Effects of Flexible Ureteroscopy on Renal Blood Flow
Condition: Circulatory; Change
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): flexible ureteroscopy; Doppler Ultrasound examination; laser lithotripsy
Intervention type(s): Procedure; Device; Device
Intervention description(s): 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.; 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.; 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.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: flexible ureteroscopy; blood flow