A minipig model for urodynamic evaluation of infravesical obstruction and its possible reversibility.

Abstract

The aim of our study was to create reproducible partial bladder outlet obstruction and to evaluate the resulting urodynamic changes. Thirty-one female Yucatan microswine were randomly divided into obstructed and control groups. In the obstructed group of 21 animals, an artificial 4.5-cm. sphincter cuff was placed around the bladder neck. Fourteen of these minipigs were eventually deobstructed. In the controls (unobstructed sham-operated group), the sphincter cuff was removed prior to closure. Urodynamic measurements were conducted at 2, 4, 8 and 12 weeks postobstruction in conscious animals restrained in specially designed adjustable cages. (with all pressures in cm.H2O): 1) Unobstructed sham controls: Pdet,open 28.8 Pdet (Qmax) 22.5, Qmax 30.8 ml. per second, Pdet,isv 61.7, urethral resistance relation (URA) 7.7 cm.H2O, and Watts factor (WF) 4.7 W/m.2; 2) Obstructed group: Pdet,open 85.2; Pdet (Qmax) 94.4, Qmax 5.6 ml. per second, Pdet,isv 135.2, mean URA 74.3 cm.H2O and WF 13.5 W/m.2; 3) Deobstructed group: Pdet,open 39.9, Pdet (Qmax) 25.9, Qmax 25.0 ml. per second, Pdet,isv 58.0, mean URA 8.9 cm.H2O and WF 5.4 W/m.2. This animal model of reversible infravesical obstruction has given consistent and reproducible pressure flow data in the conscious, upright state.