Severe urinary retention is not a common condition, but may occur following some pelvic surgeries or other medical conditions. Electrical stimulation of the bladder has been examined as a means of managing this difficult problem. We conducted preliminary investigations in cats to prove the hypothesis that pelvic-plexus (bladder-neck) stimulation would produce greater micturition response with reduced side effects, such as animal movement or discomfort, than bladder-wall stimulation with electrodes implanted higher on the bladder wall. We used model microstimulators that mimic the look and function of commercial microstimulators, but that we constructed. We instrumented four female cats during a survival surgery. Animals recovered well and studies were conducted over a 1-month period in the conscious animal and under anesthesia. We performed a variety of studies with different stimulation parameters and electrode locations to evaluate our hypothesis. In the active animal, we supplied only low currents, but two animals responded to stimulation with bladder contractions and voiding. Following anesthesia, higher stimulating currents resulted in greater bladder contractions during stimulation in two of the three animals. In two cases, pelvic-plexus (bladder-neck) stimulation induced greater micturition responses than direct bladderwall stimulation. In conclusion, we learned from these preliminary observations that stimulation at the pelvic plexus (bladder neck) may induce a better micturition response than stimulation higher on the bladder-wall. Newly available commercial microstimulators should be further studied for the treatment of urinary retention.

Abstract-Severe urinary retention is not a common condition, but may occur following some pelvic surgeries or other medical conditions. Electrical stimulation of the bladder has been examined as a means of managing this difficult problem. We conducted preliminary investigations in cats to prove the hypothesis that pelvic-plexus (bladder-neck) stimulation would produce greater micturition response with reduced side effects, such as animal movement or discomfort, than bladder-wall stimulation with electrodes implanted higher on the bladder wall. We used model microstimulators that mimic the look and function of commercial microstimulators, but that we constructed. We instrumented four female cats during a survival surgery. Animals recovered well and studies were conducted over a 1-month period in the conscious animal and under anesthesia. We performed a variety of studies with different stimulation parameters and electrode locations to evaluate our hypothesis. In the active animal, we supplied only low currents, but two animals responded to stimulation with bladder contractions and voiding. Following anesthesia, higher stimulating currents resulted in greater bladder contractions during stimulation in two of the three animals. In two cases, pelvic-plexus (bladder-neck) stimulation induced greater micturition responses than direct bladderwall stimulation. In conclusion, we learned from these preliminary observations that stimulation at the pelvic plexus (bladder neck) may induce a better micturition response than stimulation higher on the bladder-wall. Newly available commercial microstimulators should be further studied for the treatment of urinary retention.

No abstract

Abstract-This feasibility study was conducted to evaluate design features of the novel intraurethral valved catheter, Surinate (Urovalve, Inc; Newark, New Jersey). The device extends from the bladder neck to just beyond the external sphincter and contains a valve that can be activated by an external magnet for bladder emptying. Five patients were recruited from the Edward Hines Jr Department of Veterans Affairs Hospital spinal cord injury population. We conducted cystometry and cystoscopy to evaluate the lower urinary tract. Then, the device was inserted for 24 hours with careful monitoring. The catheter was removed from the first patient because he developed autonomic dysreflexia during implantation. The next four patients used the catheter overnight and tolerated it well: one with independent use and two with increased abdominal pressure. Emptying time was 208 +/-99 s, residual was 42 +/-33 mL, and the first-stream flow rate was 1.8 +/-0.7 mL/s. The safety tether was used in three patients because the extraction device did not work. Results showed effective implantation and stability of the device in the urethra. However, objectives for use and extraction were not met. This feasibility study provided important information that will help guide design improvements for the intraurethral valved catheter.