Complications of transurethral resection of the prostate

Published on 13/02/2015 by admin

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Complications of transurethral resection of the prostate

Marie L. De Ruyter, MD

Transurethral resection of the prostate (TURP), one of the more common surgical procedures performed in men over age 60, is the standard surgical treatment for benign prostatic hypertrophy (BPH) when symptomatic obstruction of urinary outflow occurs. A variety of factors have led to decreasing mortality and morbidity rates associated with this procedure, including increased awareness of BPH, which has led to earlier treatment, and the availability of new drugs and new surgical techniques, which are associated with lower rates of complications.

In a traditional TURP, resection of the prostate is performed during cystoscopy using a resectoscope with an electrocautery loop. The morbidity rate of 7% to 20% is associated with longer resection times (>90 min), larger gland size (>45 g), acute urinary retention, and age greater than 80 years. One of the most serious complications associated with TURP, TURP syndrome (Box 166-1) occurs in 2% to 15% of patients treated with this approach. Postoperative bleeding with the need for blood transfusion occurs in about 2% to 4.8% of patients who develop TURP syndrome.

Box 166-1

Signs and Symptoms of Transurethral Resection of the Prostate Syndrome

Cardiovascular and Respiratory	Central Nervous System	Metabolic	Other
Hypertension Bradyarrhythmias/tachyarrhythmias Congestive heart failure Pulmonary edema and hypoxemia Myocardial infarction Hypertension	Agitation/confusion Seizures Coma Visual disturbances (blindness)	Hyponatremia Hyperglycinemia Hyperammonemia	Hypo-osmolality Hemolysis

From Malhotra V, Sudheendra V, O’Hara J, Diwan S. Anesthesia and the renal and genitourinary systems. In: Miller RD, ed. Anesthesia. 7th ed. Vol. 2. Philadelphia: Churchill Livingstone; 2009: Chap. 65.

With newer surgical techniques, however, TURP syndrome occurs in as few as 1.1% of patients, such that anesthesia providers are now unlikely to encounter patients with this complication.

Treatment

Medical options

One of the reasons the incidence of complications of TURP is decreasing is that many men are successfully treated medically, and for those whose symptoms progress, the prostate may not be as large as it might have been without medical treatment; therefore, the operative procedure has a shorter duration and is associated with fewer complications. The medical treatment of BPH includes the oral administration of α-adrenergic antagonists (e.g., tamsulosin) or 5α-reductase inhibitors (e.g., finasteride). If medical treatment is unsuccessful or symptoms progress and the patient is a surgical candidate, a TURP may be performed to treat symptoms.

Surgical options

TURP is performed under direct vision. The most common procedure in the past was performed with a modified cystoscope (resectoscope) with a monopolar electrically energized wire loop. Bleeding was controlled with a coagulating current. Continuous irrigation was used to distend the bladder and remove blood and dissected prostatic tissue. Because the prostate contains large venous sinuses, it was inevitable that irrigating solution would be absorbed into the vascular system. The volume absorbed depended on three factors: the hydrostatic pressure, duration of the resection, and number and size of the opened venous sinuses. The hydrostatic pressure is determined by the height of the irrigating fluid above the patient. Prostate venous sinuses have a pressure of approximately 10 mm Hg. The duration of the TURP was dependent upon the size of the prostate and experience of the surgeon. Approximately 10 to 30 mL of irrigating solution is absorbed per minute of resection time. The choice of irrigation solution is dependent on several factors as discussed later.

Monopolar TURP is still considered by many as the treatment of choice for very enlarged prostates (50-80 g); however, this “gold-standard” is marred by the previously mentioned significant morbidity and mortality rates.

Recently, several alternatives have been introduced that are associated with good results and fewer complications (e.g., bleeding and TURP syndrome). The use of a bipolar electrosurgical device allows the urologist to use alternative irrigation solutions, which are associated with fewer complications. “Plasma TURP” refers to a TURP in which a bipolar electrode, in the shape of a mushroom, generates a “plasma” corona on its surface. The energy simultaneously vaporizes tissue and coagulates all but the largest blood vessels; because of the type of energy used, the procedure can be performed with saline as the irrigation solution, which all but eliminates the possibility of TURP syndrome developing.

Another new technology that has been in use for about a decade is the “green-light laser”—a high-power (80-W) potassium-titanyl-phosphate laser emitting a green laser beam of light that also vaporizes and coagulates blood vessels. For some urologists, this technique has become the treatment of choice for TURP and is associated with fewer short-term (i.e., perioperative) complications.

Irrigation solutions

The choice of which irrigating fluid to use when performing a TURP depends on many factors, including the optical properties of the fluid, its degree of ionization, and its potential for inducing hemolysis, as well as on the technology being used to resect the prostate. Distilled water was often used in the past as an irrigation solution because of its excellent optical properties and low cost, but distilled water is not often used in current practice because of its potential for inducing marked dilutional hyponatremia and intravascular red blood cell hemolysis.

Lactated Ringer’s and normal saline solutions cannot be used if a monopolar electrosurgical probe is used because these solutions are highly ionized and promote current dispersion from the monopolar resectoscope. However, the newer surgical techniques mentioned above that employ a bipolar probe or a laser device can be performed with normal saline as the irrigating solution, which results in a much lower incidence of TURP syndrome. Normal saline is well tolerated when absorbed intravascularly.

Glycine (1.5%) is a low-cost, nonelectrolytic, and only slightly hypo-osmolar fluid that can be used during monopolar therapy. However, if large amounts of glycine are absorbed, transient blindness and encephalopathy can evolve, as can potential complications associated with increased fluid load.

Sorbitol (2.7%) and mannitol (0.54%) have the advantage of being nonelectrolytic, isosmolar, and rapidly cleared from the plasma but are expensive and can lead to complications resulting from increased intravascular fluid load.

Specific complications

Turp syndrome

TURP syndrome, a constellation of symptoms and signs caused by excessive absorption of the irrigating fluid, may occur at any time perioperatively. Patients who undergo a TURP with a neuraxial anesthetic and who remain awake will often complain of nausea, headache, and dizziness as the first manifestations of TURP syndrome, which progresses to dyspnea and confusion. Agitation often ensues, associated with elevated blood pressure and bradycardia; if no treatment is implemented, seizures and cardiac arrest may follow (see Box 166-1). Diagnosing TURP syndrome in patients who undergo TURP with general anesthesia may be difficult because the first signs are hypertension and severe refractory bradycardia, followed in short order by seizure and cardiac arrest. These signs develop most often in patients with preexisting compromised myocardial function whose compromise leaves them unable to handle the increased intravascular absorption of the irrigating solution.

The TURP syndrome develops because of circulatory overload and hyponatremia. The former is associated with the amount of irrigating solution that is absorbed, which in turn depends on cardiovascular status, amount and rapidity of absorption of irrigating solution, and amount of surgical blood loss. Dilutional hyponatremia associated with TURP is a hypervolemic hyponatremic condition representing excess total body water with normal total body sodium. If resection time is longer than 90 min or the patient has mild symptoms of TURP syndrome, such as nausea, headache, dizziness, or mild confusion, his serum sodium should be measured. If hyponatremia is present, the patient should be treated with fluid restriction and a loop diuretic (furosemide 5-20 mg administered intravenously). If serum sodium concentration is below 120 mEq/L or the patient develops severe signs and symptoms of water intoxication (twitching, visual disturbance, hypotension, dyspnea, seizures), treatment should be instituted immediately with hypertonic (3%) saline at a rate of 100 mL/h or less, allowing the most rapid correction of plasma sodium concentration. The volume of distribution of sodium equals total body water, so free water excess can be estimated from the following formula:

< ?xml:namespace prefix = "mml" />Total body water = weight (in kg) × 0.6

From this, an estimation of the mEq of Na⁺ necessary to normalize the plasma sodium concentration can be obtained:

Sodium deficit = (140 – observed plasma Na+) × total body water

Hypertonic 3% saline contains 513 mEq of Na⁺ per liter and should be administered at a rate no faster than 100 mL/h. Once the symptoms have abated (or the sodium concentration rises above 120 mEq/L), the hypertonic saline should be stopped, and furosemide (40-60 mg) should be intravenously administered to aid free-water excretion by the kidneys. Frequent serum sodium measurements should be obtained. Too rapid correction of hyponatremia can cause seizures, central pontine myelinolysis, and permanent brain damage.

Glycine toxicity

Glycine toxicity usually manifests as visual disturbances and transient blindness but may also include other signs and symptoms seen in TURP syndrome. The mechanism of action may be attributed to glycine acting as an inhibitory neurotransmitter because it has a distribution similar to that of γ-aminobutyric acid in the retina, spinal cord, and brainstem.

Ammonia toxicity

Ammonia is a major byproduct of glycine metabolism. Hyperammonemia usually manifests with nausea and vomiting, followed by encephalopathy.

Blood loss

Assessment of blood loss is difficult during a TURP because of dilution of blood with the absorbed irrigation fluid, which maintains intravascular volume, so that the usual hemodynamic responses to blood loss are not seen. The amount of blood loss is directly proportional to the vascularity of the prostate, length of the operation, and the weight of the prostate gland resected. Continuous postoperative bleeding may indicate a coagulopathy, since patients undergoing TURP have a higher incidence of fibrinolysis. Dilutional thrombocytopenia should also be considered in the differential diagnosis.

Hypothermia

Hypothermia, which has not been shown to be influenced by anesthetic technique, could be another cause of confusion in the elderly patient undergoing a TURP.

Bacteremia

Despite preoperative intravenous administration of antibiotics, bacteremia commonly occurs during a TURP and can lead to the development of sepsis. However, bacteremia is usually asymptomatic and is treated with antibiotics to cover gram-positive and gram-negative organisms. Sepsis has been reported to occur in as many as 6% to 7% of patients undergoing a TURP, with septic shock being the first manifestation of the condition.

Perforation of bladder or urethra with extravasation

Bladder perforation most often occurs during difficult resections by the cutting loop or knife electrode. These perforations can be either extraperitoneal (most common) or intraperitoneal. In the awake patient, extraperitoneal perforation may present as pain in the periumbilical, inguinal, or suprapubic region. Intraperitoneal perforation usually occurs through the bladder wall. Pain may be generalized to the upper abdomen or referred from the diaphragm to the shoulder. Other signs and symptoms include pallor, sweating, nausea, vomiting, shortness of breath, abdominal rigidity, hypotension, and hypertension.

Prevention of complications

In general, a TURP is an elective procedure. Therefore, optimizing the patient’s preoperative state prior to surgery is always recommended and may minimize anesthetic risks. Surgical risks can be reduced by limiting the duration of the operation, using isosmotic solutions, limiting the depth of dissection, and limiting the pressure of irrigating solution (60 cm H₂O is suggested). Use of spinal anesthesia should promote earlier detection of complications.

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