Renal pelvic pressure responds with augmented increases to increments in intraabdominal pressure

Background/Purpose: Flaw of a fluid through a collapsible tube is under the influence of various factors including the external compressing pressure. Because the intraabdominal pressure may compress the ureter, an experimenta l study has been planned to determine and compare the normal intraabdominal and renal pelvic pressures and the alterations in renal pelvic pressure in response to the increments in intraabdominal pressure in the rabbits. Methods: Eight adult rabbits were used for the experiment. Under general an esthesia, an urethral catheter, a nasogastric tube, and an intraperitoneal catheter were placed to measure intravesical ([VP), intragastric (IGP), and intraabdominal pressures (IAP), respectively. Intracranial pressure monito rization catheter was placed into the renal pelvis to monitor intrapelvic p ressure (IPP). Basal pressure measurements have been recorded. The pressure s have been recorded in every 5 minutes, and IAP has been increased gradual ly about 3 to 4 cm of water pressure in every step for 30-minute periods. Results: Increases in the intrapelvic pressure values have been significant ly higher than the increases in the IAP (P<.001). A significant correlation has been found between IPP and IAP (P =.000, r = 0.866). By using linear r egression analysis the relationship has been found to be IPP = 7.303 + 1.98 5 (IAP), Intragastric pressure values have been higher compared with IAP va lues (P <.001), whereas intravesical pressures have not differed from IAP ( P>.05). Conclusions: Elevations in IAP results in augmented increases in the IPP. P oiseuille and Laplace Laws suggest this augmented increase to resemble prox imal ureteric obstruction. Increases in IAP may simulate proximal ureteric obstruction and may take part in the pathogenesis of hydronephrosis. J Pedi atr Surg 36:907-904. Copyright (C) 2001 by W.B. Saunders Company.