Pharmacological effect on pyeloureteric dynamics with a clinical perspective: a review of the literature

Fluid absorption during flexible ureteroscopy with intelligent control of renal pelvic pressure: a randomized controlled trial

PURPOSE

To investigate fluid absorption and its influencing factors during flexible ureteroscopy with intelligent control of renal pelvic pressure (RPP).

METHODS

A total of 80 patients with upper urinary tract calculi underwent flexible ureteroscopy with intelligent control of RPP by pressure-measuring ureteral access sheath and were randomly divided into four groups. The RPP of Groups A, B, and C were set at - 5, 0 and 5 mmHg, respectively. Conventional flexible ureteroscopy with uncontrolled pressure served as control Group D. The perfusion flow rate was set at 100 ml/min in the four groups, with 20 patients in each group. The fluid absorption was measured by 1% ethanol every 10 min. Operation time, stone-free rate, and complications were recorded.

RESULT

Seventy-three patients were finally included in the RCT. The general and preoperative data of the patients were comparable between the groups. The fluid absorption of Groups A, B, and C was significantly less than that of Group D (P < 0.01). Fluid absorption and operation time were positively correlated, and the correlation coefficients R were 0.864, 0.896, 0.918, and 0.947, respectively (P < 0.01). The fluid absorption of patients with vomiting, fever and ureteral injury was greater than that of patients without complications in the four groups (P < 0.01). In different groups, fluid absorption was greater in patients with ureteral injury Post-Ureteroscopic Lesion Scale (PULS) 1-3 than in noninjured patients (P < 0.01).

CONCLUSION

Flexible ureteroscopy with intelligent control of RPP effectively reduces the absorption of perfusion fluid. Operation time and ureteral injury are also key factors affecting perfusion fluid absorption.

REGISTRATION NUMBER AND DATE

NCT05201599; August 11, 2021.

In vivo ureteroscopic intrarenal pressures and clinical outcomes: a multi-institutional analysis of 120 consecutive patients

OBJECTIVES

To evaluate the pressure range generated in the human renal collecting system during ureteroscopy (URS), in a large patient sample, and to investigate a relationship between intrarenal pressure (IRP) and outcome.

PATIENTS AND METHODS

A prospective multi-institutional study was conducted, with ethics board approval; February 2022-March 2023. Recruitment was of 120 consecutive consenting adult patients undergoing semi-rigid URS and/or flexible ureterorenoscopy (FURS) for urolithiasis or diagnostic purposes. Retrograde, fluoroscopy-guided insertion of a 0.036-cm (0.014″) pressure guidewire (COMET™ II, Boston Scientific, Marlborough, MA, USA) to the renal pelvis was performed. Baseline and continuous ureteroscopic IRP was recorded, alongside relevant operative variables. A 30-day follow-up was completed. Descriptive statistics were applied to IRP traces, with mean (sd) and maximum values and variance reported. Relationships between IRP and technical variables, and IRP and clinical outcome were interrogated using the chi-square test and independent samples t-test.

RESULTS

A total of 430 pressure traces were analysed from 120 patient episodes. The mean (sd) baseline IRP was 16.45 (5.99) mmHg and the intraoperative IRP varied by technique. The mean (sd) IRP during semi-rigid URS with gravity irrigation was 34.93 (11.66) mmHg. FURS resulted in variable IRP values: from a mean (sd) of 26.78 (5.84) mmHg (gravity irrigation; 12/14-F ureteric access sheath [UAS]) to 87.27 (66.85) mmHg (200 mmHg pressurised-bag irrigation; 11/13-F UAS). The highest single pressure peak was 334.2 mmHg, during retrograde pyelography. Six patients (5%) developed postoperative urosepsis; these patients had significantly higher IRPs during FURS (mean [sd] 81.7 [49.52] mmHg) than controls (38.53 [22.6] mmHg; P < 0.001).

CONCLUSIONS

A dynamic IRP profile is observed during human in vivo URS, with IRP frequently exceeding expected thresholds. A relationship appears to exist between elevated IRP and postoperative urosepsis.

Intrarenal pressure study using 7.5 French flexible ureteroscope with or without ureteral access sheath in an ex-vivo porcine kidney model

INTRODUCTION

7.5F digital fURS and 9.5/11.5F ureteral access sheaths (UAS), both conventional (cUAS) and vacuum-assisted (vaUAS), are commercially available. Irrigation increases intrarenal pressure (IRP). This study analyzes the IRP with various irrigation rates using 7.5F fURS without UAS or with either cUAS or vaUAS in an ex-vivo porcine model. Pyelo-tubular backflow was also studied during these experiments.

MATERIALS AND METHODS

11 porcine kidneys were used. 7.5F digital fURS was tested without UAS and with 9.5/11.5F cUAS and vaUAS. 6F pressure monitor catheters were placed into the upper and lower calyces. IRPs were recorded under different irrigation rates. When vaUAS was used, the air vent was either open or closed. 300 mmHg aspiration pressure was chosen. Lastly, contrasted irrigation fluid was delivered until IRP reached above 30 mmHg. Fluoroscopy images were obtained at 5 mmHg intervals over this threshold to study the pyelo-tubular backflow.

RESULTS

Using cUAS, IRP reached 30 mmHg with irrigation rates between 60 and 70 cc/min. Using vaUAS with vent closed, IRP never exceeded 10 mmHg with irrigation up to 120 cc/min. vaUAS with vent open performed marginally better than cUAS. fURS without UAS performed better than cUAS. Pyelo-tubular backflow became prominent at 40 mmHg.

CONCLUSION

In an ex-vivo porcine model, 7.5F fURS could be used safely without UAS with irrigation rates up to 120 cc/min. The safety margin dropped to 60-70 cc/min with cUAS. vaUAS with vent closed maintained IRP < 10 mmHg with irrigation rates up to 120 cc/min. Pyelo-tubular backflow was observed with IRP > 35 mmHg.

Upper urinary tract pressures in endourology: a systematic review of range, variables and implications

OBJECTIVES

To systematically review the literature to ascertain the upper tract pressures generated during endourology, the relevant influencing variables and clinical implications.

MATERIALS AND METHODS

A systematic review of the MEDLINE, Scopus and Cochrane databases was performed by two authors independently (S.C., N.D.). Studies reporting ureteric or intrarenal pressures (IRP) during semi-rigid ureteroscopy (URS)/flexible ureterorenoscopy (fURS)/percutaneous nephrolithotomy (PCNL)/miniaturized PCNL (mPCNL) in the period 1950-2021 were identified. Both in vitro and in vivo studies were considered for inclusion. Findings were independently screened for eligibility based on content, with disagreements resolved by author consensus. Data were assessed for bias and compiled based on predefined variables.

RESULTS

Fifty-two studies met the inclusion criteria. Mean IRP appeared to frequently exceed a previously proposed threshold of 40 cmH₂ O. Semi-rigid URS with low-pressure irrigation (gravity <1 m) resulted in a wide mean IRP range (lowest reported 6.9 cmH₂ O, highest mean 149.5 ± 6.2 cmH₂ O; animal models). The lowest mean observed with fURS without a ureteric access sheath (UAS) was 47.6 ± 4.1 cmH₂ O, with the maximum peak IRP being 557.4 cmH₂ O (in vivo human data). UAS placement significantly reduced IRP during fURS, but did not guarantee pressure control with hand-operated pump/syringe irrigation. Miniaturization of PCNL sheaths was associated with increased IRP; however, a wide mean human IRP range has been recorded with both mPCNL (lowest -6.8 ± 2.2 cmH₂ O [suction sheath]; highest 41.2 ± 5.3 cmH₂ O) and standard PCNL (lowest 6.5 cmH₂ O; highest 41.2 cmH₂ O). Use of continuous suction in mPCNL results in greater control of mean IRP, although short pressure peaks >40 cmH₂ O are not entirely prevented. Definitive conclusions are limited by heterogeneity in study design and results. Postoperative pain and pyrexia may be correlated with increased IRP, however, few in vivo studies correlate clinical outcome with measured IRP.

CONCLUSIONS

Intrarenal pressure generated during upper tract endoscopy often exceeds 40 cmH₂ O. IRP is multifactorial in origin, with contributory variables discussed. Larger prospective human in vivo studies are required to further our understanding of IRP thresholds and clinical sequelae.

Evaluation of renal oxygenation by near-infrared spectroscopy during endoscopic injection of bulking agents in children with vesicoureteral reflux

BACKGROUND

Near infrared spectroscopy (NIRS) is the measuring of regional tissue oxygenation (rSO2) by interpreting oxyhemoglobin and deoxyhemoglobin signals that come back by transmitting near infrared light to tissues. The effect of endourological interventions on renal perfusion in children is largely unknown.

AIMS

To evaluate the effects of endoscopic injection of bulking agents (EIBA) for vesicoureteral reflux (VUR) on renal oxygenation (RO) using renal NIRS monitoring, which shows renal perfusion and oxygenation changes.

STUDY DESIGN

Case-control study.

METHODS

Group I had bilateral inguinal surgery, Group II cystoscopy, and Group III, EIBA for VUR with 30 patients in each group. During the operation, vital signs, peripheral oxygen saturation, end-tidal carbon dioxide, and renal regional oxygen saturation index (rSO2) values by bilateral renal NIRS monitoring were recorded. NIRS values before induction (T0) to postoperative (Tend) were determined. A 20% or more reduction in renal rSO2 (%20↓rSO2) was considered significant. Group III was also evaluated as subgroup III-A (not having "%20↓rSO2") and subgroup III-B ("%20↓rSO2").

RESULTS

The rSO2 decrease was observed in the first 5 min for both sides in group III. The most significant drop was at T30 for the right kidney and a significant decrease in rSO2, 20% or more, was observed in 6 renal units of 4 patients having higher SFU grading and renal scar in group III.

CONCLUSION

EIBA may transitionally impair renal oxygenation. Higher SFU grading and renal scar may increase the risk of renal hypoxia during EIBA.

The effect of irrigation rate on intrarenal pressure in an ex vivo porcine kidney model-preliminary study with different flexible ureteroscopes and ureteral access sheaths

INTRODUCTION

Ureteral access sheath (UAS) and irrigation are used in flexible ureteroscopy (fURS). Both conventional UAS (cUAS) and vacuum-assisted UAS (vaUAS) are currently available. Irrigation increases the intrarenal pressure (IRP). Our objectives were to study the effects of various irrigation rates on IRP using different sizes of fURS in different sizes and functions of UAS.

MATERIALS AND METHODS

Ten freshly harvested porcine kidneys served as the study subjects. 11/13F and 12/14F cUAS and vaUAS with 2.8 mm and 3.2 mm fURS were experimented on in various scope/sheath combinations. 6F pressure monitor catheters were placed into upper, middle, and lower calyces. IRPs were recorded under different irrigation rates in cUAS and vaUAS, with either 150 or 300 mmHg aspiration pressures, and with air vent either open or closed.

RESULTS

12/14F cUAS with 2.8 mm fURS could maintain IRPs below 35 mmHg with irrigation rates up to 200 cc/min. With 3.2 mm fURS, the rate dropped to 110-120 cc/min. With 12/14F vaUAS and vent closed, the IRP remained less than 5 mmHg at 200 cc/min irrigation for both fURS. For 11/13F cUAS, the < 35 mmHg threshold for 2.8 mm fURS was 80-90 cc/min; for 3.2 mm fURS, it was 30-40 cc/min. For 11/13F vaUAS with vent closed, IRPs remained < 5 mmHg at 200 cc/min irrigation for both scopes.

CONCLUSION

Both 12F cUAS and vaUAS can be used safely with 2.8 mm fURS up to 200 cc/min irrigation. With either a smaller sheath or a larger scope, vaUAS with vent closed can maintain IRP in a safe range up 200 cc/min irrigation. vaUAS with vent open performed marginally better than cUAS.

Influencing factors of acute kidney injury following retrograde intrarenal surgery

PURPOSE

To investigate the influencing factors of acute kidney injury (AKI) following retrograde intrarenal surgery (RIRS).

METHODS

The data of patients who underwent RIRS for kidney stones between January 2018 and June 2022 at two tertiary centers were retrospectively analyzed. Demographic data of patients were obtained. According to kidney disease: Improving Global Outcomes (KDIGO) criteria, those with and without AKI were divided into two groups. Preoperative, intraoperative, and postoperative predictive factors of patients were investigated between the groups. In addition, the influencing factors of AKI were examined by multivariate analysis.

RESULTS

This study included 295 (35.7%) women and 532 (64.3%) men. The mean age was 50.03 ± 15.4 years (range 18-89), and mean stone size was 15.5 ± 6.1 mm (range 6-47). Overall, 672 of patients (81.3%) were stone-free after the initial treatment. According to KDIGO, 110 of patients (13.3%) had AKI during the postoperative period. Univariate analysis showed that stone size (P = .003), previous stone surgery (P = .010), renal malformations (P = .017), high operative time (P =  < .001), high preoperative creatinine value (P = .036), intraoperative complications (P = .018), and postoperative urinary tract infection (P = .003) had significant influence on the AKI after RIRS. Multivariate analysis excluded previous stone surgery, high preoperative creatinine value, renal malformations, and intraoperative complications from the logistic regression model, whereas other factors maintained their statistically significant effect on AKI, indicating that they were independent predictors.

CONCLUSIONS

Stone size, operative time, postoperative urinary tract infection, and diabetes mellitus are significant predictors of AKI. During RIRS, urologists should consider the factors that increase the risk of AKI and evaluate the treatment outcomes based on these factors.

Comparison of intrarenal pressure between convention and vacuum-assisted ureteral access sheath using an ex vivo porcine kidney model

OBJECTIVE

This study aimed to prove the vacuum-assisted ureteral access sheath (vaUAS) is more effective in maintaining a lower IRP than conventional ureteral access sheath (cUAS).

MATERIALS

The model consisted of 12 freshly harvested adult porcine kidneys.

METHODS

Either a 12/14F cUAS or vaUAS was alternately inserted into the ureter to one cm below the renal pelvis. Upper, middle, and lower calyces were punctured, and 6F pressure monitor catheters were introduced. IRP with cUAS was monitored using various irrigation rates. IRP with vaUAS was monitored with the same irrigation rates; various aspiration pressures; and vent fully closed, 50% closed, and fully open.

RESULTS

cUAS with irrigation rate of 50 cc/min resulted in IRP < 30 mmHg. 50 to 100 cc/min should be used with caution. When irrigation rate exceeded 100 cc/min, IRP rose to ≥ 30 mmHg in most instances. With vent closed, vaUAS with vacuum pressure ≥ 150 mmHg and irrigation rate of 50 cc, 100 cc, and 150 cc/min generally resulted in IRPs < 5 mmHg. With vent half closed, vaUAS with vacuum pressure ≥ 300 mmHg and irrigation rate of ≤ 100 cc/min avoided IRP > 30 mmHg. vaUAS with vent open showed limited advantages over cUAS.

CONCLUSION

vaUAS maintains lower IRP than cUAS under same parameters. Both vaUAS and cUAS can be used when irrigation is ≤ 50 cc/min vaUAS showed clear advantages over cUAS in maintaining lower pressure when irrigation rate is ≥ 100 cc/min.

Monitoring renal oxygenation status by near-infrared spectroscopy during ureterorenoscopy in children

BACKGROUND

: Near-infrared spectroscopy (NIRS) monitoring demonstrates renal blood flow, perfusion, and oxygenation changes. This study aimed to evaluate the effects of pediatric endourological interventions (PEI) on regional oxygen saturation value (rSO2) usingrenal NIRS monitoring.

METHODS

Patients having bilateral inguinal surgery (group I), cystoscopy (group II), and ureterorenoscopy (group III), 20 patients in each group, were included in the study. NIRS values before induction (T0) and at 5 min (T5), 10 min (T10), 15 min (T15), 20 min (T20), 25 min (T25), 30 min (T30) of the surgical procedure, and at the postextubation (Tend) were determined. The amount of irrigation fluid was recorded in groups II and III. The ureterorenoscopy group was also evaluated as two subgroups, as group III-R with patients having a "20%↓rSO2" and as group III-NoR, not having a "20%↓rSO2".

RESULTS

The mean total volume of irrigation was higher in group III, but the difference was not significant between the subgroups III-R and III-NoR. Renal rSO2 decreased significantly in T25, T30, and T-end values in group III. "20%↓rSO2" was seen in 1 patient in group II and 7 patients in group III. In the subgroups III-R, all patients had an obstructive pathology and significant preoperative hydronephrosis with a mean renal pelvis AP diameter of 21.1 ± 16.4 mm.

DISCUSSION

Although rSO2 significantly improves postoperatively, our data may suggest that congenital and acquired obstructive pathologies with hydronephrosis, prolonged operative time with continuous irrigation, and instrument movement in a narrow lumen may increase intrarenal pressure and the risk of renal hypoxia in endourological interventions. Preoperative evaluation of kidney functions and a meticulously well-planned intervention can prevent possible complications.

Comparison of intrarenal pressure between convention and vacuum-assisted ureteral access sheath using an ex vivo porcine kidney model

OBJECTIVE

This study aimed to prove the vacuum-assisted ureteral access sheath (vaUAS) is more effective in maintaining a lower IRP than conventional ureteral access sheath (cUAS).

MATERIALS

The model consisted of 12 freshly harvested adult porcine kidneys.

METHODS

Either a 12/14F cUAS or vaUAS was alternately inserted into the ureter to one cm below the renal pelvis. Upper, middle, and lower calyces were punctured, and 6F pressure monitor catheters were introduced. IRP with cUAS was monitored using various irrigation rates. IRP with vaUAS was monitored with the same irrigation rates; various aspiration pressures; and vent fully closed, 50% closed, and fully open.

RESULTS

cUAS with irrigation rate of 50 cc/min resulted in IRP < 30 mmHg. 50 to 100 cc/min should be used with caution. When irrigation rate exceeded 100 cc/min, IRP rose to ≥ 30 mmHg in most instances. With vent closed, vaUAS with vacuum pressure ≥ 150 mmHg and irrigation rate of 50 cc, 100 cc, and 150 cc/min generally resulted in IRPs < 5 mmHg. With vent half closed, vaUAS with vacuum pressure ≥ 300 mmHg and irrigation rate of ≤ 100 cc/min avoided IRP > 30 mmHg. vaUAS with vent open showed limited advantages over cUAS.

CONCLUSION

vaUAS maintains lower IRP than cUAS under same parameters. Both vaUAS and cUAS can be used when irrigation is ≤ 50 cc/min vaUAS showed clear advantages over cUAS in maintaining lower pressure when irrigation rate is ≥ 100 cc/min.

Risk of Sepsis in Retrograde Intrarenal Surgery: A Systematic Review of the Literature

Context

Objective

Evidence acquisition

Evidence synthesis

Conclusions

Patient summary

Salbutamol for analgesia in renal colic: study protocol for a prospective, randomised, placebo-controlled phase II trial (SARC)

BACKGROUND

Renal colic is the pain experienced by a patient when a renal calculus (kidney stone) causes partial or complete obstruction of part of the renal outflow tract. The standard analgesic regimes for renal colic are often ineffective; in some studies, less than half of patients achieve complete pain relief, and a large proportion of patients require rescue analgesia within 4 h. Current analgesic regimes are also associated with significant side effects including nausea, vomiting, drowsiness and respiratory depression. It has been hypothesised that beta adrenoreceptor agonists, such as salbutamol, may reduce the pain of renal colic. They have been shown to impact a number of factors that target the physiological causes of pain in renal colic (ureteric spasm and increased peristalsis, increased pressure at the renal pelvis and prostaglandin release with inflammation). There is biological plausibility and a body of evidence sufficient to suggest that this novel treatment for the pain of renal colic should be taken to a phase II clinical trial. The aim of this trial is to test whether salbutamol is an efficacious analgesic adjunct when added to the standard analgesic regime for patients presenting to the ED with subsequently confirmed renal colic.

METHODS

A phase II, randomised, placebo-controlled trial will be performed in an acute NHS Trust in the East Midlands. Patients presenting to the emergency department with pain requiring IV analgesia and working diagnosis of renal colic will be randomised to receive standard analgesia ± a single intravenous injection of Salbutamol. Secondary study objectives will explore the feasibility of conducting a larger, phase III trial.

DISCUSSION

The trial will provide important information about the efficacy of salbutamol as an analgesic adjunct in renal colic. It will also guide the development of a definitive phase III trial to test the cost and clinical effectiveness of salbutamol as an analgesic adjunct in renal colic. Salbutamol benefits from widespread use across the health service for multiple indications, extensive staff familiarity and a good side effect profile; therefore, its potential use for pain relief may have significant benefits for patient care.

TRIAL REGISTRATION

ISRCTN Registry ISRCTN14552440 . Registered on 22 July 2019.

Can Urinary KIM-1 and NGAL Predict Management Endoscopic Surgery in Acute Unilateral Obstructive Stone Disease? Results from a Prospective Cohort Study

INTRODUCTION

Kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) are the leading novel biomarkers used efficiently in acute kidney injury (AKI). The levels of these biomarkers increase especially in the early period of nephrotoxic and ischemic renal damage. In this study, we aimed to investigate the clinical importance of NGAL and KIM-1 biomarkers used in the effective evaluation of kidney functions in patients with acute unilateral obstructive stone disease (AUOSD) in the management of endoscopic surgery.

MATERIALS AND METHODS

We prospectively included patients who underwent endoscopic surgery due to AUOSD between January 2018 and December 2019. Urine KIM-1 and NGAL values of the patients were measured preoperative period, postoperative 4th h, and postoperative 7th day. The patients were evaluated according to the location and size of the stone, the degree of renal hydronephrosis, the duration of the operation, complications, and JJ stent placement.

RESULTS

The study enrolled 50 patients. Urinary KIM-1/Cr and urinary NGAL/Cr ratios were higher in postoperative 4th h than in others (p < 0.001). Also, we found that urinary KIM-1/Cr and urinary NGAL/Cr ratios with Grade 2 and higher hydronephrosis were statistically higher than Grade 0-1 hydronephrosis (p < 0.001 and p: 0.042, respectively). Additionally, a preoperative urinary KIM-1 value of 1.24 ng/mL had a sensitivity of 78% and a specificity of 63% to predict the presence of hydronephrosis. When urine KIM-1 and NGAL results were compared with surgery time, stone size and location, serum creatinine (sCr) value, and Post-Ureteroscopic Lesion Scale grade, the difference was not statistically significant. Postoperative 7th day NGAL/Cr and KIM-1/Cr ratios were statistically higher in those with JJ stents placed (p: 0.03 and p: 0.004, respectively).

CONCLUSION

KIM-1 and NGAL can be used in our assessment of renal function in patients with AUOSD, even if sCr is normal. Also, these biomarkers can predict the presence of hydronephrosis. It can be helpful in determining the time of surgical treatment, as well as providing information in the follow-up of patients with JJ stents after treatment.

Prospective Evaluation of Ipsilateral and Contralateral Renal Blood Flow During Retrograde Intrarenal Surgery

OBJECTIVES

To evaluate the changes of peak systolic velocity(PSV), end-diastolic velocity(EDV), and resistive index(RI) of renal and arcuate arteries at the ipsilateral and contralateral kidneys during the retrograde intrarenal surgery.

METHODS

The patients who had RIRS for the treatment of renal stones were prospectively included in the study. An experienced radiologist performed doppler ultrasonography of the ipsilateral and contralateral kidney before the surgery just after the anesthesia and at the end of the surgery before stenting. The PSV, EDV, and RI of renal and arcuate arteries at the ipsilateral and contralateral kidneys were measured.

RESULTS

A total of 53 patients were included in the study. The postoperative mean PSV, EDV, and RI of renal arteries at the ipsilateral and contralateral arteries were similar to preoperative values. The mean PSV and RI of the arcuate arteries at the ipsilateral kidney significantly increased postoperatively (P = 0.032, P = 0.012) The postoperative mean PSV, EDV, and RI of arcuate arteries did not change significantly during the surgery. The age, gender, and flexible ureteroscopy time did not affect the change of renal and arcuate arterial PSV, EDV, and RI at the ipsilateral and contralateral kidneys.

CONCLUSION

The elevation of intrarenal pressure during RIRS did not change the blood flow at the major arteries of the ipsilateral and contralateral kidneys. On the other hand, there was a significant increase at the RI of the arcuate arteries in the ipsilateral kidney which was proposed to be related to the vasoconstriction of minor vasculature of the kidney.

[Role of pressure and temperature in ureterorenoscopy and percutaneous nephrolitholapaxy : Pressure and temperature changes during stone treatment]

Ureterorenoscopy and percutaneous nephrolitholapaxy are minimally invasive procedures and are the standard procedures for the treatment of kidney stones and ureteral calculi. To achieve an adequate view, in both methods an optimal and sufficient irrigation flow is necessary. The intrarenal pressure is influenced by the irrigation pressure and irrigation volume and has to be controlled. Pathologically elevated intrarenal pressure can lead to irreversible damage of the kidneys. Lasers are frequently used for stone fragmentation. It has been shown in studies that the laser energy can lead to an increase in the temperature and that thermal effects can also damage the kidneys. This article provides the surgeon with an overview about the effects of temperature and pressure changes during ureterorenoscopy and percutaneous nephrolitholapaxy and how damages can be avoided.

Pressure matters: intrarenal pressures during normal and pathological conditions, and impact of increased values to renal physiology

PURPOSE

To perform a review on the latest evidence related to normal and pathological intrarenal pressures (IRPs), complications of incremented values, and IRP ranges during endourology.

METHODS

A literature search was performed using PubMed, restricted to original English-written articles, including animal, artificial model, and human studies. Different keywords were: percutaneous nephrolithotomy, PCNL, ureteroscopy, URS, RIRS, irrigation flow, irrigation pressure, intrarenal pressure, intrapelvic pressure and renal pelvic pressure.

RESULTS

Normal IRPs range from zero to a few cm H₂O. Pyelovenous backflow may occur at pressure range of 13.6-27.2 cm H₂O. During upper tract endourology, complications such as pyelorenal backflow, sepsis, and renal damage are directly related to increased IRPs. Duration of increased IRPs and concomitant obstruction are independent predictors of complication development.

CONCLUSIONS

IRP increase remains a neglected predictor of upper tract endourology complications and its intraoperative monitoring should be taken into consideration. Further research is necessary, to quantify pressures generated during upper tract endourology, and introduce means of controlling them.

Risks of flexible ureterorenoscopy: pathophysiology and prevention

Currently, indications for flexible ureterorenoscopy (fURS) are expanding, mainly due to technological advancements. Although data from clinical series definitely presents fURS as a safe procedure, serious complications including sepsis and ureteral lesions do occur. These complications seem to be a result of the unique elements of fURS, ureteral access and irrigation, pushing normal upper urinary tract physiology into pathophysiological processes, including intrarenal/pyelo-veneous backflow and ureteral contractions, potentially resulting in septic, haemorrhagic and ureteral lesional complications. Knowledge on normal upper urinary tract physiology are crucial for understanding how these harmful effects of fURS may be avoided or minimized. The pathophysiology of intrarenal pressure increases and ureteral access will be discussed as a basis for understanding preventive measures. Role of antibiotics, ureteral access sheaths, safty guidewires, pain medication, prestenting and pharmacologic modulation of pyeloureteral dynamics are reviewed from a pathophysiological perspective.

Comparison of renal pelvic pressure and postoperative fever incidence between standard- and mini-tract percutaneous nephrolithotomy

This study was proposed to compare the clinical effectiveness of mini-tract percutaneous nephrolithotomy (MPCNL) with standard-tract percutaneous nephrolithotomy (SPCNL) and verify whether MPCNL is associated with both higher renal pelvic pressure (RPP) and incidence of postoperative fever. A total of 228 patients with kidney stone were randomly allocated to the MPCNL group (n=114) and SPCNL group (n=114). Both intraoperative and postoperative indexes along with the incidence of complications were compared between the two treatment groups. RPP was measured using a baroreceptor which was connected to an open-ended ureteric catheter during the operation of percutaneous nephrolithotomy. The MPCNL group exhibited significantly longer average operation time, more average amount of flush water, and lesser average amount of bleeding during the operation than the SPCNL group (p<0.05). Moreover, significantly lesser average amount of postoperative serum creatinine, shorter average hospital stay, and more average amount of postoperative hemoglobin were observed in the MPCNL group than in the SPCNL group (p<0.05). MPCNL were more applicable to clear caliceal stones (p<0.05), whereas SPCNL were more effective for the removal of simple pelvic stones. The difference in the incidence of postoperative fever between the two treatment groups also appeared to be significant (p<0.05). Logistic regression provided solid evidence that both RPP and its accumulation time at which RPP≥30 mmHg significantly affected the incidence of postoperative fever. MPCNL was correlated with both higher RPP and increased likelihood of postoperative fever compared with SPCNL.

Pathophysiological aspects of ureterorenoscopic management of upper urinary tract calculi

PURPOSE OF REVIEW

Indications for ureterorenoscopy are expanding without hard scientific evidence to support its efficacy. Therefore, it is extremely important to focus on potential harmful effects of the procedure itself. This review explores how physiology of the upper urinary tract reacts to ureterorenoscopy, potentially translating into harmful effects, and how such pathophysiological processes may be minimized.

RECENT FINDINGS

Complications to ureterorenoscopy and postoperative pain seem to be related to intrarenal pressure and/or access. Mean intrarenal pressures in the range of 60-100 mmHg during ureterorenoscopy without access sheaths have been measured, thus by far exceeding the threshold for intrarenal backflow, potentially resulting in septic complications. Intrarenal pressure may be reduced by use of ureteral access sheaths, which, however, may cause ureteral damage due to the limited size of the ureter and strain-induced ureteral contractions (peristalsis). Different receptor types modulate this peristaltic activity. β-receptor agonists have been investigated in animal and human trials for the purpose of relaxing the ureter. In randomized, placebo-controlled trials in pigs and humans, usage of the β-receptor agonist isoproterenol in the irrigation fluid has shown a potential for reducing both intrarenal pressure and ureteral tone during ureterorenoscopy.

SUMMARY

Upper urinary tract physiology has unique features that may be pushed into pathophysiological processes by the unique elements of ureterorenoscopy: access and irrigation. Pharmacological ureteral relaxation during ureterorenoscopy deserves further attention with regard to reducing complications and postoperative pain.

β-Adrenoreceptor agonists in the management of pain associated with renal colic: a systematic review

OBJECTIVES

To determine whether β-adrenoreceptor agonists are effective analgesics for patients with renal colic through a systematic review of the literature.

SETTING

Adult emergency departments or acute assessment units.

PARTICIPANTS

Human participants with proven or suspected renal colic.

INTERVENTIONS

β-adrenoreceptor agonists.

OUTCOME MEASURES

Primary: level of pain at 30 min following administration of the β-agonist. Secondary: level of pain at various time points following β-agonist administration; length of hospital stay; analgesic requirement; stone presence, size and position; degree of hydronephrosis.

RESULTS

256 records were screened and 4 identified for full-text review. No articles met the inclusion criteria.

CONCLUSIONS AND IMPLICATIONS

There is no evidence to support or refute the proposed use of β-agonists for analgesia in patients with renal colic. Given the biological plausibility and existing literature base, clinical trials investigating the use of β-adrenoreceptor agonists in the acute setting for treatment of the pain associated with renal colic are recommended.

TRIAL REGISTRATION NUMBER

CRD42015016266.

Verapamil Inhibits the Pelvic Pressure Increase Corresponding to Flow Perfusion in the Porcine Percutaneous Renal Puncture Model

PURPOSE

To estimate the effects of verapamil on pelvic pressure and investigate the possible systemic side effects in the porcine model during the procedure of increasing perfusion rates.

MATERIALS AND METHODS

In the experimental group, the pelvic pressure was recorded with increasing perfusion rates of the renal pelvis (0, 2, 4, 6, 8, 10, 14 and 20 ml/min) in response to intraluminal administration of increasing concentrations of verapamil (0, 0.1, 1, 10 and 100 µg/ml) in isotonic saline. In the isotonic saline group, the pressure flow study was also done by increasing perfusion rates of the renal pelvis per animal using isotonic saline without verapamil.

RESULTS

Perfusion with 1, 10 and 100 µg/ml verapamil caused a decrease in pelvic pressure as a response to increasing flow rates, whereas perfusion with 0.1 µg/ml verapamil did not obviously inhibit the increase of pelvic pressure at all perfusion rates compared with other concentrations. Importantly, the mean systolic blood pressure and mean heart rate were stable despite the increase of flow rates and verapamil concentrations. In the isotonic saline group, perfusion with isotonic saline resulted in an increase in the pelvic pressure with an increase in flow rates each time.

CONCLUSIONS

Endoluminal administration of verapamil reduces pelvic pressure significantly without any untoward systemic cardiovascular side effects.

How should patients with cystine stone disease be evaluated and treated in the twenty-first century?

Cystinuria continues to be one of the most challenging stone diseases. During the latest decades our knowledge of the molecular basis of cystinuria has expanded. Today 160 different mutations in the SLC3A1 gene and 116 in the SLC7A9 gene are listed. The full implications of type A, B or AB status are not yet fully understood but may have implications for prognosis, management and treatment. Despite better understanding of the molecular basis of cystinuria the principles of recurrence prevention have remained essentially the same through decades. No curative treatment of cystinuria exists, and patients will have a life long risk of stone formation, repeated surgery, impaired renal function and quality of life. Therapy to reduce stone formation is directed towards lowering urine cystine concentration and increasing cystine solubility. Different molecules that could play a role in promoting nucleation and have a modulating effect on cystine solubility may represent new targets for cystinuria research. Investigation of newer thiol-containing drugs with fewer adverse effects is also warranted. Determining cystine capacity may be an effective tool to monitor the individual patient's response. Compliance in cystinuric patients concerning both dietary and pharmacological intervention is poor. Frequent clinical follow-up visits in dedicated centres seem to improve compliance. Cystinuric patients should be managed in dedicated centres offering the complete range of minimal invasive treatment modalities, enabling a personalized treatment approach in order to reduce risk and morbidity of multiple procedures.

Pharmacological modulation of ureteric peristalsis in a chronically instrumented conscious pig model: effect of adrenergic and nitrergic modulation

PURPOSE

To evaluate the role of adrenergic and nitrergic signaling on ureteric peristaltic frequency and contraction force in vivo using a large animal model.

METHODS

Twelve female pigs (72 ± 4 kg) were chronically instrumented with an electronic pressure-monitoring catheter in the right ureter. Nephrostomy, cystostomy, and arterial and venous catheters were left in situ. Ureteral peristalsis was recorded before and after the administration of propranolol, isoprenaline, doxazosin, urapidil, phenylephrine, LNNA (Nω-nitro-L-arginine), and L-arginine.

RESULTS

α1-Adrenergic receptor stimulation resulted in an increased P max and peristaltic frequency. However, α1-inhibition decreased P max alone. Similarly, β-adrenergic stimulation decreased P max and peristaltic frequency, whereas β-inhibition increased only P max. LNNA administration increased P max in the distal ureter and hydrostatic pressure in the pyelocalyceal system. L-Arginine did not affect P max or frequency, but resulted in a significantly higher diuresis. Either agonist or antagonist of NO did not affect peristaltic frequency and length of contraction.

CONCLUSIONS

Activation of α- and β-adrenergic receptors, respectively, stimulates and inhibits ureteric peristalsis. The biological effect of NO on ureteric motility is regionally determined and corresponds to the distribution of NOS-positive nerves. Inhibition of NOS activity increases P max in the distal ureter and tonic activity of the ureteric muscle resulting in higher hydrostatic pressure in the renal pelvis.

Intraluminal pressure profiles during flexible ureterorenoscopy

Background

Irrigation and instrumentation during ureterorenoscopic procedures may cause increased pressure in the renal pelvis (PP) with potential harmful adverse effects. In order to assess the pressure increases during ureterorenoscopy, we measured the intraluminal renal pelvic pressure during retrograde intrarenal stone surgery (RIRS).

Methods

Twelve patients admitted for RIRS were included. Irrigation rate was standardized to 8 ml/min. A ureteral catheter was retrogradely placed in the renal pelvis for PP measurements. PP was measured one time per second during insertion of the Storz Flex-X2 ureteroscope and during stone treatment.

Results

Baseline PP was mean 10(±4.0) mmHg. During simple ureterorenoscopy, PP was mean 35(±10) mmHg. During stone management the average PP was 54(±18) mmHg and pelvic pressure peaks up to 328 mmHg occurred. In a 5-min standardized period of simple ureterorenoscopy, 83 pressure peaks >50 mmHg were measured in average per patient (range 2–238). Forced irrigation with a 20 ml syringe resulted in pressure peaks up to 288 mmHg.

Conclusion

Very high pelvic pressures are obtained during flexible ureterorenoscopy. Taking into consideration that the threshold for pyelovenous backflow is around 30 mmHg, it is concerning that PPs >300 mmHg are not uncommon during these procedures. Methods to monitor and lower the PP during ureterorenoscopy, therefore, are considered of importance.

Fluid-electrolyte and renal pelvic pressure changes during ureteroscopic lithotripsy

Abstract The objective of the study was to evaluate fluid-electrolyte and renal pelvic pressure (RPP) changes during ureteroscopic lithotripsy. Fifteen patients were detected with residual ureteral calculi after minimally invasive percutaneous nephrolithotomy (MPCNL), distal ureter calculi in three, midureter calculi in four, proximal calculi in eight. RPP was measured via the percutaneous nephrostomy tube by urodynamic study at irrigation pressures of 50, 100 and 200 mmHg. Haemoglobin (Hb), haematocrit (Hct), blood urea mitrogen (BUN), creatinine (Cre), serum sodium (Na(+)), potassium (K(+)), chlorine (Cl(-)) were recorded before and after ureteroscopic lithotripsy. There were no significant differences between Hb, Hct, BUN, Cre, Na(+), K(+), Cl(-) values. Baseline RPP was (16.37 ± 3.14) cmH(2)O, RPPs were 46.06 ± 6.85 cmH(2)O, 99.07 ± 14.62 cmH(2)O and 166.27 ± 33.08 cmH(2)O at irrigation pressures of 50, 100 and 200 mmHg, they were much higher than baseline RPP (p < 0.0001). RPP in the proximal ureter was much higher than in the distal and middle ureter, 50.98 ± 4.52 cmH(2)O versus 40.44 ± 4.07 cmH(2)O (p = 0.0004), 110.26 ± 2.39 cmH(2)O versus 86.29 ± 11.60 cmH(2)O (p = 0.0014), 193.21 ± 5.88 cmH(2)O versus 135.47 ± 20.95 cmH(2)O (p = 0.0002) at irrigation pressures of 50, 100 and 200 mmHg. There were no significant changes in fluid-electrolyte. RPP was significantly increased during ureteroscopic lithotripsy, it was correlated with the irrigation pressure and the position in the ureter.

Visceral pain originating from the upper urinary tract

Pain originating from the upper urinary tract is a common problem and stone colic is one of the most intense pain conditions that can be experienced in the clinic. The pain is difficult to alleviate and often leads to medical attention. In humans, pain mechanisms of the upper urinary tract pain are still poorly understood, which often leads to a trial and error approach in clinical pain management. Pain from the upper urinary tract seems to have all the characteristics of pure visceral pain, including referred pain with or without hyperalgesia/trophic changes in somatic tissues and viscero-visceral hyperalgesia. However, further studies are needed to better understand these visceral pain mechanisms with regard to optimising pain management. This review gives an introduction to visceral pain in general and upper urinary tract pain in particular, with special reference to pain pathways and pharmacological and non-pharmacological pain modulation.

Adjuvant therapy after surgical stone management

The aim of this article was to review the most widely researched adjuvant medical therapies for the surgical management of urolithiasis. Articles were identified and reviewed from PubMed and Medline databases with MeSH headings focusing on the various surgical treatments of urolithiasis and adjuvant therapy. Additional articles were retrieved from references and conference proceedings. Surgical treatments reviewed included shockwave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy. Adjuvant therapy was considered medical or complementary therapy as an adjunct to these surgical interventions. Adjuvant therapy for the surgical management of urolithiasis has been documented to increase stone-free rates, reduce stone remission rates, prevent renal damage, and decrease postoperative morbidity. A variety of agents have been studied, ranging from antioxidants to alpha-blockers and to alkalinizing agents. Additionally, there is increasing interest in complementary adjuvant therapy (ie, acupuncture). Adjuvant therapy is a fertile area for research in the surgical management of urolithiasis. The optimal agents have yet to be determined and therefore further investigation is warranted and necessary.

Shared occupational risks for transitional cell cancer of the bladder and renal pelvis among men and women in Sweden

BACKGROUND

Unlike cancer of the bladder, cancer of the renal pelvis is not considered an occupational cancer and little is known about risks among women.

METHODS

Using the Swedish national census and cancer registry-linked data (1971-1989), we identified transitional cell cancers of the renal pelvis (N = 1,374) and bladder (N = 21,591). Correlation between cancer sites for the standardized incidence ratios (SIR) were determined using Pearson's coefficient of the log SIR. Relative risks of job exposure matrix variables were calculated using Poisson regression.

RESULTS

Both cancer sites were significantly elevated among women and men employed in the machine/electronics industry, sedentary work, and indoor work, and men in the metal industry. The highest proportion of the bladder (12%) and renal pelvis (14%) cancers occurred among men employed in shop and construction metal work. Risks by industry were more correlated among women (r = 0.49, P = 0.002) than men (r = 0.24, P = 0.04). Cancers of the renal pelvis were elevated in several occupational and industry groups for which there was no elevated bladder cancer risk.

CONCLUSION

Cancers of the renal pelvis and bladder share common occupational risk factors that may be more frequent among women. In addition, there may be some jobs that pose an increased risk specifically for cancer of the renal pelvis but not bladder.

Irrigation with isoproterenol diminishes increases in pelvic pressure without side-effects during ureterorenoscopy: a randomized controlled study in a porcine model

OBJECTIVE

Recently, we showed that endoluminally administered isoproterenol (ISO) inhibits muscle function of the pyeloureter in swine. This may be of value in managing increases in pelvic pressure during upper urinary tract endoscopy. The purpose of this study was to examine the effect of endoluminally administered ISO on increases in pelvic pressure and cardiovascular function during flexible ureterorenoscopy.

MATERIAL AND METHODS

The study was performed in anaesthetized female pigs. In terms of endoscopic procedures, the pigs were randomized as follows: Group 1, irrigation with 0.1 microg/ml ISO added to saline (n=12); and Group 2, irrigation with saline (n=10). A 5-Fr catheter was retrogradely placed in the renal pelvis and an 8-Fr catheter in the bladder for pressure measurements. Flexible ureterorenoscopy was performed with constant irrigation at a perfusion rate of 8 ml/min. Pelvic, bladder and blood pressure and heart rate were registered continuously.

RESULTS

Mean baseline pelvic pressure was identical in both groups: 12+/-2.3 mmHg in Group 1 and 14+/-3.6 mmHg in Group 2 (p=0.26). During ureterorenoscopy, mean pelvic pressure increased to 26+/-2.3 mmHg in Group 1 and to 38+/-3.1 mmHg in Group 2. Hence ISO reduced the pressure increase due to ureterorenoscopy by 42% (p<0.001). Pelvic pressure seemed to be independent of bladder pressure, which showed no difference between the two groups (p=0.067). Blood pressure and heart rate showed no significant differences between the two groups: p=0.425 and p=0.166, respectively.

CONCLUSIONS

ISO (0.1 microg/ml) added to irrigation fluid significantly reduces the increase in pelvic pressure during ureterorenoscopy in pigs, without concomitant side-effects.