Artificial urinary sphincter 800

ARTIFICIAL URINARY SPHINCTER 800 JORDAN BROWN, M.D. PABLO MORALES, M.D. From the D e p a r t m e n t of Urology, New York University Medical Center, New York, New York

ABSTRACT--With the refinements in the Sphincter 800, better patient selection and improved surgical techniques, the artificial urinary sphincter now oJJers a viable treatment alternative in the management oJ urinary incontinence arising #om sphincteric incompetence.

Urinary incontinence may be the consequence of sphincteric incompetence. Individuals with such incontinence may respond to pharmacologic agents designed to increase bladder capacity and sphincteric resistance, in addition to intermittent catheterization if high residual urine is also present. Many patients in this group, however, will not respond to the combined therapy and are doomed to a lifetime with pads, urine bags, or catheters. Fortunately with improved technology during recent years, implantation of an artificial urinary sphincter has become a viable treatment option that now can be offered to many of these patients. Estimates indicate there are approximately 800,000 individuals in the United States who are potential candidates for implantation of an artificial urinary sphincter. Thus far, approximately 5,000 artificial sphincters have been implanted by different surgeons in the United States since its first introduction by Scott in 1972.*

There are patients however who did not fulfill these criteria but who were successfully implanted with an artificial urinary sphincter after pharmacologic measures and corrective surgery (sphincterotomy, bladder flap urethroplasty, or vesical augmentation). Relative contraindications to implantation include intractable urethral stricture, poor detrusor compliance, detrusor hyperreflexia unimproved by pharmacologic means, small fibrotic bladder, and physical or mental incapacitation. Patient evaluation should consist of a careful clinical history, complete urologic examination, and

Patient Selection and Evaluation The ideal candidate for implantation of an artificial urinary sphincter should have the following: 1. Unobstructed lower urinary tract. 2. Adequate bladder capacity, pressures and acceptable residual urine. 3. No detrusor hyperreflexia, or if present, can be controlled pharmacologically. 4. Viable tissue at the site of cuff implant. 5. Sufficient manual dexterity and motivation. 6. No progressive neurologic disease involving bladder function. 7. Sterile urine. *Scott FB, Bradley WE, and Timm GW: Treatment of urinary incontinence by an implantable prosthetic sphincter, Urology 1: 252 (1973).

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Artificial urinary Sphincter 800. (Courtesy of American Medical Systems.)

FIGURE 1.

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Activated

Deactivated

FIGURE 2. Physiologic design of Sphincter 800. (Courtesy of American Medical Systems.)

urodynamic testing to assess the bladder's ability to store and expel urine adequately. A careful history will help determine the nature and duration of urinary incontinence. Physical examination should confirm the incontinence, evaluate the neurologic status, and measure residual urine. Urine culture should be obtained, and if positive, the bacilluria should be treated with the proper antibiotics and implantation deferred until the culture is negative. Urography should reveal no significant dilation of the upper urinary tract and no accumulation of residual urine. Cystoseopy should be done to rule out stricture or prostatic obstruction that would impede complete emptying of the bladder. If an obstructive process is present, surgical correction should be done prior to rather than coincident to implantation. Paraplegic patients with detrusor-sphincter dyssynergia and incomplete bladder emptying should have sphincterotomy. Conditions that required implantation of an artificial urinary sphincter are listed in decreasing order of frequency: myelomeningocele, radical prostatectomy, simple prostatectomy, spinal cord injury, neurogenic bladder, stress incontinence, pelvic trauma, bladder exstrophy, epispadias, and sacral agenesis. Description of Device The Sphincter 800 is the newest generation of artificial sphincters. A major break-through is the introduction of a new control pump to replace the control assembly and deflation pump of the 791-792 models. The new control pump can be used to activate 6r deactivate the device without additional surgery. There is an undoubted advantage in not pressurizing the cuff at the time of initial surgery especially when there is a question as to the viability of the cuff site. Moreover, it will be easier to perform postoperatively such procedures as cystoscopy and transurethral surgery because the device can be deactivated during the procedure.

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The Sphincter 800 has three components: control pump, occlusive cuff, and pressure-regulating balloon (Fig. 1). All three components are filled with a fluid that is isotonic to minimize the transfer of fluid across the silicone which is a semipermeable membrane. When implanted, the prosthesis simulates normal sphincter function by opening and closing the urethra (vesical neck or bulbous urethra) at the control of the patient (Fig. 2). To urinate, the patient squeezes the deflate bulb of the control pump in the scrotum or labium until it feels empty of fluid. This causes the fluid that pressurizes the cuff to move from the cuff into the pressure-regulating balloon. With the cuff empty, urine passes through the urethra. As soon as the patient stops squeezing the pump, the fluid in the balloon that has been transferred from the pump and cuff begins to return slowly to those components. After a few minutes, the cuff is again sufficiently refilled to occlude the urethra or bladder neck. The control pump is implanted in the scrotum or labium. The upper part of the control pump contains the resistor and valves needed to transfer fluid to and from the cuff, and a deactivation button connected to a deactivation valve. The bottom half of the control pump is a deflate bulb which the patient squeezes to transfer fluid within the system. To deactivate the device, the cuff is first deflated by squeezing the deflate bulb. The deflate bulb is then allowed to refill, and when full, the deactivation button is pressed, causing a block in the fluid pathway from the balloon to the cuff and vice versa. To activate, the deflate bulb is squeezed quickly and forcefully--this should unseat the deflate valve and reopen the fluid pathway. The occlusive cuff is implanted either at the bladder neck (male or female) or the bulbous urethra (male). The cuff occludes the urethra by applying pressure circumferentially. It is available in eleven sizes, ranging from 4.5 to 11 cm in length. All cuffs

UROLOGY / MAY1984 / VOLUMEXXIII, NUMBER5

are 2 cm wide. The proper size is determined by measuring the circumference around the urethra or vesical neck intraoperatively. A cuff sizer is available for this purpose. The pressure-regulating balloon is implanted in the prevesical space and controls the amount of pressure exerted by the occlusive cuff. The thickness of the wall of the balloon determines the pressure that each balloon can produce. The balloons are available in four standard ranges: 51-60 cm water, 61-70 cm water, 71-80 cm water, and 80-91 cm Xvater. The pressure applied to the urethra or vesical neck should occlude the lumen but should be less than the blood pressure of the vessels enclosed by the cuff, otherwise pressure necrosis could occur. The implanting surgeon should use the lowest balloon pressure needed to achieve continence. To permit radiographic monitoring, either of the following solutions can be used for filling the system: Hypaque 25%, dilute 1 part dye with 1 part sterile water; or Cysto-Conray II, dilute 2 parts dye with 1 part sterile water. If the patient is allergic to iodine, a normal isotonic solution of saline should be used. Operative Method If the male patient uses an external collecting device, it should be discontinued for one week prior to hospitalization, and the penile skin should be cleansed daily. Oral broad-spectrum antibiotics are given five days prior to hospitalization, and on hospitalization, parenteral antibiotic therapy with aminoglycoside and penicillin-like antibiotics for two days preoperatively. To minimize the incidence of infection further, the genitalia and lower abdomen are scrubbed with povidone-iodine soap twice a day while the patient waits for the operation. In the operating room a ten-minute skin scrub with povidone-iodine soap precedes the draping. During the operation, the wounds are sprayed at ten-minute intervals with antibiotic solution. We use a solution containing 1 Gm of kanamycin and 50,000 units of bacitracin in 500 ml of sterile saline. The incontinence cuff can be implanted around the bladder neck in male and female patients if the bladder neck has not been altered by previous surgery or trauma, and around the bulbous urethra in the male patient. The smallest cuff will not fit a child's urethra, so an implant in a child will have to be around the vesical neck. Moreover, a child's urethra is perhaps too fragile and erosion prone. A bulbous urethral implant is technically easier than in the vesical neck and is preferred for the postprostatectomy patient. However, the erosion rate with the bulbous urethral implant is higher, and the incidence of associated infection and postoperative stress incontinence also higher. On the other hand, the vesical neck implant appears to be more physiologic because of its proximity to the normal sphincteric mechanism. Moreover, the bladder neck tolerates

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Ficur~E 3. Bulbous urethral approach. (Courtesy of American Medical Systems.) compression better than the bulbous urethra, and a balloon with a higher pressure range can be used effectively to achieve continence.

Bulbous urethral approach (Fig. 3) The patient is placed in a low lithotomy position. Identification and dissection of the bulbous urethra is facilitated by using a urethral distender. The urethral distender can be prepared by tying the cut finger of a surgical glove to the end of a catheter. The catheter is then passed into the bulbous urethra and the rubber finger gently inflated. A midline incision is made in the median raphe of the perineum to expose the bulbous urethra. The bulbocavernosus muscles are divided vertically and retracted laterally exposing the bulb. The bulbous urethra is mobilized by sharp and blunt dissection until its 12-o'clock attachments are reached. The urethra at the 12-o'clock position is vulnerable to surgical injury and should be freed carefully. Once around the urethra, the dissection should be widened to permit the placement of a 2-cm wide cuff. The urethra is then checked to determine whether or not it has been injured by compressing it proximal to the area of dissection and injecting saline into the urethral meatus. The intact urethra will distend and no leakage of the injected fluid will occur. In case of doubt, urethroscopy should be done to ascertain the urethral integrity. The circumference of the urethra is measured with a cuff sizer, and the proper size cuff is selected and filled with fluid to drive out all the air. The fluid is then removed and the cuff's tubing clamped. The cuff is now passed around the mobilized bulbous urethra and buttoned in place. The mid and distal bulbs have been used as the site for the cuff. We prefer the distal site just proximal to the decussation of the crura where the cuff will be less likely to be compressed when the patient sits.

The field of operation is then moved to the suprapubic area where a small transverse incision is made just above the pubis and carried down to the anterior rectus fascia which is also divided in line with the incision. The cuff's tubing is passed subcutaneously with a tube passer from the perineum into the lateral aspect of the suprapubic incision and exits between the Scarpa fascia and the anterior rectus fascia. A balloon of the appropriate pressure range is filled to a volume of 18 cc fluid and connected to the cuff's tubing to fill the cuff temporarily and allow for individual variations in the fit of the cuff around the urethra. The tubings of the cuff and balloon are then clamped, the connector removed, and the fluid remaining in the balloon aspirated. The pressure regulating balloon is placed in the prevesical space after retracting the recti muscle laterally from the midline. The tube passer is used to bring the balloon's tubing through the anterior abdominal fascia near the internal inguinal ring and threaded through the inguinal canal out to the external inguinal ring. The balloon is then filled with 16 cc fluid; this amount of solution in the balloon will properly pressurize the cuff for continence. By blunt dissection from the external inguinal area, a pocket for the control pump is created in the scrotum on the same side as the cuff's tubing. The space should be just sufficient to accommodate the pump and not too large to allow twisting of the pump or kinking of its tubes. The control pump is filled with fluid, and its two tubings are clamped prior to implantation. The tubes from the balloon and cuff and the two tubes from the control pump are collected at the area of the external inguinal ring, trimmed to appropriate lengths, and connected to each other, respectively. To assure proper connections of the tubings, the control pump's tubing that connects to the cuff's tubing is marked with a "C" and has an unbeveled end, and the tubing that connects to the balloon's tubing is marked with a "B" and has a beveled end. The connections are made with plastic connectors and are secured with 3-0 polypropylene ties. Before closing the wounds, the prosthesis should be pumped to confirm its appropriate connection and function. This can be accomplished by squeezing the deflate bulb and opening the cuff. The bladder is then filled with 200 ml of saline and Credg pressure applied over the bladder and pressure-regulating balloon. This generally induces a gush of fluid from the bladder. The deflate bulb and the cuff are then allowed to refill and the Cred6 pressure reapplied. If the artificial sphincter is functioning properly, the flow of fluid from the bladder will be significantly lessened in amount and force during Cred~ pressure. Urethral profilometry is a less reliable test and not recommended. The wounds are closed and no drains are used. A 14-F Foley catheter is left indwelling. The Sphincter 800 is routinely deactivated as described previously.

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The period of catheter drainage and deactivation are determined by the circumstances at the time of implantation and tissue viability at the cuff site. Bladder neck approach (Fig. 4)

A transverse abdominal incision is made immediately adjacent to the pubis and deepened directly through the fascia and recti muscle. The prevesical space is exposed, and the vesical neck is located by palpating the balloon of an indwelling Foley catheter. Incisions into the transversalis fascia or endopelvic fascia on each side of the bladder neck will increase the exposure and allow palpation of the catheter and trigone anteriorly. In the female, a plane is dissected posterior to the bladder neck and trigone and anterior to the vagina. The relationship of the vagina to the trigone can be determined by frequently palpating with a finger in the vagina. In the male, dissection is done posterior to the bladder neck and trigone and anterior to the vas deferens, ampulla, and seminal vesicles. The dissection is facilitated by palpating the characteristic vas deferens posteriorly, and the catheter and trigone anteriorly. If the bladder is inadvertently opened, it should be closed water tight in two layers with absorbable sutures. If the vagina is opened, it should likewise be closed. However, at times a deliberate opening of the bladder well above the cuff site can be of great help during the dissection under the bladder neck and trigone because the interior of the bladder can then not only be visualized but also palpated. Once a passage has been created under the bladder neck and trigone, a spreading action of a right-angle clamp or scissors will dilate the passage enough to permit the placement of a cuff. After controlling the usual venous bleeding that ensues, a proper size cuff is selected and implanted. Implantation of the pressure-regulating balloon and control pump, and connections of the tubings

are done as described for the bulbous urethral approach, except the control pump in the female is placed in the labium. The device should always be tested and deactivated. A 16-F Foley catheter is left indwelling. The wound is closed, and no drains are used. The period of catheter drainage and deactivation are similarly influenced by the circumstances during surgery and viability of the bladder neck tissue. Complications

Mechanical The artificial urinary sphincter is a man-made mechanical device and as such is susceptible to mechanical failures. Leakage of fluid is the most common mechanical problem and can occur in the cuff, pump, balloon, or tubing, but usually involves the cuff. In the event that surgical revision is necessary for a leak in the system, the component that is the site of leakage can be easily identified electrically during surgery with the aid of an ohm meter. The Silastic elastomer now used in the cuff and pressureregulating balloon is particularly noted for its elasticity, strength, and recovery property, and it is anticipated that the incidence of leakage will diminish. Malfunction in the delay fill resistor previously located in a separate control assembly and now incorporated in the control pump has been rare provided the organic iodide used to fill the system is prepared in the prescribed manner. The deactivation-activation mechanism has only been in recent use and has not yet been reported as a source of sphincter failure.

Surgical The artificial sphincter is surgically implanted, and the ultimate outcome is to some extent dependent on the skill and experience of the implanting surgeon. The bladder neck or bulbous urethra may be injured, and the injury may not have been recognized and adequately managed. This could lead to infection and tissue necrosis and necessitate total removal of the prosthesis. The connecting tubes may have been trimmed to an improper length during the implant procedure and subsequently create a kink that prevents transfer of fluid from one component to another. A kink in the tubing may be suspected from the x-ray films, including an oblique view. Blockage also can occur in the control assembly from blood, debris, or crystals. A control pump implanted in a capacious space may twist on itself and create a kink in its tubing, or may migrate upward and be difficult to operate. An incorrectly selected cuff size or pressure-regulating balloon may contribute to tissue necrosis or continued incontinence.

ficial urinary sphincter, like any other prosthetic device, is susceptible to infection and may have to be removed as a consequence. Preoperative treatment of bacilluria and continued sterility of the urine are therefore important. Some cases of infection may have been secondary to erosion, and it is difficult to distinguish between these complications in the late postoperative period. It can be anticipated, however, that the erosion rate will be lessened considerably by using the deactivation option in the Sphincter 800. It is also obvious that ideally, tissue at the site of cuff implant should be well vascularized and nonfibrotic, and if not so, another site for the implantation should be selected. Results Further technical refinements in the sphincter device and improvements in patient selection and surgical techniques have led to a growing confidence among urologists in the use of the artificial urinary sphincter as a treatment alternative in managing some forms of urinary incontinence. American Medical Systems compiled data in 1982 on 486 patients implanted with the current model of the artificial urinary sphincter at that time (AS742 and AS791-92) from eleven medical centers that included ours. The compilation was analyzed by the life-table method and showed that there was a 77 per cent (___4.5 %) probability that the patient implanted would have a successful result twenty-seven months from the date of surgery. Males and females achieved similarly favorable outcomes. Mechanical complications were less common than surgical or medical problems. When these occur, complications were generally seen in the first six months. Patient groups with different etiologies were found to have varying rates of erosion; those with myelomeningoceles had an 85-per cent success rate while postprostatectomy cases had a 70-per cent success rate. Our own experience with the artificial urinary sphincter consists of 61 implanted patients. We classified our results as good, improved, or failed. A good result was when the patient became continent or employed a maximum of one or two pads for urinary leakage. An improved result was when the patient changed pads only when he or she voided, and managed to remain socially acceptable. A failed result indicated the patient was socially unacceptable as a result of incontinence or the device had to be removed. If revision of the prosthesis was required and succeeded, the patient was included in the good or improved result in accordance with the above criteria. But if the patient was awaiting a surgical revision, he was included in the failed category. An analysis of our results showed 70 per cent good or improved results in 61 patients.

Medical Medical problems are due to infection, tissue erosion, or poor tissue pliability or vascularity. The arti-

New York, New York 10016 (DR. BROWN)

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