The effect of bladder outflow obstruction on detrusor blood flow changes during the voiding cycle in conscious pigs

Purpose: We monitored detrusor blood flow in pigs with bladder outflow obstruction. Materials and Methods: Partial urethral obstruction was created in 9 immature, female large white pigs with an implanted ring, and 10 normal animals were used for comparison. Urodynamic parameters and detrusor blood flow were measured using chronically implanted access catheters and laser Doppler fibers. Repeated recordings were made from each animal while it was lightly sedated. Results: The animals with implanted rings developed prolonged, high pressure voiding contractions in association with poor urinary flow, indicating bladder outflow obstruction, and had evidence of detrusor instability. In obstructed and normal animals detrusor blood flow was maintained during bladder filling. Elevated detrusor pressure during voiding significantly decreased blood flow to similar levels in each group. The duration of the ischemic period was much greater in obstructed animals. Conclusions: Bladder outflow obstruction is associated with repeated episodes of prolonged detrusor ischemia which may account for the biochemical and neuronal alterations in such bladders.