Abstract
ABSTRACTPurpose:High intra-renal pressures during flexible ureteroscopy have been associated with adverse renal tissue changes as well as pyelovenous backflow. Our objective was to investigate the effect of various intra-renal pressures on histologic changes and fluid extravasation during simulated ureteroscopy.Materials and Methods:Twenty-four juvenile pig kidneys with intact ureters were cannulated with an Olympus flexible ureteroscope with and without a ureteral access sheath and subjected to India ink-infused saline irrigation for 30 minutes at constant pressures ranging from sphygmomanometer settings of 50mm, 100mm and 200mmHg. Renal tissue samples were collected, processed and stained, and were evaluated by a blinded pathologist for depth of ink penetration into renal parenchyma as a percentage of total parenchymal thickness from urothelium to renal capsule.Results:The mean percentage of tissue penetration for kidneys with ink present in the cortical tubules at sphygmomanometer pressure settings of 50, 100, and 200mm Hg without a ureteral access sheath was 33.1, 31.0 and 99.3%, respectively and with ureteral access sheath was 0, 0 and 18.8%, respectively. Overall, kidneys with an access sheath demonstrated a smaller mean tissue penetration among all pressure compared to kidneys without a sheath (6.3% vs. 54.5%, p=0.0354). Of kidneys with sheath placement, 11% demonstrated any ink compared to 56% of kidneys without sheath placement.Conclusions:Pressurized endoscopic irrigation leads to significant extravasation of fluid into the renal parenchyma. Higher intra-renal pressures were associated with increased penetration of irrigant during ureteroscopy in an ex-vivo porcine model.
Highlights
High intra-renal pressures may occur during ureteroscopy, percutaneous nephrolithotomy, and from hydronephrosis in an obstructed system and may result in the phenomenon of pyelovenous backflow by which there is communication of urine between renal fornices and renal veins [1,2,3]
In percutaneous nephrolithotomy it has been demonstrated that pyelovenous backflow due to high intra-renal pressure is associated with post-operative fever [5, 7]
Kidneys with an access sheath demonstrated a smaller mean tissue penetration among all pressures compared to kidneys without a sheath (6.3% vs. 54.5%, p=0.035)
Summary
High intra-renal pressures may occur during ureteroscopy, percutaneous nephrolithotomy, and from hydronephrosis in an obstructed system and may result in the phenomenon of pyelovenous backflow by which there is communication of urine between renal fornices and renal veins [1,2,3]. Intra-renal pressures that exceed 20-40mm Hg have been shown to result in pyelovenous backflow [4, 5]. In percutaneous nephrolithotomy it has been demonstrated that pyelovenous backflow due to high intra-renal pressure is associated with post-operative fever [5, 7]. May be around 8% and that when a ureteral access sheath (UAS) is used, larger diameters may be associated with lower rates of SIRS [8]. A larger diameter UAS has been shown to decrease intra-renal pressures and improve irrigation [10]
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