Mean Post-void Residual Urine Research Articles

Dog model for studying detrusor instability secondary to acutely induced variable bladder outlet obstruction.

Involuntary detrusor contractions often cause irritative symptoms such as urgency and incontinence. A dog model for acutely induced variable bladder outlet resistance was developed to investigate the possible role of prostatic afferent nerve fibers in the development and maintenance of detrusor instability. Fifty-eight mongrel dogs (weight range 19.5-36.5 kg) were divided into five groups: group I (n = 11) had surgically induced bladder outlet obstruction. Group II (n = 14) had urinary obstruction and bilateral sectioning of the lowest branches of the pelvic plexus supplying the prostate. Group III (n = 10) had prostate denervation only. Groups IV (n = 10) and V (n = 13) were sham-operated and controls, respectively. In the obstructed groups (I and II), an artificial urinary sphincter (length 4.5-6.0 cm) was placed around the bladder neck and connected to a reservoir placed subcutaneously to allow postoperative adjustments of urinary resistance. All dogs were evaluated at baseline and postoperatively at 1, 3, and 6 months with uroflowmetry, postvoid residual urine volume, cystometry as well as serum creatinine, and urinalysis. Occurrences of detrusor instability were not associated with prostatic denervation input. The mean peak flow rates decreased significantly in the obstructed groups at all follow-ups, but did not change significantly in the nonobstructed groups. Postoperatively, the mean maximum bladder capacity was significantly decreased for groups I and II only. However, a significant correlation between maximum bladder capacity and maximum detrusor pressure could not be detected at any time point in any of the groups. Mean postvoid residual urine volume varied considerably in all groups over time. Creation of a urinary model of infravesical obstruction was associated with considerable problems. In our dog model of bladder outlet obstruction, prostatic sensory nerve fibers appear not to be involved in detrusor instability. Surgical induction of a constant model of bladder outlet obstruction was difficult even in a large animal. The observations from the present study raise questions about the validity of obstructive urinary animal models.

Bladder replacement by detubularized ileal loop:

To evaluate the results obtained with a technique of bladder replacement using a detubularized ileal tract, developed by the authors. Since 1983, 34 patients have undergone an orthotopic bladder replacement using 35-40 cm of ileum, detubularized and shaped into an 'S' to create a neobladder with a capacity of 100-120 mL. The ureters were anastomosed directly to a 10 cm long intact afferent loop which serves as an anti-reflux mechanism, while a 2 cm long efferent, spatulated loop was used for urethral anastomosis. The mean (SD) follow-up was 32 (33) months. All the patients were continent during the day, with socially convenient intervals between voids; 3 years after the operation, 10 of 12 patients were continent during the night, with intervals of 2-4 h between voids. The mean post-void residual urine volume was 41 mL and no patient required self-catheterization. There were no derangements of the metabolic status of patients. This technique was applied knowing that a detubularized intestinal loop has the remarkable ability to increase in capacity over time. Therefore, to maintain the reservoir in good condition over a long period it is important to construct it with an intra-operative capacity of < 120 mL, thus reducing the length of intestine required. This may explain the satisfactory metabolic status of these patients. Moreover, the triplication of the mesentery helps to maintain the sphericity of the neobladder and provides support for the neobladder in the lower pelvis, where it retains the same position as a normal bladder.

Laser Prostatectomy Performed with a Right-angle Firing Neodymium: Yag Laser Fiber at 60 Watts Power Setting

A total of 50 patients with symptomatic bladder outlet obstruction due to benign prostatic hyperplasia was entered into a prospective trial of laser prostatectomy performed with the right-angle firing neodymium:YAG laser fiber at 60 watts power setting. Mean estimated resectable prostatic weight was 30 gm. with a mean prostatic urethral length of 3.3 cm. Nine patients (18 percent) were in urinary retention requiring catheterization before treatment. Mean energy delivery was 30,834 joules (range 14,400 to 127,800) with a mean operative time of 31 minutes. Efficacy of treatment was assessed at 3, 6 and 12 months postoperatively by standardized American Urological Association symptom scores, peak urinary flow rates and post-void residual urine volumes. At preoperative baseline the mean symptom score was 20.8, mean peak urinary flow rate 7.6 cc per second, and mean post-void residual urine volume 353 cc. At 1 year postoperatively mean symptom score was 8.4, mean peak urinary flow rate was 18.7 cc per second and mean post-void residual urine volume was 175 cc. Two patients required retreatment for residual tissue. There were 6 complications including 5 bladder neck contractures requiring incision (10 percent) and 1 case of postoperative prostatitis requiring antibiotic therapy (2 percent). Of 37 evaluable sexually active patients 31 (84 percent) reported preservation of antegrade ejaculation postoperatively.

Impact of prostate size on the outcome of transurethral laser evaporation of the prostate for benign prostatic hyperplasia

Objectives The aim of this study was to evaluate efficacy and safety of transurethral evaporation of the prostate (TUEP) using neodymium:yttrium-aluminumgarnet (Nd:YAC) laser in prostate glands of various sizes. Methods One hundred consecutive patients with benign prostatic hyperplasia (BPH) and prostate volumes less than 40 cc (group I, n = 41), 41 to 80 cc (group II, n = 39), and more than 80 cc (group III, n = 20), who had preoperative prostate volume estmation by transrectal ultrasound and had completed a minimum of 3 months' followup, underwent TUEP. At baseline, and at 3 and 6 months, American Urological Assocation (AUA) score, peak flow rate (PFR), postvoid residual urine (PVR), and complications, if any, were documented. Results There were no significant differences in failure rates, complications, or ability to improve symptom score, PFR, and PVR between patients with prostate glands of various sizes. The mean improvement in PFR at 6 months was: group 1, 9.9 cc/s (1 16%); group II, 7.4 cc/s (81%); and group III, 9.2 cc/s (107%). Reduction in AUA score was: group 1, 14.6 (63%); group II, 17.7 (71%); and group III, 16.2 (70%). PVR was: group I, 62.5 cc (51%); group II, 31.4 cc (16%), and group III, 71 cc (83%) (differences not significant). The patients in urinary retention were separately analyzed (group I, 9, group II, 12, and group III, 5) and mean PFR at 6 months was: group I, 18.5 cc/s, group II, 15 cc/s, and group III, 17.1 cc/s. Mean AUA score at 6 months was: group I, 25.8; group II, 21; and group III, 23.6. Mean PVR score was: group I, 370 cc, group II, 439 cc; and group III, 400 cc (differences not significant). Mean postoperative catheterization time was higher in patients with glands larger than 80 cc (2.2 versus 2.9 versus 4.7 days in groups I, II, and III, respectively, P < 0.009 between groups II and III). Incidence of urinary tract infection (10 versus 0%) was greater in patients receiving only 48-hour as opposed to 10-day postoperative antibiotics. Conclusions TUEP appears to be a safe and effective treatment for relief of symptom of BPH and improvement of PFR in patients with all sizes of prostate glands.