Extracorporeal Shock Wave Lithotripsy ( ESWL).pptx

ESWL in Urology

1. Extracorporeal Shock Wave Lithotripsy ( ESWL) Dr Sheraz Hamayun PGR Urology Department SGRH

2. It is a non-invasive procedure that uses shock waves to break kidney stones into small fragments . DEFINITION

3. The concept of using shock wave to fragment stone was noted in 1950s by Russia. It was than rediscovered in 1963 by Dornier , a German aircraft corporation, that shockwaves originating from passing debris in atmosphere can crack something that is hard. First patient was treated in 1980 by using Dornier HM-1 lithotripter by Christian Chaussy , B. Forssmann, and D. Jocham . . Then HM-2 in 1982 and HM-3 in 1983 Historical Background

4. 1 ST GENERATION has a large water bath plus electrohydraulic shockwave source. Generations of lithotriptor

5. 2 nd GENERATION has a electrohydraulic , electromagnetic, or piezoelectric shock wave source. Shock waves are transmitted by means of a water cushion or partial water bath. 3 rd Genration

6. A shock wave generator : Electrohydraulic Electromagnetic Piezoelectric Basic Components of Lithotripsy Machine

7. Electrohydraulic Shock Wave Generator

8. Electromagnetic Shock Wave Generator

9. Piezoelectric Shock Wave Generator

10. A coupling system to transfer energy from outside to inside the body. Effective coupling should have properties similar to those of human skin. It can cause Echymosis Pain Hematomas Skin Breakdown If air is entrapped by hair on the skin, by any prior bandages for previous percutaneous surgery, or improperly degassed fluid or air in coupling cushion can significantly impede the shock wave resulting into above mentioned complications and in adequate fragmentation of stone. Coupling can be provided by two methods.

11. Water bath coupling system Water cushion coupling system Coupling gel like in USG

12. A Focusing system which consists of Fluoroscope Imaging Ultrasound Imaging Small or poorly calcified stone cam also be identified by placing retrograde ureteral stent and then injecting contrast for identifying the calyx and filling defect which is a stone.

13. Mechanism of action of shock wave A typical shockwave consists of a short compressive front of 40 Mpa pressure followed by a longer lower amplitude tensile pressure of 10 Mpa with a entire pulse lasting for 4 micro second. The ratio of positive to negative pressure is 5:1.

14. Spall fracture Squeezing and splitting due to circumfrential pressure Shear stress Super focusing Cavitation Dynamic fracture M echanism of stone communition

15. Stone Size Most effective for stone less than 1cm stone free rate 80%. And for 1-2cm its 60%. Stone Location Stone free rate at 3 months Upper calyx 71 – 81 % Middle calyx 74-84% Lower calyx 37-68% Renal pelvis 86-89% Factors affecting fragmentation of stone

16. Anatomy of the collecting system Calyceal diverticulum Horse shoe kidney Pujo Any obstruction Renal ectopia Stone Composition Brushite stone , cystine stone , and calcium oxalate monohydrate are hard stones they should be treated with ESWL when they are less than 1.5cm. Over all CT attenuated Hounsfield unit should be less than 1000. Degree of obesity skin to stone distance should be 10cm for effective ESWL at 0, 45 and 90 degree angle

17. Large stone >1.5 cm Any prior obstruction Poorly viualised stone Pyonephrosis Indication of Dj stenting

18. Indications Contraindications Stone less than 2cm in the kidney upper pole , mid pole or Renal pelvis . Stone less than 1 cm in upper ureter . Dearranged coagulation profile. Pregnancy Pyelonephritis Distal obstruction Tumor in shock wave area Aneurysm Any bleeding diathesis

19. Advantages Disadvantages Non-invasive Safe No general anesthesia Short treatment time May require repetition Not suitable for hard stones Painful May cause complications

20. Finding out the location of stone Fasting B lood pressure C ardiac status ( Any pacemaker ) LMP of the patient if female. Premedication antibiotic prophylaxis. Any gross skeletal abnormality contracture, or excessive weight Brief the patient about treatment Pre procedure evaluation

21. Lie the patient supine on the table. Using iliac crest , spine and ribs as land mark, move the patient in the mid of removable board of lithotripsy table. Remove the board of table and apply gel to coupling wate r cushion. Move the coupling cushion to treatment position. Increase pressure of coupling cushion pressure to touch the skin of patient. Procedure

22. Apply soft pad or sand on opposite of the patient. Screening in PA view adjust position of patient Move the table in center to adjust position and also height of the table.

23. Select suitable parameters Power 100 – 12o Hz Voltage 12 - 24 kv Frequency 6o – 90 / min ( max 2000 – 3000) Sequence of shock wave step wise increase from low to high intensity Two step power ramping low to high example first 1oo wave at 12kv then 2000 at 24kv It has been proven that 200 to 500 shock wave at 12kv reduce the chance of intracapsular hemorrhage and is effective and safe Intra procedure Consideration

24. Monitor the blood pressure , heart rate , and pain of the patient . Monitor the stone size and location of the stone and readjust the position.

25. E ncouraged to walk. Observe for 1 hour in ward. Fluid intake. Gross haematuria . Abdominal pain. Obtain x-ray kub . P otassium citrate. Post Procedure care

26. Gross Hematuria Intracapsular hematoma Edema Structural and functional Hypertension Decrease renal plasma flow Post procedure complications