First and Second Generation Lithotripsy in Children: Results, Comparison and Followup

0022-5347/95/1536-1969$03.00/0 THEJOURXAL OF UROLOGY Copyright 0 1995 by AMERICAN UROLOCICAL ASSOCIATION, INC.

Vol. 153, 1969-1971,June 1995 Printed in U S A

FIRST AND SECOND GENERATION LITHOTRIPSY IN CHILDREN: RESULTS, COMPARISON AND FOLLOWUP ALLAN C. VAN HORN, JAY B. HOLLANDER AND EVAN J. KASS From the Department of Urology, William Beaumont Hospital, Royal Oak, Michigan

ABSTRACT

During a 5-year period 32 children and adolescents 4 to 18 years old underwent 35 extracorporeal shock wave lithotripsy (ESWL*) treatments for 37 calculi. The unmodified Dornier HM3 lithotriptor was used in 21 cases (60%)while the remaining cases were treated with the Siemen Lithostar lithotriptor. The HM3 necessitated general anesthesia in 67%of patients and the Lithostar necessitated intravenous sedation in 86%. The majority of pediatric lithotripsy treatments were performed on an outpatient basis (24) or during an overnight hospital stay (3) while 8 were done on a n inpatient basis. Of the 37 stones treated with 1 ESWL session 68% resolved, 19%had residual fragments less than 4 mm., 8%had residual fragments greater than 4 mm. and 5% required a n endoscopic procedure for resolution. When success rates by lithotriptor were examined no significant difference between the 2 machines was identified although the HM3 treated larger stones (p = 0.0499). There were no statistical differences in regard to success and the use of stents, patient age or stone location between the 2 lithotriptors. Three patients required adjuvant procedures, and complications and morbidity developed in 2 and 5, respectively. All children or parents were contacted for followup (range 7 to 67 months). One child required ESWL for a new stone while another passed a stone without intervention. Only 1 child with a residual fragment less than 4 mm. became symptomatic but needed no intervention while 1 of 3 with fragments greater than 4 mm. needed intervention. No patients required open or percutaneous intervention. KEYWORDS: extracorporeal shockwave lithotripsy, kidney, ureter

The introduction of extracorporeal shock wave lithotripsy (ESWL) by Chaussy et a1 in the early 1980s revolutionized the management of upper urinary tract calculous disease in adults.1.2 Overall success rates have been high, complications low and postoperative recovery short.3 As lithotripsy experience was gained and the practicing urologist became comfortable with the use of ESWL in adults, greater numbers of children were treated with ESWL as the initial modality for stone disease. Although the incidence of urolithiasis in children is only 2 to 3%, when conservative therapy fails or patients present with larger calculi a noninvasive solution would be desirable to the child and urologist.4 Reports of successful ESWL in children were first published in 1986 with subsequent series in the late 1980s and early 1990s from the United States and Europe.”lo We report on 32 patients treated at a single institution with the unmodified Dornier HM3 and the second generation Siemen Lithostar lithotriptors. Patient characteristics, morbidities, success rates, complications, adjuvant procedures, comparison of lithotriptors and long-term followup are described. PATIENTS AND METHODS

Between February 1987 and February 1992, 19 male and 13 female patients 4 to 18 years old (average age 14.8) underwent 35 ESWL treatments at a single multi-user institution. Median patient age was 15 years (HM3, 16 and Lithostar, 15). The standard Dornier HM3 lithotriptor was used initially (3.5 years) and was later replaced by the second generation Siemen Lithostar lithotriptor (1.5 years). During this study period the HM3 was used in 21 patients (60%) while the Lithostar was used in 14 (40%).No mechanical gantry modifications were made although treating smaller children required foam padding. Accepted for publication October 7, 1994. * Dornier Medical Systems, Inc., Marietta, Georgia.

Preoperative evaluation included a history and physical examination. Preoperative laboratory evaluations were obtained at the discretion of the attending physician and varied from child to child although every child underwent urinalysis andor urine culture. No urinalysis revealed bacteria and no urine culture yielded greater than 100,000 colonies per ml. An excretory urogram, renal ultrasound, film of the kidneys, ureters and bladder or combination of these studies was used in the diagnosis, location and definition of the stone burden. These 32 children underwent 35 ESWL treatments for 37 calculi. Treatments included 19 right, 16 left and no bilateral procedures. Three patients were treated twice while no patients were treated more than twice. Stones were located in the renal pelvis (151, calices (17) and upper ureter (5). Average stone size was 6.53 X 9.05 mm. (range 5 to 17 X 2 to 13) in greatest cross-sectional diameter. Preoperative ureteral stents were placed in 22 patients (12 on the right and 10 on the left side) while the remaining 13 treatments were performed in situ. The majority of stents were used in our earlier treatments with the HM3 (17 of 21,81%) while only 36% of procedures (5 of 14) with the Lithostar were done with preoperative stenting. No child was treated with an indwelling percutaneous nephrostomy tube. More than half of our patients (18 of 35) presented with abdominayflank pain alone, 37%presented with gross hematuria associated with abdominaUflank pain and 6%presented with gross hematuria alone. One stone was found incidentally, and 1 child presented with fever and emesis. At presentation 7 of 32 patients (22%)had been treated for a previous stone episode. It should be noted that no patient in our group was diagnosed with myelomeningocele or neurogenic bladder, or had any form of urinary diversion. Of the 21 patients treated with the HM3, 14 required general anesthesia and 7 needed a regional block. In contrast, the Lithostar necessitated general anesthesia in 2 patients while the remaining 12 were successfully treated using intravenous sedation alone.

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FIRST AND SECOND GENERATION LITHOTRIPSY IN CHILDREN

More than two-thirds of the children (24) were treated as outpatients, 22% (8) were treated as inpatients and 8% (3) required overnight hospitalization. Stone-free was defined as complete resolution of all stone fragments on followup film of the kidneys, ureters and bladder, and renal ultrasound or excretory urography. Statistical analysis was performed using the Mann-Whitney U test or chi-square analysis with statistical significance considered as p <0.05.

TABLE2. Followup results No. Pts. No. (%) Outcome Stone-free Fragment size: Less than 4 mm.

23

6

1(4) Passed stone spontaneously 1(4) Repeat ESWL for new stone 2 (17) Pain and hematuria with no intervention 1 (33) Repeat ESWL

Greater than 4 mm. 3 32 Total Followup 6 to 67 months with 100%of patients or parents contacted.

RESULTS

Mean shock waves per reno-ureteral unit differed for each lithotriptor. The HM3 averaged 1,746 shock waves (range 450 to 3,000)while the Lithostar averaged 4,082 shock waves (range 1,500 to 6,000). An average maximum of 17 kV. was used on the Lithostar and a slightly higher average was used on the HM3 (maximum 19 kV. and minimum 18 kV.).Ofour 32 cases sufficient stone fragments for analysis were recovered in 19 (59%).The majority of stones (69%)were composed of calcium oxalate while 5 children had calcium oxalate phosphorus stones (26%).One child had a primary calcium phosphate stone but no child was identified as having a struvite or cystine stone. Of the 37 stones treated with 1 ESWL treatment 68%were resolved on followup while 2 patients needed ureteroscopy to become stone-free. Of the 37 stones 7 (19%)had residual fragments less than 4 mm. and 3 (8%)had residual fi-agments greater than 4 mm. If success is defined as cases with calculi fragmented to less than 4 111111. or stone-free cases, then our overall success rate was 87%.Success according to lithotriptor is shown in table 1. There was no statistical difference between success rate for each machine but the HM3 treated larger stones (p = 0.0499). Likewise, there was no statistical difference between success rate and the use of stents, patient age or stone location for the 2 lithotriptors. Adjuvant procedures consisted of endoscopic stone removal (2 cases) or repeat ESWL (1). No child required percutaneous manipulation or an open procedure. Excluding adjuvant procedures (urosepsis and ureteroscopy for stent migration), a postoperative complication developed in 2 of 35 cases (5.7%). Five other children had postoperative morbidity consisting of an emergency room visit for renal colic but no hospitalization and 3 patients needed brief hospitalization for renal colic. All patients or parents were followed by telephone interview. Followup ranged from 7 to 67 months (average 37.5). Outcomes in each case are shown in table 2. DISCUSSION

With the advent of ESWL the treatment of adult urological stone disease has changed. Lithotriptors are widely available to the majority of urologists and have become first line therapy in most adults with renal and upper ureteral calculi.11 Likewise, there is now a growing body of evidence to suggest that ESWL is the preferred method of treatment in the pediatric patient with upper urinary tract calculous disease,5.7.8.10.12-14 As our experience with pediatric lithotripsy grows the way in which we treat these patients is also changing. Second and third generation ESWL machines and our comfort level with

TABLE1. Success rates by lithotriptor No. Stones (31 HM3

Stone-free Fragment size Ims than 4 m m Greater than 4 mm Stone-Frep on ureterowopy Totals

Lithostar

15 ( 6 5 )

lO(711

5 (22, 2 19, 1- '4, 29(1OOI

2 (141 1 171 1 17,

1 4 m i

pediatric ESWL have allowed intravenous anesthesia to be administered to a majority of patients who undergo lithotripsy. We used intravenous anesthesia alone in 86%of our patients who were treated with the second generation Lithostar. Others have had similar experience with this lithotriptor. Abara et a1 used a similar technique of neuroleptic anesthesia or no anesthesia in 60% and 40%, respectively, of pediatric lithotripsy patients.6 Marberger et a1 used no anesthesia in more than two-thirds of pediatric patients treated with a Wolf piezoelectric lithotriptor.8 The newer generation lithotriptors are bathless and, therefore, require no modifications of the gantry or adjustment of water level. Furthermore, with smaller focal areas possible damage to the lung is minimized. We had no cases of postoperative hemoptysis although in smaller children (less than 135 cm. or 30 kg.) with upper pole calculi pulmonary shielding should be considered.15 More than two-thirds of our patients were treated as outpatients while in the majority of previous series patients required variable inpatient postoperative hospitalization. As newer lithotripsy machines become less painful the need for general anesthesia will diminish, allowing shorter convalescence and outpatient treatment. We believe that, unless a patient has complicating medical problems, outpatient ESWL with minimal anesthesia is applicable to the preponderance of pediatric patients treated with newer second and third generation lithotriptors. Of our patients 88%presented with flank pain and/or gross hematuria, which is similar to the experience of others and 10,149 16 Likewise, analysis of stone our adult patients.5~6.9~ fragments revealed a picture similar to that of adults in which calcium oxalate was the predominant stone type. This pattern has been seen in several series.5-6*14,17 Our stonefree rate for 1 ESWL treatment was 68%,which compares to similar pediatric lithotripsy serie~.~~6.14.18 If success is considered to be those cases that were stone-free as well as those with fragments less than 4 mm., then our overall success rate is 87%. Two patients (1 HM3 and 1 Lithostar) required an endoscopic adjuvant procedure for painful obstructing stone fragments that failed to pass with conservative therapy. Another endoscopic procedure was needed for a migrated ureteral stent, which was considered a postoperative complication. Our 5.7% adjuvant procedure rate is comparable to other series although percutaneous techniques were used in most studies.6.lo, 13,l5 In our series we had 2 cases (5.7%) of posttreatment complications and 5 of morbidity consisting of renal colic. It is unclear why significant renal colic necessitated an emergency room visit in 14%of our cases. No open procedures were required in any of our patients. As minimally invasive therapy we believe that these success and complication rates are acceptable and we continue to advocate ESWL as first line therapy in the select pediatric stone patient. To our knowledge we report the first series to compare lithotriptors at a single institution in the pediatric population. There was no selection bias of patients since only 1 lithotriptor was used, that is the Dornier HM3 initially and the Siemen Lithostar more recently. However, preoperative

FIRST AND SECOND GENERATION LITHOTRIPSY IN CHILDREN

stents were placed in a higher percentage of patients treated with the HM3, in part due to the more recent, growing opinion that stents may not be necessary in most pediatric ESWL patients and our continuing comfort level with pediatric lithotripsy.s,12When patient age, stone location or use of stents was considered we found no statistical difference in success rates between the Dornier HM3 and Siemen Lithostar. Similar performance by the lithotriptors may be explained by less body wall impedance in young adults and greater fragility of pediatric stones, which may offset differences in focal areas, size and pressure between the lithotriptors. Only 1 child in our study group with a pelvic kidney who had a residual fragment less than 4 mm. became symptomatic. He has had 1 episode of abdominal pain and gross hematuria but has needed no hospital treatment or intervention. The other children with fragments less than 4 mm. have had no episodes of renal colic, infection or obstruction necessitating an emergency room visit, hospitalization or urological intervention. However, 1 of 3 children with fragments greater than 4 mm. in our series needed operative intervention. Although the goal of all intervention should be a stone-free state, we found that patients with small residual fragments less than 4 mm. have done well and we recommend following these children. Children with larger fragments should undergo intervention and followup with the goal of becoming stone-free. However, we recognize that fragment size depends on patient size and/or age and smaller children may be less tolerant of fragments that would pass in a larger child.

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lithotripsy. J . Urol., 135 1127,1986. 4. Vahlensieck, W.and Bastian, H. P.: Clinical features and treatment of urinary calculi in childhood. Eur. Urol., 2 129,1976. 5. Sigman, M., Laudone, V. P., Jenkins, A. D., Howards, S. S., Riehle, R., Jr., Keating, M. A. and Walker, R. D.: Initial experience with extracorporeal shock wave lithotripsy in children. J . Urol., 138 839,1987. 6. Abara, E., Merguerian, P. A,, McLorie, G. A., Psihramis, K. E., Jewett, M. and Churchill, B. M.: Lithostar extracorporeal shock wave lithotripsy in children. J. Urol., part 2, 144:489, 1990. 7. Vandeusen, H., Devos, P. and Baert, L.: Electromagnetic extracorporeal shock wave lithotripsy in children. J. Urol., 145 1229,1991. 8. Marberger, M., Turk, C. and Steinkogler, I.: Piezoelectric extracorporeal shock wave lithotripsy in children. J. Urol., 142:349, 1989. 9. Newman, D. M., Coury, T., Lingeman, J . E., Mertz, J . H. O., Mosbaugh, P. G., Steele, R. E. and Knapp, P. M.: Extracorporeal shock wave lithotripsy experience in children. J. Urol., 136 238,1986. 10. Kroovand, R. L., Hamson. L. H. and McCullough, D. L.: Extracorporeal shock wave lithotripsy in childhood-J. Urol., part 2, 138 1106,1987. 11. Newman, D. M., Scott, J. and Lingeman, J. E.: Two-year foll o w of ~ Datients treated with extracomoreal shock wave lithotri&y. i.Endourol., 2 163, 1988. 12. Newman, D. M. and Kaefer, M.: Pediatric ESWL: suitability hinges on long-term renal effeds. Contemp. Urol., 9 71,1992. 13. Nijman, R. J. M., Ackaert, K., Scholtmeijer, R. J., Lock, T. W. T. and Schroder, F. H.: Long-term results of extracorporeal shock wave lithotripsy in children. J. Urol., part 2, 142:609,1989. 14. Frick, J., Kohle, R. and Kunit, G.: Experience with extracorporeal shock wave lithotripsy in children. Eur. Urol., 1 4 181, 1988. REFERENCES 15. Kramolowsky, E. V.,Willoughby, B. L. and Loening, S. A.: Extracorporeal shock wave lithotripsy in children. J. Urol., 137: 1. Chaussy, C., Schmiedt, E., Jocham, D., Brendel, W., Forssmann, 939,1987. B. and Walter, V.: First clinical experience with extracorporeally induced destruction of kidney stones by shock waves. J . 16. Shepherd, P., Thomas, R. and Harmon, E. P.: Urolithiasis in children: innovations in management. J . Urol., 140 790,1988. Urol., 127:417,1982. 2. Chaussy, C., Brendel, W. and Schmiedt, E.: Extracorporeally 17. Bohle, A., Knipper, A. and Thomas, S.: Extracorporeal shock wave lithotriDsv in Dediatric Datients. Scand. J. Urol. Nephinduced destruction of kidney stones by shock waves. Lancet, rol., 2 3 137,-1689. 2 1265,1980. 3. Drach, G. W., Dretler, S., Fair, W., Finlayson, B., Gillenwater, J., 18. Minimberg, D. T.,Steckler, R. and Riehle, R., Jr.: Extracorporeal shockwave lithotrimy GriEth, D., Lingeman, J. and Newman, D.: Report of the . -for children. h e r . J. Dis. Child., 142 279,1988. United States cooperative study of extracorporeal shock wave