The Relationship Between Pressure and Flow in the Normal Pig Renal Pelvis

Abstract

The renal pelvis pressure flow relationship of 40 normal pig upper urinary tract was investigated. During standardized studies it was disclosed that the resting pressure has a normal distribution with wide 95% confidence limits (0.3-14.7 cmH2O). When perfusion was introduced, pelvic pressure increased, the normal distribution was lost, and the 95% confidence limits were broadened to more than 30 cmH2O. A normal distribution was regained at higher flow rates. The mean increment beyond 8 ml/minute was small, only 3.7 cmH2O from 8 ml/minute to 20 ml/minute. The wide variation found in pressure responses to high flow rates and the spread of pressures at higher flow rates imply major difficulties in distinguishing, between normal and abnormal pressure flow relationships in renal pelvis.

Laser ureteral anastomosis using intraluminal albumin stent in a porcine model

“…The Whitaker test showed that the intrapelvic pressure elevated gradually with a significant increase from pre-operative values to 4 weeks post-surgery in all groups. In accordance with Mortensen et al measurements, which the intrapelvic pressure were within the normal range [11]. The exact cause of hydronephrosis remains unclear since the ureteral stents were in place, which should have protected the upper tracts from obstruction.…”

Predictive Value of Pressure Flow Studies for the Functional Outcome of Reconstructive Surgery for Hydronephrosis

“…Experiments in pigs have, however, questioned the basis of pressure flow studies, since standardised obstructions show a considerable overlap with the normal system as far as pressure responses are concerned (Mortensen et al, 1984). Moreover, chronic partial obstruction in pigs seldom shows abnormal pressures during perfusion (Mortensen et al, 1983).…”

First Prize: Laparoscopic Orthotopic Ileal Neobladder

“…Baseline Whitaker tests were not performed, as this information is available in the literature. 13 the animal model; this problem is compounded by the difficulty in catheter handling and intermittent catheterization. As a result, high-pressure voiding against a closed urethral sphincter and larger residual volumes may ensue.…”

“…All the renal pelvic pressures achieved in our study represent low-pressure drainage similar to that in a normal pig (range 5.2-25 mm Hg), as shown in a study by Mortensen and associates. 13 …”