Protocols of extracorporeal shock wave lithotripsy

For a long period of time, stone treatment in some patients has been a matter of controversy for urologists. Complex stones were traditionally removed by surgical intervention.¹Irani D, Eshratkhah R, Amin-sharifi A. Efficacy of Extracorporeal Shock Wave Lithotripsy in complex urolithias in the era of advanced Endourologic procedure. Journal of Urology 2005;2(1):13-19.   However, the surgical management of urolithiasis has now largely been replaced with a minimal invasive procedure- like extracorporeal shock wave lithotripsy (ESWL).²Jalbani MH, Deenari RA, Abro MH. Extracorporeal Shock Wave Lithotripsy (ESWL) in children. Journal of Urology 2010;16(1):78-80.  

Extracorporeal shock wave lithotripsy was first used as routine therapy for urinary lithiasis in 1980 and shortly became the main therapeutic option for kidney stones with no spontaneous passage (before introduction of this method, open surgery was the main alternative). ESWL revolutionized the treatment of urolithiasis and became the preferred option for its treatment. Now it is accepted as a highly efficacious treatment modality for most renal calculi in the pediatric population.³Shukla AR, Hoover DL, Homsy YL, Perlman S, Schurman S, Reisman EM. Urolithiasis in the low birth weight infant: the role and efficacy of extracorporeal shock wave lithotripsy. Journal of Urology 2001;165(6):2320-23.   Preoperative and long-term follow up in the pediatric population treated with ESWL suggest that it has minimal deleterious effects on functional measures, overall growth, and development of kidneys.⁴Goel MC, Baserge NS, Babu RVR, Sinha S, Kapoor R. Pediatric kidney: functional outcome after extracorporeal shock wave lithotripsy. Journal of Urology 1996;155(6):2044-2046.  ^,5Thomas R, Frentz JM, Harmon E, Frentz GD.Effect of extracorporeal shock wave lithotripsy on renal function and body height in pediatric patients. Journal of Urology 1992;148(3):1064-1066.  

Indications of ESWL

Eswl is the “Treatment of Choice” for

• Small Renal stones of any site, shape and composition
• Patients having diabetes, hypertension, respiratory disease, solitary kidney
• Patients unfit for surgery or anaesthesia
• Previously operated patients
• All age groups

Contraindications

• Pregnant women: Pregnancy remains absolute Contraindication as the risk of radiation used for imaging during Lithotripsy is too great for the foetus. Not enough data is available to foresee the effect of shockwaves on the foetus and the ovaries.
• Renal artery calcification: Care should be taken to avoid having renal artery calcifications and aortic aneurysms in the blast path.
• Bleeding diathesis
• Urinary tract infection: In case of infection, it is vigorously treated with suitable antibiotics before ESWL.

• Obstruction distal to the stone: In such a case the distal obstruction is treated first, if a stone, with ESWL or Ureteroscopic Removal.
• Children: Children treated with ESWL should have the lungs shielded by styrofoam padding. Voltage and number of shock waves should be as low as possible. Placement of wet towels or plastic intravenous fluid bags at the shock wave exit site on the abdomen may prevent severe ecchymosis from occurring.
• Severe orthopaedic deformities: For successful ESWL, the stone has to be at F2. Orthopaedic abnormalities limiting this condition cannot be treated.

Advantages

• Non invasive procedure: Since the Shockwaves are applied to the body from outside, it is preferable to operative procedures. Also acceptable from cosmetic point of view as surgery leaves ugly scars which are not there with ESWL.
• Safe- no adverse effects reported worldwide: Many studies have been conducted to monitor the patients for long time side effects, but no serious side effects were observed.
• Outdoor procedure. No hospital stay required: The patient can go home after 2-3 hours and no admission is generally required.
• No pain: Pain varies from machine to machine and from patient to patient. In modern machines like Eurolith, there is very slight amount of pain which can be controlled with analgesics. In some machines like the earlier first generation ones, some kind of anesthesia is required. Some machines require narcotic analgesics to be given or some sedatives.
• No bloodloss, hence no transfusions. No risk of aids
• No convalescence period: The patient does not require any rest after ESWL and can attend his daily chores.

Disadvantages

• Relies on normal urine flow for clearance of crushed stone particles: The excretion of the crushed stone particles is dependent upon the urine pressure. Hence the time taken for complete stone clearance varies from person to person.
• May require retreatment: Some hard stones or larger stones do require retreatment and specially in monohydrate stones, retreatment is the rule rather than the exception
• Not freely available in many countries: Economic considerations are the main factors in preventing the spread of this procedure to all corners of the world.

Principles of Eswl

ESWL is based on the principle of shock wave energy. Whenever energy is abruptly released in an enclosed space, shock waves are generated. The passage of these shock waves through substances of different acoustic impedance generates compressive stress on the boundary surface. This stress eventually overcomes the tensile strength of the object and the anterior surface of the calculi crumbles as a result. The shock waves cross to the posterior surface of the calculi and some of them are reflected back and cause further fragmentation. (Figure 1).⁶Tandan M, Reddy DN Extracorporeal shock wave lithotripsy for pancreatic and large common bile duct stones. World J Gastroenterol. 2011 October 21; 17(39): 4365-4371.  

Procedure protocol of ESWL for ureter stone

• Throughout the history of medicine perhaps no technologic advance has exerted more revolutionary effect than shock wave lithotripsy.⁷Bingjie T, Yongfeng T, Linxi Y et al Clinical analysis of ESWL treatment of renal calculi[J]. Guangzhou Medical Journal 2007;03.  
• The first-generation Dornier HM3 lithotriptor, with its large focal area and small ellipsoid aperture delivered relatively more energy to the stones and resulted in excellent stone fragmentation rates.⁸Kim FJ, Rice KR. Prediction of shockwave failure in patients with urinary tract stones. Curr Opin Urol 2006 Mar;16(2):88-92.  ^,9Lindqvist K, Holmberg G, Peeker R, Grenabo L. Extracorporeal shockwave lithotripsy or ureteroscopy as primary treatment for ureteric stones: a retrospective study comparing two different treatment strategies. Scand J Urol Nephrol 2006;40(2):113-8.  
• To increase patient comfort and eliminate the need for regional or general anesthesia, certain modifications were made and different principles of shock wave generation (electromagnetic and piezoelectric) were applied.
• With these modifications, several studies reported that ESWL with these low cost second-and thirdgeneration lithotriptors seemed to be less effective, and the re-treatment rate was as high as 45% when compared with first generation lithotriptors.¹⁰Weiland D, Lee C, Ugarte R, Monga M. Impact of shockwave coupling on efficacy of extracorporeal shockwave lithotripsy. J Endourol 2007 Feb;21(2):137-40.  ^,11Portis AJ, Yan Y, Pattaras JG, Andreoni C, Moore R, Clayman RV. Matched pair analysis of shock wave lithotripsy effectiveness for comparison of lithotriptors. Journal of Urology 2003;169(1):58-62.  
• Nevertheless, because of its minimally invasive nature and it being an outpatient procedure, ESWL is still generally considered to be the first-line therapy.
• For the vast majority of patients, ESWL is performed on an out-patient basis with no need for hospital admission following the procedure.
• ESWL procedures typically last approximately one hour. ESWL can be performed either under general anesthesia or under intravenous sedation.
• Once the patient is anesthetized, the lithotripter machine is positioned in contact with the patient’s flank on the side of the stone.
• A series of up to 2,000 shock waves are delivered to fragment the stone. ESWL is performed under X-ray guidance to accurately target the stone in efforts to maximize stone fragmentation while minimizing adjacent organ injury.
• On occasions, a ureteral stent may be required to dilate the ureter, avoid stone obstruction, and facilitate stone passage down to the bladder.

Prediction of stone-free rate after ESWL¹²Skolarikos A, Alivizatos G et al Extracorporeal Shock Wave Lithotripsy 25 Years Later: Complications and Their Prevention. European Urology 2006 ;50: 981-990.  

• The concept of stone burden- Stone size, composition, location and number of stone plays an important role in the outcome of ESWL.
  • Stone composition affects ESWL results of fragmentation and subsequent elimination – Contrary to calcium oxalate dehydrate stones (whedellite), which have a better coefficient of fragmentation and thus respond well to ESWL, cystine and calcium oxalate monohydrate (whewellite) stones are relatively resistant to ESWL treatment.
  • Calculi situated in the lower calices represent a particular problem. The success rate of ESWL is lower for lower pole calculi than for other stone locations.
  • Complex stone formations such as staghorn calculi or a high stone mass are cumbersome for ESWL.
  • The ESWL success rate decreases as the stone size increases.
  • The presence of multiple stones has also been related to a higher recurrence of stones after ESWL.
  • For proximal ureteral stones – there has been a higher success rate (65%-81%) than for lower ureteral stones (58%-67%).
  • ESWL should be considered as initial treatment in cases such as stones < 10mm.
• A decreased shock wave frequency may enhance the production of cavitation bubbles and, subsequently, lead to an improved fragmentation rate.
• ESWL yields a better clinical outcome when it is performed by an experienced user familiar with the device.
• The effectiveness of lithotripsy is affected by body mass index, and studies indicate reduced outcomes when skin-to-stone distance is greater than about 10 cm.

A study was conducted to assess the therapeutic efficiency, complications and limitations of ESWL in urolithiasis in the initial experience using a third generation electromagnetic lithotripter.¹³Tomescu P, Păş A et al Assessment of Extracorporeal Shock Wave Lithotripsy (ESWL) Therapeutic Efficiency in Urolithiasis Current health sciences Journal 2012;38(2).   Between 2007 and 2008 ESWL was performed for 167 patients with urolithiasis. 92 patients were recorded with single stone (55.1%) and 72 with multiple lithiasis (44.9%). Stone size varied between 7 and 24 mm with an average of 12.3±7.1 mm. Radio-opaque stones were found in 104 patients (62.3%) while radiolucent stones in 63 only (37.6%). Complete stone disintegration and clearance was achieved in most cases (86.2%). ESWL

is therefore the first line of treatment for urolithiasis with stone size smaller than 2.5 cm. It has an efficiency rate above 85%, low procedure time, high safety and good tolerability (new generation lithotripters do not require anesthesia) and minimal complications.

One more study retrospectively evaluated the efficacy of extracorporeal shock wave lithotripsy (ESWL) in the treatment of ureteral stones in children.¹⁴Pirincci N, Gecit I, Bilici S, Taken K, Tanik S, Ceylan K. The effectiveness of extracorporeal shock wave lithotripsy in the treatment of ureteral stones in children. Eur Rev Med Pharmacol Sci. 2012 Oct;16(10):1404-8.   Between the dates of 2005-2010, 62 children who were applied ESWL due to the ureteral stone and consisted of 42 males and 20 girls whose mean age was 6.6+/=3.1 years were evaluated. ESWL was performed in the supine position for upper ureteral stones, in the supine/prone position for middle and lower ureteral stones. Stone-free rate was determined as 93.5% in three-month follow-up of the patients. Re-treatment was done in 14.5% of the patients. According to these findings ESWL with its high stone-free rates and negligible complications is the first method to be referred in the treatment of ureteral stones in children.

Combination therapy of ESWL, tamsulosin and /or Urinary alkalizers

Although ESWL is an effective treatment of urinary calculi, it can cause complications. Stone colic, delayed stone fragment passage or obstructed ureter due to steinstresse

Group-1 patients received tamsulosin along with ESWL
Group-2 patients received only ESWL

may be of different type of clinical situation after ESWL for renal stones may occur. The alpha adrenergic antagonists are able to inhibit basal tone and peristaltic frequency, dilating the ureteral lumen and facilitating stone passage. Some studies have shown that tamsulosin facilitates earlier clearance of stone fragments and reduces pain after shockwave lithotripsy for renal calculi. Efficacy of tamsulosin in clearing the stone fragments after ESWL was studied on 139 patients, 51 in group 1 and 65 in group 2 completed. Group 1 patients received tamsulosin along with ESWL.¹⁵Naja V, Agarwal MM, Mandal AK et al Tamsulosin facilitates earlier clearance of stone fragments and reduces pain after shockwave lithotripsy for renal calculi: results from an open-label randomized study. Urology 2008 Nov;72(5):1006-11.   The success rate after 1, 2, and 3 ESWL sessions was greater in group 1 than in group 2. (Figure 1) The total days required for, total ESWL sessions required for success, and the pain experienced were significantly less in group 1. Results of this study have shown that tamsulosin facilitates earlier clearance of fragments after ESWL to renal calculi and helps reduce the severity of the pain.

One more study evaluated the efficacy of the tamsulosin oral controlled absorption system as an adjuvant therapy to extracorporeal shock wave lithotripsy (ESWL) for the expulsion of ureteral and renal stones. In this study 248 patients (186, including 77 with ureteral stones (mean size 9 mm) and 109 with renal stones (mean size 13 mm)) were included.¹⁶Georgiev MI, Ormanov DI, Vassilev VD et al Efficacy of tamsulosin oral controlled absorption system after extracorporeal shock wave lithotripsy to treat urolithiasis. Urology 2011 Nov;78(5):1023-6.   After successful ESWL, the patients were randomized to standard medical care (corticosteroids and analgesics) or standard care plus the tamsulosin oral controlled absorption system 0.4 mg/d for 1 month. The stone clearance rate, interval to the elimination of stone fragments, incidence of renal colic, and the need for rehospitalization were assessed at 4, 8, and 12 weeks.

Group 1- patients receiving standard medical care (corticosteroids and analgesics)
Group 2- patients receiving standard care plus the tamsulosin

The stone clearance rate was significantly greater for the patients treated with tamsulosin than for those in the standard care group (Figure 2). This study concluded that adjuvant treatment with tamsulosin, in addition to standard treatment with steroids and analgesics, improved the outcome of ESWL.

Combination of ESWL and urinary alkalizers

The presence of residual fragments is commonly found following modern treatments methods, particularly after ESWL. The wide range of underlying metabolic abnormalities such as hypercalciuria, hyperoxaluria, hyperuricouria and hypocitraturia can cause the formation of stones in the urinary tract metabolic abnormalities are not affected following ESWL/PCNL therapies. Effective medical management should therefore be directed primarily towards correction of the underlying abnormalities. Several authors supported the benefit of alkaline citrates in all patients undergoing shockwave lithotripsy for the significant improvement in rates of alleviation the calcium oxalate stone-forming activity and positively influence the preexisting stone clearance and dissolution. Study was conducted to evaluate the preventive effects of alkaline citrate on stone recurrence as well as stone growth post- ESWL or PCNL in patients with calcium-containing stones. In this study total of 76 patients with calcium calculi who were stone-free or had residual stones less than 4 mm following ESWL and PCNL were enrolled. Patients were randomly divided into two groups.¹⁷Lojanapiwat B, Tanthanuch M, Pripathanont C et al Alkaline citrate reduces stone recurrence and regrowth after shockwave lithotripsy and percutaneous nephrolithotomy Int Braz J Urol 2011 Sep-Oct;37(5):611-6.  

After 12- months of follow up – results of this study were as follows.

This study concluded that potassium citrate provides positive effects on stone-forming activities in calcium stone patients suffering from urolithiasis following treatment with ESWL and PCNL procedures at the 12-month follow-up.

One more study conducted to provide a non-invasive efficient modality for the treatment of radiolucent renal stones in children. This study evaluated the efficacy of combined use of ESWL and dissolution therapy.¹⁸Mokhless IA, Sakr MA, Abdeldaeim HM, et al Radiolucent renal stones in children: combined use of shock wave lithotripsy and dissolution therapy. Urology 2009 Apr;73(4):772-5.   According to the results of this study, stone-free rate of 100% was achieved in all 24 patients after 3 months of combined use of extracorporeal shock wave lithotripsy and dissolution therapy. This study concluded that combined ESWL and dissolution therapy accelerated stone clearance and delayed stone recurrence. The use of ESWL and medical therapy as a combined modality is a safe and effective treatment of radiolucent renal stones in children.

Conclusion

ESWL is safe, effective, noninvasive and a convenient way of treatment for upper ureteral stones. Studies have supported the significant effect of tamsulosin/potassium citrate along with ESWL for treating urinary stones. The success rate can be increased and the recurrence rate of stone formation can be reduced using combination therapy of ESWL and tamsulosin and potassium citrate for the effective outcome.

References

1. Irani D, Eshratkhah R, Amin-sharifi A. Efficacy of Extracorporeal Shock Wave Lithotripsy in complex urolithias in the era of advanced Endourologic procedure. Journal of Urology 2005;2(1):13-19.
2. Jalbani MH, Deenari RA, Abro MH. Extracorporeal Shock Wave Lithotripsy (ESWL) in children. Journal of Urology 2010;16(1):78-80.
3. Shukla AR, Hoover DL, Homsy YL, Perlman S, Schurman S, Reisman EM. Urolithiasis in the low birth weight infant: the role and efficacy of extracorporeal shock wave lithotripsy. Journal of Urology 2001;165(6):2320-23.
4. Goel MC, Baserge NS, Babu RVR, Sinha S, Kapoor R. Pediatric kidney: functional outcome after extracorporeal shock wave lithotripsy. Journal of Urology 1996;155(6):2044-2046.
5. Thomas R, Frentz JM, Harmon E, Frentz GD.Effect of extracorporeal shock wave lithotripsy on renal function and body height in pediatric patients. Journal of Urology 1992;148(3):1064-1066.
6. Tandan M, Reddy DN Extracorporeal shock wave lithotripsy for pancreatic and large common bile duct stones. World J Gastroenterol. 2011 October 21; 17(39): 4365-4371.
7. Bingjie T, Yongfeng T, Linxi Y et al Clinical analysis of ESWL treatment of renal calculi[J]. Guangzhou Medical Journal 2007;03.
8. Kim FJ, Rice KR. Prediction of shockwave failure in patients with urinary tract stones. Curr Opin Urol 2006 Mar;16(2):88-92.
9. Lindqvist K, Holmberg G, Peeker R, Grenabo L. Extracorporeal shockwave lithotripsy or ureteroscopy as primary treatment for ureteric stones: a retrospective study comparing two different treatment strategies. Scand J Urol Nephrol 2006;40(2):113-8.
10. Weiland D, Lee C, Ugarte R, Monga M. Impact of shockwave coupling on efficacy of extracorporeal shockwave lithotripsy. J Endourol 2007 Feb;21(2):137-40.
11. Portis AJ, Yan Y, Pattaras JG, Andreoni C, Moore R, Clayman RV. Matched pair analysis of shock wave lithotripsy effectiveness for comparison of lithotriptors. Journal of Urology 2003;169(1):58-62.
12. Skolarikos A, Alivizatos G et al Extracorporeal Shock Wave Lithotripsy 25 Years Later: Complications and Their Prevention. European Urology 2006 ;50: 981-990.
13. Tomescu P, Păş A et al Assessment of Extracorporeal Shock Wave Lithotripsy (ESWL) Therapeutic Efficiency in Urolithiasis Current health sciences Journal 2012;38(2).
14. Pirincci N, Gecit I, Bilici S, Taken K, Tanik S, Ceylan K. The effectiveness of extracorporeal shock wave lithotripsy in the treatment of ureteral stones in children. Eur Rev Med Pharmacol Sci. 2012 Oct;16(10):1404-8.
15. Naja V, Agarwal MM, Mandal AK et al Tamsulosin facilitates earlier clearance of stone fragments and reduces pain after shockwave lithotripsy for renal calculi: results from an open-label randomized study. Urology 2008 Nov;72(5):1006-11.
16. Georgiev MI, Ormanov DI, Vassilev VD et al Efficacy of tamsulosin oral controlled absorption system after extracorporeal shock wave lithotripsy to treat urolithiasis. Urology 2011 Nov;78(5):1023-6.
17. Lojanapiwat B, Tanthanuch M, Pripathanont C et al Alkaline citrate reduces stone recurrence and regrowth after shockwave lithotripsy and percutaneous nephrolithotomy Int Braz J Urol 2011 Sep-Oct;37(5):611-6.
18. Mokhless IA, Sakr MA, Abdeldaeim HM, et al Radiolucent renal stones in children: combined use of shock wave lithotripsy and dissolution therapy. Urology 2009 Apr;73(4):772-5.