Haemodynamic evidence for per-operative cardiac stress during transurethral prostatectomy. Preliminary communication

The effects of irrigation fluid on core temperature in endoscopic urological surgery

AIMS AND METHOD

A prospective observational study of 100 patients undergoing various types of endoscopic urological surgery including transurethral resection of the prostate (TURP), transurethral resection of bladder tumour (TURBT), percutaneous nephrolithotomy (PCNL) and Cystoscopies, was reformed to determine the temperature difference between preoperative and postoperative core temperatures and to determine whether this change was related to the age, weight, type of anaesthetic, operation duration, type of operation, amount of irrigant fluid used and whether warming the fluid to 370C made a difference to the degree of temperature change. All the above variables were recorded for each patient as well as the preoperative and postoperative temperatures. Statistical analysis was carried out using SPSS.

RESULTS

The mean age was 64 years and the mean weight was 75kg in the study. Seventy-six patients had a general anaesthetic while 24 had a spinal anaesthetic. The study included 29 TURPs, 10 TURBTs, six PCNLs and 55 Cystoscopies. Age and type of anaesthetic did not correlate significantly with temperature change. As weight increased patients tend to preserve their core temperature more efficiently. The highest degree of temperature drop was in the PCNL group. There was a significant relationship between the duration of operation and temperature drop (p<0.05) as well as the amount of irrigation fluid used (p<0.05). Average temperature drop for patients who underwent irrigation with fluid at room temperature (n=43) was 1.37 degrees C and 0.95 degrees C for those whose fluids were warmed to body temperature (n=57). This difference was statistically significant (p=0.03).

CONCLUSIONS

There is a drop in temperature in patients undergoing most endoscopic operations on the GU tract and this appears to be multifactorial in origin, relating significantly to weight, amount of irrigation fluid used, type and duration of operation. Warming irrigant fluid to body temperature appears to significantly reduce the degree of temperature drop with consequent potential benefit.

Effect of warm intravenous and irrigating fluids on body temperature during transurethral resection of the prostate gland

Background

Transurethral resection of the prostate gland with irrigation fluid at room temperature leads to perioperative hypothermia which could give rise to adverse cardiovascular events in the perioperative period. The use of isothermic irrigation fluid reduces but does not eliminate this risk. Routine use of warm intravenous fluids along with isothermic irrigation had not been documented. This study set out to investigate the effect of the use of warm intravenous fluid together with isothermic irrigation fluid on the body temperature in patients undergoing transurethral resection of the prostate gland.

Methods

One hundred and twenty consented patients with obstructing benign prostatic hyperplasia were randomly assigned to one of 3 groups. Group 1 received irrigation and intravenous fluids at room temperature, group 2 received warmed irrigation fluid at 38°C along with intravenous fluid at room temperature while group 3 patients received warmed irrigation fluid and warmed intravenous fluids at 38°C. Their perioperative body temperature changes were monitored, analyzed and compared.

Results

The mean decrease in body temperature at the end of the procedure was significantly greater in group 1 (0.98 ± 0.56°C) than in group 2 (0.42 ± .21°C) (p < 0.001). Significantly more patients in group 1 also experienced shivering. However, in group 3, there was no significant change in the mean body temperature (p > 0.05) and none of them felt cold or shivered.

Conclusion

It is concluded that the use of isothermic irrigation fluid together with warm intravenous fluids during TURP prevents the occurrence of perioperative hypothermia.

Trial registration number

CCT-NAPN-15944

TROPONIN T AND N-TERMINAL PRO-BRAIN NATRIURETIC PEPTIDE CHANGES IN PATIENTS UNDERGOING TRANSURETHRAL RESECTION OF THE PROSTATE

PURPOSE

We investigated whether transurethral resection of the prostate (TURP) caused subclinical myocardial damage or cardiac dysfunction by measuring troponin T (Trop T) and N-terminal pro-brain natriuretic peptide (pro-BNP).

MATERIALS AND METHODS

A total of 52 consenting patients took part in this study. All had a detailed medical history including cardiac history taken. On the day of the operation all patients had troponin T, pro-BNP, full blood count and urea, electrolytes and creatinine measured preoperatively. A preoperative and postoperative electrocardiogram was performed. Patients in renal failure were excluded from analysis. During the operations factors such as blood loss, operative time, tissue resected and fluid absorption were monitored. On postoperative day 1 all the previously mentioned tests were repeated.

RESULTS

Mean patient age was 71 years (range 52 to 85). Eight patients had a history of associated cardiac problems. Mean preoperative and postoperative hemoglobin were 14.1 gm/dl (range 10.5 to 17) and 13.3 gm/dl (range 9.9 to 16.2), respectively. None of the patients had significant (greater than 1,000 ml) fluid absorption during TURP, which was calculated using ethanol tagged glycine. Mean blood loss measured with a photometer was 129.7 ml (range 0 to 1,800). Mean operative time was 28.4 minutes (range 5 to 50) and mean weight of prostatic tissue resected was 15.2 gm (range 1 to 47). Preoperative Trop T was less than 0.01 mcg/ml in all patients and mean pro-BNP was 39.2 pg/ml (range 0.5 to 866). Postoperative Trop T was less than 0.01 mcg/ml in all but 1 patient who experienced chest pain after TURP and had an increased Trop T (0.28 mcg/ml). Mean postoperative pro-BNP was 54.57 pg/ml (range 1 to 679). A total of 37 patients had an increase in pro-BNP which was still within the reference range for the age group. There were no significant electrocardiogram changes postoperatively. The Trop T changes were not statistically significant (Wilcoxon sign ranked test p = 0.31) although they may be clinically significant.

CONCLUSIONS

Our study indicates that in patients with no prior cardiac history TURP does not cause myocardial damage indicated by nonincrease of Trop T. There are slight increases in pro-BNP after TURP in some patients although the exact clinical significance is uncertain.

Validation of the ethanol breath test and on-table weighing to measure irrigating fluid absorption during transurethral prostatectomy

OBJECTIVE

To determine the agreement between on-table weighing and the ethanol breath test in measuring the fluid absorption of patients during transurethral prostatectomy (TURP), and to assess the practicality of on-table weighing in the clinical setting.

PATIENTS AND METHODS

The absorption of irrigating fluid by the patient during TURP can lead to adverse sequelae, including cardiac stress. Despite modern techniques irrigant may still be absorbed and therefore methods to detect absorption are important. Most methods are impractical or inaccurate, but the expired ethanol technique and continuous on-table weighing are more promising. TURP was undertaken in 44 men (mean age 71 years) using continuous flow 1.5% glycine/1% ethanol as the irrigating solution. Intraoperative irrigant absorption was calculated by the ethanol breath test, using published formulae. Absorption measured by the weighing machine was calculated as (weight gain + blood loss - fluid given), and blood loss by the Hemocue method.

RESULTS

The mean (sd) resected weight was 23 (14) g at a mean resection rate of 0.74 g/min. The mean (range) absorption using the balance was 456 (- 343 to 2486) mL, and using the ethanol breath test was 435 (44-2750) mL, with the mean of the differences being - 17 mL, with a 95% confidence interval (CI) of - 81 to -40, the 95% limits of agreement being - 389 to 356 mL (95% CI - 458 to - 337 and 297 to 418 mL).

CONCLUSIONS

Both methods are comparable and measure irrigating fluid absorption to levels of accuracy that are useful clinically. Either method could (and should) be used in routine practice.

Haemodynamic changes detected during open prostatectomy and transurethral resection for benign prostatic hyperplasia

To detect possible intraoperative haemodynamic differences, 60 patients undergoing transurethral (n = 18) or open prostatectomy (n = 42) for benign prostatic hyperplasia were evaluated. The same type of general anaesthesia was used in the two groups. Data, including temperature and cardiac output, were collected at five standard times during the procedures. No significant differences were found between the two groups. However, in all patients, irrespective of the operation, significant decreases in cardiac output and increases in systemic resistance occurred during surgery. Body temperature showed a mild, insignificant decrease, which may play a role in determining the mild haemodynamic derangement observed in all patients. Our patients subjected to open prostatectomy and transurethral resection presented the same kind of haemodynamic derangement, with no significant differences. Therefore it seems unlikely that the kind of surgery could play a relevant role in the late mortality rate of these patients.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a pathologic disorder that develops in response to the action of dihydrotestosterone on the aging prostate and to changes in stromal and epithelial cells in this exocrine gland. The current therapies for this disorder are chosen after other causes for irritative and obstructive symptoms have been excluded and the status of the urinary tract has been assessed. This evaluation includes a detailed medical history, a thorough genitourinary and neurological examination, assessment of serum prostate specific antigen and creatinine levels, as well as a urinalysis. A urodynamic evaluation consisting of a combined pressure-flow study is required if the diagnosis of obstruction is to be made. Patients with minimal symptoms and normal test results require no therapy. Mild to moderate symptoms can be controlled, at least temporarily, with alpha-adrenergic blockers such as terazosin or doxazosin. A subset of BPH patients with obstructive symptoms respond to the 5 alpha-reductase inhibitor finasteride. Early results with minimally invasive treatments such as laser prostatectomies, hyperthermia, and ultrasonic and radiofrequency ablation appear encouraging for those with moderate symptoms of prostatism. Severe symptoms, urinary retention, gross hematuria, recurrent urinary tract infections, bladder calculi, and hydronephrosis or renal insufficiency warrant transurethral incision, resection, vaporization, or open prostatectomy (for very large neoplasms). Although the morbidities of these latter surgical therapies are not insignificant, these treatments offer the best and most durable results for relief of obstruction and amelioration of symptoms.

A method of measuring fluid balance during transurethral resection of the prostate

OBJECTIVE

To design a practical system for non-invasively monitoring fluid balance during transurethral resection of the prostate (TURP) and other endoscopic procedures.

MATERIALS AND METHODS

Load cell transducers are incorporated into a platform placed under the operating table. Output is passed to a digital weighmeter and then to a portable computer. The raw data is filtered using software written by the authors (CAL) and the output displayed both numerically and graphically on the computer screen. The device was tested under laboratory conditions and then assessed in the clinical setting.

RESULTS

The device proved stable in both the laboratory and clinical settings. Examples of the common patterns generated during TURP are presented. The prototype has been used routinely in our practice to warn the surgeon and anaesthetist of fluid overload and has been used to monitor fluid balance in several studies.

CONCLUSIONS

This instrument provides a practical method of monitoring total fluid balance during TURP. It can be used with either general or regional anaesthesia and provides information not otherwise available. It provides an early warning of significant changes in total fluid balance, particularly irrigant fluid absorption. Use of this device serves to prevent development of the TUR syndrome, a potentially fatal complication of endoscopic surgery. Our ultimate aim is to produce a refined version that is simple, compact and cheap enough to be used routinely in all urological theatres. The cost of a single episode of intensive care for a patient developing iatrogenic complications from irrigant absorption would offset the cost of such a device.

Complications of laser prostatectomy

The appeal of laser therapy is rooted in its absence of complications relative to the gold standard of transurethral electroresection. As in any evaluation of a new medical intervention, efficacy must be weighed against the degree of complications that accompany it. Although there has been a relative paucity of literature specifically addressing the safety of this new modality, several studies are presented testifying to the clinical efficacy and relative absence of complications of laser prostatectomy.

Fluid absorption and circulating endotoxins during transurethral resection of the prostate

Recent publications report increased cardiovascular morbidity and mortality after transurethral prostatic resection (TURP). Repeated breath-ethanol monitoring with a new infrared device permits a highly sensitive peroperative registration of fluid absorption. A prospective study in 52 patients revealed surprisingly high rates of intravascular fluid loads without clinical manifestations. Only 4 patients developed clinical signs of the TUR syndrome. Immunological work-up in 41 patients demonstrated circulating endotoxins and significant rise of endogenous tumour necrosis factor (TNF) in 3 of these patients. In 11 patients transient endotoxins could be detected during resection under prophylactic parenteral antibiosis. In the face of less invasive approaches to benign prostatic hyperplasia, close intraoperative monitoring and antibiotic coverage should be demanded as a routine procedure during TURP. Elective surgery should be delayed until appropriate antibiotic therapy has been given.

Haemodynamic effects of transurethral prostatectomy

Thoracic bio-impedance cardiography was used to study the haemodynamic changes in 28 patients undergoing transurethral prostatectomy (TURP) under either general or spinal anaesthesia. Cardiac output and mean arterial pressure fell with induction of general anaesthesia, whilst mean arterial pressure and systemic vascular resistance fell with induction of spinal anaesthesia. The transthoracic fluid index fell during resection under general anaesthesia, but no significant haemodynamic changes were seen during resection under either anaesthetic. This study suggests that resection has no specific adverse haemodynamic consequences. Spinal anaesthesia may produce less haemodynamic disturbance than general anaesthesia in patients undergoing TURP and formal comparison of the 2 techniques seems necessary.

Intra-operative myocardial ischaemia detected by biplane transoesophageal echocardiography during transurethral prostatectomy

Recent studies have shown an increased late mortality rate due to cardiovascular causes after transurethral compared with open prostatectomy. This has been linked to the demonstration of haemodynamic changes during transurethral prostatectomy, which may cause ischaemic myocardial injury. We used transoesophageal echocardiography (currently the most sensitive modality for detecting myocardial ischaemia) to study 26 patients during prostatectomy under general anaesthesia. Evidence of myocardial ischaemia (as shown by the development of new regional wall motion abnormalities of the left ventricle) occurred in 4 of 22 patients during transurethral and in 3 of 4 patients during retropubic prostatectomy. An intra-operative fall in systolic as well as diastolic blood pressure occurred in 21 of 22 patients during the transurethral procedure and in all 4 patients during retropubic prostatectomy. The duration of anaesthesia and the operation, and the intra-operative blood loss did not differ significantly between patients with and without evidence of intra-operative myocardial ischaemia. However, the maximum intra-operative fall in systolic and diastolic blood pressure, as well as the mass of the prostatic tissue removed, were significantly greater in patients with than in those without evidence of intra-operative myocardial ischaemia, suggesting that the latter may be related to the extent of surgery and the degree of intraoperative hypotension. In this study, 7 of 26 patients (27%) showed evidence of myocardial ischaemia during prostatectomy. However, it remains difficult to explain why intra-operative myocardial ischaemia should result in an increased cardiovascular mortality rate several years after the operation.

Haemodynamics and fluid balance after intravenous infusion of 1.5% glycine in sheep

With the aim of studying the pathophysiological background of the "TUR syndrome", we gave six conscious ewes an intravenous infusion of 57 ml/kg of 1.5% glycine solution over 40 min. Isotonic saline infusions served as controls. Central haemodynamics were monitored. The plasma concentrations of protein, K, Na and vasopressin, and plasma osmolality were measured repeatedly for up to 4 h. The urinary excretions of Na, K and osmoles were also followed. Both infusions caused an elevation of the mean arterial pressure. With glycine, the pressure increased from 93 +/- 4 to 112 +/- 12 mmHg (12.4 +/- 0.5 to 14.9 +/- 1.6 kPa) (mean +/- s.d.). The pulmonary capillary wedge pressure increased from 7 +/- 3 to 16 +/- 3 mmHg (0.9 +/- 0.4 to 2.1 +/- 0.4 kPa) and remained slightly elevated. The central venous pressure rose from 2 +/- 3 to 11 +/- 3 mmHg (0.3 +/- 0.4 to 1.5 +/- 0.4 kPa) but returned to baseline within 30 min after the infusion. Infusion of glycine resulted in a decrease in the plasma Na concentration from 144 +/- 3 to 114 +/- 4 mmol/l. The plasma osmolality decreased from 290 +/- 2 to 280 +/- 1 mosmol/l, and remained low. There was a median 6-fold increase in plasma vasopressin concentration, while saline did not elicit vasopressin release. Despite the absence of electrolytes in glycine solution, the urinary excretion of sodium amounted to 106 +/- 40 mmol. We conclude that i.v. infusion of 1.5% glycine solution in sheep causes a transient circulatory strain and natriuresis. Moreover, a vasopressin-mediated reduction of maximal water excretion contributes to persisting hypoosmolality.

Haemodynamic evidence for cardiac stress during transurethral prostatectomy

OBJECTIVE

To compare haemodynamic performance during transurethral prostatectomy and non-endoscopic control procedures similar in duration and surgical trauma.

DESIGN

Controlled comparative study.

SETTING

London teaching hospital.

PATIENTS

33 men aged 50-85 years in American Society of Anesthesiologists risk groups I and II undergoing transurethral prostatectomy (20), herniorrhaphy (eight), or testicular exploration (five).

MAIN OUTCOME MEASURES

Percentage change from baseline in mean arterial pressure, heart rate, Doppler indices of stroke volume and cardiac output, and index of systemic vascular resistance, and change from baseline in core temperature.

RESULTS

In the control group mean arterial pressure fell to 11% (95% confidence interval -17% to -5%) below baseline at two minutes into surgery and remained below baseline; there were no other overall changes in haemodynamic variables and the core temperature was stable. During transurethral prostatectomy mean arterial pressure increased by 16% (5% to 27%) at the two minute recording and remained raised throughout. Bradycardia reached -7% (-14% to 1%) by the end of the procedure. Doppler indices of stroke volume fell progressively to 15% (-24% to -6%) below baseline at the end of the procedure, and the index of cardiac output fell to 21% (-32% to -10%) below baseline by the end of the procedure. The index of systemic vascular resistance was increased by 28% (17% to 38%) at two minutes, and by 46.8% (28% to 66%) at the end of the procedure. Core temperature fell by a mean of 0.8 (-1.0 to -0.6) degrees C. Significant differences existed between the two groups in summary measures of mean arterial pressure (p less than 0.05), Doppler indices of stroke volume (p less than 0.005) and cardiac output (p less than 0.005), index of systemic vascular resistance (p less than 0.0005), and core temperature (p less than 0.0001).

CONCLUSIONS

Important haemodynamic disturbances were identified during routine apparently uneventful transurethral prostatectomy but not during control procedures. These responses may be related to the rapid central cooling observed during transurethral prostatectomy and require further study.

Estimation of irrigant absorption during transurethral resection of the prostate. Assessment of fluorescein as a marker

Absorption of irrigating solution may complicate transurethral resection of the prostate (TURP), and a system which warns of fluid overload reliably would be of benefit in the prevention of these complications. Fluorescein can easily be detected at very low concentrations in blood and can be added to the irrigating solution in amounts invisible to the naked eye, providing a possible means of easily monitoring the absorption of irrigant solution during TURP. To test this hypothesis, the plasma concentration of fluorescein was determined at intervals after intraperitoneal injection in rats. Although the published data on fluorescein suggest that it meets the criteria for a suitable marker substance to be introduced into the irrigant solution, the results show that plasma fluorescein is constant and not dose related. The addition of fluorescein to the irrigant solution would not provide a quantitative means of determining the volume of irrigant absorbed. The use of other substances may provide the answer to this major clinical problem. We have defined a set of criteria which such a substance should fulfil.