Experimental assessment of graded ureteral obstruction utilizing liquid and gaseous perfusion techniques

Ureteral perfusion studies (Whitaker's test) utilizing both saline and carbon dioxide were performed in nonobstructed canine ureters and in ureters subjected to a standardized partial and high grade obstruction to characterize the pattern of pressure response. Three separate ranges of pressure elevation were identified with each perfusate and a high degree of correlation between saline and CO2 pressures was observed. However, a significant overlap between the pressure range for nonobstructed and partially obstructed ureters was noted. This overlap must be carefully considered in human studies before defining clinically significant obstruction on the basis of an absolute perfusion pressure value.