Hyperammonemia

Benign prostatic hyperplasia (BPH) is a condition that affects many men. Treatment of this condition includes medical, noninvasive, and surgical approaches. Transurethral resection of the prostate (TURP) has been used successfully to treat BPH since 1930;1 however, the TURP procedure uses an irrigating solution that has the potential to cause transurethral resection (TUR) syndrome.

A new technology now is available for performing TURP that uses saline irrigation, eliminating the risk of TUR syndrome. In addition, until recently, the use of monopolar current was the only method available for electrosurgery in urology procedures. The bipolar TURP, however, uses bipolar electrosurgery, which does not travel through the body and creates less risk of electrical shock.

ANATOMY OF THE PROSTATE

The prostate is a glandular, fibromuscular organ that lies at the base of the bladder and surrounds the urethra. It is the size of a large chestnut (ie, approximately 4 cm x 3 cm x 2 cm) and is divided into the right and left lateral lobes and the median lobe (Figure 1). (2) The ejaculatory ducts from the seminal vesicles enter the prostate and continue to the prostatic portion of the urethra. The prostate produces a milky, thin, alkaline fluid. During coitus, the prostate gland contracts and promotes the expulsion of semen during ejaculation. (3)

[FIGURE 1 OMITTED]

The section of the urethra that traverses the prostate gland is called the prostatic urethra. This area is lined with a thin, smooth muscle layer that is continuous with the lining of the bladder wall. This smooth muscle is the involuntary sphincter of the posterior urethra in the male. The small mucosal, intermediate submucosal, and large main prostatic secretory glands are arranged concentrically around the prostatic urethra. The enlargement of the small mucosal glands causes BPH. (4) This occurs in the area of the prostate that surrounds the urethra, so urinary obstruction can result.

BENIGN PROSTATIC HYPERPLASIA

Benign prostatic hyperplasia is a nonmalignant enlargement of the mucosal glands of the prostate. It is age related with increased incidence as a man ages. Fifty percent of men age 60 and older are affected by BPH, and 80% to 90% of men age 80 years and older are affected. (5) Although BPH is not a life-threatening disorder, it does interfere with quality of life. Daytime frequency of urination may limit activities, and nocturia prevents restful sleep.

Pathophysiology of BPH. Circulating androgens that are produced primarily in the testes are responsible for the proper functioning of the prostate gland. The prostate binds circulating testosterone and converts it to the hormone dihydrotestosterone. The enzyme 5-reductase, which is produced in the prostatic stroma, must be present for this process to take place. The dihydrotestosterone binds to androgen receptors in the prostatic epithelium, and cellular reproduction takes place. During the aging process, the amount of circulating and bound testosterone decreases. This should reduce the potential for BPH, but the amount of androgen receptors increases so that overgrowth of the prostate still can occur. (6)

Benign prostatic hyperplasia creates bladder outlet obstruction in two ways. The enlarging lobes of the prostate create a compressive obstruction of the urethra, resulting in decreased force and caliber of the urinary stream. The process of micturition requires the smooth muscle of the urethral sphincter to relax and distend so urine can flow freely. In men with BPH, this smooth muscle in the prostatic urethra is hypertrophied. This hyperplasia prevents the relaxation of the sphincter, and the outflow of urine is impeded. (7)

Symptoms associated with BPH are both irritative and obstructive and include

* decreased urinary stream force;

* hesitancy;

* increased daytime frequency (ie, voids at least every two hours);

* nocturia (ie, waking with an urge to void);

* post-void dribble, and

* urinary retention (ie, feeling that the bladder is not emptying completely).

Urinary retention can result in urinary tract infections, bladder stones, hematuria, and renal insufficiency. (8)

Patient evaluation. Although BPH is a nonmalignant condition, a diagnostic workup should be conducted to rule out prostatic cancer. The symptoms of BPH interfere with quality of life, and treatment should be approached with this in mind. The Agency for Health Care Policy and Research developed guidelines for the management of BPH in 1994. The key components in the evaluation include history, physical examination, digital rectal examination to assess size and presence of masses in the prostate, urinalysis, blood testing for serum creatinine to evaluate kidney function, and prostate-specific antigen (PSA) to screen for prostate cancer. (9) A patient with a PSA level higher than 4.0 mg per dL is a candidate for further prostate cancer testing. (10)

The American Urological Association developed the international prostate symptom score to assist in the assessment of BPH and its effects on the patient. (11) This tool includes questions about bladder emptying, frequency, urgency, nocturia, and urinary stream. The scores range from zero (ie, mild) to 35 (ie, severe). A watch and wait attitude may be taken for patients who do not feel their symptoms are significant. Patients with severe symptoms require some form of treatment for BPH.

Current treatment for BPH is based on symptom relief and can range from medical to noninvasive to surgical. Table 1 presents alternative treatments for symptoms of BPH. Heat therapy treatments are considered noninvasive and are performed under local anesthesia in a urologist's office. (12)

SURGICAL TREATMENT OF BPH

Transurethral resection of the prostate is the gold standard for treatment of BPH. This procedure results in the best improvement of symptoms and urine flow rates. (13) Until recently, the TURP procedure was the only surgical treatment alternative to open prostatectomy. (14) Although new minimally invasive techniques are available, patient satisfaction is high and postoperative complaints are fewer with the TURP procedure. (15)

Transurethral resection of the prostate is performed to remove the hyperplastic tissue in the prostatic urethra. (16) A resectoscope with a wire loop electrode is inserted into the urethra. This wire loop electrode is passed along the prostatic tissue and cuts away the tissue to remove the obstruction in the urethra. (17)

Monopolar TURP. Typically, TURP is performed using monopolar electric current and a wire loop electrode. Prostatic tissue is cut away using the cutting current of the electrosurgical unit (ESU). Bleeding is controlled using the coagulation current. (18) When using monopolar energy, the current flows from the active electrode (ie, the wire loop) to a ground? The electrical energy that is not absorbed by tissue travels through the patient to an ESU grounding pad. To avoid conduction of this electrical energy to surrounding tissues, a nonconductive irrigating solution is used. The most commonly used irrigating fluid is glycine because it is electrically inert and provides a clear visual field. (20) In addition, glycine is metabolized to ammonia in the liver. (21)

Transurethral resection syndrome. Monopolar TURP has some limitations, including the size of the prostate gland and procedure time. These limitations are set to avoid the potential risk of TUR syndrome. The risk of developing TUR syndrome increases with a gland larger than 45 g or resection time greater than 90 minutes. (22) Two percent of prostate resections are estimated to result in TUR syndrome. (23)

Transurethral resection syndrome is caused by the absorption of fluids, which results in dilutional hyponatremia and water intoxication. (24) During a TURP procedure, irrigating fluid is used to aid in visualization. As tissue is cut, bleeding occurs. The fluid flow must be enough to clear the surgical site of bleeding, so the pressure of the fluid must be greater than or equal to the pressure of the blood coming from the tissue. The open capillaries in the cut tissue provide access for the irrigating fluid to enter the bloodstream, (25) which results in a hypervolemic state with dilutional hyponatremia. (26) When using glycine, this absorption also can include hyperammonemia and lead to cerebral edema and seizures. (27)

Bipolar TURP. New technology has made a bipolar method of TURP available? The same procedure is performed, but the electrical energy is delivered using a bipolar generator. An ionized plasma pocket is created that allows resection or vaporization of tissue along with hemostasis. (29) In the bipolar system, both the active and return electrodes are contained within the instrument, (eg, the wire loop, vaporization electrode). (30) No ESU grounding pad is required. The electrical energy is contained within the electrode so the effect is localized, and there is no passage of electricity through the patient. In contrast to monopolar energy delivery, the bipolar technique requires an electrolytic medium to conduct the electrical energy from the active to the return electrode. Saline conducts electrical current so it is used as irrigation for bipolar TURP. Performing TURP with saline eliminates the possibility of TUR syndrome, (31) so limitations in gland size and procedure time also are eliminated.

NURSING CONSIDERATION FOR BIPOLAR TURP

Preparation for bipolar TURP requires the circulating nurse to have warm saline irrigation fluid and the bipolar generator in the OR. A special resectoscope is required to hold the bipolar electrode because of the unique nature of the system. Setup for the procedure includes

* TURP instruments (eg, cystoscope, resectoscope working element, continuous flow sheath, light cable, ESU cord, electrode) (Figure 2);

[FIGURE 2 OMITTED]

* bipolar ESU generator (Figure 3);

[FIGURE 3 OMITTED]

* stirrups;

* warm saline irrigation fluid;

* TURP tubing; and

* video camera equipment and monitor, if used.

Nursing care is essentially the same for patients undergoing either the monopolar or bipolar procedure. The circulating nurse meets the patient preoperatively and completes an assessment. The nurse verifies the procedure with the patient and answers any questions. The nurse determines whether the patient has any metal implants or a pacemaker. This is important to know, but because bipolar energy is being used, there is no concern with electrical current traveling through the body. After reviewing the chart and the surgical consent form, the nurse is ready to take the patient to the surgical suite.

The patient is placed in the lithotomy position after administration of spinal or general anesthesia. No dispersive ESU grounding pad is required as the technology used is bipolar. The patient is prepped and draped. The urologist passes a cystoscope into the urethra to visualize the surgical area. If a camera is used, the circulating nurse connects this. The electrode is placed in the resectoscope and then connected to the connecting cable, which is inserted into the bipolar generator. The generator defaults to the recommended settings for the electrode, which the circulating nurse verifies with the urologist. The foot pedal is covered and placed within comfortable reach of the urologist. The irrigation fluid (ie, saline) is hung on an IV pole. The fluid is either warmed in a warming cabinet or run through a fluid warmer.

The bipolar electrode functions optimally when warm saline is used. If the loop electrode is used, prostate tissue is evacuated using either an Elick evacuator or a Toomey syringe. When the vaporization electrode is used, there is no tissue to evacuate. Upon completion of the procedure, a catheter may be inserted, depending on the amount of bleeding. A three-way catheter is used if continuous irrigation is required. A two-way catheter may be used if there is no evidence of bleeding and irrigation is not necessary. The patient then is transferred to the postanesthesia care unit.

CONCLUSION

During an 11-month period, 25 patients underwent vaporization of the prostate during bipolar electrosurgical procedures at the Cleveland Clinic Urological Institute. Patients ranged in age from 61 to 90 years with an average age of 79. None of the patients required transfusions, and length of stay based on urological procedure alone, without taking comorbidities into account, was 1.9 days. Twenty-three of these patients had a catheter for 2.6 days. All the patients voided well, and there was no significant postoperative dysuria or incontinence. Bladder scans verified minimal residual urine volume. (32) Based on this data, preliminary conclusions are that the bipolar method for transurethral resection or vaporization of the prostate is safe and efficient; eliminates concern for hemolysis, hyponatremia, or glycine toxicity; and causes little or no bleeding. (33)

Although there are other treatments available, TURP remains the gold standard of treatment for men with BPH. The risk of TUR syndrome is a concern in TURP procedures using monopolar energy and glycine irrigation. A new technology now is available that eliminates the risk of TUR syndrome and allows urologists to perform TURP procedures on larger glands. This is valuable because more men are choosing medical options for treatment of BPH and present for surgery when the prostate is enlarged to a size that could create a higher risk when using glycine and monopolar energy.

Table 1

ALTERNATIVE TREATMENTS FOR BENIGN PROSTATIC HYPERPLASIA (BPH)

Herbal supplements

Saw palmetto is a commonly used plant extract marketed to relieve symptoms of BPH. There is no scientific data to support the effects or actions of herbal therapy. (1)

Alpha-blockers

Alpha-blockers relax the smooth muscle tone in the prostate to improve urinary flow rates. These medications include terazosin hydrochloride, doxazosin mesylate, and tamsulosin hydrochloride. (2)

Hormone therapy

Finasteride inhibits 5-alpha-reductase and blocks the conversion of testosterone to dihydrotestosterone. The effect is reduced prostate size with improved urine flow and decreased symptoms. (3)

Transurethral needle ablation

Needles deliver high frequency radio waves to prostate tissue. Heat is generated, and the tissue is destroyed. The procedure is performed under local anesthesia, although some experts believe the procedure requires more than local anesthesia. Symptom relief may take several weeks after treatment. (4)

Transurethral microwave thermotherapy

This is another form of heat therapy. Heat is delivered to the prostate tissue through microwave pulses transmitted by a device inserted into the urethra. Additional treatments may be necessary to maintain adequate urinary stream. The procedure is contraindicated for those with pacemakers, metal implants, or implanted defibrillators. (5)

Laser

There are three categories of laser therapy, including visual laser ablation, interstitial laser coagulation, and holmium: yttrium aluminum garnet resection. (6) Laser energy is delivered to and destroys the prostate tissue. Laser therapy is most effective for men who are on crystalline warfarin sodium or aspirin therapy because there is no bleeding associated with the procedure. (7) Irritative voiding symptoms are a common complaint after laser treatment. (8)

NOTES

(1.) V Glaser, "Men's health: Individualizing BPH treatment," Patient Care 35 (June 30, 2001) 28-39.

(2.) Ibid.

(3.) Ibid.

(4.) "What are the surgical and other procedures for benign prostatic hyperplasia?" WebMD, http://my.webmd.com/content/article/1680.50537 (accessed 8 May 2002); Glaser, "Men's health: Individualizing BPH treatment," 28-39.

(5.) "What are the surgical and other procedures for benign prostatic hyperplasia?"

(6.) M A Cabelin, S A Kaplan, "BPH: Update on new technology ... benign prostatic hyperplasia," Contemporary Urology 13 (May 2001) 46-56.

(7.) "What are the surgical and other procedures for benign prostatic hyperplasia?"

(8.) C D Zippe, "TURP remains procedure of choice in severe BPH," Urology News (1996), http://www.clevelandclinic.org/urology/news/prostate/05-08.htm (accessed 15 Jan 2003).

Editor's note: The author wishes to acknowledge Gerard DeOreo, MD, for his contributions to the development of this article.

NOTES

(1.) A Chambers, "Transurethral resection syndrome--It does not have to be a mystery," AORN Journal 75 (January 2002) 159.

(2.) H M Seidel et al, Mosby Guide to Physical Examination, fourth ed (St. Louis: Mosby, 1999) 671.

(3.) C M Porth, Pathophysiology: Concepts of Altered Health States, fifth ed (Philadelphia: Lippincott, 1998) 1152.

(4.) Ibid.

(5.) V Glaser, "Men's health: Individualizing BPH treatment," Patient Care 35 (June 30, 2001) 28-39.

(6.) P G Beare, J L Myers, Adult Health Nursing, third ed (St Louis: Mosby, 1998) 1699.

(7.) Ibid.

(8.) Ibid, 1700.

(9.) Porth, Pathophysiology: Concepts of Altered Health States, fifth ed, 1170.

(10.) Glaser, "Men's health: Individualizing BPH treatment," 28-39.

(11.) Beare, Myers, Adult Health Nursing, third ed, 1701.

(12.) Glaser, "Men's health: Individualizing BPH treatment," 28-39.

(13.) M T MacFarlane, Urology: House Officer Series, third ed (Philadelphia: Lippincott Williams & Wilkins, 2001) 113.

(14.) Chambers, "Transurethral resection syndrome--It does not have to be a mystery," 159.

(15.) C D Zippe, "TURP remains procedure of choice in severe BPH," Urology News (1996), http://www.clevelandclinic.org/urology/news/prostate/05-08.htm (accessed 15 Jan 2003).

(16.) Beare, Myers, Adult Health Nursing, third ed, 1700.

(17.) "What are the surgical and other procedures for benign prostatic hyperplasia?" WebMD, http://my.webmd.com/content/article/1680.50537 (accessed 8 May 2002).

(18.) M A Cabelin, S A Kaplan, "BPH: Update on new technology ... benign prostatic hyperplasia," Contemporary Urology 13 (May 2001) 46-56.

(19.) K Isaacson, "New developments in radiofrequency technology for laparoscopic surgery," Contemporary Ob/Gyn (April 15, 2002) 30.

(20.) M I Resnick, A J Schaeffer, Urology Pearls (Philadelphia: Hanley & Belfus, Inc, 2000) 85.

(21.) S Imaik et al, "Interactive case report in anesthesia/critical care," The Internet Journal of Anesthesiology 3 no 1 (1999), http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ ijaJvo13n1/case.xml (accessed 15 Jan 2003).

(22.) Resnick, Schaeffer, Urology Pearls, 85.

(23.) Ibid.

(24.) Ibid.

(25.) Chambers, "Transurethral resection syndromeilt does not have to be a mystery," 161.

(26.) Imaik et al, "Interactive case report in anesthesia/critical care."

(27.) Chambers, "Transurethral resection syndrome--It does not have to be a mystery," 162.

(28.) "Current and coming in endourology: Highlights of the 18th World Congress on Endourology and SWL and the 16th Basic Research Symposium, Sept 14-17, 2000, Sao Paulo, Brazil," Reviews in Urology 3 (Winter 2001) 6-9. Also available at http://www.medreviews.com/pdfs/articles/riu-winter2001-8498con.pdt (accessed 15 Jan 2003).

(29.) S E Strop, L May, "Plasmakinetic vaporization and vaporesection of prostate and bladder tissue," (Abstract) Journal of Endourology 15 suppl (November 2001) A139.

(30.) Isaacson, "New developments in radiofrequency technology for laparoscopic surgery," 30-33.

(31.) "Current and coming in endourology: Highlights of the 18th World Congress on Endourology and SWL and the 16th Basic Research Symposium, Sept 14-17, 2000, Sao Paulo, Brazil," 7.

(32.) G DeOreo, personal communication with the author, Cleveland, July 2, 2002.

(33.) Ibid.

Paula Bishop, RN, MSN, CNOR, is a clinical specialist at Gyrus Medical, Inc, Maple Grove, Minn.

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