EURURO-6264; No. of Pages 7
EUROPEAN UROLOGY XXX (2015) XXX–XXX
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Platinum Priority – Stone Disease
Editorial by XXX on pp. x–y of this issue
Does Stepwise Voltage Ramping Protect the Kidney from Injury
During Extracorporeal Shockwave Lithotripsy? Results of a
Prospective Randomized Trial
Veronika Skuginna y, Daniel P. Nguyen y, Roland Seiler, Bernhard Kiss,
George N. Thalmann, Beat Roth *
Department of Urology, University of Bern, Bern, Switzerland
Article info
Abstract
Article history:
Accepted June 14, 2015
Background: Renal damage is more frequent with new-generation lithotripters. However,
animal studies suggest that voltage ramping minimizes the risk of complications following
extracorporeal shock wave lithotripsy (SWL). In the clinical setting, the optimal voltage
strategy remains unclear.
Objective: To evaluate whether stepwise voltage ramping can protect the kidney from
damage during SWL.
Design, setting, and participants: A total of 418 patients with solitary or multiple unilateral
kidney stones were randomized to receive SWL using a Modulith SLX-F2 lithotripter with
either stepwise voltage ramping (n = 213) or a fixed maximal voltage (n = 205).
Intervention: SWL.
Outcomes measurements and statistical analysis: The primary outcome was sonographic
evidence of renal hematomas. Secondary outcomes included levels of urinary markers of renal
damage, stone disintegration, stone-free rate, and rates of secondary interventions within
3 mo of SWL. Descriptive statistics were used to compare clinical outcomes between the two
groups. A logistic regression model was generated to assess predictors of hematomas.
Results and limitations: Significantly fewer hematomas occurred in the ramping group
(12/213, 5.6%) than in the fixed group (27/205, 13%; p = 0.008). There was some evidence
that the fixed group had higher urinary b2-microglobulin levels after SWL compared to the
ramping group (p = 0.06). Urinary microalbumin levels, stone disintegration, stone-free rate,
and rates of secondary interventions did not significantly differ between the groups. The
logistic regression model showed a significantly higher risk of renal hematomas in older
patients (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00–1.05; p = 0.04). Stepwise
voltage ramping was associated with a lower risk of hematomas (OR 0.39, 95% CI 0.19–0.80;
p = 0.01). The study was limited by the use of ultrasound to detect hematomas.
Conclusions: In this prospective randomized study, stepwise voltage ramping during SWL
was associated with a lower risk of renal damage compared to a fixed maximal voltage
without compromising treatment effectiveness.
Patient summary: Lithotripsy is a noninvasive technique for urinary stone disintegration
using ultrasonic energy. In this study, two voltage strategies are compared. The results show
that a progressive increase in voltage during lithotripsy decreases the risk of renal hematomas
while maintaining excellent outcomes.
Trial registration: ISRCTN95762080
# 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.
Associate Editor:
Christian Gratzke
Keywords:
Extracorporeal shockwave
lithotripsy
Randomized trial
Renal damage
Voltage ramping
y
These authors contributed equally to this work.
* Corresponding author. Department of Urology, University Hospital Bern, CH-3010 Bern,
Switzerland. Tel. +41 31 6323621; Fax: +41 31 6322180.
E-mail address: [email protected] (B. Roth).
http://dx.doi.org/10.1016/j.eururo.2015.06.017
0302-2838/# 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Skuginna V, et al. Does Stepwise Voltage Ramping Protect the Kidney from Injury During
Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial. Eur Urol (2015), http://dx.doi.org/10.1016/
j.eururo.2015.06.017
EURURO-6264; No. of Pages 7
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EUROPEAN UROLOGY XXX (2015) XXX–XXX
1.
Introduction
Introduction of the Dornier HM-3 lithotripter in the early
1980s for extracorporeal shockwave lithotripsy (SWL)
revolutionized the treatment of urolithiasis [1]. Major
urologic associations currently recommend SWL as firstline treatment for kidney stones <2 cm located in the pelvis
or upper or middle calices [2,3]. In recent years, several
new-generation lithotripters have been introduced, many
of which are being used in clinical practice. Although SWL is
generally considered a safe procedure, it is associated with
postintervention renal hematomas in 0.5–13% of all cases
according to prospective data [4–7]. Severe hematomas can
initiate an inflammatory response, resulting in scar formation and damage to tubules with subsequent loss of
functional renal mass [8].
Against this background, current research is dedicated
to improving SWL treatment strategies to minimize the
risk of hematomas while maintaining or improving clinical
effectiveness. Porcine models have shown that stepwise
voltage ramping can significantly reduce the extent of renal
parenchymal hemorrhagic lesions [9]. To date, clinical
evidence has come only from trials with a small number
of participants and/or suboptimal study design [10–12].
Notwithstanding their shortcomings, these studies suggest
that voltage ramping is safe and may even confer a
protective effect compared to fixed voltage treatment.
However, data on the impact of voltage application on
clinical effectiveness are conflicting [10–12].
To redress the deficiencies of previous studies, we conducted a well-powered, single-blinded, prospective randomized
trial to evaluate the effect of stepwise voltage ramping on
renal damage during SWL of kidney stones.
2.
Patients and methods
2.1.
Patients and randomization
From July 2010 to March 2013, 418 patients (296 males and 122 females)
16 yr of age requiring elective or emergency SWL were randomized
without stratification by a software program to treatment using
the Modulith SLX-F2 lithotripter (Storz Medical AG, Trägerwilen,
Switzerland) with either stepwise voltage ramping or a fixed maximal
voltage (Fig. 1). Unrestricted randomization was chosen because of the
high number of patients to be recruited. Use of a password-protected
computer database ensured allocation concealment until the intervention. Inclusion criteria were solitary or multiple unilateral radiopaque
kidney stones <3 cm in diameter, ability to receive neuroaxial regional
or general anesthesia, and informed consent. Exclusion criteria were a
Enrollment
Assessed for eligibility: n = 536
Excluded: n = 118
♦ Not meeting inclusion criteria: n = 1
♦ Declined to participate: n = 7
♦ Sent for treatment with HM3: n = 110
Randomized: n = 418
Allocation
Allocated to voltage ramping ESWL: n = 213
♦ Received allocated intervention: n = 213
♦
Allocated to fixed voltage ESWL: n = 205
♦ Received allocated intervention: n = 205
Did not receive allocated intervention: n = 0
♦
Did not receive allocated intervention: n = 0
Follow-up
Lost to follow-up: n = 15
♦ On day 1: n = 0
♦ At 3 mo: n = 15
Lost to follow-up: n = 9
♦ On day 1: n = 0
♦ At 3 mo: n = 9
Discontinued intervention: n = 0
Discontinued intervention: n = 0
Analysis
Analyzed:
♦ On day 1: n = 213
♦ At 3 mo: n = 198
Analyzed:
♦ On day 1: n = 205
♦ At 3 mo: n = 196
Excluded from analysis: n = 0
Excluded from analysis: n = 0
Fig. 1 – Consolidated Standards of Reporting Trials diagram enumerating the patients screened, randomized, allocated to each treatment arm, lost to
follow-up, and included in the final analysis. HM3 = Dornier HM-3 lithotripter; ESWL = extracorporeal shockwave lithotripsy.
Please cite this article in press as: Skuginna V, et al. Does Stepwise Voltage Ramping Protect the Kidney from Injury During
Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial. Eur Urol (2015), http://dx.doi.org/10.1016/
j.eururo.2015.06.017
EURURO-6264; No. of Pages 7
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EUROPEAN UROLOGY XXX (2015) XXX–XXX
concurrent ureteral stone and contraindications to SWL according to
ratios (ORs) and 95% confidence intervals (CIs) were calculated in a
standard guidelines: pregnancy, uncompensated bleeding diathesis
univariate logistic regression model to test for the effect of the mode of
(anticoagulation or platelet anti-aggregation therapy), and uncontrolled
voltage application and previously described risk factors on the risk of
urinary tract infection [2,3]. Patients sent by a referring urologist with an
renal hematomas: age (continuous), female gender, body mass index
explicit request for treatment with a Dornier HM-3 lithotripter were also
(BMI; continuous), and number of SWs (continuous) [15–17]. A two-
excluded (Fig. 1). The study protocol was approved by the ethics
sided value of p < 0.05 was considered statistically significant.
committee of Bern Canton, Switzerland (protocol number 089/10).
2.2.
Treatment protocol
All patients received SWL treatment under regional or general anesthesia
to eliminate pain as a limiting factor and to keep respiratory movements
regular, a common practice at our department. The Modulith SLX-F2
is a third-generation electromagnetic lithotripter that uses both inline
fluoroscopy and ultrasound to locate the stone. The standard focal size
(6 mm 28 mm) was used for both groups. In the ramping group,
treatment started with a series of 500 SWs at level 7 (corresponding
to 14 kV) followed by 1000 SWs at level 8 (16 kV) and 1000 SWs at
level 9 (18 kV). In the fixed group, 2500 SWs at level 9 were administered.
In both groups, treatment was terminated before reaching the maximum
number of SWs on documentation of complete fragmentation on x-ray.
The SW delivery rate was heartbeat–triggered [6]. Every SWL treatment
was performed by the same technician, who had >25 yr of experience,
under the supervision and guidance of a specially trained resident and
senior staff member.
2.3.
Follow-up
Patients were followed up 1 d and 3 mo after SWL using ultrasound to
evaluate the presence of subcapsular or perirenal hematoma, and by
kidney, ureter, and bladder (KUB) x-ray to categorize the degree of stone
disintegration: stone-free, fragments <2 mm, fragments of 2–5 mm, or
3.
Results
Patient and stone characteristics are listed in Table 1. The
proportion of stones located in the lower calyx, for which
clearance rates are usually lower [18], was comparable
between the groups. The mean number of SWs, mean SW
frequency, and mean total voltage applied per patient did
not differ between the groups.
At 24 h after SWL, significantly fewer renal hematomas
were noted in the ramping (12/213, 5.6%) than in the
fixed group (27/205, 13%; difference 7.5 percentage points,
95% CI 1.9–13; p = 0.008). All patients with renal hematomas remained hemodynamically stable and were managed
conservatively; none of them required blood transfusions.
There was evidence that mean urinary b2-microglobulin
levels 24 h after SWL were higher in the fixed than in the
ramping group, although the difference did not reach
significance using ANCOVA to adjust for baseline values
(p = 0.06; Table 2). There was no significant difference in
post-SWL urinary microalbumin levels between the groups
(p = 0.9). Stone-free rates at 3 mo (146/198, 74% in the fixed
group vs 148/196, 76% in the ramping group; difference
1.8 percentage points, 95% CI –6.8 to 10; p = 0.7), stone
fragments >5 mm. All radiographic images were evaluated by the same
blinded reader to minimize interobserver variability. If the patient was
classified as stone-free according to KUB x-ray 1 d after SWL, no further
imaging was performed at the 3-mo follow-up. Complications and
Table 1 – Patient and kidney stone characteristics
secondary interventions were prospectively assessed by a blinded study
Ramping
group
nurse. Urine samples were obtained before and 24 h after SWL and
analyzed for tubular (b2-microglobulin) and glomerular (microalbumin)
damage [13].
2.4.
Outcomes measures
The primary outcome was evidence of renal hematomas on routine
sonography 24 h after SWL. Secondary outcomes were (1) levels of
b2-microglobulin and microalbumin in urine 24 h after SWL; (2) the
degree of stone disintegration 3 mo after SWL; (3) the stone-free rate
3 mo after SWL; (4) the number of secondary interventions (including
repeat SWL, JJ stent placement, percutaneous nephrolithotomy, and
ureteroscopy); and (5) complications other than hematomas (eg, urinary
tract infections, renal colic, or steinstrasse) within 3 mo of SWL. The
severity of complications was graded according to the Dindo-Clavien
classification. Stone composition was documented if available.
2.5.
Statistical analysis
SAS 9.1 (SAS Institute, Cary, NC, USA) was used for statistical analyses. On
the assumption that the incidence of renal hematomas is 5% [6] after
treatment with fixed maximal voltage and 0.45% after treatment with
voltage ramping and that the dropout rate is 7% [6], a sample size of
428 patients was required to gain a statistical power of 80% (b = 0.2)
using a two-sided test at a significance level of 5% (a = 0.05). Clinical
Patients (n)
Gender, n (%)
Female
Male
Median age, yr (IQR)
Median body mass index,
kg/m2 (IQR)
Pretreatment, n (%)
None
Percutaneous nephrostomy
JJ stent
Mean total shockwaves, n (SD)
Mean shockwave frequency, n/min (SD)
Mean total voltage per
patient, kV (SD)
Stone diameter, n (%)
<5 mm
5–10 mm
10–20 mm
>20 mm
Stone location, n (%)
Solitary stone
Lower calyx
Other
Multiple stones
Including lower calyx
Not including lower calyx
213
65
148
55
27
126
3
84
2424
72
40440
41
102
55
15
Fixed
group
205
(31)
(69)
(44–64)
(24–30)
(59)
(1)
(39)
(313)
(9.4)
(323)
(19)
(48)
(26)
(7)
57
148
53
26
129
5
71
2382
72
41610
44
109
43
9
(28)
(72)
(42–65)
(24–30)
(63)
(2)
(35)
(378)
(11)
(526)
(21)
(53)
(21)
(4)
66 (31)
74 (35)
72 (35)
66 (32)
52 (24)
21 (10)
53 (26)
14 (7)
outcomes were compared using the x2 test, Fischer’s exact test, and
analysis of covariance (ANCOVA) [14], as appropriate. Adjusted odds
IQR = interquartile range; SD = standard deviation.
Please cite this article in press as: Skuginna V, et al. Does Stepwise Voltage Ramping Protect the Kidney from Injury During
Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial. Eur Urol (2015), http://dx.doi.org/10.1016/
j.eururo.2015.06.017
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EUROPEAN UROLOGY XXX (2015) XXX–XXX
Table 2 – Urinary levels of b2-microglobulin and microalbumin before (day 0) and after (day 1) shockwave lithotripsy by mode of voltage
application
Ramping group
b2-Microglobulin
Day 0
Day 1
Microalbumin
Day 0
Day 1
Fixed group
0.18 0.38
0.31 0.64
0.15 0.20
0.90 2.92
116.3 178.6
433.0 435.2
131.3 204.8
442.7 543.5
Difference, % (95% CI)
p value
0.42 (–0.02 to 0.86)
0.06
5.5 (–111.2 to 122.1)
0.9
CI = confidence interval.
Data are presented as mean standard deviation. All p values were calculated using analysis of covariance.
Table 3 – Clinical outcomes at 3 mo after extracorporeal shock wave lithotripsy (ESWL)
Ramping group
Stone disintegration (n = 394), n (%)
Stone-free/no fragments
Fragments <2 mm
Fragments 2–5 mm
Fragments >5 mm
Secondary intervention (n = 418), n (%)
Repeat ESWL
Percutaneous nephrolithotomy
Ureterorenoscopy
Complications other than hematoma (n = 418), n (%)
Grade I
Grade II
Grade IIIa
Grade IIIb
Grade IV/V
a
146
34
13
5
23
18
4
1
10
5
–
4
1
–
Fixed group
(74)
(17)
(7)
(3)
(11)
(8)
(2)
(0.5)
(5)
(2)
148
25
19
4
20
15
3
2
7
1
1
5
–
–
(2)
(0.5)
(76)
(13)
(10)
(2)
(10)
(7)
(1)
(1)
(3)
(0.5)
(0.5)
(2)
Difference, % (95% CI)
1.8 (–6.8 to 10)
–4.4 (–12 to 2.7)
3.1 (–2.4 to 8.8)
–0.5 (–0.4 to 0.3)
–1 (–7.0 to 4.9)
–1.1 (–6.5 to 4.2)
–0.4 (–3.4 to 2.6)
0.5 (–1.8 to 3.1)
–1.3 (–2.8 to 5.4)
–1.9 (–4.9 to 0.7)
–
0.6 (–2.6 to 3.9)
–
–
p value
0.7
0.2
0.3
>0.9
0.7
0.7
>0.9
0.6
0.5
0.2
–
0.7
–
–
*
*
*
*
*
*
CI = confidence interval.
x2 test; all other p values were calculated using Fischer’s exact test.
a
Dindo-Clavien classification.
*
disintegration, rates of secondary interventions, and complications other than hematomas did not significantly differ
between the groups (Table 3).
The logistic regression model showed a higher risk of
renal hematoma in older patients (OR 1.03, 95% CI 1.00–
1.05; p = 0.04), and stepwise voltage ramping was associated with a lower risk (OR 0.39, 95% CI 0.19–0.80; p = 0.01,
Table 4). There was some evidence that BMI is associated
with a higher risk of hematomas, although this did not reach
significance (OR 1.06, 95% CI 0.99–1.13; p = 0.09). Of note,
total energy applied to patients with and without renal
hematoma did not differ within the groups (40 995 vs
40 412 kV in the ramping group, p = 0.6; 42 036 vs
41 582 kV in the fixed group, p > 0.9).
Table 4 – Univariate logistic regression analysis of variables
associated with renal hematomas 24 h after shockwave lithotripsy
Variable
Age
Female gender
Body mass index
Mode of energy application
Number of shockwaves
Odds ratio
(95% confidence interval)
1.03
1.09
1.06
0.39
1.00
(1.00–1.05)
(0.53–2.22)
(0.99–1.13)
(0.19–0.80)
(0.999–1.001)
p value
0.04
0.8
0.09
0.01
0.4
Stone analysis was available for 114/213 (54%) patients
in the ramping group and 110/205 (54%) patients in the
fixed group. There was no significant difference in stone
composition between the groups (p = 0.4; Supplementary
Fig. 1).
4.
Discussion
Since the advent of new-generation lithotripters, the
increase in the frequency of renal hematomas associated
with their use, most likely because of smaller focal zones
and higher peak pressures, has raised concerns among the
urologic community [19]. Although rarely symptomatic,
renal hematomas may have devastating long-term effects
[8]. Optimization of energy protocols is therefore an area of
active research. The present study, representing the largest
prospective randomized clinical trial investigating the
effect of the mode of voltage application, demonstrates a
beneficial effect of voltage ramping on renal damage
without compromising clinical effectiveness.
Lambert et al [11] reported on a randomized trial
comparing voltage ramping and fixed energy during SWL.
Although urinary markers for renal damage were routinely
collected, the study design did not determine renal
hematomas as an outcome and therefore the investigators
did not systemically search for them. Moreover, the trial had
Please cite this article in press as: Skuginna V, et al. Does Stepwise Voltage Ramping Protect the Kidney from Injury During
Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial. Eur Urol (2015), http://dx.doi.org/10.1016/
j.eururo.2015.06.017
EURURO-6264; No. of Pages 7
EUROPEAN UROLOGY XXX (2015) XXX–XXX
only 45 patients. Nevertheless, significant changes in
microalbumin and b2-microglobulin levels documented
1 wk after SWL suggested less renal damage for voltage
ramping. However, no changes were seen 24 h after SWL.
These results contrast with our own, as we found evidence
that b2-microglobulin levels (as a marker of tubular damage
[13]), but not of microalbumin (as a marker of glomerular
damage [13]), were higher in the fixed group 24 h after
SWL, although the difference in b2-microglobulin not reach
significance (p = 0.06). Under the hypothesis that 1 d may be
too short for sufficient expression of urinary markers of
renal damage in urine, we cannot exclude that higher levels
of both urinary b2-microglobulin and microalbumin would
have been detected at a later time point in the fixed group,
as shown by Lambert et al [11]. However, others have
demonstrated that microalbumin and b2-microglobulin
were increased 24 h after SWL [13,19,20].
The kinetic energy of SWs cause stone fragmentation
mainly via tear and shear forces and cavitation, but SWs
also affect the surrounding renal parenchyma [21]. This may
cause tearing of vessels, resulting in subcapsular or perirenal
hematoma [21]. Renal hematomas may lead to parenchymal
fibrosis and subsequent functional loss analogous to that
produced by blunt renal trauma [8,22]. The mechanisms
underlying the protective effect of stepwise voltage ramping
are not fully understood. Willis et al [9] demonstrated that
low-energy pretreatment of porcine kidneys significantly
reduced the size of renal hemorrhagic lesions compared to
no pretreatment. The authors hypothesized that lowenergy SWs induce some degree of renal vasoconstriction,
rendering vessels stiffer and less susceptible to rupture
during the application of higher voltages. This hypothesis
was later corroborated in studies by the same group
demonstrating that pretreatment with low-energy SWs
induces early renal vasoconstriction during the application
of high-energy SWs [23]. By contrast, vasoconstriction
occurred only after SWL if pretreatment was absent.
Nevertheless, effectors causing vasoconstriction during
SWL are unknown and further research is needed to elucidate
the full mechanism behind the renal protective response seen
during voltage ramping.
We found that age constitutes a risk factor for renal
hematoma, in agreement with data reported by Dhar et al
[15] showing a 1.67-fold increase in the risk of renal
hematomas using a Modulith SLX (Storz) lithotripter for
each 10-yr increment in age [15]. Possible reasons for their
findings and ours could be increased capillary fragility
associated with age and other uncontrolled factors such as
intake of drugs affecting hemostasis (eg, selective serotonin reuptake inhibitors) or underlying medical comorbidity. Our study also demonstrated some evidence that
patients with higher BMI suffered renal hematomas more
frequently. This was also shown in a retrospective study of
10 887 SWL treatment sessions on 6177 patients [16]. Obesity is a state of chronic systemic inflammation and is
characterized by oxidative stress that enhances the
vulnerability of the vascular basement membrane, which
in turn may increase the risk of bleeding during SWL
[24,25]. In view of the above findings, we argue that in
5
patients with advanced age and/or high BMI, caution
should be exercised during SWL, and concomitant treatment of both kidneys should be avoided.
In terms of clinical effectiveness, stepwise voltage
ramping performed as well as a fixed maximal voltage.
However, it should be kept in mind that the upper bound of
the 95% CI for the difference in stone-free rates (10%) did not
exclude a clinically relevant difference in favor of the fixed
group. In vitro and in vivo studies have suggested that a
progressive increase in voltage during SWL produces
greater stone comminution, mainly by maintaining favorable stress-wave and cavitation bubble dynamics that leads
to constant fragmentation rates [26,27]. In the study by
Lambert et al [11], the ramping group achieved a stone-free
rate of 81% (18/22) compared to 48% (11/23) in the fixed
group [11]. The definition of stone-free was less stringent
than in the present study, as patients with fragments
<2 mm after a single SWL session were also deemed
to be stone-free. In another small randomized trial, Demerci
et al [10] reported similar stone-free rates for voltage
ramping and fixed voltage. Unfortunately, those two studies
recruited insufficient numbers of patients for definitive
conclusions. Moreover, in the study by Demerci et al [10],
patients underwent multiple SWL sessions without this
confounding factor being taken into account. Interestingly,
Honey et al [12], comparing immediate versus delayed
voltage escalation in 160 patients, showed lower success
rates (defined as sand or fragments 4 mm) for the latter
method. Reasons for this finding, which conflicts with those
of other studies, are unclear, but they could be related to
differences in stone burden, stone composition and location, level of operator experience, ramping protocol, and the
type of lithotripter used. Overall, the discrepancy between
our study and other studies may be explained by differing
definitions of success and differences in sample size.
Although well powered, our study design did not define
criteria for clinical effectiveness as a primary outcome, and
given the experimental and theoretical background, superior clinical effectiveness for stepwise voltage ramping
seems to be plausible.
Our prospective randomized trial is not without limitations. Renal hematomas were systemically diagnosed by
ultrasonography, which may have lower sensitivity and
specificity for the diagnosis of renal hematomas than
magnetic resonance imaging (MRI) or computed tomography
(CT), according to which the incidence of renal hematomas
after SWL is 15–24% [28–30]. Nevertheless, ultrasonography
remains an easily accessible and cost-effective imaging
modality. Furthermore, the clinical relevance of very small
hematomas not seen on ultrasound and only on MRI or CT is
questionable.
Another limitation of our study is that the number of
total SWs administered at maximal energy (18 kV) was
higher in the fixed than in the ramping group. It has been
shown that renal injury and impairment are greater at
higher SW voltages [21]. However, there was no significant
difference in total energy applied per kidney/patient
between the two groups. Furthermore, the total energy
applied to patients with and without post-SWL hematoma
Please cite this article in press as: Skuginna V, et al. Does Stepwise Voltage Ramping Protect the Kidney from Injury During
Extracorporeal Shockwave Lithotripsy? Results of a Prospective Randomized Trial. Eur Urol (2015), http://dx.doi.org/10.1016/
j.eururo.2015.06.017
EURURO-6264; No. of Pages 7
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EUROPEAN UROLOGY XXX (2015) XXX–XXX
did not differ within the two groups. We therefore attribute
the protective effect on the kidney to the voltage ramping
strategy.
extracorporeal shockwave lithotripsy in a series of 324 consecutive sessions with the DOLI-S lithotripter: incidents, characteristics, multifactorial analysis and review [in Spanish]. Arch Esp
Urol 2008;61:889–914.
[8] Evan AP, Willis LR, Lingemann JE, McAteer JA. Renal trauma and the
5.
Conclusion
risk of long-term complications in shock wave lithotripsy. Nephron
1998;78:1–8.
Stepwise voltage ramping had a beneficial effect on renal
damage compared to a fixed maximal voltage. Furthermore,
there were no significant differences in treatment effectiveness between the two SWL strategies.
[9] Willis LR, Evan AP, Connors BA, Handa RK, Blomgren PM, Lingeman
JE. Prevention of lithotripsy-induced renal injury by pretreating
kidneys with low-energy shock waves. J Am Soc Nephrol 2006;17:
663–73.
[10] Demirci D, Sofikerim M, Yalçin E, Ekmekçioğlu O, Gülmez I,
Author contributions: Beat Roth had full access to all the data in the study
Karacagil M. Comparison of conventional and step-wise shockwave
and takes responsibility for the integrity of the data and the accuracy of
lithotripsy in management of urinary calculi. J Endourol 2007;21:
the data analysis.
1407–10.
[11] Lambert EH, Walsh R, Moreno MW, Gupta M. Effect of escalating
Study concept and design: Roth.
versus fixed voltage treatment on stone comminution and renal
Acquisition of data: Skuginna, Nguyen, Kiss, Beat Roth.
injury during extracorporeal shock wave lithotripsy: a prospective
Analysis and interpretation of data: Veronika Skuginna, Daniel P. Nguyen,
Beat Roth.
Drafting of the manuscript: Veronika Skuginna.
Critical revision of the manuscript for important intellectual content:
Nguyen, Seiler, Kiss, Thalmann, Roth.
randomized trial. J Urol 2010;183:580–4.
[12] Honey RJ, Ray AA, Ghiculete D, Pace KT. Shock wave lithotripsy: a
randomized, double-blind trial to compare immediate versus
delayed voltage escalation. Urology 2010;75:38–44.
[13] Cevik I, Ozveren B, Ilçöl Y, Ilker Y, Emerk K, Akdaş A. Effects of
Statistical analysis: Skuginna, Nguyen, Roth, Institute of Mathematics,
single-shot and twin-shot shockwaves on urinary enzyme concen-
University of Bern, Switzerland.
trations. J Endourol 1999;13:403–8.
Obtaining funding: None.
Administrative, technical, or material support: Thalmann.
Supervision: Roth, Nguyen.
Patient acquisition and randomization: Nguyen, Seiler, Kiss, Roth.
Financial disclosures: Beat Roth certifies that all conflicts of interest,
including specific financial interests and relationships and affiliations
relevant to the subject matter or materials discussed in the manuscript
(eg, employment/affiliation, grants or funding, consultancies, honoraria,
stock ownership or options, expert testimony, royalties, or patents filed,
received, or pending), are the following: None.
Funding/Support and role of the sponsor: None.
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Appendix A. Supplementary data
poreal shock wave lithotripsy of lower calyx calculi: how much is
treatment outcome influenced by the anatomy of the collecting
system? Eur Urol 2007;52:539–46.
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.
eururo.2015.06.017.
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