MINIPIG MODEL FOR THE STUDY OF VOIDING PARAMETERS IN THE CONSCIOUS STATE AND NATURAL POSTURE - NORMAL URODYNAMIC PROFILES

Objective To provide baseline data on an animal model in which collect ing and voiding can be accurately characterized urodynamically in the conscious state and natural posture. Methods Thirty-one female Yucatan microswines (age 4 - 8 months, weight 11 - 43 kg) were used. Portcath eters were placed in the bladder and peritoneal cavity, and reservoirs were implanted under the back skin for easy access. For urodynamic st udy, conscious pigs were restrained in specially designed adjustable c ages. The portcatheter reservoirs were connected by 20-gauge needles a nd tubings to a UDS-120 digital computer polygraph to measure the tota l bladder pressure (p(ves)) and abdominal pressure (P-abd). A flow met er was placed behind and underneath the animal to measure the uroflow. Diuresis was induced with furosemide, and 2-4 voiding cycles were mon itored. Isovolumetric detrusor pressure (P-det,P-isv) was obtained in the last cycle by manual interruption of flow per vagina. Urodynamic i nvestigations were performed satisfactorily in all animals. Results Th e voided volume was 102 - 340 ml (mean 181.7 +/- 11.9 ml). Seven pigs had residual urine (4 - 39 ml, mean 14.3 +/- 4.7 ml). The initial open ing pressure at the start of voiding was 19.9 +/- 1.5 cmH(2)O; detruso r pressure at maximum flow rate was 15.7 +/- 1.3 cmH(2)O; average flow was 12.6 +/- 0.7 ml/s; maximum flow rate was 20.7 +/- 1.1 ml/s; Pdet, isv was 51.6 +/- 2.4 cmH(2)O; flow time was 15.9 +/- 1.2 seconds; mean resistance factor (R) was 0.06 +/- 0.01 cmH(2)O ml(-2)s(2); mean uret hral resistance factor (URA) was 7.10 +/- 0.51 cmH(2)O; and mean stren gth of voiding detrusor contraction was 3.91 +/- 0.20 W/m(2). Conclusi on The above model allows reliable measurement of pressure-flow parame ters in the conscious state and natural posture, permitting in-vivo ur odynamic characterization of obstructive voiding dysfunction and corre lation with detrusor structure.