shock wave lithotripsy

After the lithotripsy treatment, he was instructed to drink more water and be more active, collect stones for analysis.

If renal colic occurs when lithiasis occurs, you can use medicine to relieve pain and relieve spasms. Oral calculus is taken orally, and if necessary, a drip infusion can be used to reduce inflammation. Depending on the situation, they are asked whether they should restrict their movements and whether they use positional stones. Individual patients need to be hospitalized for observation and treatment.

The patient came to the hospital for review of KUB within 1-2 weeks after lithotripsy.