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Biomedical subjects

D A Rivas

Publications and source records attributed to D A Rivas.

At least 37 records · Page 2Linked to original sources
PubMed1997

In-vivo whole bladder response to anticholinergic and musculotropic agents in spinal cord injured rats.

The purpose of this study was to compare the effect on urodynamic parameters of anticholinergic and musculotropic agents in sham injured and spinal cord injured (SCI) rats. A standard rat SCI model induced by impact trauma was employed. Cystometrograms were performed under urethane anesthesia four weeks after SCI. Bladder capacity and voiding pressure were determined at the point of micturition monitored urodynamically and visually. The effect of oxybutynin chloride (0.01-0.1 mg/kg), propantheline bromide (0.05-0.5 mg/kg) and flavoxate hydrochloride (0.1-1.0 mg/kg) were assessed independently in sham injured and SCI rats (n = 10 in each group). Bladder capacities were 0.6 +/- 0.2 and 7.1 +/- 1.6 ml in sham and SCI rats (p < 0.01), respectively. Maximal filling pressure was 17.5 +/- 5 mmHg in sham and 25 +/- 5 mmHg in SCI rats (p < 0.05). Bladder capacity increased with all three medications. Administration of oxybutynin, propantheline and flavoxate in sham rats resulted in bladder capacities of 0.88 +/- 0.3, 0.71 +/- 0.3 and 0.8 +/- 0.2 ml, respectively (p < 0.01). In SCI rats, these drugs resulted in bladder capacities of 9.8 +/- 1.1, 7.9 +/- 1.3 and 8.8 +/- 2.0 ml, respectively (p < 0.01). No significant change in maximum filling pressure occurred. We conclude that anticholinergic and musculotropic agents caused a similar increase in bladder capacity in both sham and SCI rats. Oxybutynin enhanced bladder capacity more than propantheline or flavoxate.

Animals↗
PubMed1997

Rectus urethromyoplasty of radical prostatectomy anastomosis decreases postoperative incontinence and anastomotic stricture; technique and preliminary results.

PURPOSE: To investigate the effect of rectus urethromyoplasty on vesicourethral anastomosis healing during radical retropubic prostatectomy (RRP) and in an animal model. MATERIALS AND METHODS: Three groups of 10 female rats were studied. After complete urethral transection, group A animals underwent a primary urethral anastomosis, while rectus urethromyoplasty was used to reinforce the anastomosis of the animals in group B. Group C animals served as controls. All animals underwent urodynamic evaluation one month postoperatively, then were sacrificed for histological analysis. In 3 clinical subjects at the time of RRP, a 2-3 cm x 6-8 cm. strip of rectus muscle was isolated with its blood supply intact, emanating from an inferior epigastric artery pedicle. This muscular band was used to encircle the vesico-urethral anastomosis, suspending it slightly but without tension, and securing it to the pubic symphysis. RESULTS: The micturition pattern, bladder capacity, and leak point pressure of the 3 groups of animals were not significantly different. Histological examination of the rectus sling revealed viable muscle with histofibroblast, collagen, and blood vessel ingrowth from the vascular rectus muscle into the urethra. Three successful clinical rectus urethromyoplasty cases were performed with over 12 months of follow-up. CONCLUSIONS: Reinforcement of the vesico-urethral anastomosis using rectus urethromyoplasty at the time of radical prostatectomy may improve continence by increasing urethral support and mucosal coaptation. This technique may decrease the incidence of stricture formation by augmenting blood supply available for healing of the anastomosis. Rectus urethromyoplasty may be especially beneficial to patients with an increased risk of requiring adjuvant radiation therapy post-prostatectomy.

Anastomosis, Surgical↗
PubMed1996

Laplace's law and the risks and prevention of bladder rupture after enterocystoplasty and bladder autoaugmentation.

The purpose of this study was to utilize a rat model of bladder augmentation to determine the effect on bladder rupture pressure and volume of bladders augmented using myomyotomy autoaugmentation, intestinal patch ileocystoplasty alone, and a combination of ileocystoplasty and detrusor-myoplasty techniques. Four groups of female rats were studied: 1) sham animals served as controls, 2) ileocystoplasty, 3) autoaugmentation using a myomyotomy technique, and 4) ileocystoplasty reinforced with a rectus muscle flap to envelop the augmented bladder (detrusormyoplasty). One month after surgery bladder rupture pressure and volume were determined by cystometry. Sham control rats manifested bladder rupture at a mean pressure of 154 +/- 43 mmHg and mean volume of 2.5 +/- 2.0 ml. Myomyotomy animals demonstrated a diminished mean rupture pressure and rupture volume (101 +/- 13 mmHg and 1.2 +/- 0.4 ml, respectively) compared to control (both P < 0.05). Ileocystoplasty animals demonstrated bladder rupture at a significantly higher volume of 4.0 +/- 1.9 ml than either myomyotomy or control animals (P < 0.05), although rupture pressure of 111 +/- 49 mmHg did not differ significantly from control values (P = 0.55). The combination of ileocystoplasty and detrusor-myoplasty yielded a statistically significant increase in rupture pressure (262 +/- 108 mmHg) than the other three groups (P < 0.05). Rupture volume in this group of animals did not differ significantly from animals with ileocystoplasty but without detrusormyoplasty (P = 0.46). Bladder autoaugmentation results in a significantly reduced rupture pressure and volume than noted in the native bladder. Although ileocystoplasty significantly increases bladder capacity, the risk of urinary extravasation is also increased with this technique. The combination of ileocystoplasty and detrusor-myoplasty affords not only an increase in bladder capacity, but also significantly increases rupture pressure and thereby decreases the risk of bladder rupture after bladder augmentation.

Animals↗
PubMed1996

Comparison of bladder rupture pressure after intestinal bladder augmentation (ileocystoplasty) and myomyotomy (autoaugmentation).

OBJECTIVES: To compare the risk of bladder rupture of bladder augmentation using ileocystoplasty versus that of autoaugmentation with myomyotomy in a rat model. METHODS: Bladder rupture pressure and volume of three groups of female Sprague-Dawley rats were determined by cystometry. The first group of 11 rats had undergone ileocystoplasty using a detubularized 1 -cm segment of ileum. A second group of 9 rats had undergone autoaugmentation with myomyotomy. One month after surgery the animals were studied cystometrically to determine the bladder rupture pressure, then killed. A third group, consisting of 10 nonoperated rats, was studied and served as controls. RESULTS: Nonoperated, control rat bladders were able to sustain 154 +/- 43 mm Hg pressure and 2.5 +/- 2.0 mL volume prior to bladder rupture. Conventional ileocystoplasty was noted to increase bladder capacity to 4.0 +/- 1.9 mL, but decrease rupture pressure to 111 +/- 49 mm Hg. Myomyotomy resulted in a mean bladder rupture volume of 1.2 +/- 0.4 mL, with a rupture pressure of 101 +/- 13 mm Hg. The rupture pressure after myomyotomy is significantly lower than that of the native bladder (P < 0.001), whereas the rupture volume after myomyotomy is significantly lower than either after the ileocystoplasty or with the native bladder (P < 0.001). Bladder rupture occurred at the augmented ileal bladder dome in 7 of 11 ileocystoplasty animals and at the anastomotic suture line in 4 animals. Bladder rupture occurred at the area of bladder diverticulum in all 9 myomyotomy animals. Among controls, no specific site pattern of bladder rupture was noted. CONCLUSIONS: Bladder augmentation with myomyotomy increases vulnerability to urinary extravasation, evidenced by a significantly reduced rupture pressure and bladder volume at rupture when compared to the native bladder.

Animals↗
PubMed1996

Urodynamics of spinal cord injury.

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.

Electromyography↗
PubMed1996

Epidemiology of current treatment for sexual dysfunction in spinal cord injured men in the USA model spinal cord injury centers.

This study is a prospective multicenter cooperative survey of the evaluation and treatment of erectile dysfunction in men with spinal cord injury (SCI). Uniform database questionnaires were completed prospectively by patients seeking therapy for erectile dysfunction. Eighty-five SCI men aged 17-68 years (mean age = 26 +/- 17) were enrolled. Mean duration of traumatic SCI was 3 +/- 3.2 years (Range = 0.3-18 years). The level of injury was cervical in 20 patients, thoracic in 31, lumbar in 29 and sacral in five. Patients were fully evaluated and then counseled as to their therapeutic options. Twenty-eight chose to use a vacuum erection device (VED), 26 preferred pharmacological penile injection and five used both intracorporeal therapy and VED. The remainder were managed with marriage and sexual counseling in 10 patients, three underwent penile prosthesis placement and two used topical pharmacotherapy. Four patients used other forms of treatment and in nine no therapy was recommended. Of the patients that used pharmacologic injection only, 74 percent used papaverine as a single agent, 20 percent used papaverine with phentolamine, five percent used prostaglandin E (PGE1) alone and one percent used a mixture. Patients using injection therapy report sexual intercourse a mean of 3 +/- 3.4 times per month as compared with 5 +/- 3.2 times per month in those using VED. Five intracorporeal injection patients developed priapism while two patients using the VED developed subcutaneous bleeding and one developed penile ischemia. We conclude that although a spectrum of erectile dysfunction treatment is present among SCI centers, VED and pharmacological penile injection are by far the two most popular methods of treatment and papaverine is the most common drug. The incidence of complications is small in the model centers.

Adolescent↗
PubMed1996

Intravesical capsaicin in neurologic impaired patients with detrusor hyperreflexia.

Capsaicin is known to be neurotoxic for C-fiber afferents. We investigated the intravesical application of capsaicin in the treatment of detrusor hyperreflexia (DH) in seven patients (ages 23-52) with neurologic impairment. The patients were evaluated with both ice-water cystometry and formal video-urodynamic studies. Four biweekly courses of intravesical capsaicin treatment were administered using increasing concentrations (100 microM, 500 microM, 1 mM, and 2 mM). Treatment effect was monitored using a bladder diary and urodynamic evaluation one month after capsaicin treatment. Prior to treatment, six of the seven patients demonstrated a positive ice-water test and DH. Two patients were not able to complete the study due to discomfort attributed to capsaicin. Five of the seven patients completed the four courses of increasingly concentrated capsaicin. Three patients noted symptomatic improvement while two did not. The mean urodynamic bladder capacity significantly increased from 124 +/- 39 ml pre-capsaicin to 231 +/- 62 ml one month post-capsaicin in the three patients with symptomatic improvement (p < 0.05). Urodynamic testing revealed that one of the six patients with a positive ice-water test lost that response after intravesical capsaicin. Intravesical capsaicin is a novel and promising treatment for detrusor hyperreflexia in neurologically impaired patients.

Administration, Intravesical↗
PubMed1996

Urologic manifestation of spinal cord sarcoidosis.

We present the first report of neurogenic lower urinary tract dysfunction associated with neurosarcoidosis. Urodynamic findings of detrusor hyperreflexia with detrusor-sphincter dyssynergia correlate with this patient's magnetic resonance imaging (MRI) examination which found intramedullary involvement at the mid-thoracic level.

Adult↗
PubMed1996

Endoluminal ultrasonographic and histologic evaluation of periurethral collagen injection.

To determine the acute and chronic ultrasonographic and histologic characteristics of injected glutaraldehyde cross-linked collagen in an animal model in order to enhance the therapeutic efficacy of the delivery of collagen for the treatment of urinary incontinence, three different depths of endoluminal ultrasound-guided injection (submucosal, intramuscular, periadventitial) of collagen into the urethral and bladder walls in two Yucatan mini pigs were investigated. The ultrasonographic characteristics of the injected material were examined 1, 4, 8, and 12 weeks later. A separate set of collagen injections, into the dermis and intramuscular layer of the lateral thigh of the animals, was undertaken with small-parts ultrasound guidance and follow-up. The injected tissues of the bladder, urethra, and thigh were ultrasonographically and histologically examined 3 months post-injection. Acutely injected collagen appeared hypoechoic on ultrasonography, although echogenicity increased over time. Submucosally injected collagen remained contained, forming a discrete collection of the material, whereas periadventitially injected collagen dispersed immediately. The ultrasonographic appearance and size of collagen collections correlated directly with their histologic identification and measurement. Injected collagen generated little inflammatory reaction, although infiltration by histiofibroblasts and neovascularization of the injected collagen occurred. Submucosal collagen injection resulted in superior longevity compared with intramuscular injection. From the results of our study, we hypothesize that durable success with collagen injection for the treatment of urinary incontinence is attributable to histiofibroblast infiltration of the injected collagen. When injected collagen is replaced with a hypertrophic scar, long-lasting clinical success is likely. If the injected collagen is replaced with a contracted scar, however, urethral coaptation may not persist. Endoluminal ultrasonography is helpful in ensuring the accurate submucosal location of collagen injection and in avoiding dispersion of the material and should enhance therapeutic efficacy in the treatment of urinary incontinence.

Animals↗
PubMed1996

Urological symptomatology in patients with reflex sympathetic dystrophy.

PURPOSE: We determined the effect of reflex sympathetic dystrophy on lower urinary tract function. MATERIALS AND METHODS: A total of 20 consecutive patients (16 women and 4 men) with neurologically verified reflex sympathetic dystrophy was referred for voiding symptoms, including urgency, frequency, incontinence and urinary retention. No patient had had voiding symptoms before the initial trauma that induced reflex sympathetic dystrophy. Evaluation included medical history, physical examination, video urodynamic testing and cystoscopy. RESULTS: Mean patient age was 43.4 +/- 10.2 years (range 28 to 58) and mean duration of urological symptoms was 4.9 +/- 3.6 years (range 1 to 14). Urodynamic study demonstrated a mean cystometric bladder capacity of 417 +/- 182 ml. (range 120 to 700). The urodynamic diagnoses included detrusor hyperreflexia in 8 patients, detrusor areflexia in 8, sensory urgency in 3 and detrusor hyperreflexia with detrusor-external sphincter dyssynergia in 1. In 4 women genuine stress urinary incontinence was also documented urodynamically. CONCLUSIONS: Reflex sympathetic dystrophy may have a profound effect on detrusor and sphincter function.

Adult↗
PubMed1996

Reversible clinical outcome after sphincter stent removal.

PURPOSE: We determined whether the self-expanding sphincter stent, a potential alternative to conventional external sphincterotomy for the treatment of detrusor external sphincter dyssynergia, causes a permanent effect on the lower urinary tract. MATERIALS AND METHODS: Four spinal cord injured men with voiding symptoms of detrusor external sphincter dyssynergia as noted by complete urological evaluation, including a video urodynamic study, were treated with the self-expanding sphincter stent. However, the device was explanted 6 months or longer after insertion in all 4 cases due to stent migration (3) and difficulty with condom catheter urinary drainage (1). RESULTS: All stents were removed completely without damage to the urethra. Mean voiding pressure decreased from 62.5 +/- 39.4 to 20.7 +/- 6.5 cm. water after sphincter stent placement. One year after stent explantation mean voiding pressure remained unchanged from preoperative values of 58.5 +/- 21.5 cm. water. No patient had stress urinary incontinence or endoscopically apparent urethral strictures. CONCLUSIONS: The stent can be removed even after complete epithelialization and an extended interval without damage to external sphincter function or urethral stricture formation. The urinary sphincter stent is an effective, reversible treatment for patients with detrusor external sphincter dyssynergia.

Adult↗
PubMed1996

Fascial sling correction of kinked efferent limb in patients with continent diversion and catheterization difficulty.

PURPOSE: We determined the efficacy of using a rectus fascial sling to revise an angulated efferent limb in patients with continent urinary diversion and difficulty with intermittent catheterization. MATERIALS AND METHODS: Two spinal cord injured women who underwent modified Indiana pouch urinary diversion required revision of each efferent limb because of difficulty with catheterization. A strip section of anterior rectus sheath was harvested and used to fix the efferent limb in position, assuring freedom from angulation and facilitating catheterization. RESULTS: Both patients remained continent for more than 2 years postoperatively and neither had further difficulties with catheterization or required additional surgery. CONCLUSIONS: Use of the rectus fascial sling in continent urinary diversion enables fixation of the efferent limb to facilitate catheterization and enhance continence.

Adult↗
PubMed1996

Gracilis muscle dynamic urethral sphincter myoplasty: rat model experience.

PURPOSE: Dynamic urethral sphincter myoplasty (skeletal muscle urinary sphincter reconstruction) using a neurovascularly intact gracilis muscle was investigated in a rat model. MATERIALS AND METHODS: In female Sprague-Dawley rats, a unilateral gracilis anticus muscle flap was dissected from the medial thigh, preserving the medial muscular insertion, vascular flow, and innervation. This muscle graft was used to completely encircle the urethra and was fixed in position. Urodynamic leak point pressure (LPP) and bladder volume at leakage were measured with cystometry after 1 month, using an 18 gauge catheter placed through the bladder dome with a constant infusion rate of 0.2 ml. per minute. In addition, the effect of electrical stimulation of the gracilis myoplasty (current parameters: 1 to 10 mA, 1 to 60 Hz, 0.05 to 1 msec. duration) on intravesical leak point pressure was noted during cystometry. RESULTS: The gracilis muscle measured 3.8 +/- 0.3 cm. in length, 0.5 +/- 0.1 cm. in width and 0.2 +/- 0.1 cm. in thickness. Blood flow rates to the grafted and contralateral gracilis myoplasty were similar at 43 +/- 26 and 51 +/- 30 g.cm.3, respectively (p = 0.46). The leak point pressure (LPP) of control, unstimulated gracilis myoplasty and gracilis myoplasty with electrical stimulation were 28 +/- 8, 32 +/- 12, and 85 +/- 27 mm.Hg (p < 0.01). Bladder volumes at LPP in the 3 respective groups were 0.5 +/- 0.2, 0.6 +/- 0.3 and 1.2 +/- 0.6 ml (p < 0.01). CONCLUSIONS: Gracilis myoplasty is not obstructive, as substantiated by unchanged leak point pressure and leak point capacity. Myoplasty with low current stimulation, however, significantly increased LPP and leak point capacity.

Animals↗
PubMed1996

The role of renal scintigraphy in the evaluation of spinal cord injury patients with presumed urosepsis.

PURPOSE: We attempted to differentiate pyelonephritis, defined as upper urinary tract parenchymal infection, from fever due to other sources in patients with spinal cord injury by radioisotope renal scintigraphy. MATERIALS AND METHODS: A total of 13 consecutive spinal cord injury patients 21 to 54 years old (level of injury C4 to cauda equina) was hospitalized with urosepsis. The diagnosis was based on medical history, physical examination and laboratory evaluation, including blood, urine, sputum and wound fluid culture and sensitivity, and a 99mtechnetium glucoheptonate renal scan for pyelonephritis. Renal scan results were compared to 1 or more of several studies performed in each case, including ultrasonography, excretory urography and axial computerized tomography. RESULTS: Glucoheptonate renal scintigraphy accurately diagnosed pyelonephritis in all 7 patients with a scintigraphic B lesion. In 2 patients with a C lesion on scintigraphy, representing a cortical scar, other sources of sepsis were identified. In the 4 patients with negative renal scans pyrexia was attributed to active decubitus wound infection and osteomyelitis. Positive and negative predictive values of renal scanning were each 100%. CONCLUSIONS: Nuclear medicine renal scanning is a valuable adjunct in the evaluation of sepsis and presumed urosepsis in the spinal cord injury population.

Adult↗
PubMed1996

The effect of urinary tract reconstruction on neurologically impaired women previously treated with an indwelling urethral catheter.

PURPOSE: We investigated the changes in sexuality and quality of life that evolve after lower urinary tract reconstruction in neurologically impaired women previously treated with an indwelling urethral catheter. MATERIALS AND METHODS: A total of 18 neurologically impaired women treated with an indwelling urethral catheter underwent bladder reconstruction. Pubovaginal sling urethral compression was required to restore perineal dryness in 13 patients and was the only operation required in conjunction with intermittent catheterization in 3. Eight patients underwent ileocystostomy, that is creation of a "bladder chimney," and 4 underwent augmentation cystoplasty with creation of a continent catheterizable stoma. In 3 patients ileocystoplasty alone with intermittent urethral catheterization was performed. All patients were followed 6 to 40 months (mean 18) after reconstructive surgery using a 9-part questionnaire to score numerically the effect of surgical reconstruction on sexuality and quality of life issues. RESULTS: On a scale of 0 (worst) to 5 (best) mean score for self-esteem improved from 1 preoperatively to 4 postoperatively, self-image from 1 to 4, sexual desire from 2 to 4 and ability to cope with disability from 1 to 4, respectively. In 4 of the 15 women who were sexually active preoperatively the frequency of sexual intercourse doubled from a mean of 3 to 6 times per month, respectively, and all 4 women reported improved sexual satisfaction. All 13 patients with pelvic pain and 5 with symptoms of autonomic dysreflexia noticed significant improvement if not complete resolution of the symptoms. CONCLUSIONS: Neurogenic lower urinary tract dysfunction treated with an indwelling urethral catheter is detrimental to sexuality and quality of life in neurologically impaired women. Urinary tract reconstruction restores not only quality of life but also sexuality by improving self-image, self-esteem and the ability to cope. Indwelling catheterization as a method of long-term urinary treatment should be avoided in women.

Adult↗
PubMed1995

Autonomic dysreflexia in a rat model spinal cord injury and the effect of pharmacologic agents.

The object of this study was to develop a spinal cord injury (SCI) rat model for autonomic dysreflexia (AD), assessing the effect of alpha-adrenergic and calcium channel blockade and to determine the relationship of detrusor-external sphincter dyssynergia (DESD) to the development of AD. A laminectomy was performed in male rats at the T4 or T10 level and a controlled 50 g cm blunt SCI was induced using an impounder. Four weeks after injury, changes in arterial blood pressure and heart rate were monitored while simultaneous cystometry (CMG) and pelvic floor electromography (EMG) were performed in vivo in sham (control) and spinal cord injured rats. The effects of terazosin (0.1 mg/kg), diltiazem (0.5 mg/kg), and oxybutynin chloride (0.1 mg/kg) on hemodynamic changes were assessed independently. Both T4 and T10 SCI rat displayed evidence of DESD (enhanced pelvic floor EMG activity at cystometric capacity) while control rats did not. Only T4 injured rats exhibited evidence of AD, with mean blood pressure elevations from 82.9 +/- 13.6 to 93.9 +/- 11.3 mm Hg (P < 0.01) and a mean heart rate decrease from 332.2 +/- 56.5 to 311.1 +/- 54.5 beats/min (P = 0.02) at cystometric capacity. The intravenous administration of terazosin or diltiazem abolished the AD response during CMG. The administration of oxybutynin exhibited the ability to increase bladder capacity and improve compliance in all 3 groups but did not blunt AD. The rat model of SCI effectively reproduced hemodynamic changes consistent with the AD complex in T4 level SCI but not T10 level SCI animals, despite incomplete lesions. Blockade with either an alpha-1 or a calcium channel antagonist effectively ablated the AD response to bladder distention. Anticholinergic agents had no effect on AD. DESD frequently accompanies autonomic dysreflexia, although the development of AD is not a prerequisite for DESD.

Adrenergic alpha-Antagonists↗