Histopathologic effects of extracorporeal shock wave lithotripsy on rabbit kidney

Summary Despite the widespread clinical use of the lithotriptor, the margin of safety for the kidney during shock wave application is substantially unknown. Although a series of pilot studies have been performed in laboratory animals, long-term follow-up is mandatory to establish the effect of extracorporeal shock wave lithotripsy (ESWL) and subsequent dose-dependent changes on the kidneys. An experimental study was performed in 45 rabbits; to define and compare the early and late complications of ESWL in the kidneys. The rabbits were divided into three groups of 15 animals each that received 1000, 1500 or 3000 shock waves respectively at 15–20 kV. The rabbits in each group were killed and necropsy performed within 24 h for the first 5 animals, 1 week for the second 5 animals and 2 months post-ESWL for the last 5 animals. Dose-dependent moderate damage (subcapsular hemorrhage, interstitial hemorrhage, capsular tension and perirenal hemorrhage) were noted in all kidneys at 24 h after treatment. Evidence of permanent changes (some fibrosis, tubular and glomerular damage, chronic inflammatory alterations) was noted in long-term follow up. Complete necrosis of the treated kidney was not encountered in this study.     

Citrate and vitamin E blunt the shock wave-induced free radical surge in an in vitro cell culture model

Free radical formation plays a major role in shock wave lithotripsy induced renal damage. Moreover, previous studies suggest that free radicals may also promote de novo calcium oxalate crystallization of previously damaged urothelium. Citrate is a known inhibitor of renal stone formation and has also been used as a free radical scavenger. Using an in vitro model with Madin-Darby canine kidney (MDCK) cells, we investigated the influence of two free radical scavengers, citrate and vitamin E, on the prevention of the shock wave-induced free radical surge. Suspensions of MDCK cells were placed in containers for shock wave exposure. Six groups of six containers each were examined: (a) no scavengers 0 shocks, (b) no scavengers 100 shocks, (c) citrate 0 shocks, (d) citrate 100 shocks, (e) vitamin E 0 shocks, (f) vitamin E 100 shocks. An unmodified HM3 was used to deliver 100 shocks at 24 kV. The cell groups that were not shocked acted as the control group and were handled identically, except for the lack of shock wave exposure. After shock wave administration, the containers were emptied and cell suspensions were immediately centrifuged. The supernatant was examined for lactate dehydrogenase (LDH) and 8-isoprostane (8-IP), markers of cellular injury and free radical formation, respectively. Intracellular LDH uniformly increased in all groups exposed to shock wave energy. Similarly, 8-IP increased in all shocked groups. However, the 8-IP increase was significantly reduced when the free radical scavengers were employed. As citrate is a well-known inhibitor of calcium nephrolithiasis, its mechanism of action may be further enhanced, based on its ability to reduce free radical formation, by a protective effect on the urothelium. These data further support the use of citrate based medications during the peri-operative period of shock wave lithotripsy, not only to inhibit stone formation and facilitate fragment passage, but also to reduce the incidence of shock wave induced renal damage. Further studies are warranted to clinically test this hypothesis.     

Short-term changes in renal function after extracorporeal shock wave lithotripsy in children.

PURPOSE: To our knowledge despite numerous studies the biological effect of extracorporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc., Marietta, Georgia) on the function of the immature kidney has not yet been evaluated. We determined the short-term effect of ESWL on renal function in children. MATERIALS AND METHODS: In a 5-year period 65 children were treated for 77 kidney stones by ESWL and followed regularly at our department. In 16 children the short-term effect of shock wave energy was studied by measuring blood parameters (sodium, potassium, urea, creatinine and C-reactive protein), urinary electrolytes (sodium, potassium and creatinine), urinary enzyme activity (aspartate transaminase, alanine transferase, alkaline phosphatase and lactate dehydrogenase) and the excretion of beta 2-microglobulin. Samples were obtained immediately before and 2 hours after ESWL, and on days 1, 2, 8, 15, 30 and 90 after treatment. RESULTS: Morphological changes in the kidneys were not detected by ultrasound during followup. No significant changes were noted in overall renal function, serum parameters or urine electrolytes. A significant elevation in the excretion of aspartate transaminase, alkaline phosphatase, lactate dehydrogenase and beta 2-microglobulin was observed, indicating proximal tubular dysfunction and cell destruction. Enzyme levels returned to baseline within 15 days. CONCLUSIONS: Our results demonstrate that shock wave energy induces transient functional damage of tubular function in children. Minimizing the kV. and number of shocks may decrease the deleterious effect. When considering functional regeneration time, the minimal interval between 2 shock wave treatments should be at least 15 days. The long-term effect needs further investigation.     

Do extracorporeal shock waves affect urinary excretion of glycosaminoglycans?

Urinary excretion of glycosaminoglycans (GAGs) was studied in 9 anaesthetised dogs and 10 patients with single kidneys. The animals were studied for 4 to 5 hours after administration of shock waves to 1 kidney, the contralateral organ serving as control. Urinary excretion of GAGs was measured on both sides. The patients were studied 0 to 24 and 32 to 56 h after extracorporeal shock wave lithotripsy (ESWL). In the animals an increased mean urinary excretion of GAGs was observed on both sides; this was more marked in the treated kidney. The increase reflects tissue injury in the exposed kidney induced by the extracorporeal shock waves. No increase in mean urinary excretion of GAGs was observed in the patients.     

Effect of SWL on renal hemodynamics: could a change in renal artery contraction–relaxation responses be the cause?

The aim of this study was to reveal the effect of shock wave lithotripsy (SWL) on renal artery contraction–relaxation responses and the relation of this effect with renal hemodynamics. Twenty-four rabbits are divided into six different groups. The first two groups evaluated as the control groups. After isolating the kidneys, we applied phenylephrine (Ph) and acetylcholine (Ach) in the first group and sodium nitroprusside (SNP) and histamine (H) in the second group. In the third, fourth, fifth and sixth groups, 14.5?kV shock wave (SW) was focused on the left kidneys. We adjusted the number of shocks to a total of 500, 1,500, and 3,000?SW, in the third, fourth and fifth groups, respectively. After isolating the kidneys, Ph, Ach was given in groups 3, 4 and 5. In the sixth group, to get the SNP and the H responses, 3,000 shocks modality was utilized. Marked contractile responses were obtained by phenylephrine in the control group. In kidneys that were exposed to 500 shocks SWL procedures, a decrease in contractile responses and hence, in perfusion pressures in different concentrations of phenylephrine was noted. However, a notable change in relaxation responses occurred after 3,000-shock applications. No difference in relaxation responses to nitroprusside, a direct vasodilating agent, was observed in any group, compared to the control group. Another cause of deterioration of renal hemodynamics after SWL can be attributed to the reduction in renal artery contraction–relaxation responses that result in the vascular smooth muscle and endothelial damage.     

Effect of initial shock wave voltage on shock wave lithotripsy-induced lesion size during step-wise voltage ramping

OBJECTIVE

To determine if the starting voltage in a step‐wise ramping protocol for extracorporeal shock wave lithotripsy (SWL) alters the size of the renal lesion caused by the SWs.

MATERIALS AND METHODS

To address this question, one kidney from 19 juvenile pigs (aged 7–8 weeks) was treated in an unmodified Dornier HM‐3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA) with either 2000 SWs at 24 kV (standard clinical treatment, 120 SWs/min), 100 SWs at 18 kV followed by 2000 SWs at 24 kV or 100 SWs at 24 kV followed by 2000 SWs at 24 kV. The latter protocols included a 3–4 min interval, between the 100 SWs and the 2000 SWs, used to check the targeting of the focal zone. The kidneys were removed at the end of the experiment so that lesion size could be determined by sectioning the entire kidney and quantifying the amount of haemorrhage in each slice. The average parenchymal lesion for each pig was then determined and a group mean was calculated.

RESULTS

Kidneys that received the standard clinical treatment had a mean (sem ) lesion size of 3.93 (1.29)% functional renal volume (FRV). The mean lesion size for the 18 kV ramping group was 0.09 (0.01)% FRV, while lesion size for the 24 kV ramping group was 0.51 (0.14)% FRV. The lesion size for both of these groups was significantly smaller than the lesion size in the standard clinical treatment group.

CONCLUSIONS

The data suggest that initial voltage in a voltage‐ramping protocol does not correlate with renal damage. While voltage ramping does reduce injury when compared with SWL with no voltage ramping, starting at low or high voltage produces lesions of the same approximate size. Our findings also suggest that the interval between the initial shocks and the clinical dose of SWs, in our one‐step ramping protocol, is important for protecting the kidney against injury.     

Temporal effects of shock wave lithotripsy.

Previous studies have demonstrated that renal parenchymal injury following extracorporeal shock wave lithotripsy is dependent upon shock wave power as well as the total number of shock waves administered. In order to determine the deleterious effects of temporal versus cumulative doses of shock wave administration, adult female rabbits were divided into five groups receiving either: 1000 shock waves in one session; 2000 shock waves in one session; 2000 shock waves in two sessions, one week apart; unilateral nephrectomy without lithotripsy; or anesthesia only as control population. One month following lithotripsy, renal functional studies for gamma glutamyl transferase and N-acetyl-beta-glucosaminidase revealed persistent enzymuria in the animals treated with 2000 shocks in one session. Pathologic studies in these animals confirmed an increased area of periglomerular and intratubular fibrosis when compared to animals managed by either 1000 shocks or 2000 shocks in divided doses (p less than 0.01). These findings suggest the importance of avoiding single treatments with large doses of shock waves and favor the administration of multiple small-doses of shock waves to minimize renal damage during the treatment of patients with hard or large calculi.     

The effect of discharge voltage on renal injury and impairment caused by lithotripsy in the pig

The present study was designed to determine the effects of shock wave voltage (kV) on lesion size and renal function induced by shock wave lithotripsy (SWL) in the 6- to 8-wk-old pig. Each SWL-treated pig received 2000 shock waves at 12, 18, or 24 kV to the lower pole calyx of one kidney. A group of sham SWL pigs served as time controls. Bilateral GFR, renal plasma flow (RPF), and para-aminohippurate (PAH) extraction were measured 1 h before and 1 and 4 h after SWL in all treated and sham animals. The kidneys were removed at the end of each experiment for morphometric analysis. The SWL-induced lesion increased significantly in size as shock wave energy was increased from 12 to 24 kV. PAH extraction, a measure of tubular function, was not significantly affected at 12 kV, was transiently reduced at 18 kV, and was reduced for the duration of the experiment at 24 kV. GFR and RPF, however, were significantly and similarly reduced at the 1 h post-SWL period at all three kilovolt levels. At the 4-h post-SWL period, both GFR and RPF had returned to baseline levels. Lesion size and tubular injury were correlated with changes in kilovoltage, while changes in renal hemodynamics were already maximal at the lowest discharge voltage. These findings suggest that renal microvessels are highly sensitive to shock waves and that frank injury to tubules and vessels may be more closely related to discharge energy than is renal blood flow.     

In vivo assessment of free radical activity during shock wave lithotripsy using a microdialysis system: the renoprotective action of allopurinol.

PURPOSE: Shock wave lithotripsy is believed to cause renal damage directly through cellular injury from high energy shock waves and indirectly through vascular injury and resultant ischemia, which gives rise to oxygen free radical compounds. The transient and volatile nature of free radicals and derived products makes their detection difficult. Moreover, certain medications may provide a protective effect against shock wave lithotripsy induced renal parenchymal injury. We introduced an innovative microdialysis system for in vivo sampling of interstitial fluids that can be analyzed for free radical mediated lipid peroxidation products after shock wave lithotripsy treatment in the swine model. In addition, this system was used to test the antioxidant or renoprotective action of allopurinol. MATERIALS AND METHODS: Ten juvenile swine were assigned to a nonmedicated control group that underwent shock wave lithotripsy or to a group that was premedicated with allopurinol before shock wave lithotripsy. Each group of animals underwent shock wave lithotripsy to the lower pole of the right kidney and received a total of 10,000 shock waves. Dialysate fluid was collected at 1,000-shock wave increments via probes surgically implanted into the lower pole of the right and left kidneys before lithotripsy. Samples were immediately preserved in liquid nitrogen and subsequently analyzed for the presence and concentration of conjugated diene levels, a measure of lipid peroxidation. Five additional juvenile swine were assigned to a sham treated group that did not undergo shock wave lithotripsy. Dialysate fluid was collected from the lower pole of the right and left kidneys to establish baseline or pre-lithotripsy levels of conjugated dienes. RESULTS: After shock wave lithotripsy conjugated diene levels increased almost 100-fold over that in the right kidneys of the nonmedicated control group. The difference was statistically significant compared to levels in the contralateral untreated kidneys (p <0.01). Right kidneys in the group premedicated with allopurinol did not demonstrate an increase in conjugated diene levels during shock wave lithotripsy. CONCLUSIONS: The results of this study confirm shock wave lithotripsy induced free radical activity as well the antioxidant and protective nature of allopurinol. The newly described microdialysis system enables real-time sampling of interstitial fluids during shock wave lithotripsy. It represents a unique method for assessing free radical formation and evaluating the protective effects of additional antioxidant medications.     

Shock wave lithotripsy causes ipsilateral renal injury remote from the focal point: the role of regional vasoconstriction

PURPOSE: Shock wave lithotripsy induced renal damage can occur as a result of multiple mechanisms, including small vessel injury and free radical production. Previous studies have demonstrated that shock wave lithotripsy exerts a regional change in renal hemodynamics, resulting in a global reduction in the glomerular filtration rate and renal plasma blood flow. We determined if biochemical evidence of cellular damage could be identified in ipsilateral locations remote from the shock wave site or in the contralateral kidney, suggesting regional or systemic alterations in renal function. MATERIALS AND METHODS: Ten juvenile female swine underwent open insertion of microdialysis probes into the renal parenchyma at the right upper and lower poles, and left lower pole. The animals were divided evenly into a sham and a treatment group. Dialysate samples were collected from all 3 sites from the sham group at 10-minute intervals for 100 minutes and quantitatively assessed for conjugated dienes, a measure of lipid peroxidation and free-radical activity, signifying renal cellular damage. The animals in the treatment group underwent shock wave lithotripsy focused on the right lower pole. Dialysate samples were collected from all 3 sites at baseline and at 1,000 shock intervals for a total of 10,000 shocks and analyzed for conjugated dienes. The results from the sham and treatment groups as well as from the different locations within each group were compared using Student's t test. RESULTS: The mean conjugated diene ratio for the sham group was 3.59, 3.42 and 2.7 microM. for the right upper and lower poles, and left kidney (p >0.05). A dose related increase in conjugated diene ratio levels from the right lower pole (lithotripsy site) and to a lesser degree from the ipsilateral right upper pole were observed, which were significantly different from sham group measurements or the contralateral kidney of the treatment group (p <0.05). The elevation in conjugated diene levels at the lithotripsy site was also noted to be significantly greater than that of the upper pole of the ipsilateral kidney (p <0.05). CONCLUSIONS: The increase in free radical activity at a site remote from the treated region suggests detrimental global effects from shock wave lithotripsy therapy. These observations could be the result of vasoconstriction throughout the treated kidney with resultant ischemia-reperfusion injury. Although these global renal effects may subject patients with baseline renal dysfunction to irreversible renal damage, the clinical significance of our findings is unclear and warrants further investigation.     

不同能量冲击波对猪肾近期病理损伤的实验研究

目的探讨体外冲击波能量大小与肾脏损伤的关系。方法将体重28—35kg的白猪36头，根据冲击电压的不同，随机分为A、B、C、D、E组，其中E组为对照组。每组按观察时间不同又分为4个亚组，分别于冲击后即刻、1周、2周和3周取双侧肾脏，肉眼和光镜下观察其形态的改变。结果所有受冲击的肾脏均有损伤性改变，且损伤随电压的增加而加重，随时间的推移而逐渐恢复，当电压超过13kV后，所引起的损伤是不可逆的（至少短期内）。结论当冲击电压≤13kV时，冲击波所引起的损伤在1—3周内基本可以恢复，而一旦超过13kV，则会造成肾脏不可逆性病理改变。本实验结果为临床ESWL能量参数的选择提供了参考依据。     

A comparison of stone damage caused by different modes of shock wave generation.

A standard stone phantom was used to compare stone damage after extracorporeal shock wave administration from electrohydraulic, electromagnetic and piezoelectric lithotripters. For each machine, a low and high shock wave intensity setting was chosen: 18 & 24 kV for electrohydraulic; 16 & 19 kV for electromagnetic; power levels 1 and 4 for piezoelectric. The shock wave was focused either at the front (surface facing the wave source) or back surface of the stone and 50, 100, 200 or 400 shocks were delivered to different stone groups. Effects of varying physical properties in the stone phantom were also investigated. Stone damage was described in terms of volume loss and both depth and width of the resulting damage crater. At the lower intensity settings, all three machines produced stone volume loss which was linearly related to the number of shock delivered. At higher intensity settings, volume loss increased rapidly as the number of shocks increased. With the same number of shocks, stone volume loss was greatest with the electrohydraulic machine, followed by electromagnetic and piezoelectric lithotripters for both low and high intensity settings. Damage craters from the piezoelectric device were narrow and deep; those from the electromagnetic machine were of the shape of a right angle circular cone; whereas those from the electrohydraulic lithotripter were shallow and wide. At the high intensity settings, damage from the piezoelectric and electrohydraulic lithotripters appeared to depend upon the position of the focal point with a higher volume loss when the shock waves were targeted at the front surface of the stone. For the electromagnetic device, a higher volume loss was found when we positioned the focal point at the back surface of the stone phantom. Stone phantoms with lower mechanical strength and acoustic impedance were more easily damaged than those with higher values. Finally, a computer regression model was developed to express volume loss in terms of the intensity setting, focal position and number of shocks for each lithotripter.     

Effects of Extracorporeal Shock Wave Lithotripsy to One Kidney on Bilateral Glomerular Filtration Rate and PAH Clearance in Minipigs

Purpose

This study examined the acute time course of effects of extracorporeal shock wave lithotripsy (ESWL)¹ on renal hemodynamics in anesthetized minipigs with and without pretreatment with verapamil.

Materials and Methods

We applied ESWL (2000 shocks, 24 kV, unmodified Dornier HM3), to the right kidneys of isoflurane-anesthetized female pigs. Urine flow and renal hemodynamics were monitored from each kidney via ureteral balloon catheters. Arterial blood pressure and bilateral urine flow, glomerular filtration rate (GFR, inulin clearance) and renal plasma flow (RPF, para-aminohippurate clearance) were monitored for 45 minutes before ESWL, and at 1, 4 and 24 hours after ESWL.

Results

Treatment with ESWL consistently caused unilateral hematuria and subcapsular renal hematomas in the shocked kidneys and significantly reduced GFR and RPF in those kidneys at 1 and 4 hours after ESWL. Urine flow was reduced through 24 hours in the shocked kidneys. Renal plasma flow, but not GFR, was significantly reduced in the contralateral (unshocked) kidneys at 1 and 4 hours after ESWL to the other kidneys. Verapamil blunted the ESWL-induced reductions of urine flow, GFR and RPF in the shocked kidneys and eliminated the reduction of RPF in the unshocked kidneys.

Conclusions

These experiments demonstrate that ESWL to 1 kidney acutely impaired hemodynamics in both kidneys and that verapamil attenuated the response in the shocked kidneys and eliminated it in the contralateral unshocked kidneys.     

Stones in anomalous kidneys: Results of treatment by shock wave lithotripsy in 150 patients

OBJECTIVE: To determine the efficacy of shock wave lithotripsy (SWL) in anomalous kidneys. METHODS: From October 1990 to October 2002, 150 patients (93 men and 57 women) with anomalous urinary tracts, including 45 horseshoe kidneys, 57 duplex kidneys, 30 malrotated kidneys, 14 pelvic and four crossed ectopic kidneys were treated with SWL for urolithiasis at the Gazi University Faculty of Medicine. Shock wave lithotripsy was performed with Siemens Lithostar plus (Siemans, Erlanger, Germany) device and all procedures were carried under fluoroscopic control. Results: The mean shock wave number and intensity received by the patients was 3770 (range, 1380-4100) shocks and 18.4 (range, 16.1-19) kV per session, respectively. The minimum success rate was obtained in patients with lower calyceal (50%) followed by middle calyceal (60%) calculi. The stone-free rate decreased and the number of sessions per patient increased with increasing stone diameter (dm). In patients with a stone dm > 30 mm, only 34% could be stone-free, compared to a rate of 92% for calculi dm < 10 mm. The overall stone free rate at the third month was 68%. The best stone-free rates were obtained in patients with ureteral duplication (80.7%). The stone-free rates in horseshoe, malrotated, pelvic and crossed ectopic kidneys were found to be 66.7%, 56.7%, 57.2% and 25%, respectively. CONCLUSION: Shock wave lithotripsy might be an effective and minimally invasive treatment alternative in stone-bearing anomalous kidneys. The type of anomaly, stone burden and localization seem to be the main parameters effecting the treatment success.     

Effects of extracorporeal shock wave lithotripsy on the structure and function of rabbit kidney

An animal model was developed to investigate the effect of extracorporeal shock wave lithotripsy (ESWL) on a normal kidney. Rabbits were treated with 3,000 shock waves at 18 kV to each kidney. Blood and urine samples were collected daily before and after shock wave treatment. Serum levels of hemoglobin, creatinine, lactic dehydrogenase (LDH), creatinine phosphokinase (CPK), and total protein were determined. Urine determination of volume, total protein, hemoglobin, and creatinine were also made. All kidneys, after sacrifice, were subjected to histologic analysis. The average pre-treatment creatinine clearance of our rabbits was 8.3 ml./min. After the treatment, a significant (p less than 0.01) reduction in creatinine clearance was noted for four days. The reduction was to 0.61 ml./min. on day one, 0.87 on day two, 1.04 on day three, and so forth. Urine hemoglobin rose significantly (p less than 0.01) for the first three days from 0.0 to 1.5 gm./dl. Histologic examination at seven days showed focal subcapsular hemorrhage, tubular dilation, and interstitial hemorrhage. Histologic evaluation at two months revealed focal interstitial fibrosis. In conclusion, this study reveals that shock waves to the kidney have short term physiologic effects on renal function and permanent focal histologic effects, which do not effect long term physiologic function. Further research on the effects of ESWL on renal function and structure could be facilitated with the use of this model.     

The role of silicone ureteral stents in extracorporeal shock wave lithotripsy of large renal calculi

Between November 1984 and December 1985 extracorporeal shock wave lithotripsy was used to treat 1,645 kidneys at our institution. A total of 646 kidneys with stone burden greater than 14 mm. was evaluated with regard to the impact of silicone ureteral stents in post-extracorporeal shock wave lithotripsy morbidity. Our results indicate that small stones were pulverized and eliminated with minimum morbidity. Larger stones frequently were associated with post-treatment ureteral obstruction by sand and fragments. Of 283 kidneys with stone burden exceeding 25 mm. pretreatment placement of silicone ureteral stents reduced complications from 26 to 7 per cent and auxiliary procedure rates from 15 to 6 per cent. Silicone ureteral stents protect the kidney from ureteral obstruction, and allow for safe and effective extracorporeal shock wave lithotripsy of large renal calculi.     

Shockwave lithotripsy: dose-related effects on renal structure, hemodynamics, and tubular function

BACKGROUND AND PURPOSE: Shockwave lithotripsy (SWL) predictably damages renal tissue and transiently reduces function in both kidneys. This study characterized the effects on renal function of a supraclinical dose of shockwaves (SWs) (8000) in porcine kidneys and tested the hypothesis that such excessive treatment would intensify and prolong the resulting renal impairment. MATERIALS AND METHODS: Pigs aged 6 to 7 weeks were anesthetized and assigned to one of three groups. Groups 1 (N=8) and 2 (N=6) each received 8000 SWs at 24 kV (Dornier HM3) to the lower-pole calix of one kidney. Group 3 (7 pigs) received sham treatment. Renal function was monitored for the first 4 hours after SW treatment in Group 1 and for 24 hours in Group 2. Plasma renin activity was measured in Groups 2 and 3. RESULTS: The renal lesions produced by 8000 SWs comprised 13.8%+/-1.4% of the renal mass. In the 4-hour protocol, this injury was associated with marked reduction of the glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion in both kidneys, although fractional sodium excretion was reduced only in the shocked kidneys. In the 24-hour protocol, GFR and RPF remained below baseline in shocked kidneys at 24 hours. Evidence of progressive ischemic injury was noted in shocked tissue at 24 hours after SW treatment. CONCLUSIONS: These findings support the hypothesis that the severity of the renal injury caused by SWL is related to the number of SWs administered and demonstrate the connection in this relation between renal structure and function.     

Clinical efficacy of high frequency jet ventilation during extracorporeal shock wave lithotripsy of renal and ureteral calculi: a comparison with conventional mechanical ventilation

The use of high frequency jet ventilation compared to conventional mechanical ventilation during general anesthesia for extracorporeal shock wave lithotripsy of renal or ureteral calculi can reduce stone movement. This decrease in stone movement theoretically lessens the total shock and energy requirements for stone fragmentation and perirenal tissue damage. To assess these theoretical advantages of high frequency jet ventilation, we studied patients undergoing extracorporeal shock wave lithotripsy to determine differences in stone movement during high frequency jet and conventional mechanical ventilation (30 patients), and in total shock requirements (1,174 patients). Mean stone movement in the 30 patients was 34.3 +/- 4.3 mm. during conventional mechanical ventilation compared to 4.1 +/- 1.9 mm. during high frequency jet ventilation (p less than 0.001). Mean total shocks were 1,542 +/- 212 (452 patients) during conventional mechanical ventilation compared to 1,217 +/- 165 (722 patients) during high frequency jet ventilation (p less than 0.001). Only 1 patient in the study had clinically significant perirenal tissue damage. We conclude that high frequency jet ventilation when compared to conventional mechanical ventilation results in clinically and economically beneficial decreases in total shocks for extracorporeal shock wave lithotripsy fragmentation of renal or ureteral calculi.     

The endourological management of complications associated with horseshoe kidney

PURPOSE: Horseshoe kidneys are the most common renal fusion anomalies. Ureteropelvic junction obstruction, urolithiasis and renal malignancies are the most common complications that occur in this patient population. Endourological management of these complications has decreased perioperative morbidity. We identified the applications of minimally invasive surgery for treating complications secondary to horseshoe kidney. MATERIALS AND METHODS: A comprehensive literature review of the different endourological approaches in the management of complications secondary to horseshoe kidney was performed using MEDLINE. RESULTS: Ureteropelvic junction obstruction can be managed by percutaneous endopyelotomy or laparoscopic pyeloplasty with good results. Small stones associated with horseshoe kidney are best managed by shock wave lithotripsy, while stones that have failed management by shock wave lithotripsy or are greater than 2 cm. are best managed percutaneously. All patients should undergo metabolic evaluation. Ureteroscopy or shock wave lithotripsy is associated with a higher residual stone rate than the percutaneous approach. Laparoscopic nephrectomy is a safe and feasible option for benign and malignant horseshoe kidney diseases. CONCLUSIONS: Endourological techniques can be safe and effective for treating complications secondary to horseshoe kidney.     

Extracorporeal shock wave lithotripsy treatment of calculi in horseshoe kidneys

From June 1985 to November 1986, 17 patients with calculi in horseshoe kidneys presented to our hospital for evaluation and possible treatment with extracorporeal shock wave lithotripsy. Of these patients 14 were treated with extracorporeal shock wave lithotripsy; the calculi in 2 could not be localized and focused at the F2 focal point, and 1 was asymptomatic and has been followed conservatively. Four patients required repeat extracorporeal shock wave lithotripsy. Adjunctive procedures included preoperative retrograde catheter placement (5 patients), postoperative percutaneous nephrostolithotomy (1), ureteroscopy for ureteral fragments (2) and placement of a double pigtail stent (1). Of 14 patients 11 (79 per cent) have been rendered free of fragments with extracorporeal shock wave lithotripsy and adjunctive measures as needed. We conclude that most patients with calculi in a horseshoe kidney can be managed primarily with extracorporeal shock wave lithotripsy.