Does an alcolmeter in the hands of an anesthesiologist make TURP safer? - Results from a case-control study.

BACKGROUND: This hospital-based, prospective, case-controlled study was carried out to monitor fluid absorption during transurethral resection of the prostrate (TURP) by marking the irrigating fluid with ethanol for signs of TURP syndrome. Addition of ethanol allows early detection and prevention of full blown TURP syndrome as also the volume of fluid absorbed can be measured. SUBJECTS AND METHODS: Patients were divided into two groups of 50 each, taking males undergoing TURP belonging to ASA (American Society of Anesthesiologists) I and II. Group 1 received irrigation with 1.5% glycine alone and group 2 received irrigation with 1.5% glycine along with ethanol during TURP. The primary outcome measure was the detection of TURP syndrome using end expiratory ethanol levels and comparing with serum electrolytes and clinical manifestations. The secondary outcome measures, the hemodynamic parameters such as heart rate, systolic and diastolic pressures, and oxygen saturation were recorded during the intraoperative period after spinal anesthesia and then postoperatively till the end of the first hour in the recovery room. STATISTICAL ANALYSIS: Chi-square test, Student's t-test and Pearson's correlation coefficient 'r'.
RESULTS: Mean resection time in the ethanol positive patients (36.36 min) was significantly higher than that in the ethanol negative patients (22.08 min) (P < 0.01). The estimated fluid absorbed was statistically significant in 45 minutes of resection in three patients with positive ethanol readings (P < 0.05). Resection was temporally stopped in 16 patients (32%) and permanently in 1 patient (2%), whose resection time reached 60 min. A positive correlation was found between total fall in serum sodium and maximum expiratory ethanol concentration. There was a significant difference in the heart rate between the two groups in the 40(th) minute (P < 0.05).
CONCLUSION: Ethanol is a noninvasive, easy-to-use marker in irrigating fluid for assessing fluid absorption. It forewarns to take corrective measures earlier than both fall in sodium and manifestations of TURP syndrome, allowing successful completion of TURP.

INTRODUCTION

The basic aim of our study was to know whether there is any added advantage of using ethanol in irrigating fluid compared to measuring biochemical parameters and clinical manifestations and how the anesthesiologist can contribute in safe and successful completion of TURP though the practice is well established in the west.

SUBJECTS AND METHODS

This prospective case-control study was conducted on 100 male patients belonging to ASA I and ASA II, in the age group of 60 and above, who underwent TURP as an elective surgery under spinal anesthesia. After the approval of our hospital's Ethics Committee, written informed consent was taken from all patients.

Group stratification was done on preanesthetic rounds dividing patients into two groups of 50 each, taking every alternate patient in each group. Group 1 received 1.5% glycine and group 2 received 1.5% glycine marked with 0.7% ethanol during TURP. Glycine was tagged with ethanol by taking out 30 ml of glycine from 3 l of 1.5% glycine bag, adding 30 ml of absolute alcohol into the bag, making it 0.7%. The irrigation fluid container was kept at a height of 50 cm for all patients in both the groups. On preanesthetic check-up baseline serum electrolytes were sent. Patients were asked to refrain from alcohol for 24 hours.

Monitoring TURP syndrome

Any intraoperative manifestations of TURP syndrome, namely blurring of vision, nausea, chest pain, and breathlessness, were observed and recorded in both the groups and the surgeon was warned. Breath alcohol estimations were done every 15 minutes from the start of resection to the end. Electrolytes were estimated every 30 minutes from resection time till 1 hour after completion. Pulse rate, blood pressure, and SpO2 (oxygen saturation) were monitored every 15 minutes till 1 hour postoperative.

Injection furosemide was given in the following situations:

Resection time >1 hour.

Symptoms of intravascular absorption appeared:

Positive ethanol readings were noted. (Those with history of alcohol abuse were excluded from the study.).

Serum sodium values <135 meq/l.

Patients with preoperative sodium ≤135 meq/l, clinically asymptomatic with further decline in values.

Both groups were taught how to blow into the intoxilyzer. Intoxilyzer S-D5 series, Lions laboratories, was used for breath alcohol estimations which had a digital display in the range of 0-50 units. The value had to be divided by 100 to derive the concentration in milligrams per deciliter. Patients were kept 6 hours nil orally and given 5 mg Diazepam in the morning of the surgery.

On the operating table, intravenous access was obtained; SpO2, blood pressure, and ECG (electrocardiogram) monitoring were done. Spinal block was given under full asepsis in the L3-L4 intervertebral space with a 25 G Quincke's needle, and 2.5-3 ml of 0.5% heavy bupivacaine injected according to the expected duration of surgery. Once anesthetized, the patient was placed in the lithotomy position.

A disposable mouthpiece was fixed atop the Intoxilyzer [Figure 2] and the patient was asked to hold one end of the mouthpiece in his mouth and inhale deep when the “BLO” sign appeared on the screen [Figure 3]. This was followed by a “FLO” sign when the patient had to exhale continuously into the mouthpiece [Figure 4]. If done correctly a “beep” sound was heard. Following which ethanol levels were measured and displayed. If incorrect the “VOL” sign appeared, the procedure had to be repeated. The end expiratory ethanol levels were recorded and tabulated for statistical analysis. The surgeon was warned at the first positive alcohol reading, as it signified fluid absorption. Any intraoperative clinical manifestations of TURP syndrome, i.e., blurring of vision, nausea, chest pain, and breathlessness, were observed, recorded, and the surgeon warned.

Figure 2

Alcolmeter used for measuring expiratory ethanol levels for fluid absorption

Figure 3

When the patient blows into the disposable pipe attached to the Alcolmeter “blo” sign appears

Figure 4

When the patient exhales correctly into the disposable pipe “flo” sign appears and ethanol measurements are made

Whisker plots to describe the primary and secondary outcome measures. Oxygen saturation at different times of measurement

Whisker plots to describe the primary and secondary outcome measures. Association of TURP syndrome and decrease in serum sodium

The volume of irrigating fluid absorbed was estimated using Hahn's Nomogram.[8]

Fluid absorbed (ml) = (weight in kg × 0.6 × fall in serum sodium) ×1000/155.

The resection time was noted, which was defined as the time when the resectoscope was inserted and resection started. The results were compiled and analyzed statistically using the Chi-square test, Student's t-test, and Pearson's correlation coefficient “r.”

RESULTS

A total of 100 male patients were enrolled into the study, belonging to the age of 60-96 years. Majority of patients belonged to the ASA-II category in both the groups. The major indication for undergoing a TURP was benign prostatic hypertrophy (BPH) in both groups (89%) while only 11% patients had prostatic cancer.

In group 1, four patients (8%) had TURP syndrome. Of these four patients, two patients (4%) had clinical manifestations of TURP syndrome, which included chest pain and shortness of breath in one patient and nausea in one patient. Hyponatremia was seen in all four patients, with three patients recovering in the postoperative period. Resection was temporarily stopped and furosemide administered to all four patients. The mean resection time in these patients was 27 minutes [Table 1, page 1].

Table 1

TURP syndrome: Manifestation and intervention

In group 2, 17 patients (34%) were found to have TURP syndrome on the basis of expiratory ethanol levels, clinical manifestations, hyponatremia, calculated fluid absorption, and resection time. Ethanol levels were found positive in 11 (22%) of these 17 patients. In 9 (18%) of the above 11 patients ethanol levels declined further suggesting absorption was via intravascular route. In 1 (2%) of the 9 patients, ethanol levels (46 mg/dl) approached the endpoint of our warning limit on the intoxilyzer (~50 mg/dl) at the end of 60 minutes of resection and the resection was permanently stopped [Table 1, page 1]. The mean resection time in groups 1 and 2 was 20 + 7 min (range 10-45 minutes) and 25 + 12 min (range 10-60 minutes) which was statistically significant (P < 0.05). In the four patients in group 1, who manifested TURP syndrome, the mean resection time was 27 min. In these patients the mean calculated fluid absorbed was 2029 ml. Mean resection time in ethanol positive patients was 36 + 13 minutes, which was significantly higher than in those who were ethanol negative (mean 22 + 9 minutes) (P < 0.01) [Figure 1d and f-whisker plots].

Figure 1d

Whisker plots to describe the primary and secondary outcome measures. Expiratory ethanol at different times of measurement

Figure 1f

Whisker plots to describe the primary and secondary outcome measures. Association of ethanol positivity and resection time

A positive correlation was found between the amount of fluid absorbed and resection time, but this correlation was statistically insignificant (P > 0.10). A positive correlation was found between maximum ethanol levels (3 + 9 mg/dl) and the overall decrease in serum sodium (2 + 6 meq/L). [Table 2] Fluid absorbed from end expiratory ethanol concentration was calculated using Hahn's Nomogram [Table 3, page1].

Table 2

Association between TURP syndrome and maximum decrease in serum sodium levels

Table 3

Estimated irrigated fluid absorption from expiratory ethanol concentration using nomogram (Hahn, 1999)

The mean heart rates at the 40th minute of resection were 82 bpm (beats per minute) in group 1 and 68 bpm in group 2 which were statistically significant (P < 0.05) [whisker plots Figure 1a]. In both the groups mean systolic blood pressure decreased from the baseline value in the first minute and at varying intervals intraoperative: group 1 - the baseline value of 127 + 13 mm Hg to 116 mm Hg in 1 minute, being lowest in 50 minutes -105 mm Hg (P < 0.05, 1st-30th min; P < 0.01,40th minute). In group 2 the baseline value of systolic blood pressure 132 + 15 mm Hg decreased to 120 mm Hg in 1 minute, being lowest in 30 minutes intraoperatively - 106 mm Hg [whisker plots Figure 1b)].

Figure 1a

Whisker plots to describe the primary and secondary outcome measures. Heart rate at different times of measurement

Figure 1b

Whisker plots to describe the primary and secondary outcome measures. Systolic blood pressure at different times of measurement

DISCUSSION

TURP remains the gold standard treatment for BPH despite competing alternatives being available.[1] Although generally a safe operation, intravascular fluid absorption occurs frequently in TURP.[2] In our study there was difference in the mean resection time in both groups, which was statistically significant. The positive breath analyzer readings limited the time and the amount of resection in those who absorbed irrigating fluid. At the same time, they allowed the continuation of resection after temporarily halting, following positive ethanol readings, during which time interventions like injection. Furosemide and fluids (normal saline) could be infused to promote diuresis. After intervention and temporary cessation of resection, the ethanol levels reduced and resection resumed till completion. In our study, in the four patients in group 1, who manifested the TURP syndrome, the mean resection time was 27 min. In these patients the mean calculated fluid absorbed was 2029 ml.

A positive correlation could be found between the amount of fluid absorbed and resection time. This observed difference in the resection time of the two groups can be attributed to use of alcolmeter to detect fluid absorption early in group 2, with timely intervention and prolongation of safe resection thereafter. Though no statistical significant difference was found in the operating time between the two groups, it was found to be comparable. Okeke et al.,[3] in their study to evaluate usefulness of a tracer of 1% ethanol in 1.5% glycine in the early detection of fluid absorption in 120 patients found no statistical difference in the operating time of patients who absorbed and those who did not absorb irrigating fluid, hence concluding that operating time was not a factor in the prediction of the TURP syndrome.[2]

A positive correlation was found between maximum ethanol levels and overall decrease in serum sodium. This is in accordance with the studies of Hahn[4] in 60 TURP patients using 1% ethanol as the marker who found a positive correlation between the end expiratory alcohol levels and the fall in serum sodium levels (r2 = 0.88).

There was statistically significant difference in the heart rates observed between the two groups in the 40th min. (P < 0.05). This observation can be explained by the effect of absorption of irrigating fluid,[5] which leads to similar findings, as well as a greater fall in heart rate in the postoperative period, which however was not observed in our study. The fall in systolic blood pressure was found to be statistically significant at the various time intervals in both groups individually (P < 0.05 and P < 0.01). The fall in systolic blood pressure can be attributed to fluid absorption during surgery, the incidence increasing with volumes greater than 2 l being absorbed (Olsson et al.).[6] No statistical difference was found in the mean serum sodium and potassium levels between the two groups (P > 0.10) [Figures 1g and h-whisker plots]. A positive correlation was found between the amount of fluid absorbed and the decrease in sodium levels though the correlation was insignificant (P > 0.10).

Figure 1g

Whisker plots to describe the primary and secondary outcome measures. Serum sodium at different times of measurement

Figure 1h

Whisker plots to describe the primary and secondary outcome measures. Serum potassium at different times of measurement

Although the ethanol breath test allows early detection of fluid absorption in TURP patients, it has its limitations as an early warning device when fluid is absorbed by the extra-vascular route.[7] In this situation, the absorption of ethanol into the circulation takes about 20 min, resulting in a delay in detection. The pattern of ethanol changes indicates whether intravascular or extra vascular absorption is occurring.[8] There is an increase in the end expiratory levels with fluid absorption and a decrease in the levels once the bladder irrigation is stopped. The rapidity of response suggests that the route is through the severed prostatic veins. Contrary to the above, a slow but sustained increase in the ethanol levels that remains unchanged or even increases after completion of TURP is seen in the extra vascular route of absorption. Resection must be stopped immediately for adequate management. Otherwise, a life-threatening TURP syndrome may develop despite ethanol monitoring of fluid absorption.[4910]

Hahn in 1990 studied the fluid and electrolyte dynamics during TURP syndrome and found chest pain in 3 patients out of 10 patients who manifested TURP syndrome.[11] Hahn et al.[3] studied the potential benefits of using 1% ethanol as the tracer of fluid absorption along with glycine as the irrigating fluid during TURP. They observed chest pain in 2 out of 77 patients who were symptomatic. This symptom manifested in those who absorbed > 1000 ml fluid similar to our study. Thus, from our study it is evident that TURP syndrome can present in a varied manner. Failure or late detection of the manifestations of TURP syndrome or of hyponatremia,[12] can lead to the full presentation of this condition, resulting in premature termination of resection along with a poor postoperative outcome, even fatality.[6] However, the use of ethanol as a marker for fluid absorption allowed early detection of TURP syndrome, and on instituting timely intervention, in successful completion of surgery in most of our patients.[1316]

Ethanol monitoring is a simple, easily performed, noninvasive technique, which does not require prolonged processing.[715] The tracer substance is usually familiar to the patient and readily accepted. Using the alcolmeter we could prolong the resection time safely enough. Using Hahn's Nomogram, calculation of the volume of fluid absorbed during TURP was easy.[16] Although the role of ethanol is known the usage is still infrequent in the developing nations and this is the reason why the present study was undertaken.

On the other hand, although cost feasibility was not sought for during the study, it must be mentioned that the intoxilyzer (SD-5) used was made available from Germany (not being available in India at the time of the study) and was an expensive gadget (Rs. 25,000). Accessibility of absolute alcohol was difficult as a license had to be obtained to go about the study. The study needed the patient to learn the use of the intoxilyzer. The breath analysis was conducted in the lithotomy position, which was difficult for some of the patients.

The feasibility of using ethanol on a regular basis as an early warning method during TURP surgery needs to be further studied by including a larger group of patients.[7]