Saddle block versus subarachnoid block for transurethral resection of prostate surgery: A randomized comparative study

Revathy Bejoy; Derlin Thomas; Suhura Beevi

doi:10.4103/BJOA.BJOA_120_20

ORIGINAL ARTICLE

Year : 2020 | Volume : 4 | Issue : 4 | Page : 178-182

Saddle block versus subarachnoid block for transurethral resection of prostate surgery: A randomized comparative study

Revathy Bejoy¹, Derlin Thomas², Suhura Beevi¹
¹ Department of Anaesthesiology, Azeezia Institute of Medical Sciences and Research, Kollam, Kerala, India
² Department of Anaesthesiology, Amala Institute of Medical Sciences, Thrissur, Kerala, India

Date of Submission	01-Jul-2020
Date of Decision	11-Aug-2020
Date of Acceptance	07-Sep-2020
Date of Web Publication	05-Oct-2020

Correspondence Address:
Dr. Derlin Thomas
Department of Anaesthesiology, Amala Institute of Medical Sciences, Thrissur, Kerala
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/BJOA.BJOA_120_20

Abstract

Background: Regional anesthesia is usually preferred over general anesthesia for transurethral resection of the prostate (TURP). Spinal anesthesia increases the risk of hypotension. Saddle block provides a block that is dense in lumbosacral and lower thoracic dermatomes; hence, hemodynamic derangement will be less. In this study, we aimed at comparing the hemodynamic stability and anesthetic efficacy of subarachnoid block versus saddle block in patients undergoing TURP. Patients and Methods: After obtaining written informed consent, a prospective randomized comparative study was conducted in 90 patients, 50–70 years, of ASA physical status 1–2 scheduled for TURP. They were randomly allocated into two groups of 45 each. Group SA received spinal and Group SB received saddle block using the same volume (2.5 ml) of hyperbaric bupivacaine. Hemodynamic parameters such as heart rate (HR), systolic, diastolic, and mean arterial blood pressure (BP), and height of block were recorded in both groups. If hypotension was present, ephedrine bolus intravenously was administered, and the total requirement of vasopressor was noted. Results: Maximum decrease in HR from baseline was low in Group SB (P = 0.008). Maximum fall in systolic, diastolic, and mean BP was also found to be low (P = 0.005), (P = 0.001), and (P = 0.001), respectively, in Group SB. In Group SB, time to achieve T10 sensory level was delayed, whereas the level of motor blockade was low according to the modified Bromage score. Ephedrine consumption was also low in Group SB (P = 0.001) versus Group SA. Conclusion: Saddle block can be safely administered in TURP for elderly patients, with the reduced hemodynamic imbalance and vasopressor requirement.

Keywords: Hemodynamic changes, saddle anesthesia, spinal anesthesia, transurethral resection of the prostate

How to cite this article:
Bejoy R, Thomas D, Beevi S. Saddle block versus subarachnoid block for transurethral resection of prostate surgery: A randomized comparative study. Bali J Anaesthesiol 2020;4:178-82

How to cite this URL:
Bejoy R, Thomas D, Beevi S. Saddle block versus subarachnoid block for transurethral resection of prostate surgery: A randomized comparative study. Bali J Anaesthesiol [serial online] 2020 [cited 2023 Mar 22];4:178-82. Available from: https://www.bjoaonline.com/text.asp?2020/4/4/178/299871

Introduction

Elderly individuals can develop the same illness as the rest of the population, but with their diminished physiologic reserve, long-term persistence of diseases and the cumulative effects of comorbid conditions behoove the anesthesiologists to assure quality care in anesthetic management with diminished morbidity and mortality.^[1],[2] Transurethral resection of the prostate (TURP) is the most common surgical procedure performed for bladder outlet obstruction due to benign prostatic hypertrophy, commonly seen in elderly males.

Regional anesthesia is generally preferred in TURP considering its innumerable advantages over general anesthesia.^[3],[4] However, the major complication commonly observed in spinal technique is hypotension.^[5],[6],[7] This reduction in systemic vascular resistance may be even up to 25% in the geriatric population with cardiovascular compromise, when compared with normal healthy adults in whom, it may be only between 15% and 18%.^[8] The resultant hypotension is usually treated with intravenous (IV) fluids or with vasopressor agents. However, the generous use of IV fluids to correct this hypotension can result in serious complications in the elderly population with an already compromised cardiopulmonary reserve.

With epidural anesthesia, these hemodynamic alterations are more gradual and less severe, but there is always a possibility of sacral sparing causing incomplete surgical anesthesia.^[9] A technique of injection of hyperbaric local anesthetic solutions into subarachnoid space with the patient in sitting position, popularly known as “ saddle block”, provides a block that is dense in sacral, lumbar, and lower thoracic dermatomes with lessened hemodynamic derangement and minimal circulatory overload.^{[7],[10],[11],[12]}

Hence, after taking into account of all the merits and demerits of regional anesthetic techniques, we designed this study to compare the hemodynamic effects and requirement of vasopressor in elderly patients undergoing TURP, when administered with either saddle block or conventional subarachnoid block.

Patients and Methods

After procuring approval of the institutional ethics committee (AEC/REV/2015/16; dated on 12/11/2015) and written informed consent, 90 patients aged between 50 and 70 years of ASA physical status (PS) 1–2, who underwent TURP surgery, were enlisted in this prospective, randomized comparative study. Based on the previous study,^[11] we calculated the minimum sample size as 42 for each group. Patients with a history of allergy to local anesthetic, psychiatric or neurologic illness, morbid obesity, coagulation disorder, or refusal to study procedure were exempted from our study.

During the thorough preanesthetic examination on the preoperative day, a written file containing all the information about the anesthesia technique to be performed was provided to all the selected patients, before taking consent. On the day of surgery after arriving at the operating room, all standard monitors were connected, and baseline heart rate (HR), SpO₂, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MABP) were documented. After securing an IV cannula of 18G, patients were preloaded with normal saline 0.9% at a rate of 10 ml/kg for a period of 20 min before administering regional anesthesia. Premedications with midazolam 0.5–1 mg and ondansetron 50 μg/kg were also given to all patients.

Using a computer-generated random number list, 90 patients were assigned into two groups of 45 each using a serially numbered, sealed-opaque envelopes. Group SA (subarachnoid block group) received 2.5 ml of 0.5% hyperbaric bupivacaine using a 25G Quincke needle at L3–L4 or L4–L5 intervertebral space by midline approach with the patient in lateral decubitus position after confirming free flow of cerebrospinal fluid. Immediately after the injection, patients were made to lie down flat for 10 min. Group SB (saddle block group) received 2.5 ml of 0.5% hyperbaric bupivacaine with the patient in the sitting position. After administering the drug, patients were kept in the sitting position for the next 10 min and then were positioned supine. All patients were monitored in the operation room using an electrocardiograph, a noninvasive blood pressure (BP) cuff, and an oxygen saturation probe. Data were recorded every 5 min for the first 30 min and then every 10 min until the end of surgery. Clinically relevant hypotension (decrease in MAP >20% of baseline) was treated with a bolus of 6 mg ephedrine. The level of sensory blockade was measured bilaterally using a wet swab test at 3, 5, 10, 30, 45, 60, and 120 min after injection, whereas the level of motor blockade was assessed using the modified Bromage scale. The assessment of the motor blockade was done at 10 and 120 min after injection. Time to reach maximum sensory block, maximum motor block, operation time, amount of irrigating fluid used, and perioperative complications if any, were also recorded. The inability to achieve a sensory blockade up to T10 dermatome was considered as a failed block.

The primary outcome of our study was to evaluate and compare the hemodynamic effects and vasopressor requirement on administering either subarachnoid block or saddle block. The secondary outcomes included the assessment of sensory and motor blockade achieved with spinal as well as saddle block and side effects if any.

The statistical calculations were performed using the software Statistical Package for the Social Sciences (SPSS) for Windows version 17.0 (SPSS Inc., Chicago, IL, USA). The following statistical methods were employed in the present study. The mean and standard deviation were used for descriptive statistics. The level of significance was set at 0.05. After performing the Shapiro–Wilk test, data except baseline were found to be nonnormally distributed, and hence, nonparametric tests were used. Unpaired t-test and Mann–Whitney U-test were used for quantitative data; Chi-square test and Fisher Exact t-test were used for qualitative data.

Results

We screened 100 patients for this prospective, randomized comparative study. We excluded ten patients from our study for not fulfilling the inclusion criteria. Hence, a total of 90 patients were recruited and assigned into two groups of 45 each. All these patients finished the study and were available for further follow-up and collection of data [Figure 1].

Figure 1: Consort flow diagram

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Both groups were comparable with regard to age, height, weight, ASA PS, and duration of surgery [Table 1]. Baseline HR, SBP, MABP, and DBP were also comparable in both groups [Table 2]. The fall in HR, SBP, MABP, and DBP from baseline was significantly less in Group SB when compared to Group SA during the initial 20 min after administration of intrathecal bupivacaine [Table 2]. A statistically significant increased fall in MABP was recorded in Group SA even after 20 min of drug administration [Table 2]. The number of patients who required ephedrine as well as the total consumption of ephedrine for treating hypotension was significantly reduced in Group SB [Table 3].

Table 1: Patient characteristics

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Table 2: Comparison of maximum fall in heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure from baseline between the two groups

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Table 3: Comparison of the two groups based on the amount of ephedrine consumption

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Both groups attained a T10 dermatomal sensory blockade. However, the time taken to achieve that sensory level was delayed in Group SB. A statistically significant reduction in the intensity of motor blockade was recorded in Group SB both at 10 min and 120 min [Table 4].

Table 4: Comparison of two groups based on the modified Bromage scale at 10 min and 120 min

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Discussion

In this study, we observed a statistically significant fall in HR, SBP, MABP, and DBP from baseline in Group SA during the initial 20 min after administration of intrathecal bupivacaine, when compared with Group SB. A statistically significant increased fall in MABP was recorded in Group SA even after 20 min of drug administration. Besides, the number of patients who required ephedrine, as well as the total consumption of ephedrine for treating hypotension, was significantly lessened in Group SB. While comparing the sensory and motor blockade between the groups, we found that even though both groups attained a T10 dermatomal sensory blockade, the time taken to achieve that sensory level was delayed in Group SB. Furthermore, a statistically significant decrease in the intensity of motor blockade was observed in Group SB both at 10 min and 120 min.

TURP is the treatment of choice for benign prostatic hyperplasia. Since the perioperative mortality and morbidity during TURP largely depends on the anesthetic technique, various studies had been conducted in the past comparing different techniques, drugs, as well as drug combinations with varying results.^{[7],[11],[13]} Spinal anesthesia with a level of sensory blockade up to T10 dermatome is considered as the preferred technique for TURP by anesthesiologists worldwide. However, the most usual sequelae with spinal anesthesia are the rapid change in HR and BP. Moreover, a fall in central venous pressure and pressure of the periprostatic venous plexus increases the absorption of irrigation fluid and may cause TURP syndrome and glycine toxicity. Since such a drastic change can increase the perioperative mortality and morbidity of TURP, especially in geriatric patients with multiple comorbidities, our aim was to formulate a method of satisfactory anesthesia with minimal hemodynamic disturbances.

Even though countless researches had been done previously, depicting the usefulness of regional anesthesia for TURP,^{[7],[14],[15]} there are not many studies reported on spinal saddle block. Hence, this study was conducted to compare the effects of saddle block and conventional subarachnoid block in old age patients undergoing TURP.

No significant difference in baseline HR was monitored between the groups. Furthermore, there was no record of any significant bradycardia in both groups which necessitated treatment. Baraka et al.^[16] in their study observed a maximum fall in HR after 15–20 min of intrathecal bupivacaine. However, in this study, while comparing the maximum difference in HR from baseline, Group SA demonstrated a statistically significant fall during the first 20 min after the administration of the drug.

Group SA also showed a drastic fall in BP during the initial 20 min which was found to be significant both clinically and statistically, which were similar to the results obtained by Critchley et al.^[17] where they demonstrated a 25% fall in systemic arterial pressure from the baseline in elderly patients undergoing TURP under spinal anesthesia. Moreover, we faced such significant hypotension in Group SA even after preloading all the patients in both groups, and this corroborates the results by Arndt et al.^[18] as they found a drastic hemodynamic change necessitating medical management during subarachnoid block regardless of vasoconstrictor or IV fluid prophylactic administration. Group SB also recorded a fall in BP, but it was more gradual, and the requirement of vasopressor (ephedrine) was found to be significantly low in those, which is correlating with the results observed by Ozmen et al.^[11] as they concluded that saddle block is associated with stable hemodynamic, in their study comparing spinal, epidural, and saddle anesthesia in TURP. A combination of prehydration, limiting the level of blockade by saddle technique along with low sympathetic denervation, helped us to maintain a stable hemodynamic in patients of Group SB. Similarly, Bhattacharyya et al.^[7] also noticed that the incidence of hypotension and requirement of vasopressor was less in the saddle group in comparison with the spinal group.

All patients in both groups achieved a T10 dermatome level. At 20 min after intrathecal injection of hyperbaric bupivacaine, we noticed that even though a similar level of sensory blockade (T10) was achieved in both groups, the time taken to reach that sensory level was delayed in Group SB with significantly minimal hemodynamic variations. Numerous studies have shown that the saddle block will be initially more restricted, but eventually reaches a level similar to that which would have been attained had the patient been kept supine immediately after injection.^[12],[19]

In our study, a statistically significant reduction in the intensity of motor blockade was recorded in Group SB both at 10 and 120 min. Intense motor block causes delay in recovery, thereby prolonging the hospital stay considering day care surgical standards. Hence, less motor blockade facilitates faster patient mobilization. It also helps to decrease the fall in BP by the maintenance of the calf muscle pump. In our study, surgery does not demand a complete motor block. However, for other urological procedures like transurethral resection of bladder tumor, a complete motor block is needed. Lateral wall resection of the bladder can cause obturator nerve stimulation and may result in bladder perforation.

In our study, with regard to mean age, height, weight, ASA PS, and duration of surgery, both the groups were comparable. Hence, no correlation with hemodynamic or level of the blockade was noticed. All patients in our study had the anesthetic drug injected in the L3–L4 interspace through a midline approach using a Quincke needle with the same velocity (0.2 ml/s) and with the orifice of the spinal needle turned cephalad, taking into account the results of previous studies.^[15],[20]

Oxygen saturation remained stable in both groups. Hypothermia and shivering were managed with forced air warmer, warm IV fluids, and IV pethidine. Postoperative pain is usually not so grave after TURP, although uneasiness from bladder spasm or from the urinary catheter may arise. We managed it with paracetamol IV infusion and the local application of lignocaine jelly. Postdural puncture headache was complained by 3 out of 90 patients and was managed with bed rest, oral or IV fluids, and paracetamol tablets. During the perioperative period, we did not encounter any TURP syndrome, bladder perforation, or septicemia in both groups.

A few limitations of our study include patients with decompensated functional reserve were exempted from the study as well as elderly patients above 70 years. Hence, future studies are required before concluding about the safe administration of saddle block in the above mentioned population. Furthermore, we used a fixed dose of bupivacaine for all patients irrespective of individual variation, which can be possibly titrated with further studies.

Conclusion

Saddle block is a safer technique for providing adequate anesthesia, with greater hemodynamic stability and minimal vasopressor requirement, in elderly patients undergoing TURP.

Acknowledgment

We thank Mr. Kevin Suresh, who conducted the statistical analysis of the data of our study. We also express our sincere gratitude to all the patients who participated in the study and to the staff of the Department of Anesthesiology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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