The impact of siphoning effect on renal pelvis pressure during ureteroscopy using an in vitro kidney and ureter model.

Purpose: To experimentally measure renal pelvis pressure (P) in an ureteroscopic model when applying a simple hydrodynamic principle, the siphoning effect.

Methods: A 9.5Fr disposable ureteroscope was inserted into a silicone kidney-ureter model with its tip positioned at the renal pelvis.

Assessing renal tissue temperature changes and perfusion effects during laser activation in an in vivo porcine model.

Introduction: High fluid temperatures have been seen in both in vitro and in vivo studies with laser lithotripsy, yet the thermal distribution within the renal parenchyma has not been well characterized. Additionally, the heat-sink effect of vascular perfusion remains uncertain. Our objectives were twofold: first, to measure renal tissue temperatures in response to laser activation in a calyx, and second, to assess the effect of vascular perfusion on renal tissue temperatures.

Change in renal blood flow in response to intrarenal pressure alterations induced by ureteroscopy in an in-vivo porcine model.

Introduction: High irrigation rates are commonly used during ureteroscopy and can increase intrarenal pressure (IRP) substantially. Concerns have been raised that elevated IRP may diminish renal blood flow (RBF) and perfusion of the kidney. Our objective was to investigate the real-time changes in RBF while increasing IRP during Ureteroscopy (URS) in an in-vivo porcine model.

Effect of outflow resistance on intrarenal pressure at different irrigation rates during ureteroscopy: in vivo evaluation.

To maintain visualization and control temperature elevation during ureteroscopy, higher irrigation rates are necessary, but this can increase intrarenal pressure (IRP) and lead to adverse effects like sepsis. The IRP is also dependent on outflow resistance but this has not been quantitatively evaluated in a biological system. In this study, we sought to characterize the IRP as a function of irrigation rate in an in vivo porcine model at different outflow resistances.

Thermal Safety Boundaries for Laser Power and Irrigation Rate During Ureteroscopy: In Vivo Porcine Assessment With a Ho:YAG Laser.

Objective: To map thermal safety boundaries during ureteroscopy (URS) with laser activation in two in vivo porcine subjects to better understand the interplay between laser power, irrigation rate, and fluid temperature in the collecting system.

Methods: URS was performed in two in vivo porcine subjects with a prototype ureteroscope containing a thermocouple at its tip. Up to 6 trials of 60 seconds laser activation were carried out at each selected power setting and irrigation rate.

Quantification of outflow resistance for ureteral drainage devices used during ureteroscopy.

Purpose: Since renal pelvis pressure is directly related to irrigation flowrate and outflow resistance, knowledge of outflow resistance associated with commonly used drainage devices could help guide the selection of the type and size of ureteral access sheath or catheter for individual ureteroscopic cases. This study aims to quantitatively measure outflow resistance for different drainage devices utilized during ureteroscopy.

Methods: With measured irrigation flowrate and renal pelvis pressure, outflow resistance was calculated using a hydrodynamic formula.

Laser Heating of Fluid With and Without Stone Ablation: Assessment.

Laser lithotripsy can cause excessive heating of fluid within the collecting system and lead to tissue damage. To better understand this effect, it is important to determine the percentage of applied laser energy that is converted to heat and the percentage used for stone ablation. Our objective was to calculate the percentage of laser energy used for stone ablation based on the difference in fluid temperature measured in an model when the laser was activated without and with stone ablation.

Characterization of Fluid Dynamics and Temperature Profiles During Ureteroscopy with Laser Activation in a Model Ureter.

Ureteral thermal injury has been reported in patients following ureteroscopy with laser lithotripsy due to overheating of fluid within the ureter. Proper understanding of this risk necessitates knowing the volume of fluid available to absorb laser energy. This can be approximated as the volume of fluid that mixes during laser activation, since energy transfer through fluid is dominated by convection.

Laser operator duty cycle effect on temperature and thermal dose: in-vitro study.

Purpose: High-power laser lithotripsy can elevate temperature within the urinary collecting system and increase risk of thermal injury. Temperature elevation is dependent on power settings and operator duty cycle (ODC)-the percentage of time the laser pedal is depressed. The objective of this study was to quantify temperature and thermal dose resulting from laser activation at different ODC in an in-vitro model.

Chilled Irrigation for Control of Temperature Elevation During Ureteroscopic Laser Lithotripsy: Porcine Model.

Multiple studies have shown significant heating of fluid within the urinary collecting system with high-power laser settings. Elevated fluid temperatures may cause thermal injury and tissue damage unless appropriately mitigated. A previous study demonstrated that chilled (CH) (4°C) irrigation slowed temperature rise, decreased plateau temperature, and lowered thermal dose during laser activation with high-power settings.

Patterns of Laser Activation During Ureteroscopic Lithotripsy: Effects on Caliceal Fluid Temperature and Thermal Dose.

Characterizing patterns of laser activation is important for assessing thermal dose during laser lithotripsy. The objective of this study was twofold: first, to quantify the range of operator duty cycle (ODC) and pedal activation time during clinical laser lithotripsy procedures, and second, to determine thermal dose in an caliceal model when 1200 J of energy was applied with different patterns of 50% ODC for 60 seconds. Data from laser logs of ureteroscopy cases performed over a 3-month period were used to calculate ODC (lasing time/lithotripsy time).

Effect of Chilled Irrigation on Caliceal Fluid Temperature and Time to Thermal Injury Threshold During Laser Lithotripsy: Model.

High-power lasers (100-120 W) have widely expanded the available settings for laser lithotripsy and facilitated tailoring of treatment for individual cases. Previous and studies have demonstrated that a toxic thermal dose to tissue can result from treatment within a renal calix. The objective of this study was to compare thermal dose and time with tissue injury threshold when using chilled (CH) irrigation and room temperature (RT) irrigation.