European Journal of Cardiovascular Medicine

Spinal anaesthesia is the technique of choice for transurethral resection of the prostate (TURP). The signs and symptoms of water intoxication, fluid overload, and bladder perforation can be recognized early because the patient is awake. Also, there is less incidence of postoperative nausea and vomiting (PONV) and better postoperative pain relief than general anaesthesia. It is important to limit the distribution of spinal anaesthesia to reduce adverse hemodynamic and pulmonary effects in elderly patients because of co-existing cardiac and pulmonary diseases. Even though a high-level block may be untenable because of physiological effects, a sensory level of T10 is needed for satisfactory anaesthesia . Higher sensory levels mask the symptoms (abdominal or shoulder pain and/or nausea and vomiting) of accidental perforation of the bladder or prostatic capsule in the awake patient and also cause adverse cardiopulmonary effects.¹

By using very small doses of local anaesthetic (LA), one can limit the distribution of spinal block, but low-dose bupivacaine cannot provide an adequate level of sensory block. Intrathecal opioids enhance the analgesic effect of subanaesthetic doses of local anaesthetic and make it possible to achieve successful spinal anaesthesia by using otherwise inadequate doses of local anaesthesia.²

Local anaesthestics are conventionally used alone in spinal anaesthesia, but a variety of adjuvants are now being popularized. Co-administration of these agents allows for the reduction in the required dose of LA, with the advantage of motor block sparing and faster recovery while still producing the same degree of analgesia and also helps in decreasing the incidence of adverse effects associated with them like a high sympathetic blockage. TURP is one of the most commonly performed urological procedures in geriatric populations so it is important to conduct this surgery safely.

Aim and Objective

The main objective of the study was to compare the conventional dose of bupivacaine and low dose of bupivacaine-fentanyl spinal anaesthesia in maintaining hemodynamic stability in patients undergoing transurethral resection of the prostate.

The design used was a hospital-based prospective observational study conducted at the Department of Anaesthesiology, Rama Medical College, Hospital & Research Centre, Hapur, after getting approval from the Institutional Research and Ethics Committee (IREC). The study period was 1 year. The study sample size was calculated as n=2x(Z1-a/2+Z1-b/2)2xS2 from a previous study.³

After getting written informed consent, 90 patients planned for elective TURP under spinal anaesthesia who met the study criteria were consecutively recruited to the study till the sample size was met, with 47 in each group. Patients were selected according to inclusion and exclusion criteria.

Inclusion Criteria

1. Patients attending elective operation theatre for TURP surgery.
2. American Society of Anesthesiologists Physical Status (ASA PS ) I &II patients.
3. Age-60 - 80 yrs.

Exclusion Criteria

1. Any contraindication to regional anesthesia.
2. Pre-existing neurological deficit in the distribution to be anesthetized.
3. History of allergy to bupivacaine or fentanyl.

Study procedure

Study participants were chosen according to the eligibility criteria, and were consecutively divided into two groups of 47 each. Group F consisted of patients who received a low dose of bupivacaine–fentanyl spinal anaesthesia and group B consisted of patients who received a conventional dose of bupivacaine. Appropriate fasting guidelines were advised and premedication was as per departmental protocol. The patients were attached with standard ASA monitors (NIBP, ECG, PULSE OXIMETER) in theatre and were monitored throughout surgery until the patient was shifted to the recovery room. A large bore (18G) intravenous line was secured and started with 500ml Ringer lactate solution. A combined spinal epidural technique was used. Epidural space was identified at the L2-3 interspace using an 18G Tuohy needle and loss of resistance to air technique. The epidural catheter was inserted into the epidural space and secured with tape, but no medication was injected via this catheter. Then a 23G/25G Quincke spinal needle was introduced in the L3-4 intervertebral space using a midline approach.

After observing the free flow of clear cerebrospinal fluid, Group F received an intrathecal injection of plain 0.5% bupivacaine 5mg with 25mcg fentanyl diluted to 2ml with sterile water and Group B received only 0.5% plain bupivacaine 7.5mg diluted to 2ml with sterile water. The patients were placed in a supine position until the sensory blockade reached the highest dermatomal level. Motor blockade was assessed at the time of reaching peak sensory level and this was considered the maximum motor blockade.26 G needle and spirit swab were used to detect the cephalad spread of spinal anaesthesia by loss of pinprick and cold sensation every 3 minutes from injection until the level stabilized for four consecutive tests. The tests were then conducted every 10 minutes until two-segment regression. Further testing was then performed at 20 min intervals in the recovery room until recovery up to the S2 dermatome. The patients were provided continuous face mask oxygen. The high dermatomal level of sensory blockade, the time to reach this level, motor blockade at the time of reaching peak sensory level, the time to two-segment regression, and the time to  S2 sensory regression were recorded. Motor blockade was assessed with a Bromage scale(0=no motor block,1=hip blocked,2=hip and knee blocked,3=hip, knee, and foot blocked). The duration of the motor block was considered as the time when the Bromage score returned to zero. The pain was assessed every 10 minutes from the beginning of surgery using a 10-cm visual analog pain scale.

Pulse rate, oxygen saturation by pulse oximetry, and blood pressure were monitored and recorded throughout the surgery until the patient was shifted to the recovery room. Adverse effects such as nausea, vomiting, shivering, pruritus, respiratory depression, and transient neurological symptoms if any were recorded. Hypotension was defined as a decrease in SAP of< 85 mmHg or <75% from the baseline value and bradycardia was defined as heart <50 beats/min.

Statistical Analysis

Categorical and quantitative variables were expressed as frequency (percentage) and mean ± SD respectively. An Independent t-test was used to compare quantitative parameters between categories. The test used to find an association between categorical variables was the Chi-square test. For all statistical interpretations, p<0.05 was considered the threshold for statistical significance. Statistical analyses were performed by using a statistical software package SPSS, version 27.0

Ethical considerations

Ethical committee clearance was obtained before data collection. The study did not interfere with the planned procedure. No added expenses to the patient were incurred. Informed written consent was obtained from all participating patients. Strict patient confidentiality was ensured throughout the study.

Spinal block was successful in all patients. Patient characteristics such as age, height, and weight were similar between groups[Table 1]. The peak sensory level attained was not statistically significant but the time to reach the peak level was found to be significant with Group B attaining a faster sensory level[Table 2]

Table 2: Comparison of peak sensory level and time to reach peak level based on group

Table 3: Comparison of 2segment regression, S2 regression, and duration based on group

**: - Significant at 0.01 level

Table 4: Comparison of hypotension and hypotension based on group

**: - Significant at 0.01 level

Two-segment regression differences and duration were not found to be statistically significant though the S2 regression was found to be faster in the conventional dose group and statistically significant. There was no significant difference between the groups concerning duration [Table 3].

The occurrence of hemodynamic instability (hypotension, bradycardia) was more in group B, compared to group F. The occurrence of hypotension was 42.6% in group B compared with 29.8% in group F. The occurrence of bradycardia was 23.4% in group B compared with 12.8% in group F [Table 4]. Sensory block was adequate for all surgery in both groups.

There were no cases of respiratory depression or any other serious complications such as cardiac or respiratory arrest.

The present study demonstrated that the addition of fentanyl to bupivacaine maintains the duration of the block with a lesser dose of bupivacaine and less incidence of complications like hypotension and bradycardia, though with similar sensory level and the onset of peak sensory level. In the present study, the duration, and level of sensory block were similar while time to peak sensory level and S2 regression time were lesser in the low-dose bupivacaine-fentanyl group.

Even though the prostate gland is mainly supplied by sensory branches from the pelvic plexus, the block must extend to sensory dermatome T12–L1 to prevent the pain or abdominal discomfort from the bladder distention with irrigation fluid. A spinal block to T10 is often required to guarantee the elimination of the discomfort caused by bladder distension. Some authors have studied low-dose diluted local anesthetic without adjuvants to shorten recovery time and limit the distribution of the spinal anaesthesia block. But the block provided an inadequate level of sensory block⁴ Beers et al reported that mid-lumbar block level provided adequate anaesthesia for TURP when bladder pressure was kept low. Also, a sensory block extending to T10 is necessary to provide adequate analgesia, since monitoring of intravesical pressure is not available always.⁵

Hypotension in the elderly is a serious adverse effect as cardiac contractility and heart rate increases are limited. So it is very vital to restrict this exaggerated physiological response of hypotension during spinal anasthesia. Some methods of preventing hypotension during spinal block include fluid preloading and prophylactic use of vasopressors such as phenylephrine or inotrope such as ephedrine. But these measures are not without their problems. Fluid loading has repeatedly been shown to be of little benefit if used alone.^6,7,8 Excessive fluid loading may also lead to serious complications like pulmonary edema or urinary retention.⁹ Also, vasoactive drugs can cause tachycardia or bradycardia depending on their pharmacological profile which is deleterious in the elderly. This problem can be effectively prevented by the use of low-dose bupivacaine. The vital finding of the present study was the significantly lower incidence of hypotension and bradycardia in the low-dose bupivacaine-fentanyl group.

Others have also studied the addition of fentanyl to LA to achieve similar results. Akcaboy, Z et al showed that, by using low dose bupivacaine 0.5% (4 mg) with 25 μg fentanyl, an adequate SA with shorter block duration and PACU stay can be obtained than using conventional dose prilocaine 2% (50 mg) with 25 μg fentanyl for TURP surgery. Better hemodynamic stability can also be provided.¹⁰ Prajapati J, used 5 mg intra-thecal bupivacaine with fentanyl 25 μg for spinal anesthesia in TURP surgery which provided adequate anesthesia in elderly patients and was associated with a lower incidence of hypotension and shivering than a conventional dose of bupivacaine. The addition of fentanyl improved the quality of the block, increased the duration of the sensory block, and made the blockade hemodynamically more stable than the conventional dose of bupivacaine.¹¹ Kim et al demonstrated that low-dose diluted bupivacaine with fentanyl 25 μg or sufentanil 5 μg can provide adequate anaesthesia without haemodynamic instability for TURP in elderly patients. However, sufentanil was superior to fentanyl in the quality of the spinal block produced.¹² Ben David et al showed that fentanyl added to bupivacaine did not affect the median block level, but it intensified sensory blockage and increased the duration of sensory blockage.¹³ Many studies have demonstrated that low doses of local anasthetics when supplemented by intrathecal opioids enhance analgesia ^14-16 without sympathetic or motor block.¹⁵

There are concerns regarding the use of opioids in the elderly population especially intrathecally. In the present study, there were no cases of respiratory depression. This finding was previously reported by Varrassi et al who observed that 25 mcg of intrathecal fentanyl during spinal anaesthesia did not alter respiratory parameters such as respiratory rate, minute ventilation, EtCO2, respiratory drive, timing, or the ventilatory response to CO2 when they were non-premedicated.¹⁷ Some studies have reported respiratory depression in the elderly with 25 mcg intrathecally with LA, but those cases were associated with concomitant use of benzodiazepines.¹⁸ Martyr and Clark opined that it was safe to use small doses of intravenous midazolam with intrathecal fentanyl in elderly patients because low-dose fentanyl is unlikely to produce respiratory depression.¹⁹

In our study, intrathecal fentanyl increased the dermatomal spread without affecting motor functions. These results are consistent with those studies in which it has been demonstrated that fentanyl added to a small dose of local anaesthestics improves the quality of block and increased the duration of sensory block [3,10-12]. Other surgeries such as caesarean delivery have been safely done using this combination ²⁰

TURP is one of the most common urological procedures done in the elderly population. Spinal anaesthesia is the anaesthetic technique commonly used. A sensory level of T10 is needed for satisfactory regional anaesthesia for TURP. Low-dose bupivacaine–fentanyl spinal anaesthesia provides an adequate sensory level in patients undergoing TURP. More importantly, this combination maintains haemodynamic stability in elderly patients undergoing TURP.

Low-dose bupivacaine [bupivacaine 5 mg in dextrose8%]with fentanyl 25ug spinal anaesthesia used in TURP decreases the occurrence of hemodynamic instability (hypotension and bradycardia) in elderly patients as compared to conventional doses of bupivacaine. It also provides an adequate sensory block for the procedure. Intrathecal fentanyl helps in dermatomal spread without affecting motor functions.

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