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NCT Number: NCT03023488

Effects of Flexible Ureteroscopy on Renal Blood Flow

Aim of this study is to investigate the effects of increased intrarenal pressure during flexible ureteroscopy on renal blood flow.

Patients undergoing flexible ureteroscopy (F-URS) and laser lithotripsy for kidney stones according to European Association of Urology (EAU) guidelines on Urolithiasis will be included in the study after having signed an informed consent form. The pre- and post-operative evaluation and management will be performed according to EAU Guidelines on Urolithiasis. Additionally, as a non-invasive test, bilateral renal power Doppler US will be performed to patients pre- and post-operatively. The pre-operative Doppler US will be performed 2 days prior to surgery and the post-operative Doppler US will be performed in the first 24 hours following surgery. The changes on blood flow in renal artery and arcuate artery will be recorded.

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Key information

Conditions

Circulatory; Change

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

About this study

Aim of this study is to investigate the effects of increased intrarenal pressure during flexible ureteroscopy on renal blood flow.

Patients undergoing flexible ureteroscopy and laser lithotripsy for kidney stones according to EAU guidelines on Urolithiasis will be included in the study after having signed an informed consent form. The pre- and post-operative evaluation and management will be performed according to EAU Guidelines on Urolithiasis. Additionally, as a non-invasive test, bilateral renal power Doppler US will be performed to patients pre- and post-operatively. The pre-operative Doppler US will be performed 2 days prior to surgery and the post-operative Doppler US will be performed in the first 24 hours following surgery. The changes on blood flow in renal artery and arcuate artery will be recorded.

Flexible ureteroscopy has been a key component of kidney stone management in the last 20 years. Even for stones larger than 2 cm, flexible ureteroscopy can be performed with high success and low complication rates. Ureteral access sheaths are key contributors to flexible ureteroscopy as they provide easy and repeated access to upper urinary tract and decreased intrarenal pressures due to easy flow back of the irrigation solution.

The increased pressures during flexible ureteroscopy have been an important research area in the last years. Due to irrigation solution and irrigational pumping to provide a clearer vision during flexible ureteroscopy, intrarenal pressures rise and after a certain point pyelo-sinusoidal, pyelo-venous and pyelo-lymphatic backflow starts. It has been shown that this backflow starts when pressure rises above 40 cmH2O (centimeters-water / unit of pressure measurement). Schwalb et al. demonstrated in their study that in kidneys subject to high intrarenal pressure, denudation and flattening of the caliceal urothelium, submucosal edema and congestion are observed. Due to these deleterious effects on urothelium, renal extravasation and bacterial translocation can occur and complications may arise.

Renal Doppler US, due to its non-invasive nature, has been widely used to measure localized blood flow in the kidneys, to evaluate hemodynamic parameters in acute kidney injury. Intrarenal backflow and its consequences such as submucosal edema and congestion may decrease blood flow especially around the calyces subject to high pressures and this situation may result in acute kidney injury.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients between ages 18-65
  • Patients undergoing flexible ureteroscopy + laser lithotripsy according to EAU Guidelines on Urolithiasis

Exclusion criteria

  • Pregnant patients
  • Patients with already-diagnosed urological malignancies
  • Patients ineligible for flexible ureteroscopy due to concomitant co-morbidities

Treatment and study plan

flexible ureteroscopy

Procedure

Flexible ureteroscopy is an endourological procedure performed for kidney stones. The flexible ureteroscope is a device used to reach the renal cavities through the natural urinary tract in a retrograde fashion. During the operation, irrigation fluid is used to expand the cavities to provide space for movement of the device and also to provide clear vision.

Doppler Ultrasound examination

Device

peak systolic velocities (PSV) and end diastolic velocities (EDV) of the arteries will be measured and then resistive index (RI) and pulsatility index (PI) will be calculated.

laser lithotripsy

Device

The laser fiber extending into the cavities through the working channel of the ureteroscope is used to fragment the stones. Laser energy is generated by the laser machine and transmitted to the stones via the laser fiber.

Primary outcomes

  1. Peak Systolic Velocities (PSV) Measurement by Renal Doppler Ultrasound (US) Examination Evaluating the Effects of Flexible Ureteroscopy (F-URS) on Renal Blood Flow by Demonstrating the Change Between the Pre-operative and Post-operative Parameters.

    Time frame: The doppler examination will be performed 2 days before surgery and the change will be assessed within 1 day of the operation. So, the initial evaluation will be performed and change of values will be assessed 72 hours after the initial evaluation

    Doppler US will be performed at two times: 2 days prior to surgery and within the first 24 hours following F-URS to show the change between the pre-operative and post-operative periods. Doppler examination includes renal arteries and arcuate arteries. For each patient, the following parameters are measured: peak systolic velocities (PSV) and end diastolic velocities (EDV), resistive index (RI) and pulsatility index (PI) of the arteries. The unit for PSV and EDV is cm/sec. RI and PI doesn't have a unit, they are quantitative measures calculated from PSV and EDV.

    PSV is the maximum velocity in the renal and arcuate arteries in the systolic phase of each heart pulse.

  2. End Diastolic Velocities (EDV) Measurement by Renal Doppler Ultrasound (US) Examination Evaluating the Effects of Flexible Ureteroscopy (F-URS) on Renal Blood Flow by Demonstrating the Change Between the Pre-operative and Post-operative Parameters.

    Time frame: The doppler examination will be performed 2 days before surgery and the change will be assessed within 1 day of the operation. So, the initial evaluation will be performed and change of values will be assessed 72 hours after the initial evaluation

    Doppler US will be performed at two times: 2 days prior to surgery and within the first 24 hours following F-URS to show the change between the pre-operative and post-operative periods. Doppler examination includes renal arteries and arcuate arteries. For each patient, the following parameters are measured: peak systolic velocities (PSV) and end diastolic velocities (EDV), resistive index (RI) and pulsatility index (PI) of the arteries. The unit for PSV and EDV is cm/sec. RI and PI doesn't have a unit, they are quantitative measures calculated from PSV and EDV.

    EDV is the velocity in the renal and arcuate arteries at the end of the diastolic phase of each heart pulse.

  3. Resistive Index (RI) Calculation by Renal Doppler Ultrasound (US) Examination Evaluating the Effects of Flexible Ureteroscopy (F-URS) on Renal Blood Flow by Demonstrating the Change Between the Pre-operative and Post-operative Parameters.

    Time frame: The doppler examination will be performed 2 days before surgery and the change will be assessed within 1 day of the operation. So, the initial evaluation will be performed and change of values will be assessed 72 hours after the initial evaluation

    Doppler US will be performed at two times: 2 days prior to surgery and within the first 24 hours following F-URS to show the change between the pre-operative and post-operative periods. Doppler examination includes renal arteries and arcuate arteries. For each patient, the following parameters are measured: peak systolic velocities (PSV) and end diastolic velocities (EDV), resistive index (RI) and pulsatility index (PI) of the arteries. The unit for PSV and EDV is cm/sec. RI and PI doesn't have a unit, they are quantitative measures calculated from PSV and EDV.

    Resistive index is calculated as the difference between PSV and EDV, divided by PSV [(PSV - EDV) / (PSV)].

    An increased resistive index can be considered as a marker of intrarenal arterial stiffness and is associated with worsening of renal function and tubulointersitial damage.

  4. Pulsatility Index (PI) Calculation by Renal Doppler Ultrasound (US) Examination Evaluating the Effects of Flexible Ureteroscopy (F-URS) on Renal Blood Flow by Demonstrating the Change Between the Pre-operative and Post-operative Parameters.

    Time frame: The doppler examination will be performed 2 days before surgery and the change will be assessed within 1 day of the operation. So, the initial evaluation will be performed and change of values will be assessed 72 hours after the initial evaluation

    Doppler US will be performed at two times: 2 days prior to surgery and within the first 24 hours following F-URS to show the change between the pre-operative and post-operative periods. Doppler examination includes renal arteries and arcuate arteries. For each patient, the following parameters are measured: peak systolic velocities (PSV) and end diastolic velocities (EDV), resistive index (RI) and pulsatility index (PI) of the arteries. The unit for PSV and EDV is cm/sec. RI and PI doesn't have a unit, they are quantitative measures calculated from PSV and EDV.

    Pulsatility index is calculated as the difference between PSV and EDV, divided by the mean velocity [(PSV - EDV) / ((PSV + EDV) / 2)].

    Pulsatility index is used to discriminate between renal and pre-renal causes of acute kidney injury which can alter the therapeutic options in the clinical setting.

Secondary outcomes

  1. Technical Details - Size of Ureteral Access Sheath

    Time frame: 1 hour after the operation

    The size of access sheaths will be given in French measurement. E.g. 10/12 Fr

  2. Technical Details - Name of Flexible Ureteroscope

    Time frame: 1 hour after the operation

    Each ureteroscope has unique characteristics. So, every ureteroscope that will be used, will be recorded with its name. E.g. Storz Flex-X2, Olympus V1, Wolf Cobra

  3. Duration of the Flexible Ureteroscopy Operation

    Time frame: 10 minutes after the operation

    the data about the duration of the operation that will be performed for each patient and the data will be recorded in minutes.

  4. Operative Characteristics - Irrigation Pressure

    Time frame: 1 hour after the operation

    The pressure that is applied to the irrigation solution which is circulated through the ureteroscope that is used to expand the renal cavities during a flexible ureteroscopy operation. the data will be collected in cmH2O. This pressure value is a constant value and it doesn't change throughout the length of the procedure.

  5. Operative Characteristics - Intraoperative Complications

    Time frame: 1 hour after the operation

    The number of patients that has experienced any kind of intraoperative complications during the flexible ureteroscopy operation.

  6. Post-Operative Characteristics - Complications

    Time frame: The data will be recorded within 1 month after each procedure.

    The number of patients that had a complication in the first 1 month after the operation according to the Clavien Dindo Grading system (0-5).

    Clavien Dindo Grading ranges from 0 (mildest) to 5 (most severe). 0. No complications

    • Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic and radiological interventions. Allowed therapeutic regimens are drugs as antiemetics, antipyretics, analgesics, diuretics, electrolytes and physiotherapy. This grade also includes wound infections opened at the bedside
    • Complications requiring pharmacological treatment with drugs other than such allowed for grade I complications. Blood transfusions and total parenteral nutrition are also included
    • Complications requiring surgical, endoscopic or radiological intervention
    • Life-threatening complications (including CNS complications) requiring IC/ICU management
    • Death

Sponsors and collaborators

Lead sponsor

Marmara University

Other

Registry information

Important dates

Study start
2016
Primary completion
2016
Study completion
2016
First posted
Jan 18, 2017
Registry last updated
Jul 6, 2018

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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