Fluid absorption and circulating endotoxins during transurethral resection of the prostate

Fluid volume kinetics of dilutional hyponatremia; a shock syndrome revisited

OBJECTIVE

To evaluate whether the pathophysiology of shock syndromes can be better understood by comparing central hemodynamics with kinetic data on fluid and electrolyte shifts.

METHODS

We studied the dilutional hyponatremic shock that developed in response to overhydration with electrolyte-free irrigating fluid - the so-called 'transurethral resection syndrome' - by comparing cardiac output, arterial pressures, and volume kinetic parameters in 17 pigs that were administered 150 ml/kg of either 1.5% glycine or 5% mannitol by intravenous infusion over 90 minutes.

RESULTS

Natriuresis appeared to be the key factor promoting hypovolemic hypotension 15-20 minutes after fluid administration ended. Excessive sodium excretion, due to osmotic diuresis caused by the irrigant solutes, was associated with high estimates of the elimination rate constant (k10) and low or negative estimates of the rate constant describing re-distribution of fluid to the plasma after translocation to the interstitium (k21). These characteristics indicated a high urinary flow rate and the development of peripheral edema at the expense of plasma volume and were correlated with reductions in cardiac output. The same general effects of natriuresis were observed for both irrigating solutions, although the volume of infused 1.5% glycine had a higher tendency to enter the intracellular fluid space.

CONCLUSION

Comparisons between hemodynamics and fluid turnover showed a likely sequence of events that led to hypovolemia despite intravenous administration of large amounts of fluid.

Transurethral resection of the prostate syndrome: almost gone but not forgotten

Transurethral resection of the prostate (TURP) syndrome is a rare but potentially fatal syndrome with multifactorial pathophysiology that is now better understood. Unfortunately, despite this improved understanding, it is not yet obsolete and still remains a risk. Many reviews of TURP syndrome have been presented from an anesthetic perspective; this review reflects more the urologic perspective with emphasis on the importance of multidisciplinary management of this complex syndrome. We present a review of TURP syndrome that specifically assesses advances in the understanding of risk factors, pathophysiology, and techniques used to prevent this syndrome. The databases Medline, Embase, Cochrane Controlled Trial Register, and Database of Abstracts of Reviews of Effects were systematically reviewed from inception to April 2009 for the keywords TUR (P), TUR (P) syndrome, and transurethral resection of prostate. There was no language restriction for our search. Randomized controlled trials, review articles and case series were included in our search. Our review showed a declining trend in the incidence of TURP syndrome despite TURP remaining the gold standard for the management of benign prostatic obstruction. Technologic advances using an array of laser techniques, the use of bipolar circuitry, together with advances in training techniques have helped minimize the risk of development of this syndrome. This review demonstrates the complexity of TURP syndrome. Even with a greater understanding of the pathophysiology, it highlights the unpredictability of the syndrome from presenting symptoms, preventative measures, and management. TURP syndrome cannot be protocol driven and the need for vigilance, a high index of suspicion, intensive monitoring, and a multidisciplinary approach is vital.

Hemolysis in transurethral resection of the prostate using distilled water as the irrigant

BACKGROUND

To investigate the incidence and time course of hemolysis and its clinical effects following transurethral resection of the prostate (TURP) using distilled water as the irrigant.

METHODS

Between March 1996 and April 1997, 39 patients who underwent TURP due to benign prostatic hyperplasia (BPH) were randomly included in this study. The levels of plasma hemoglobin, haptoglobin and serum lactic dehydrogenase (LDH) were checked in all patients before, immediately after, and 24 hours after the operation. Serum creatinine and sodium were also checked in 24 patients starting August 1996. Significant hemolysis was identified as simultaneous elevation of plasma hemoglobin (> 10 g/dL), serum LDH and reduction of plasma haptoglobin after TURP.

RESULTS

Among the 39 subjects, hemolysis occurred in 17 (43.6%), whose plasma hemoglobin and serum LDH increased while plasma haptoglobin decreased immediately after operation (p < 0.05), but no significant differences between the data before and 24 hours after the operation were noticed. In the hemolysis group, serum creatinine increased while serum sodium decreased immediately after operation (p < 0.05), but the data before and 24 hours after the operation had no significant differences. There were no changes in serum creatinine and sodium levels after TURP in patients without hemolysis. The weight of the resected prostate was 42.5 +/- 15.5 g in the hemolysis group and 23.3 +/- 8.3 g in the nonhemolysis group, while duration of TURP was 68.9 +/- 19.6 minutes in the hemolysis group and 34.2 +/- 8.4 minutes in the nonhemolysis group. Patients with hemolysis had higher resection weight and longer resection time than those without hemolysis (p < 0.001).

CONCLUSION

Using distilled water as an irrigant for TURP might cause hemolysis, especially in patients with larger prostates and longer resection times. It is necessary to carry out every effort to shorten resection time and avoid extravasation during surgery.

Fluid absorption in endoscopic surgery

Fluid absorption is an unpredictable complication of endoscopic surgery. Absorption of small amounts of fluid (1-2 litre) occurs in 5-10% of patients undergoing transurethral prostatic resection and results in an easily overlooked mild transurethral resection (TUR) syndrome. Large-scale fluid absorption is rare but leads to symptoms severe enough to require intensive care. Pathophysiological mechanisms consist of pharmacological effects of the irrigant solutes, the volume effect of the irrigant water, dilutional hyponatraemia and brain oedema. Other less widely known factors include absolute losses of sodium by urinary excretion and morphological changes in the heart muscle, both of which promote a hypokinetic circulation. Studies in animals, volunteers and patients show that irrigation with glycine solution should be avoided. Preventive measures, such as low-pressure irrigation, might reduce the extent of fluid absorption but does not eliminate this complication. Monitoring the extent of absorption during surgery allows control of the fluid balance in the individual patient, but such monitoring is not used widely. However, the anaesthetist must be aware of the symptoms and be able to diagnose this complication. Treatment should be based on administration of hypertonic saline rather than on diuretics. New techniques, such as bipolar resectoscopes and vaporizing instead of resecting tissue, result in a continuous change of the prerequisites for fluid absorption and its consequences.

[Reabsorption syndrome after transurethral resection (TUR) of the prostate: review of physiologic, diagnostic, and therapeutic features]

In spite of the development of non-invasive strategies, surgical treatment of the prostate (TURP) and, mostly transurethral resection, is the most effective choice for patients suffering from benign prostatic hyperplasia who do not respond properly to pharmacological treatment. Absorption of hypotonic fluids used during TURP may cause hemodynamic and central nervous system disturbances. These symptoms, both taken separately or as a whole, are best known as "Transurethral prostatic resection syndrome" or "TURP syndrome". The original description of this syndrome dates from half a century ago; however, a number of items regarding its physiopathology and treatment remain unclear. We present a review of this pathological entity, compiling diagnostic and therapeutical approaches.