Restoration of rat bladder function following release of short- and long-term partial outflow obstruction

Changing patients' profile presenting for surgical management of benign prostatic hyperplasia over the past 16 years: A single-centre perspective

INTRODUCTION

We assessed the change of patients' profile presenting for symptomatic benign prostatic hyperplasia (BPH) over 16 years and its impact on surgical outcomes over this time.

METHODS

We reviewed a prospectively maintained database of patients treated with laser for symptomatic BPH since March 1998. Patients were divided into 3 consecutive time-based groups: Group 1 for patients who underwent surgery before April 2004; Group 2, between April 2004 and March 2009; and for Group 3 from April 2009 to August 2014. We reviewed demographic and preoperative data, including prostate volume; international prostate symptoms score (IPSS), quality of life (QoL), and peak flow rate (Qmax). We also recorded any perioperative and long-term complications.

RESULTS

A total of 1835 patients were included in our study, including 542 (29.5%) in Group 1, 614 (33.5%) in Group 2, and 679 (37%) in Group 3. Preoperative prostate volume was positively correlated with age at surgery (r = 0.62, p < 0.001), total energy used (r = 0.47, p < 0.001), and total operative time (r = 0.47, p < 0.001). Patients in Group 3 were significantly older (75.28 ± 8.47 in Group 3 vs. 71.11 ± 8.9 in Group 2 vs. 65.3 ± 9.04 years in Group 1, p <0.001), were more coagulopathic (18.7% Group 3 vs. 12.3% Group 2 vs. 5.9% Group 1, p < 0.001), and had significantly larger prostates (87.96 ± 49.80 in Group 3 vs. 78.44 ± 50.84 in Group 2 vs. 74.50 ± 46.53 Group 1, p < 0.001). Preoperative prostatic medications significantly increased over time (72.6% in Group 1 vs. 85.5% in Group 2, vs. 87.4% Group 3, p < 0.001). IPSS, QoL and Qmax were significantly abnormal in patients in Group 3 (p < 0.001). After a mean follow-up of 3 years, the number of patients who did not require reoperation progressively increased (94.1% Group 1 vs. 96.1% Group 2 vs. 98.3% Group 3). Age (>72 years), prostate volume (>80 cc), operative time (>95 minutes), and preoperative PSA (>6 ng/dL) were significantly associated with postoperative urinary incontinence.

CONCLUSIONS

Patients presenting for surgery due to symptomatic BPH over the last 16 years were significantly older, more morbid, and had larger prostates and more abnormal voiding parameters. Over time, patients used prostatic medications more frequently. Despite the changes in patient profiles, perioperative safety and complication rates between groups were comparable, likely due to advancements in laser technology and techniques. Age (>72 years), prostate volume (>80 cc), operative time (>95 minutes), and preoperative PSA (>6 ng/dL) were significantly associated with reversible postoperative urinary incontinence.

Impact of changing trends in medical therapy on surgery for benign prostatic hyperplasia over two decades

PURPOSE

Following the introduction of medical therapy for benign prostatic hyperplasia (BPH), we determined the effect of the change in trends in medical therapy on the indication and outcome of surgical intervention for BPH.

MATERIALS AND METHODS

We compared the basic characteristics of, weight of resected tissue of, transfusions in, and postoperative complications of patients who underwent surgery between 1985 and 1989 (before the advent of medical therapy for BPH), between 1995 and 1999 (when medical therapy was developed and became widely used as alternative treatment), and between 2005 and 2009 (when medical therapy superseded surgical intervention to become first-line treatment and when combination therapy became widely adopted).

RESULTS

At our institution, the mean age and BMI of patients increased over the past two decades (p<0.001). Hypertension, operation history, and other comorbidities also increased significantly (p<0.001, p=0.005, and p<0.001, respectively). The indications for surgery in 1985 to 1989, 1995 to 1999, and 2005 to 2009 were as follows: acute urinary retention in 34.7%, 20.2%, and 15.1% of patients and symptomatic deterioration in 61.1%, 72.3%, and 73.0% of patients, respectively. Prostate volume and the weight of resected tissue increased from 34.4±14.5 ml to 61.3±32.4 ml and from 7.2±6.4 g to 10.8±7.6 g, respectively, over two decades. Patients who underwent surgery in 2005 to 2009 had their catheters removed earlier (p<0.001). Secondary hemorrhage within four postoperative weeks and repeat transurethral resection of the prostate within 1 year decreased significantly (p=0.03 and p=0.003, respectively). No statistically significant change in impaired detrusor contractility was found (p=0.523).

CONCLUSIONS

Although patients who underwent surgery were older after widespread use of medical therapy for BPH, advancements in surgical techniques have benefitted these patients.

Urodynamic follow-up of experimental urethral obstruction in individual guinea pigs

It is unknown whether changes in bladder function due to urethral obstruction follow a specific sequence. To answer this, we adapted a small animal model to allow repeated complete pressure-flow studies, enabling individual follow-up of changes in bladder function on urethral obstruction. Obstruction was induced in guinea pigs by placing a silver ring around the urethra. Urodynamic studies were repeated under anesthesia with ketamine/xylazine. Bladders were filled and bladder pressure measured through a single suprapubic catheter. Urine flow rate was measured using an ultrasound probe around the penis. Accurate measurements of bladder pressure and urine flow rates were obtained at 1-week intervals for 11 weeks in individual guinea pigs. In the control animals, the urodynamic parameters did not show significant changes. In the obstructed group, urethral resistance (P(low,ave)) increased from 20 to 35 cm H(2)O after 4 weeks and remained at that level. The maximum flow rate (Q(max)) increased from 0.17 to 0.24 mL/s after 2 to 3 weeks. After this peak, it gradually decreased to lower than the starting value after 10 to 11 weeks. The pressure at maximum flow rate (p(Qmax)) increased from 24 to 47 cm H(2)O after 6 to 7 weeks and thereafter declined. During weeks 1 through 4 of obstruction, unstable contractions were seen. All animals followed a similar sequence of patterns but at variable rates. Our animal model allows complete urodynamic follow-up of individual animals with urethral obstruction. We observed a specific sequence of changes in urodynamic patterns and parameters of bladder function.

Filling mechanics of obstructed and de-obstructed rat urinary bladders

Chronic bladder distension occurs after partial outlet obstruction and can lead to decompensation and impaired function. To quantify the degree of chronic bladder distension, we previously defined the zero pressure volume (ZPV), the largest contained volume at zero transmural pressure. In the current study, we investigated the short- and long-term effects of outlet obstruction and de-obstruction on chronic distension and passive bladder filling mechanics. Voiding patterns were measured 10 days (short term) or 6 weeks (long term) after partial bladder outlet obstruction and the bladders were tested in vitro at that time. De-obstructed bladders were obstructed for 6 weeks, and voiding patterns were measured 10 days or 6 weeks after de-obstruction, followed by in vitro testing. Mean voided volume was increased in de-obstructed bladders but not obstructed bladders. The volume of urine in the bladder at euthanasia was greater than mean voided volume in obstructed bladders and less than mean voided volume in de-obstructed bladders, indicating large residual urine in the obstructed bladders. ZPV was significantly increased only after long-term obstruction or de-obstruction. Similarly, intravesical pressure and mean bladder wall stress were increased only after long-term obstruction or de-obstruction. We conclude that tissue remodeling occurs in the bladder wall after long-term obstruction, possibly both as a result of and leading to chronic overdistension and high residual urine. Tissue remodeling occurs in the bladder wall after long-term de-obstruction, possibly due to large voided volumes. Neurourol. Urodynam. 18:659-671, 1999.