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ANALGESIA

Urethral Injury During Potassium-Titanyl-Phosphate Laser Prostatectomy Complicated by Transurethral Resection Syndrome

John A. Dilger, MD^*, Michael T. Walsh, MD^*, Mary E. Warner, MD^*, Lance A. Mynderse, MD, and Juraj Sprung, MD, PhD^*

From the Departments of *Anesthesiology, and Urology, College of Medicine, Mayo Clinic, Rochester, Minnesota.

Address correspondence and reprint requests to Juraj Sprung, MD, PhD, Department of Anesthesiology, College of Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. Address e-mail to sprung.juraj{at}mayo.edu.

Abstract

The green light potassium-titanyl-phosphate laser photoselective vaporization of the prostate is the latest modality for treatment of benign prostatic obstruction. Because of effective superficial tissue coagulation, intravascular absorption of fluid is minimal; therefore, development of transurethral resection syndrome is unlikely. To our knowledge, this is the first report of a patient undergoing photoselective vaporization of the prostate who developed full-blown transurethral resection syndrome because of intravascular absorption of sterile water. Absorption of hypotonic irrigant presumably occurred through the injury induced during insertion of the laser cystoscope.

A recent report details anesthetic implications of various types of laser resection of the prostate.1 The high-power green light potassium-titanyl-phosphate (KTP) laser, developed in the mid 1990s, is the most significant recent advancement in laser technology for treatment of benign prostatic hypertrophy.2 This technique, pioneered by Malek at the Mayo Clinic in 1997, paved the way for a new transurethral laser prostatectomy procedure known as green light photoselective vaporization of the prostate (PVP).3,4 One of numerous advantages of this technique is based on effective coagulation of blood vessels; therefore, complications associated with excessive intravascular absorption of irrigation fluid are not expected. We describe a patient who developed full-blown water intoxication known as transurethral resection (TUR) syndrome associated with hemolysis and acute renal failure during PVP. The mechanism of TUR syndrome after PVP in our patient is discussed.

CASE REPORT

Permission for a single patient case report was waived by the Mayo Clinic, Rochester MN, IRB. A 66-yr-old healthy male patient was scheduled for KTP laser transurethral resection of the prostate (TURP). The preoperative laboratory tests included creatinine of 1.1 mg/dL, hemoglobin of 15.4 mg/dL; serum sodium and potassium were 139 and 4.3 mEq/L, respectively. The patient had general anesthesia with propofol for induction (2 mg/kg) and maintenance (100 µg · kg^–1 · min^–1) with 150 µg of fentanyl. A laryngeal mask airway was used and spontaneous ventilation was maintained with 70% nitrous and 30% oxygen. The laser cystoscope was inserted without the visual (optical) obturator. This presumably resulted in some disruption of the prostatic or membranous urethra, which caused bleeding in the region of the junction between the external sphincter and the apex of the prostate. Bleeding continued intermittently near the apex of the prostate throughout the procedure during which distilled water was used as an irrigant. After 45 min of vaporization time with the 80 W KTP laser, the patient’s arterial blood pressure increased (180/100 mm Hg) and heart rate decreased (45 bpm). The oxygen saturation measured with pulse oximetry decreased from 99% to 93% on 30% inspired oxygen. Also, sudden electrocardiographic changes occurred: 1 and 3 mm ST segment elevation in leads II and V₅, respectively. IV nitroglycerin was initiated at 0.25 µg/min. Soon after initiation of nitroglycerin, his arterial blood pressure decreased to 145/80 mm Hg, and heart rate increased to 60 bpm. The procedure was completed 15 min later, the patient emerged from anesthesia, and his laryngeal mask airway was removed before transfer to the recovery room where he initially felt difficult to arouse and over the next hour he remained mildly confused. He denied chest pain, so nitroglycerin was discontinued. Laboratory work was obtained: hemoglobin 11.5 mg/dL, sodium 119 mEq/L, and potassium 4.0 mEq/L. At this time, furosemide 60 mg IV was administered in addition to infusion of normal saline at 200 mL/h. Troponin was <0.01 ng/mL (normal, <0.03), and creatine phosphokinase muscle band isoenzyme (CPK) MB 9.1 ng/mL (<6.2). Urine analysis was expectedly positive for red blood cells (RBC) >100 per high power field (hpf normal, <1) and unexpectedly positive for large amounts of free hemoglobin. His peripheral blood smear was positive for the presence of spiculated RBC, elliptocytes, and schistocytes. Two hours after arrival in the recovery room, the patient’s mental status improved and he was transferred to a regular nursing floor. The following day his creatinine level increased to 3.2 mg/dL, hemoglobin was 11 mg/dL, and serum sodium and potassium were 125 mEq/L and 4.6 mEq/L, respectively. Serum transaminases were aspartate aminotransferase 341 U/L (normal, 12–31), alanine aminotransferase 109 U/L (normal, 10–45), lactate dehydrogenase 1793 U/L (normal, 112–257), alkaline phosphatase 100 mg/dL (normal, 98–100). His total bilirubin was 8.9 mg/dL (normal 0.1–1.0), and direct bilirubin 3.4 mg/dL (0.0–0.3). Over the next 4 days his liver enzymes were improving (aspartate aminotransferase 80 U/L, alanine aminotransferase 45 U/L). Total bilirubin diminished to 1.7 mg/dL and direct bilirubin to 0.8 mg/dL. The patient was discharged on the seventh postoperative day with normal sodium (142 mEq/L) and potassium (4.1 mEq/L). He was still in acute renal failure (creatinine 3.7 mg/dL), and he was anemic (hemoglobin 9.4 mg/dL) at discharge. The renal function normalized over the next 6 mo.

DISCUSSION

Different methods of performing TURP are characterized by various rates of TUR syndrome which, in patients undergoing classical TURP, occurs between 2% and 15% of cases.5 PVP is characterized by both minimal blood loss and fluid resorption and therefore, TUR syndrome is not an expected complication. Review of the literature by Barber and Muir6 found no study that reported a significant change in serum sodium concentrations when using distilled water as irrigant during PVP. In our institution, this was the first case of TUR syndrome associated with PVP, and we have performed more than 1200 cases.

To our knowledge, this is the first report of TUR syndrome associated with hemolysis and renal failure after PVP. TUR syndrome during PVP is rare because the KTP laser effectively coagulates venous sinuses and prevents intravascular absorption of irrigant.6 In addition, fluid absorption is minimized because irrigation pressures are lower than with other TURP techniques. A study of 40 patients demonstrated that during high-power KTP laser vaporization, expired breath ethanol, used with irrigant as an indicator of systemic absorption, remained undetectable.7 Therefore, assuming preserved integrity of the prostatic urethra, the use of distilled water is considered safe during PVP. The rationale for using sterile water during PVP is based on the belief that water improves visualization of the surgical field. However, a recent randomized study demonstrated no difference in visual quality between water and saline in PVP.8 Although the absorption of water during PVP is generally considered to be negligible, one important factor was not considered in our patient, and that was the presence of prostatic urethral injury induced by the laser cystoscope leading to excessive intravascular water absorption. Because distilled water is hypotonic, its intravascular resorption caused acute hemolysis. Several steps could have prevented this complication. First, if we had used normal saline irrigation instead of sterile water, TUR syndrome could have been prevented despite the presence of prostatic urethral injury. Second, it is imperative to always use the visual (optical) obturator during insertion of the laser cystoscope because its specially designed long beak may damage the anterior urethra and/or create a false passage in the prostatic urethra with significant risk of unintended fluid absorption and bleeding.2 Third, more than expected bleeding throughout PVP should have raised a concern about the presence of an undetected urethral injury.

The earliest indications of a continuing problem in our patient were hypertension and reflex bradycardia, 45 min after the initiation of PVP. Although it is probable that the excessive absorption of water contributed to our patient’s hypertension, another mechanism for hypertension seems equally plausible, and that is the presence of free hemoglobin in the plasma.9 Free hemoglobin binds nitric oxide (vasodilator produced by endothelial cells) at least 1000 times more rapidly compared to erythrocytes. Only when hemoglobin is physically compartmentalized within the erythrocytes will nitric oxide reach concentrations within smooth muscle necessary to cause vasodilation.10 This effect is believed to be the cause of pulmonary and systemic hypertension when free hemoglobin is present in the circulation.11

Hung et al.12 describe intravascular hemolysis after TURP with distilled water. Acute renal failure occurs in the setting of hemolysis,13 and the possible culprits are attributed to either free-hemoglobin or stroma freed from destroyed RBC.14 In our patient, hypotonic water in the circulation caused hemolysis as evidenced by a precipitous decrease in hemoglobin (from 15.4 to 9.4 mg/dL), presence of spherocytes and schistocytes on peripheral blood smear, and increase in both indirect (unconjugated) bilirubin (62% of total bilirubin increase) and lactate dehydrogenase. Hemolysis also resulted in hemoglobin pigment in the urine. This together with heme proteins, which are potent oxidants, promotes free radical formation and may cause renal tubular injury.15 Cellular debris and subsequent treatment with furosemide (hypovolemia) may have contributed to the development of acute renal failure in our patient.

In conclusion, our patient suffered a mechanical injury to the prostatic urethra and water was likely absorbed through that site. This complication was not recognized early and resulted in excessive absorption of irrigant, causing fluid overload, hemolysis, and acute renal failure. The present case illustrates that the potential for TUR syndrome may be considered even with green light PVP and needs to be anticipated when the prostatic urethra suffers mechanical injury. Use of saline irrigant instead of water could have prevented hemolysis and renal failure in our patient. Based on a recent study that showed that water has no optical advantage over saline,8 it appears that there is little justification for using water irrigation during PVP.

ACKNOWLEDGMENTS

We are grateful to Emeritus Professor of Urology, Dr. Reza Malek, who pioneered the technique and clinical application of the KTP laser for the treatment of benign prostatic hyperplasia, for his suggestions during revision of this manuscript.

Footnotes

Accepted for publication March 18, 2008.

Supported by the Department of Anesthesiology, Mayo Clinic, Rochester, MN.

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Dilger, J. A. Articles by Sprung, J. Search for Related Content PubMed PubMed Citation Articles by Dilger, J. A. Articles by Sprung, J. Related Collections Complications Regional Anesthesia Technology