Canine urethral sphincter pressure profile under incremental inflation of an artificial cuff: a cadaver study

Objectives: To determine whether artificial urethral sphincter filling volume is proportional to peak pressure exerted on the urethra. Materials and Methods: Urethral pressure profilometry was performed in five female, medium-sized, mixed-breed canine cadavers following artificial urethral sphincter placement. Maximum urethral pressure was recorded following sequential incremental inflation of 0.15 mL and compared to baseline pressure and between dogs using two-way analysis of variance. Results: Artificial urethral sphincter placement in cadavers was associated with an increase in urethral pressure, which was significantly correlated with inflation volume. The correlation was non-linear and demonstrated considerable individual variation. Maximum urethral pressures after artificial urethral sphincter placement exceeded those reported in conscious continent dogs within a narrow volume range, in which a 0.15 mL infusion more than doubled maximal urethral pressures. Clinical Significance: Rapid increases in urethral pressure from the artificial urethral sphincter over a small range of filling volumes (0.15 mL increments) might explain why some clinical cases can become suddenly dysuric following incremental inflations. We suggest that smaller increments of filling (0.05 to 0.1 mL) may achieve finer pressure control.