Questions
- 1.
What is TURP syndrome, and what is the treatment?
- 2.
What other complications can occur during TURP?
- 3.
What types of irrigating fluids have been used for transurethral resection of the prostate?
- 4.
What toxicities are associated with glycine?
- 5.
What are the anesthetic options for a patient undergoing transurethral resection of the prostate?
- 6.
If a regional anesthetic is selected, what level of anesthesia is required?
- 7.
- 8.
What surgical measures can minimize the incidence of TURP syndrome?
- 9.
A 74-year-old man with a past medical history of coronary artery disease with stable angina and hypertension was scheduled to undergo transurethral resection of the prostate (TURP) for benign prostatic hypertrophy. Current medications included metoprolol, 50 mg twice a day, and amlodipine, 10 mg once a day. The physical examination was unremarkable. Heart rate was 74 beats per minute, blood pressure was 160/75 mm Hg, and respiratory rate was 12 breaths per minute. The patient was 177.5 cm tall and weighed 72 kg.
1
What is turp syndrome, and what is the treatment?
TURP syndrome is a collection of signs and symptoms that occur when excessive amounts of irrigating fluids are absorbed through the opened prostatic venous sinusoids. Absorption of fluids may result in water intoxication, hyponatremia, and hypoosmolality. Although most commonly associated with TURP, this syndrome may also occur with transurethral resection of bladder tumors, diagnostic cystoscopy, percutaneous nephrolithotomy, and endoscopic gynecologic procedures. The incidence of TURP syndrome is 0.78%–1.4%. The mortality rate in severe cases is 25%. The syndrome may be observed minutes after resection starts up to 24 hours postoperatively.
The decrease in serum sodium (Na + ) levels during TURP ranges from 3.65–10 mEq/L. Several mechanisms for this decrease in Na + have been postulated. Hyponatremia may be due to either simple dilution by the irrigating solution or diffusion of Na + into the irrigating solution at the surgical site or into the periprostatic or retroperitoneal spaces. The degree of hyponatremia is related to the rate of absorption of the irrigating fluid and not to the absolute amount absorbed.
Effects of TURP syndrome on the central nervous system include headache, restlessness, agitation, confusion, seizures, and eventually coma ( Box 36-1 ). These findings are thought to be caused by cerebral edema, with a concomitant increase in intracerebral pressure. As the neurologic condition worsens, the patient may develop decerebrate posturing, clonus, a positive Babinski sign, brainstem herniation, and ultimately death. Ocular examination often reveals bilateral dilated and sluggishly reactive pupils and papilledema. Electroencephalography often shows low-voltage activity. If coma occurs, it usually resolves within hours to days, but it can be permanent. The incidence of neurologic injury is more closely related to the rate of Na + decrease rather than the degree of hyponatremia.
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Headache
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Restlessness
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Agitation
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Confusion
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Seizures
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Coma
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Decerebrate posturing
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Clonus
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Babinski sign
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Sluggishly reacting pupils
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Papilledema
Hyponatremia and fluid overload have deleterious consequences on the heart. The initial cardiovascular effects of fluid overload include hypertension and bradycardia. However, serum Na + levels of 120 mEq/L are associated with negative inotropic effects on the heart causing hypotension, pulmonary edema, and congestive heart failure. Serum Na + levels of less than 115 mEq/L are associated with electrocardiogram (ECG) changes, such as a widened QRS complex, ventricular ectopy, and T-wave inversion. When serum Na + decreases to <100 mEq/L, respiratory and cardiac arrest may occur ( Box 36-2 ).
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Na + <120 mEq/L
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Hypotension
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Pulmonary edema
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Congestive heart failure
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Na + <115 mEq/L
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Widened QRS complex
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Ventricular ectopy
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T-wave inversion
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Na + <100 mEq/L
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Respiratory arrest
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Cardiac arrest
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If the patient develops signs and symptoms of TURP syndrome, surgery should be concluded as soon as possible. Treatment should be directed at increasing the serum Na + level and correcting volume overload by fluid restriction and administration of a loop diuretic, such as furosemide. In severe cases of hyponatremia, administration of a hypertonic saline solution (3%–5% sodium chloride) may be necessary. Rapid correction of hyponatremia has been associated with cerebral edema and central pontine myelinolysis. All other treatment is dictated by the patient’s symptoms. Supplemental oxygen should be considered, and the patient may require tracheal intubation and mechanical ventilation.
2
What other complications can occur during transurethral resection of the prostate?
Approximately 7% of all patients undergoing TURP experience a major complication. The 30-day mortality rate has been estimated to be 0.2%–0.8%. This is a marked improvement over studies performed in the 1960s, which showed a mortality rate of approximately 2.5%. Patients undergoing TURP are often elderly and have coexisting cardiopulmonary disorders making them more likely to experience complications. Because many patients are on long-term diuretic therapy, they are often dehydrated and present with electrolyte abnormalities preoperatively. Other complications associated with this procedure are described next ( Box 36-3 ).
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Bladder perforation
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Extraperitoneal or intraperitoneal
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Bleeding
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Related to size of gland and resection time
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Coagulopathy
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Dilution of coagulation factors
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Primary fibrinolysis
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Disseminated intravascular coagulopathy
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Transient bacteremia and septicemia
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Toxicity of irrigating fluids
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Hypervolemia
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Hyponatremia
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Hypothermia
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Glycine toxicities
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Transient blindness
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Hyperammonemia
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Nausea and vomiting
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Coma
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Myocardial depression
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Electrocardiogram changes
Bladder perforation
Bladder perforation occurs in approximately 1% of all TURP procedures. It may be caused by overdistention of the bladder with irrigating fluid or surgical instrumentation. An early sign of bladder perforation is decreased return of irrigating fluid. The abdomen becomes distended and often rigid. If the procedure is performed under regional anesthesia, patients may complain of pain or experience nausea and vomiting. Hypotension followed by hypertension is common.
Most perforations are extraperitoneal and benign in nature. This type of perforation causes pain in the periumbilical region. However, pain in the upper abdomen or referred pain to the shoulder may be a sign of intraperitoneal perforation, a potentially fatal complication. Diagnosis should be confirmed quickly by cystourethrography, and treatment should be with a suprapubic cystostomy.
Bleeding
The prostate is a highly vascular organ. Because large amounts of irrigation fluid are used, blood loss is difficult to assess. Intraoperative blood loss corresponds to the size of the gland and resection time. Blood loss is generally considered to occur at a rate of 2–5 mL per minute of resection time and 20–50 mL/g of prostate tissue. Blood loss is linearly related to prostate size up to 35 g, at which point blood loss tends to exceed the linear correlation. Patients with resection times of greater than 90 minutes or a prostate size of >60 g have been found to have a significant increase in morbidity associated with bleeding.
Coagulopathy
Subclinical coagulopathy occurs in approximately 6% of patients undergoing TURP, whereas clinical coagulopathy occurs approximately 1% of the time. This condition seems to correlate with the mass of resected prostatic tissue. It is a more likely event if the resected tissue is >35 g. Coagulopathy may be due to dilution of coagulation factors and platelets.
Primary fibrinolysis has also been implicated as a cause of coagulopathy. Plasminogen activator, which is responsible for converting plasminogen into plasmin, is released during these procedures. The treatment of choice for primary fibrinolysis is aminocaproic acid.
Secondary fibrinolysis may occur as a result of disseminated intravascular coagulopathy (DIC). DIC is caused by systemic absorption of prostate tissue, which is rich in thromboplastin. Consistent with this theory are the low levels of plasminogen activator, platelets, and fibrinogen that are commonly found in DIC and that frequently accompany TURP. If DIC is suspected, the treatment is symptomatic. Fluid and blood products are administered as needed. Heparin administration may be beneficial.
Transient bacteremia and septicemia
The prostate, rich in pathogens, may cause postoperative bacteremia via prostatic venous sinusoids. Indwelling urinary catheters enhance the risk. Approximately 6%–7% of patients go on to develop sepsis. Treatment consists of antibiotics and supportive care.
Toxicity of irrigating fluids
The major toxicity of irrigation fluids used today is related to massive absorption causing fluid overload, hyponatremia, and hypoosmolality. The incidence of hypoosmolality and its associated neurologic sequelae has decreased since the use of nonelectrolyte isoosmotic irrigating solutions. However, fluid overload and hyponatremia still remain a problem. During TURP, 8 L of irrigating fluid may be absorbed causing an average weight gain of about 2 kg. Some of this fluid (20%–30%) is absorbed directly into the vascular space. The remainder is absorbed into the periprostatic and the peritoneal space (interstitial space). Several factors contribute to the rate of absorption of irrigating fluid, including prostate size, integrity of the prostatic capsule, and height of the irrigating fluid container. Greater amounts of irrigating fluid are absorbed when the prostate is large because of its richer blood supply and when the prostate capsule is violated.
Certain maneuvers can limit the amount of irrigating fluid absorbed. The first is to restrict the height of the fluid container above the surgical field; this decreases hydrostatic pressure driving fluid into sinuses. When the bag is >60 cm above the patient, absorption is greatly enhanced. The second maneuver is to limit resection times to <150 minutes because 10–30 mL of irrigation fluid is absorbed per minute of resection.
Sorbitol and mannitol, both sugar alcohols, have been associated with the development of lactic acidosis and hyperglycemia. Specific effects of glycine are discussed later.
Hypothermia
Patients may develop hypothermia under either general or neuraxial anesthesia. The hypothermia can be exacerbated by using room temperature irrigating fluids. Using warmed irrigating fluid decreases heat loss and shivering. A theoretical concern exists that warming the irrigation fluids would cause vasodilation, increasing blood loss; however, this has not been shown to be a clinical problem. Because hypothermia may cause shivering, which increases venous pressure, there may be increased blood loss if the irrigating fluids are not warmed.
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