A Minipig Model for Urodynamic Evaluation of Infravesical Obstruction and its Possible Reversibility

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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.H2 O): 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.H2 O, and Watts factor (WF) 4.7 W/m.2; 2) Obstructed group: P sub det, open 85.2; Pdet (Qmax) 94.4, Qmax 5.6 ml. per second, Pdet, isv 135.2, mean URA 74.3 cm.H2 O and WF 13.5 W/m.2; 3) De-obstructed group: Pdet, open 39.9, Pdet (Qmax) 25.9, Qmax 25.O ml. per second, Pdet, isv 58.0, mean URA 8.9 cm.H2 O 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.