Extracorporeal Shock LithotripsyIntroduction to Extracorporeal Shock Wavelithotripsy (ESWL).
In February 1980, the first kidney stone patient was successfully treated by extracorporeal shock wave lithotripsy machine in Germany, which has epochal significance for the treatment of urinary stones. Extracorporeal shock wave lithotripsy has changed the traditional treatment of urinary stones and has made it possible for many patients to avoid the pain of surgery. It is currently the preferred method for the treatment of urinary stones. Together with percutaneous nephrolithotripsy and ureteroscopic endolithotripsy, it is a modern and advanced minimally invasive treatment technique for urinary stones. The principle of extracorporeal shock wave lithotripsy is a mechanical wave that travels through the medium and carries energy. When the sound waves are transmitted outward in a short pulse width, they form an acoustic pressure pulse, and once this acoustic pressure pulse reaches a high pressure peak (30-100 MPa) in a very short time (<100 ns), it forms what we call a shock wave. We use the physical action of shock waves to crush stones for the purpose of treating the disease. The physical mechanisms of extracorporeal shock wave lithotripsy include: extrusion, stripping, cavitation, fatigue and layer separation and hyperfocusing.
Extracorporeal shock wave lithotripsy must have the following conditions: 1, the right shock wave focus energy, enough to break the stone without causing damage to human organs, 2, a good shock wave conduction medium to ensure that the energy acting on the stone is not attenuated, 3, the precise positioning of the shock wave energy focus and stone site overlap, to ensure that the shock wave acts directly on the stone, to ensure that the instantaneous shock wave energy to minimize the damage to the tissue around the stone. The shock wave source of clinically used lithotripters is mainly divided into two types: liquid-electric and electromagnetic. Most hospitals still use liquid-electric shock wave lithotripters because of their high focusing energy, low manufacturing cost and easy maintenance. The electromagnetic shock wave lithotripter has accurate focus, good effect, fine grains and slight tissue damage, but the cost is high and currently only used in a few large hospitals. Our hospital adopts the German-made Siemens electromagnetic double positioning system lithotripter.
Extracorporeal shock wave source principle: 1, liquid electric shock wave, the use of high voltage discharge in water generated by the shock wave through the ellipsoidal cavity reflector focus, aimed at the body of the stone repeated impact and treatment. 2.Electromagnetic shock wave, the first conversion of electrical energy into magnetic energy, and then into mechanical energy, through the acoustic lens or parabolic reflector will form a high-energy shock wave after the focus of mechanical waves.
The positioning system of lithotripter is divided into: X-ray image positioning, B-ultrasonic image positioning, X-ray and B-ultrasonic dual positioning.
1. The advantages of X-ray positioning are clear imaging, simple operation and easy to master. The disadvantage is that it is impossible to locate negative stones and there is X-ray radiation.
2. The advantage of B-ultrasound localization is that it can observe both negative and positive stones, and there is no radiation contamination and harm to the surrounding environment and patients. Disadvantages The technical difficulty of B-ultrasound localization, especially for obese patients and ureteropelvic segment stones is not as accurate as X-ray localization. It is difficult to locate stones in individual areas with B-ultrasound alone.
3.X-ray and B-ultrasound dual positioning lithotripter can be used for both negative and positive stones.
Pre-operative tests for ESWL include routine urinalysis, abdominal radiograph (KUB), ultrasound, pyelogram (IVP), and CT 3D reconstruction if necessary. Nephrogram, electrocardiogram, renal function tests, and coagulation tests will be performed according to specific conditions. Routine urinalysis is a necessary test to help doctors determine whether there is bleeding or urinary tract infection.
1.Plain abdominal film (KUB) examination: it includes both sides of the kidney, ureter, bladder and prostate. A clear abdominal plain film can show the outline of the kidneys on both sides, the shadow of the lumbaris major muscle and the spine, and is the main means of diagnosing urinary stones. In order to ensure the quality of abdominal plain film, the patient should be prepared for bowel cleansing before the film to reduce the interference of gas accumulation in the intestine.
2. Pyelogram: It can clearly show the outline of the kidney, the morphology of the renal pelvis and calyces, the ureteral course and the function of the kidney, which is especially important for negative definite urinary tract diagnosis when the kidney function is not yet seriously damaged. It shows the exact location of the stone and provides a reliable basis for choosing the treatment plan.
3.Nephrogram: Isotope nephrogram can be used to understand the function of the kidney and urinary tract obstruction.
4.Electrocardiogram: To understand the functional status of the heart. Those with abnormal electrocardiogram should first go to internal medicine for further examination and treatment.
5. Coagulation mechanism test: Patients with suspected abnormal coagulation mechanism should undergo coagulation mechanism test.
Extracorporeal shock wave lithotripsy preoperative preparation patient preparation.
1, before treatment to understand the extracorporeal shock wave lithotripsy treatment process, eliminate the fear of psychology, take the initiative to cooperate with the doctor’s treatment.
2, agreed extracorporeal shock wave lithotripsy treatment, carry all relevant examination data, the same morning after fasting, defecation to the hospital for lithotripsy treatment. , patients with lower ureteral stones treated by ultrasound localization lithotripter should drink more water and hold urine to make the bladder full before treatment to facilitate accurate ultrasound localization.
3. Complete the essential urinary system examination routine in the outpatient clinic, such as: urine routine, abdominal plain film (KUB) and pyelogram (IVP), isotope renogram, CT, etc. Before lithotripsy treatment, the physician should understand the patient’s system-related history and urinary system examination in detail to develop a treatment plan. The shock wave focal point is aligned with the stone site, and the shock wave generator water capsule is applied between the skin and the water capsule with coupling agent to reduce the attenuation of the shock wave by air. The patient breathes as smoothly as possible during the shock process and adjusts the relationship between the focal point and the stone position at any time. The entire procedure takes about 30 to 60 minutes depending on the time of the case, and the patient is awake and quiet throughout.
Matters that should be noted after extracorporeal shock wave surgery
1, drink more water: daily water consumption should reach 2500 – 3000 ml to increase urine volume to facilitate stone removal.
2, moderate exercise: for small and medium-sized stones in the renal pelvis, ureter should increase the amount of activity, such as running, jumping, skipping rope, climbing, up and down stairs, etc., can promote the discharge of stone debris.
3.Reducing activities: For larger stones in the kidney, you should lie down relatively after lithotripsy to facilitate the gradual discharge of stone debris and avoid the formation of “stone streets” with a large number of broken stone debris, which can cause ureteral obstruction and water retention.
4.Stone discharge: For stones in the lower renal calyx, it is more difficult to discharge stone debris, so we should do head-low-foot-high exercise, several times a day and gently pat the lumbar area, by the gravity of the stone, to promote the stone into the renal pelvis and ureter, which is conducive to the discharge of stones.
5, pain: stone discharge process some patients may appear waist up, lumbar pain, urinary pain phenomenon or urine blood, mild generally do not need to deal with. For those who have persistent pain without relief, antispasmodics or pain medication can be applied.
6. Combine with herbal treatment to help stone removal and prevent stone hair regeneration. Inverted body position for stone removal: For stones in the infrarenal calyces, it is difficult to expel the lithotripsy particles because the infrarenal calyces are pocket-shaped. Therefore, active measures should be taken to facilitate the expulsion of lithotripsy particles from the body.
Several inverted lithotripsy methods are introduced.
1, inverted position: head down, feet up, the whole person is upside down (like people often say to take a big top), the most obvious effect of stone removal. This position is only suitable for young and exercise based people.
2, bedside prone semi-inverted: this method is relatively simple, most people can do, the specific practice is, prone on the edge of the bed, the waist is located on the edge of the bed, the upper half of the body facing down hands on the ground, so that the upper body to achieve inverted.
3, supine inverted oblique position in bed: for weak as well as obese patients with infrarenal calcium stones, after extracorporeal shock wave lithotripsy, this method is taken to help the discharge of stones. The practice is to use bedding and other items to raise one end of the bed, and then place the hips on the high side of the bed, so that the head is low and the feet are high in an oblique position. Although it is less effective in aiding stone removal, it is safer. It is suitable for the elderly, hypertensive patients and cerebrovascular patients.
Any of the above methods need to be repeated, and the process of assisted stone removal should be done in a moderate manner. It is better to repeat several times and not to invert for too long at a time to avoid head congestion.
Patients with stones should go to the urology clinic for review one to two weeks after extracorporeal shock wave lithotripsy. The morning of the review should be fasting so that X-rays can be taken to understand the discharge of stones.
Indications, contraindications and postoperative complications of extracorporeal shock wave lithotripsy: More than 90% of urinary stones can be treated by extracorporeal shock wave lithotripsy:
1. kidney stones: extracorporeal shock wave lithotripsy is the best option for pelvic stones less than or equal to 2 cm in diameter. 2-3 cm stones are still generally preferred, but often require multiple lithotripsy. For intractable cast or antler-shaped stones larger than 4 cm in diameter, treatment options are available on a case-by-case basis, with percutaneous nephrolithotripsy (mPNNL) preferred.
2.Ureteral stones: Extracorporeal shock wave lithotripsy is feasible for all segments of ureteral stones. However, stones that have been in the ureter for a long time or have a dense structure and burr edges are less effective. Larger stones, such as those over 2 cm in size or those with unsatisfactory results after multiple lithotripsy treatments, can be treated by ureteroscopic lithotripsy instead.
3.Bladder stones: Generally, extracorporeal shock wave lithotripsy can be used. For larger bladder stones, holmium laser lithotripsy can be used.
4.Urethral stones: Urethral stones are not suitable for direct extracorporeal shock wave lithotripsy. The specific situation should be treated differently.
5, posterior urethral stones: After anesthesia by urethral mucosal anesthetic lubricant, a blunt and rounded urethral probe at the front end is used to push the stones into the bladder, and then treated as bladder stones. A catheter should be left in place before lithotripsy.
Contraindications to extracorporeal shock wave lithotripsy: Contraindications to extracorporeal shock wave lithotripsy include: severe cardiovascular disorders, renal insufficiency, pregnancy, abnormal coagulation mechanism, wearing a cardiac pacemaker, organic obstruction of the urinary tract distal to the stone, active urinary tract infection, large and complex stones, and severe hydronephrosis with renal cortical atrophy.
I. Absolute contraindications:
1. Patients wearing cardiac pacemakers.
2, Pregnancy, 3 stones distal to the urinary tract organic obstruction, the main causes are: congenital malformation, post-surgical urinary stricture, polyps, tumors, etc.. It is not easy to discharge the obstructed stones even after they are crushed, and the crushed particles will aggravate the obstruction, so extracorporeal shock wave lithotripsy is not recommended for such patients, and the obstruction must be resolved first before extracorporeal shock wave lithotripsy is performed.
Relative contraindications:
1, abnormal coagulation mechanism, abnormal coagulation mechanism due to the possibility of haemorrhage or bleeding is not suitable for extracorporeal shock wave lithotripsy treatment.
2, serious cardiovascular disease: shock wave has the risk of aggravating the disease, for the time being, extracorporeal shock wave lithotripsy treatment is not suitable, wait for the remission of the disease and then treatment of stones.
3, renal insufficiency: the treatment plan should be decided according to the etiology. In principle, try to protect the kidney and promote the recovery of kidney function. If the insufficiency is caused by stone obstruction, the obstruction should be actively lifted, lithotripsy can be performed or other treatment modalities should be used. In case of non-obstructive insufficiency, lithotripsy should be performed after correction of renal function.
4. Urinary tract infection: Extracorporeal shock wave lithotripsy is contraindicated in acute urinary tract infection. Lithotripsy can spread the inflammation and lead to urogenic sepsis, so lithotripsy must be performed after infection control. However, for infected stones, active extracorporeal lithotripsy should be performed and post-lithotripsy antibacterial agents should be used to prevent infection. In case of infected stones, patients with persistent hyperthermia of obstructed ureter after lithotripsy should actively take other methods to release the obstruction, such as endolithotomy or surgical lithotripsy.
5. Complex stones: It is generally believed that kidney stones larger than 3 cm in diameter and ureteral stones larger than 2 cm should be treated by other methods of lithotripsy, percutaneous renal puncture lithotripsy or ureteroscopic lithotripsy. 6. Patients who are bedridden for a long time and cannot move, because of their insufficient activity stones are not easily discharged after lithotripsy.
Post-lithotripsy complications.
(a) The main manifestations of complications:
1, hematuria: the most common complication, mostly one to several times carnal hematuria. The vast majority of patients with hematuria can heal completely on their own without treatment.
2, stone street: stone street is formed by a large number of stone particles in the ureter, most of them occur after lithotripsy of large kidney stones, after the formation of stone street, some of them can be discharged by themselves, but most of them need active treatment. It is necessary to observe closely, to observe the follow-up time, and to apply extracorporeal shock wave lithotripsy to treat the stone street immediately if it is clear that the stone street is formed. Ureteroscopic lithotripsy can be used for those who cannot be released after extracorporeal shock wave lithotripsy treatment.
High fever: Rare, mostly caused by acute obstruction of the urinary tract by stones, preventive application of antibacterial agents. If a stone is found to be obstructing the urinary tract, active measures should be taken to relieve it. Once the obstruction is removed, the symptoms can be relieved.
(B) Prevention: Stones accompanied by infection must be treated before lithotripsy. For complicated kidney stones, infected stones, ureteral stones with hydronephrosis, and patients with white blood cells on routine urine examination, antimicrobial agents should be routinely applied before and after lithotripsy. Skin bruises usually do not require any treatment.
1. Coughing up blood: The suprarenal calyces are close to the lungs, and due to the respiratory movement during the lithotripsy treatment of the suprarenal calyces, the patient may have a slight coughing up of blood or blood in the sputum after the operation, which is usually not serious and can be recovered in a few days. Special attention should be paid in the treatment of suprarenal calyx stones.
2. Gastrointestinal bleeding: extremely rare, mostly due to excessive gas accumulation in the intestinal tract during extracorporeal shock wave lithotripsy.
3, cardiac complications: before lithotripsy, we should know if there is any heart disease to avoid it in time.
4, stones can not be discharged: ureteral stones are wrapped by soft tissue, the distal ureter has narrowing, stone debris can not be discharged after lithotripsy, need to cooperate with ureteroscopy for ureteral lumen lithotripsy treatment, very few patients need to undergo surgery to remove stones.
5.Stone cannot be broken open: there are very few stones that cannot be broken open by shock wave and need to take other methods for treatment.
(C) The expected effect of lithotripsy is related to the different conditions of stones
Generally speaking, the effect of stone fragmentation is better for small stones, such as renal pelvic stones below 2 cm and ureteral stones within 1 cm, which can be crushed and discharged by extracorporeal shock wave treatment. Smaller stones require multiple lithotripsy treatments due to the long duration of the disease and physical reasons. Larger stones should be crushed several times with low energy to avoid blocking the ureter with stone chips.
2.Relationship with stone site: The general order of stone fragmentation is: bladder stone, renal pelvis stone, ureteral stone. Stones in the renal calyces are not easily discharged, stones in the ureter are not easily broken and difficult to discharge if there are adhesions, and extracorporeal shock wave lithotripsy is not recommended for huge stones in the bladder. Lithotripsy can be applied.
3.Relationship with stone composition: The composition of stones determines the ease of fragmentation, from easy to difficult to fragment: magnesium ammonium phosphate, calcium oxalate dihydrate, uric acid, calcium phosphate, calcium oxalate monohydrate, cystic ammonium acid. Most stones are of mixed type. Pure cystimonium acid stones are difficult to fragment using extracorporeal shock wave.
The longer the time of stone obstruction, the worse the effect of stone fragmentation. Because of the long time of stone obstruction, inflammatory reaction, or even fibrous hyperplasia and granulation tissue growth, it is common that the stone has been crushed because of the fiber wrapping can not be discharged, in addition, because of the polyps below the stone obstruction and other reasons formed by the ureteral narrowing, the stone particles can not be discharged. Therefore, if the stone is not effective after repeated lithotripsy, other methods should be considered as adjunctive treatment.