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Dive into the research topics where David A. Rivas is active.

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Featured researches published by David A. Rivas.


The Journal of Urology | 1993

American Urological Association Symptom Index for Women with Voiding Symptoms: Lack of Index Specificity for Benign Prostate Hyperplasia

Michael B. Chancellor; David A. Rivas

An evaluation of the American Urological Association (AUA) symptom index was recently published as a valid symptom score for benign prostatic hyperplasia (BPH). To determine the specificity prospectively of the index for BPH and bladder outlet obstruction, we chose to administer the index to 38 consecutive women with voiding symptoms who were previously scheduled for video urodynamic evaluation. In each case the index was self-administered before the urodynamic study. Index determination was then repeated 1 to 4 months after the institution of therapy. Only 3 of the 38 women demonstrated true urethral obstruction. One patient exhibited urethral compression after a pubovaginal sling urethral suspension, 1 with multiple sclerosis demonstrated detrusor external sphincter dyssynergia and 1 suffered bladder neck obstruction caused by a leiomyoma. The AUA symptom index for the 35 nonobstructed women ranged from 4 to 33 (mean 17.6) Of the women 15 scored between 8 and 18, while 14 had a score of greater than 18. The mean score decreased to 9.4 after the institution of therapy, which included bladder suspension surgery, anticholinergics, timed voiding and pelvic floor exercises. Of the 3 women with bladder outlet obstruction the mean score was 22.7 before and 11.0 after therapy. A greater decrease in the AUA symptom index occurred among the obstructed group after urological therapy compared to the nonobstructed group. Our results indicate that the AUA symptom index is not specific for BPH. The index score for the women in our study rivaled the scores reported for men with BPH.


European Urology | 2001

Long–Term Effectiveness of Sacral Nerve Stimulation for Refractory Urge Incontinence

R.A. Janknegt; Magdy Hassouna; Steven Siegel; Richard A. Schmidt; Jerzy B. Gajewski; David A. Rivas; Mostafa M. Elhilali; Douglas C. Milam; Philip Van Kerrebroeck; Hero E. Dijkema; A.A.B. Lycklama à Nÿeholt; Magnus Fall; Udo Jonas; Francesco Catanzaro; Clare J. Fowler; Kimbery A. Oleson

Objectives: To evaluate the long–term efficacy of sacral nerve stimulation for refractory urinary urge incontinence. Study Design and Methods: Urge incontinent patients qualified for surgical implantation of a neurostimulator system after trial screening with percutaneous test stimulation. Surgical implantation of the InterStim System (Medtronic Inc., Minneapolis, Minn., USA) was performed in cases where a >50% reduction in incontinence symptoms was documented during the 3– to 7–day test stimulation period. The InterStim System consists of an implantable pulse generator, a transforamenally placed quadripolar lead, and an extension that connects these two devices for unilateral stimulation of the S3 or S4 sacral nerve. Efficacy for 96 implanted patients was based on urinary symptom changes as quantified in voiding diaries collected at baseline and annually after surgical implantation. Results: As compared to baseline, the group of 96 implanted patients demonstrated significant reductions in urge incontinent symptoms at an average of 30.8±14.8 (range 12–60) months with respect to the number of urge incontinent episodes per day, severity of leaking, and the number of absorbent pads/diapers replaced per day due to incontinence (all p<0.0001, respectively). Gender, pretreatment variables, and age were not found to be relevant factors that affected these results. 11 of the 96 patients underwent device explant due to lack of efficacy, pain or bowel dysfunction. These data were conservatively included in the efficacy results. No permanent injuries associated with the devices or therapy were reported. Conclusion: Sacral nerve stimulation is an effective treatment for refractory urge incontinence with sustained long–term benefit through an average of 30.8 months.


Urologic Clinics of North America | 1996

URODYNAMICS OF SPINAL CORD INJURY

Toyohiko Watanabe; David A. Rivas; Michael B. Chancellor

Historically, urologic complications have been the major source of morbidity and mortality among spinal cord injured (SCI) patients. All SCI patients should undergo urodynamic evaluation, with the initial urodynamics study done after the patient is beyond the spinal-shock phase. Management of the urinary tract in SCI individuals should be based on urodynamic principles and findings rather than on the neurologic history.


Journal of Spinal Cord Medicine | 2003

Intravesical Resiniferatoxin for Refractory Detrusor Hyperreflexia: A Multicenter, Blinded, Randomized, Placebo-Controlled Trial

Jang Hwan Kim; David A. Rivas; Patrick J. Shenot; Bruce G. Green; Michael J. Kennelly; Janet Erickson; Margie O’Leary; Naoki Yoshimura; Michael B. Chancellor

Abstract Objective: Resiniferatoxin (RTX) is an analogue of capsaicin with more than 1,000 times its potency in desensitizing C-fiber bladder afferent neurons. This study investigated the safety and efficacy of intravesical RTX in patients with refractory detrusor hyperreflexia (DH). Methods: Thirty-six (22 males, 14 females) neurologically impaired patients (20 spinal cord injury, 7 multiple sclerosis, 9 other neurologic diseases) with urodynamically verified DH and intractable urinary symptoms despite previous anticholinergic drug use were treated prospectively with intravesical RTX using dose escalation in a double-blind fashion at 4 centers. Patients received a single instillation of 100 ml of placebo (n = 8 patients) or 0.005, 0.025, 0.05 , 0.10 , 0.2, 0.5, or 1.0 fLM of RTX (n = 4 each group). A visual analog pain scale (VAPS) (0-10; 10 = highest level of pain) was used to quantify discomfort of application. Treatment effect was monitored using a bladder diary and cystometric bladder capacity at weeks 1, 3, 6, and 1 2 posttreatment. Results: Mean VAPS scores revealed minimal to mild discomfort with values of 2.85 and 2.28 for the 0.5-j-LM and 1.0-j-LM RTX treatment groups, respectively. Due to the small sample size, there were no statistically significant changes in mean cystometric capacity (MCC) or incontinence episodes in each treatment dose group. However, at 3 weeks, MCC increased by 53% and 48% for the 0.5-j-μM and 1.0-j-μM RTX treatment groups, respectively. Patients in the 0.5-j-μM and 1.0-j-μM groups with MCC < 300 ml at baseline showed greater improvements in MCC at 120.5% and 48%, respectively. In some patients, MCC increased up to 500% over baseline, despite a low RTX dose. Incontinence episodes decreased by 51.9% and 52.7% for the 0.5-j-LM and 1.0-j-LM RTX treatment groups, respectively. There were no long-term complications. Conclusion: Intravesical RTX administration, in general, is a well-tolerated new therapy for DH. This patient group was refractory to all previous oral pharmacologic therapy, yet some patients responded with significant improvement in bladder capacity and continence function shortly after RTX administration. Patients at risk for autonomic dysreflexia require careful monitoring during RTX therapy.


The Journal of Urology | 1999

LONG-TERM FOLLOWUP OF THE NORTH AMERICAN MULTICENTER UROLUME* TRIAL FOR THE TREATMENT OF EXTERNAL DETRUSOR-SPHINCTER DYSSYNERGIA

Michael B. Chancellor; Jerzy B. Gajewski; C. F Douglas Ackman; Rodney A. Appell; James Bennett; Joseph Binard; Timothy B. Boone; Michael Chetner; Julie Ann Crewalk; Alfred J. Defalco; Jenelle Foote; Bruce G. Green; Saad Juma; Suk Young Jung; Todd A. Linsenmeyer; Robert MacMillan; Michael E. Mayo; Hideo Ozawa; Claus G. Roehrborn; Patrick J. Shenot; Anthony R. Stone; Albert Vazquez; Wylly Killorin; David A. Rivas

PURPOSE We determine the long-term efficacy and safety of the UroLume stent as minimally invasive treatment for external detrusor-sphincter dyssynergia in spinal cord injured men. MATERIALS AND METHODS A total of 160 spinal cord injured men with a mean age plus or minus standard deviation of 36.3 +/- 12.1 years (range 16 to 74) were prospectively treated with an endoprosthesis at 15 centers as part of the North American UroLume trial for external detrusor-sphincter dyssynergia. Urodynamic parameters, including voiding pressure, residual urine volume and bladder capacity, were compared before treatment and at 1, 2, 3, 4 and 5 years after treatment. RESULTS Mean voiding pressure was 75.1 +/- 28.2 cm. water before treatment in the 160 patients, and 37.4 +/- 23.9 at year 1 in 97, 39.5 +/- 22.2 at year 2 in 84, 42.6 +/- 27.3 at year 3 in 61, 46.3 +/- 33.2 at year 4 in 57 and 44.2 +/- 28.9 cm. at year 5 in 41 after stent insertion (p <0.001). Residual urine volume decreased after stent placement and was maintained throughout the 5-year followup (p <0.001). Mean cystometric capacity remained constant from 269 +/- 155 before insertion to 337 +/- 182 ml. 5 years later (p = 0.17). Hydronephrosis and autonomic dysreflexia improved or stabilized in most patients with functioning stents. Stent explant was necessary in 24 patients (15%), of whom 4 (16.7%) had another stent implanted. CONCLUSIONS The UroLume stent demonstrates long-term safety and efficacy for the treatment of external detrusor-sphincter dyssynergia. The outcome was similar in men with and without previous sphincterotomy.


The Journal of Urology | 1990

Upper Urinary Tract Filling Defects: Flexible Ureteroscopic Diagnosis

Demetrius H. Bagley; David A. Rivas

There were 62 patients referred to our institution for evaluation of upper urinary tract filling defects. These patients had undergone any of several diagnostic evaluations, including computerized tomography, B-mode ultrasound scanning and urinary cytology studies with or without upper tract brush biopsy. In all cases a conclusive diagnosis could not be formulated. With the use of flexible ureteropyeloscopy complete evaluations of the upper tract lesions were performed. The upper tract endoscopic procedure provided the diagnosis in all patients, as well as allowed for therapeutic intervention in 19. There was no significant morbidity associated with any procedure. We advocate the continued development of flexible ureteropyeloscopic instrumentation and procedures. We suggest the inclusion of ureteropyeloscopy with tissue sampling of neoplasms in the evaluation of all upper urinary tract lesions, except when diagnostic ultrasound correlates the characteristics and position of the lesion as calculous disease.


The Journal of Urology | 1999

SPHINCTERIC STENT VERSUS EXTERNAL SPHINCTEROTOMY IN SPINAL CORD INJURED MEN: PROSPECTIVE RANDOMIZED MULTICENTER TRIAL

Michael B. Chancellor; Carol J. Bennett; Anne R. Simoneau; Michael V. Finocchiaro; Charles Kline; James K. Bennett; Jenelle Foote; Bruce G. Green; Sherri Martin; R. Wylly Killoran; Julie-Ann Crewalk; David A. Rivas

PURPOSE In a prospective randomized multicenter trial we compared the treatment results of conventional external sphincterotomy with those of UroLume sphincteric stent prosthesis placement in men with spinal cord injury and external detrusor-sphincter dyssynergia. MATERIALS AND METHODS We randomized 57 men with spinal cord injury in whom urodynamics verified external detrusor-sphincter dyssynergia into 2 groups to undergo either sphincter defeating procedure. We compared the primary urodynamic parameter of maximum detrusor pressure, and secondary urodynamic parameters of bladder capacity and post-void residual urine volume in men who underwent sphincterotomy or sphincteric stent placement. Parameters were measured preoperatively, and 3, 6, 12 and 24 months postoperatively. Patients completed questionnaires regarding voiding sensation and quality of life issues at each followup visit. RESULTS Demographic data of the 26 patients treated with sphincterotomy and the 31 treated with sphincteric stent placement were statistically similar. Preoperatively mean maximum detrusor pressure plus or minus standard deviation in sphincterotomy and stent cases was 98.3 +/- 27.6 and 95.7 +/- 27.7 cm. water, respectively (p = 0.73). At 12 months mean maximum detrusor pressure decreased to 48.9 +/- 16.4 and 52.6 +/- 31.6 cm. water in the sphincterotomy and stent groups, respectively (p = 0). Preoperatively mean bladder capacity in sphincterotomy and stent cases was 245 +/- 158 and 251 +/- 145 ml., respectively (p = 0.87). Bladder capacity did not change significantly in either treatment group throughout followup. Preoperatively mean post-void residual urine volume in the sphincterotomy and stent groups was 212 +/- 163 and 168 +/- 114 ml., respectively (p = 0.33). Residual urine volume decreased in each group at some but not all followup evaluations. The duration of hospitalization was greater for sphincterotomy than stenting (p = 0.036). Six stents required explantation. CONCLUSIONS The UroLume stent is as effective as conventional external sphincterotomy for treating external detrusor-sphincter dyssynergia. However, sphincteric stent placement is advantageous because it involves shorter hospitalization and is potentially reversible.


The Journal of Urology | 1994

Multicenter trial in North America of UroLume urinary sphincter prosthesis.

Michael B. Chancellor; David A. Rivas; Todd A. Linsenmeyer; Caryn A. Abdill; C. F Douglas Ackman; Rodney A. Appell; James Bennett; Joseph Binard; Timothy B. Boone; Michael Chetner; Alfred Defalco; Janelle Foote; Jerzy B. Gajewski; Bruce G. Green; Saad Juma; Robert MacMillan; Michael E. Mayo; Claus G. Roehrborn; Anthony R. Stone; W.C. Thorndyke; Albert Vazquez

We investigated the effectiveness and associated complications of treatment with an endoluminal urethral sphincter prosthesis in 153 spinal cord injury men (mean age 36 years, range 16 to 74 years) with urodynamically diagnosed detrusor-external sphincter dyssynergia. These patients were prospectively treated with a urethral sphincter stent at 15 centers in North America. Followup ranged from 2 to 33 months. Voiding pressures averaged 76 +/- 28, 42 +/- 21, 44 +/- 38, 35 +/- 18 and 32 +/- 20 cm. water, respectively, before prosthesis insertion in 153 patients and at 3 months in 123, 6 months in 114, 12 months in 98 and 24 months in 22. A significant decrease in voiding pressure was noted in the 22 patients at 24 months compared with matched preoperative data (80 +/- 25 cm. water, p = 0.03). The residual urine decreased from 181 +/- 154 ml. before insertion to 82 +/- 93 ml. at 24 months (p = 0.01). Maximum cystometric capacity remained constant, with a mean of 195 +/- 158 ml. before insertion to 248 +/- 122 ml. at 24 months (p = 0.17). No significant differences were apparent after 24 months of followup in any of the urodynamic parameters between 44 patients with and 109 without previous external sphincterotomy. Hemorrhage requiring blood transfusion, obstructive hyperplastic epithelial overgrowth and soft tissue erosion did not occur. No deleterious effects were observed on renal or erectile function. Of the patients 43 (28.1%) required 2 prostheses to bridge the external sphincter completely. Stent removal was required in 10 patients. Seven explantations were required for prosthesis migration, 1 for pain and urethral edema, 1 for inability to maintain a condom catheter, and 1 for nonepithelialization and secondary bladder neck obstruction. A total of 13 patients (8.5%) required a subsequent operation for bladder neck obstruction. Therefore, the sphincter prosthesis is an attractive modality for the treatment of external sphincter dyssynergia in patients with and without previous external sphincterotomy because of its ease of deployment and minimal associated morbidity.


The Journal of Urology | 2000

REMOVAL OF UROLUME ENDOPROSTHESIS: EXPERIENCE OF THE NORTH AMERICAN STUDY GROUP FOR DETRUSOR-SPHINCTER DYSSYNERGIA APPLICATION

Jerzy B. Gajewski; Michael B. Chancellor; C. F Douglas Ackman; Rodney A. Appell; James Bennett; Joseph Binard; Timothy B. Boone; Michael Chetner; Julie Ann Crewalk; Alfredo Defalco; Jenelle Foote; Bruce G. Green; Saad Juma; Suk Young Jung; Todd A. Linsenmeyer; Joseph N. Macaluso; Robert MacMillan; Michael E. Mayo; Hideo Ozawa; Claus G. Roehrborn; Joseph D. Schmidt; Patrick J. Shenot; Anthony R. Stone; Albert Vazquez; Wylly Killorin; David A. Rivas

PURPOSE We present the experience of the North American UroLume Multicenter Study Group with removal of the UroLume endoprosthesis. MATERIALS AND METHODS A total of 160 neurologically impaired patients were enrolled in the North American UroLume Multicenter Study Group for detrusor external sphincter dyssynergia application. Analysis was performed in 2 groups of patients in which the device was removed during insertion and after implantation, respectively. RESULTS Device retrieval was required during insertion in 21 patients (13%) mainly due to misplacement or migration in 17. Extraction was done with minimal complications and in all but 2 cases subsequent UroLume implantation was successful. Of 158 men with the device in place 31 (19.6%) required removal. In 34 procedures 44 devices were removed, mainly due to migration. Time from implantation to removal ranged from 4 days to 66 months (mean 22 months). The UroLume was removed en bloc in 20 cases and in parts or wire by wire in 19. The majority of patients had no or minimal complications after extraction. Only 2 patients had serious temporary complications, including bleeding and urethral injury, with no lasting consequences. No malignancy developed as a result of UroLume insertion. CONCLUSIONS While there is a potential for urethral injury and bleeding, UroLume endoprosthesis removal is largely a simple procedure with minimal complications and consequences.


Archives of Physical Medicine and Rehabilitation | 1995

Improved quality of life and sexuality with continent urinary diversion in quadriplegic women with umbilical stoma

Jose G. Moreno; Michael B. Chancellor; Stephen Karasick; Stacey King; Caryn K. Abdill; David A. Rivas

Quality of life issues prompted us to offer continent urinary diversion to quadriplegic women who required cystectomy for end-stage neurogenic vesical dysfunction complicated by urethral destruction as a result of chronic indwelling catheterization. Three women with spinal cord injury (SCI) and resultant quadriplegia of 5 to 15 years duration underwent continent urinary diversion. Preoperative evaluation and urodynamic studies in each showed a bladder capacity of less than 150mL, bilateral vesicoureteral reflux, recurrent febrile urinary tract infections, an incompetent urethral sphincter, and incontinence around an indwelling catheter in all three patients. Although highly motivated, these women showed minimal dexterity and were unable to perform urethral self-catheterization. Each was opposed to having an incontinent abdominal urinary stoma. The urinary reservoir was created from 30cm of detubularized right colon. The continence mechanism used an intussuscepted and imbricated ileocecal valve. The umbilicus was chosen as the urostomy site because of cosmetic appearance and ease of catheterization for a patient with minimal dexterity. Follow-up ranged from 18 to 30 months. Reservoir capacity ranged from 550 to 800mL without evidence of reflux or stomal leakage. The incidence of symptomatic autonomic dysreflexia and urinary tract infection decreased postoperatively in all patients. Of the two women who were sexually active, the frequency of activity increased from 8 to 15 episodes per month in one and 3 to 4 episodes per month in the other. Both reported improved sexual enjoyment. Body image and satisfaction with urologic management increased in all three patients. In conclusion, continent urinary diversion in selected quadriplegic patients is a reasonable alterative to incontinent intestinal urinary diversion. The umbilical stoma provides an excellent cosmetic result which patients with minimal dexterity are able to catheterize easily. Continent urinary diversion in women results in improved self-image, quality of life, and enables greater sexual satisfaction.

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Patrick J. Shenot

Thomas Jefferson University

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Bruce G. Green

University of Southern California

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William E. Staas

Thomas Jefferson University

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Bin Huang

University of Pittsburgh

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Leonard G. Gomella

Thomas Jefferson University

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Steven Mandel

Thomas Jefferson University

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