Comparison of Intrathecal Fentanyl and Buprenorphine as an Adjuvant to 0.5% Hyperbaric Bupivacaine for Spinal Anesthesia.

PURPOSE: This study was designed to evaluate and compare three groups, that is, (1) normal saline 0.5 mL with 15 mg of 0.5% hyperbaric bupivacaine normal (BN), (2) intrathecal fentanyl 25 μg (0.5 mL) as an adjuvant to 15 mg of 0.5% hyperbaric bupivacaine fentanyl (BF), and (3), 150 μg buprenorphine with 15 mg of 0.5% hyperbaric bupivacaine buprenorphine (BB) with respect to the onset and duration of sensory and motor spinal block, level of anesthesia, effects on hemodynamic parameters, requirement of postoperative analgesia, and side effects in patients aged 16-60 years undergoing surgical and orthopedic procedures requiring spinal anesthesia.
METHODS: A prospective, observational study was performed at a single center with 90 consecutive patients enrolled as per the inclusion criteria. Patients were divided into three groups of 30 each based on drugs administered, BN, BF, and BB groups, and outcome measures were recorded. The three groups were compared with the analysis of variance test for the continuous variables, with P < 0.05 considered statistically significant.
RESULTS: The groups were similarly matched with respect to age. The earliest onset of sensory block was in the BF group (2.87 min), P < 0.05. Similarly, the mean time to achieve the highest sensory level was least in the BF group (9.63 min), P < 0.05. The onset of motor blockade was earliest in the BB group (7.65 min), P < 0.05. The mean time for two segment regression was maximum in the BB group (126.03 min), P < 0.05. The mean time for regression to L1 was the longest in the BB group (200.83 min), P < 0.05. Maximum duration of analgesia after spinal drug administration was the highest in the BB group (412.17 min), P < 0.05.
CONCLUSION: The addition of both buprenorphine 150 μg and fentanyl 25 μg to 0.5% hyperbaric bupivacaine 15 mg enhances the quality and duration of sensory block for spinal anesthesia providing better postoperative analgesia, while decreasing the incidence of complications associated with each drug alone. Copyright:

INTRODUCTION

Neuraxial administration of opioids in conjunction with local anesthetics improves the quality of intraoperative analgesia and prolongs the duration of postoperative analgesia.

Hunt et al. reported that addition of fentanyl >6.25 μg to hyperbaric bupivacaine reduced intraoperative opioid requirement in patients undergoing cesarean delivery under spinal anesthesia.[1] Belzarena further demonstrated that low dose fentanyl 0.25 μg.kg−1 intrathecally with bupivacaine 0.5% provided excellent surgical anesthesia with few side effects.[2]

This study was designed to evaluate and compare three groups, that is, (1) normal saline 0.5 mL with 15 mg of 0.5% hyperbaric bupivacaine normal (BN), (2) intrathecal fentanyl 25 μg (0.5 mL) as an adjuvant to 15 mg of 0.5% hyperbaric bupivacaine fentanyl (BF), and (3) 150 μg Buprenorphine with 15 mg of 0.5% hyperbaric bupivacaine buprenorphine (BB). The onset and duration of sensory and motor spinal block, level of anesthesia, effects on hemodynamic parameters, requirement of postoperative analgesia, and side effects in patients aged 16–60 years undergoing surgical and orthopedic procedures requiring spinal anesthesia were evaluated and compared.

METHODS

After IRB approval, a prospective, observational study with randomization by the number method was performed at a single center tertiary care academic institution with 90 consecutive patients enrolled as per the inclusion criteria. All patients were undergoing surgical and orthopedic procedures involving the abdomen, pelvis, and lower limbs. Demographics were recorded, and the 90 patients were divided into three groups of 30 each based on drugs administered (3.5 mL):

BN saline (BN) group: 15 mg 0.5% hyperbaric bupivacaine (3 mL) and normal saline (0.5 mL), n = 30

BF group: 15 mg 0.5% hyperbaric bupivacaine (3 mL) and 25 μg fentanyl (0.5 mL), n = 30

BB group: 15 mg 0.5% hyperbaric bupivacaine (3 mL) and 150 μg buprenorphine (0.5 mL), n = 30.

The inclusion criteria were patients undergoing abdominal or lower limb surgeries requiring spinal anesthesia with age between 16 and 30 years, weight >40 kg, height >150 cm, American Society of Anesthesiologists physical status classes I and II with no history of cardiac, liver, neuropsychiatric diseases, or coagulation disorders.

All patients were preloaded with ringer lactate at the rate of 10 mL.kg−1 body weight. Under aseptic precautions, preparation of the back and draping was done and the L3-4 intervertebral space was identified. In the sitting position, lumbar puncture was performed with disposable 25 G spinal needle using the midline approach. Free flow of cerebrospinal fluid was ascertained before injection of the drug at the rate of 0.2 mL.s−1.

Pulse rate and blood pressure were recorded every 5 min for the first ½ h after the administration of the spinal anesthetic drug and thereafter every 10 min intraoperatively and every hour postoperatively until all the signs of spinal anesthesia had regressed. During the surgical procedure, all patients received intravenous (i.v.) fluids as calculated and blood transfusion was given if the tolerable blood loss volume was exceeded.

Time to onset of sensory block assessed by the pinprick method, motor block assessed as per the Bromage scale, highest level of anesthesia achieved and hemodynamic parameters were monitored. Pulse rate <60/min was considered as bradycardia and treated with titrated dosage of injection atropine sulfate 0.6 mg intravenously. 20%–30% fall in baseline systolic blood pressure was considered hypotension and was corrected with i.v. fluids, injection Ephedrine 6–12 mg, iv bolus and oxygen. Total duration of surgery, assessment of two segment regression, regression to L1 level, and total duration of sensory blockade in minutes were recorded.

Patients were observed in the recovery room, and pulse rate, oxygen saturation, and blood pressure were monitored. Duration of analgesia was monitored in minutes.

Appropriate statistical analysis was performed using the SPSS v. 19 software (SSPS Inc., Chicago, IL, USA). Power analysis was done apriori for sample size calculation by keeping the confidence limits at 95% and power of study at 80%, to detect a minimum of 10% difference in degree of sensory/motor blockade between the three groups. The three groups were compared with analysis of variance test for the continuous variables with P < 0.05 considered statistically significant.

RESULTS

Table 1 shows the findings of the three groups with respect to age, onset of sensory block, time to achieve highest level, onset of motor blockade, time for 2 segment regression, time for L1 regression and duration of analgesia. The groups were similarly matched with respect to age. Table 2 shows the sex distribution and types of surgeries In the three groups. There was a statistically significant difference in the three groups with respect to all the other variables as described (P < 0.05). The earliest onset of sensory block was in the BF group (2.87 min), followed by the BB group (3.67 min) and the BN group (5.25 min), P < 0.05. Similarly, the mean time to achieve the highest sensory level was least in the BF group (9.63 min) followed by the BB group (13.45 min) and the BN group (15.4 min), P < 0.05. The onset of motor blockade was earliest in the BB group (7.65 min), followed by the BF group (10.17 min) and the BN group (10.70 min), P < 0.05. The mean time for two segment regression was maximum in the BB group (126.03 min), followed by the BF group (125.57 min) and least in the BN group (89.83 min), P < 0.05. The mean time for regression to L1 was the longest in the BB group (200.83 min), followed by the BF group (192.37 min) and shortest in the BN group (161.0 min), P < 0.05. Maximum duration of analgesia after spinal drug administration was the highest in the BB group (412.17 min) followed by the BF group (283.83 min) and least in the BN group (200.53 min), P < 0.05.

Table 1

Comparison of Results of BN, BF and BB groups

	Bupivacaine + Normal saline (BN)			Fentanyl + Bupivacaine (BF)			Buprenorphine + Bupivacaine (BB)			ANOVA (P value)	BB versus	BF versus
	Mean	SD	SEM	Mean	SD	SEM	Mean	SD	SEM		BN	BN
Age (in years)	36.8	14.5	2.7	35.1	11.5	2.1	36.6	12.1	2.2	0.855	1.000	1.000
Onset of sensory block (in minutes)	5.3	2.1	0.4	2.9	0.8	0.1	3.7	1.5	0.3	0.000	0.001	0.000
Time to achieve highest level (in minutes)	15.4	4.8	0.9	9.6	4.6	0.8	13.5	4.8	0.9	0.000	0.340	0.000
Onset of motor blockade (in minutes)	10.7	3.2	0.6	10.2	2.9	0.5	7.7	2.7	0.5	0.000	0.000	1.000
Time for 2 segment regression (in minutes)	89.8	24.3	4.4	125.6	31.2	5.7	126.0	30.2	5.5	0.000	0.000	0.000
Time for L1 regression (in minutes)	161.0	37.3	6.8	192.4	32.0	5.8	200.8	39.6	7.2	0.000	0.000	0.004
Duration of analgesia (in minutes)	200.5	58.6	10.7	283.8	5.30	9.7	412.2	152.5	27.8	0.000	0.000	0.005

Table 2

Demographic and surgical details in the BN, BF, BB groups

	Group			‘P’ value
	Bupivacaine+NS (BN)	Fentanyl+Bupivacaine (BF)	Buprenorphine+Bupivacaine (BB)
Gender				>0.05
Males	24	22	26
Females	6	8	4
Surgeries				>0.05
Orthopaedic	13	18	18
Abdominal	17	12	12
Mean				>0,05
Duration (minutes)	106	112	115

Tables 3 and 4 shows the changes in blood pressure and pulse rate. Figures 1-3 show the changes in blood pressure, pulse rate and respiratory rate in the three groups. The changes in the first 30 min after drug administration and was not statistically significant (P > 0.05).

Table 3

Systolic BP in the BN, BF and BB group

Systolic blood pressure (mmHg)	Bupivacaine (1)			Fentanyl + Bupivacaine (2)			Buprenorphine + Bupivacaine (3)			ANOVA (P value)	Bupre–norphine + Bupi–vacaine (3)	Fentanyl + Bupi–vacaine (2)
	Mean	SD	SEM	Mean	SD	SEM	Mean	SD	SEM		Bupi–vacaine (1)	Bupi–vacaine (1)
Preop.	130.3	13.3	2.4	117.9	10.2	1.9	122.1	12.6	2.3	0.001	0.030	0.000
0 min.	130.3	13.3	2.4	117.9	10.2	1.9	122.1	12.6	2.3	0.001	0.030	0.000
5 min.	120.0	13.4	2.4	106.5	14.4	2.6	110.9	13.0	2.4	0.001	0.035	0.001
10 min.	113.1	13.0	2.4	102.5	11.3	2.1	104.1	12.8	2.3	0.003	0.019	0.004
15 min.	110.4	14.1	2.6	99.6	10.5	1.9	100.6	11.0	2.0	0.001	0.006	0.002
20 min.	109.5	11.2	2.0	98.3	10.7	2.0	97.3	9.1	1.7	0.000	0.000	0.000
25 min.	107.9	10.4	1.9	97.0	10.2	1.9	99.6	9.8	1.8	0.000	0.007	0.000
30 min.	107.9	10.4	1.9	96.7	9.7	1.8	98.6	9.8	1.8	0.000	0.002	0.000
40 min.	107.5	9.8	1.8	97.7	9.1	1.7	99.0	8.9	1.6	0.000	0.002	0.000
50 min.	108.1	10.1	1.8	99.8	8.7	1.6	98.6	6.6	1.2	0.000	0.000	0.001
60 min.	111.3	9.4	1.7	99.5	6.7	1.2	100.1	8.8	1.6	0.000	0.000	0.000
120 min.	112.3	9.0	1.6	101.8	6.2	1.1	103.2	9.8	1.8	0.000	0.000	0.000

Table 4

Pulse rate in the BN, BF and BB groups

Pulse rate	Bupivacaine (1)			Fentanyl+ Bupivacaine (2)			Buprenorphine+ Bupivacaine (3)			ANOVA (P value)	Bupre–norphine+ Bupi–vacaine (3)	Fentanyl+ Bupi–vacaine (2)
	Mean	SD	SEM	Mean	SD	SEM	Mean	SD	SEM		Bupi–vacaine (1)	Bupi–vacaine (1)
Preop.	83.0	15.2	2.8	79.7	8.4	1.5	82.8	13.5	2.5	0.545	1.000	0.980
0 min.	83.0	15.2	2.8	79.7	8.4	1.5	82.5	13.5	2.5	0.568	1.000	0.979
5 min.	79.0	15.6	2.8	77.6	9.5	1.7	79.7	12.9	2.3	0.824	1.000	1.000
10 min.	78.4	17.5	3.2	75.7	10.3	1.9	77.6	11.4	2.1	0.725	1.000	1.000
15 min.	78.8	13.7	2.5	75.3	10.8	2.0	75.0	10.6	1.9	0.380	0.635	0.748
20 min.	76.5	12.1	2.2	74.6	13.0	2.4	75.1	9.6	1.7	0.796	1.000	1.000
25 min.	75.4	11.8	2.1	73.0	12.2	2.2	73.8	9.6	1.7	0.710	1.000	1.000
30 min.	75.5	10.0	1.8	72.7	13.3	2.4	72.6	9.2	1.7	0.499	0.909	0.942
40 min.	75.1	8.1	1.5	72.3	12.4	2.3	72.0	7.4	1.4	0.389	0.641	0.783
50 min.	75.5	9.2	1.7	73.1	8.3	1.5	72.5	7.4	1.4	0.350	0.515	0.824
60 min.	74.8	8.8	1.6	74.9	9.6	1.8	72.9	6.9	1.3	0.589	1.000	1.000
120 min.	76.5	10.2	1.9	75.3	8.3	1.5	71.5	13.1	2.4	0.172	0.222	1.000

Figure 1

Changes in blood pressure

Figure 3

Changes in respiration rate

Changes in pulse rate

Complications are summarized in Table 5. Five patients in the BB group and two patients in the BF group complained of nausea. One patient in the BN group had inadequate analgesia and required rescue analgesia, while two patients in the BF group had the same complication. Hypotension was observed in one patient requiring the administration of injection ephedrine and bradycardia was observed in three patients requiring injection atropine 0.6 mg in the BN group.

Table 5

Complications

Complication	Group
	Bupivacaine	Fentanyl+Bupivacaine	Buprenorphine+Bupivacaine
Nausea	0	2	5
Hypotension	1	0	0
Bradycardia	3	2	0
Inadequate Analgesia	1	2	0
Pruritis	0	0	0
Sedation	0	0	0

DISCUSSION

Pharmacokinetics of the three drugs are summarized in Table 6. Previous studies have shown that addition of adjuvant intrathecal opioids prolongs the duration of analgesia and may potentiate the effects of local anesthetics.[123456] Furthermore, the dose of intrathecal opioid required, is small thereby giving the ideal state of analgesia and freedom from side effects. The concomitant use of buprenorphine or fentanyl along with the local anesthetics puts the patient in an established state of analgesia by the time the spinal anesthetic wears off. The present study was conducted in 90 patients posted for various lower abdominal and limb surgeries to compare the onset of sensory and motor block, sensory and motor characteristics of the block, duration of postoperative analgesia, and hemodynamic effects of both the drugs. These timings were statistically significant showing that addition of Fentanyl (25 μg) to 15 mg of bupivacaine (BF) hastened the onset of sensory block considerably followed by the addition of buprenorphine to bupivacaine (BB), whereas only Bupivacaine with NS (BN) took maximum time for the onset of sensory block. Studies conducted by Khanna et al. using different doses of Fentanyl intrathecally found no significant difference in the onset of sensory blockade.[3] Techanivate et al. in their study used 25 μg fentanyl with 3 mL 0.5% hyperbaric Bupivacaine and concluded that the onset of sensory block was early compared with control group (3 mL 0.5% hyperbaric bupivacaine) and the time taken to reach maximum level was also less in the fentanyl group.[4] Singh et al. in their study added 25 μg Fentanyl to 13.5 mg hyperbaric bupivacaine 0.75% and found that intrathecal fentanyl did not change the onset of sensory or motor block, or prolong the duration of bupivacaine-induced motor spinal block.[5]

Table 6

Drug pharmacokinetics

Drug	Pharmacokinetics
Fentanyl	The effect site equilibrium time between blood and brain for fentanyl is 6.4 minutes Fentanyl is highly lipophilic. Plasma protein binding of fentanyl is 80-85%. It is metabolised in the liver and intestinal mucosa to norfentanyl by cytochrome P450 34A isoform. It is excreted by the kidneys and can be detected in the urine for 72 hours after a single intravenous dose. Fentanyl is primarily eliminated by biotransformation to N–dealkylated and hydroxylated inactive metabolites. Less than 7% of the dose is excreted unchanged in the urine and only 1% is excreted unchanged in the faeces. Total plasma clearance of fentanyl is 0.5 l/hr/kg
Buprenorphine hydrochloride	Buprenorphine displays both agonist–antagonist properties and it appears to be partial agonist of the mu receptor. It is also an antagonist of the kappa receptor. Buprenorphine is highly lipophilic in nature and administration by even intrathecal route is followed by rapid transfer across the cell membrane thus producing plasma levels equal to that following intramuscular injection. In keeping with its lipid solubility, buprenorphine apparently crosses all biological membranes, including blood brain and placental barrier
Bupivacaine hydrochloride	It is a local anaesthetic agent with long duration of action. Bupivacaine is highly protein bound (96%) hence has a long duration of action. It is metabolized by the liver and excreted by the kidney.

In the present study, the mean time taken to achieve highest level was least in the BF group, maximum in the BN group and intermediate in the BB group. Khan compared intrathecal fentanyl with intrathecal buprenorphine 30 μg and found that there was no significant difference in the onset of sensory block and also concluded that the mean time for the block to reach maximum level was less in the fentanyl group than the buprenorphine group.[6]

In the present study, the time taken for two segment regression and L1 regression in BB group was the longest, intermediate in the BF group and least in the BN group. This shows that there is a prolongation in the duration of bupivacaine-induced sensory blockade. This suggests a potential synergism between fentanyl and bupivacaine and also buprenorphine and bupivacaine. Wang, et al. in their animal study showed analgesic synergism between intrathecal opioids and local anesthetics.[7] Singh, et al. used 25 μg fentanyl added to bupivacaine (2 mL) and found that the duration of two segment sensory block regression and regression to L1 dermatomes were prolonged.[5] According to Khan and Hamdani, intrathecal buprenorphine prolongs sensory block, and 35% of patients showed regression to L1 after 3 h of subarachnoid injection.[6]

Our study showed the mean time for onset of motor block was least in BB group as compared to BF and BN group, which was statistically significant. Wang et al. found experimentally that opioids and local anesthetics showed analgesic synergism in sensory and motor nociception while antinociception did not affect motor functions.[7] Singh et al. showed that intrathecal fentanyl does not have any effect on onset and duration of motor block, but in this study, the concentration of bupivacaine used was 0.75%.[5] Lipp et al. also reported the same findings using 0.15 mg of Buprenorphine with Bupivacaine.[8]

The common cardiovascular changes noted during spinal anesthesia are hypotension and bradycardia. Higher level of sympathetic blockade causes blockade of cardio acceleration fibers leading to bradycardia and causes peripheral vasodilatation leading to hypotension. In our study, a fall in systolic blood pressure was observed for all the three groups following subarachnoid block. The fall shows maximum drop of blood pressure in the BB group followed by BF and then BN group. A fall in pulse rate was also observed in all three groups, but the fall was only slightly different from each other and statistically not significant. Hoda et al. used three different does of (10 mg, 8 mg, and 6 mg) spinal bupivacaine in combination with or without Fentanyl for surgical repair of hip fracture.[9] They found that intraoperative heart rate was statistically insignificant in all three groups, but drop in systolic blood pressure between groups (with Fentanyl and without Fentanyl) was statistically significant. Sivevski showed in his study that bupivacaine 9 mg plus Fentanyl 20 μg provided spinal anesthesia for cesarean delivery with less hypotension and vasopressor requirements while ensuring excellent perioperative surgical anesthesia.[10] According to Randall et al., the frequency of hypotension did not change significantly with addition of Fentanyl, although it has also been reported that neuraxial administration of Fentanyl with local anesthetics can lead to increased incidence of hypotension.[11]

No incidence of respiratory depression was noted in our study, saturation was maintained around 96%–98% in all the three groups for a period of 24 h. Arai et al. showed that addition of intrathecal Fentanyl to hyperbaric Bupivacaine did not lead to a deterioration in maternal spirometric respiratory function in parturients undergoing cesarean section.[12]

The mean total duration of analgesia was maximum in the BB group followed by BF and least in BN group. Opioids and local anesthetics exert their anti-nociceptive effect in the spinal cord by different mechanisms. Action of Fentanyl is brief as it is rapidly cleared from spinal sites. Buprenorphine which is an agonist–antagonist is a lipid-soluble drug and rapid absorption into spinal venous plexus allows minimal increase in spinal fluid concentration. It has high affinity for narcotic receptors and therefore produces longer duration analgesia compared to other agents. Sen compared 300 μg of Buprenorphine as an adjuvant to hyperbaric Bupivacaine with only hyperbaric Bupivacaine and found prolonged postoperative analgesia, minimal disturbance of consciousness, and respiration in the buprenorphine group.[13] Capogna, et al. also used Buprenorphine 0.03 mg and 0.045 mg as adjuvant to Bupivacaine and concluded that the group receiving Buprenorphine showed prolonged postoperative analgesia with minimal disturbance of consciousness and comfortable breathing.[14] Randall, et al. used 10 μg Fentanyl with Bupivacaine and found that analgesia lasted 201 min.[11] Singh et al. used 25 μg Fentanyl with 2–5 mL Bupivacaine and reported that the patients were pain–free for 3 h.[5] Technovate et al. used 20 μg of fentanyl with 4 mL of 0.5% heavy Bupivacaine and postulated that analgesia lasted for 13 h.[4]

Few complications were observed in all 3 groups. Hunt et al. reported that the frequency of itching was increased by 80% with 50 μg fentanyl.[1] Sen reported that 10 patients had nausea and vomiting after administering 300 μg buprenorphine intrathecally.[13] Capogna et al. also had similar findings in their study.[14] Spinal anesthesia using a local anesthetic with Fentanyl has been reported to induce sedation. Kushida et al. have shown that bispectral index value was significantly decreased only by intrathecal fentanyl for cesarean section.[15] Furthermore, Techanivate et al. showed that addition of 20 mcg Fentanyl in 2.2 mL of 0.5% hyperbaric Bupivacaine with 0.2 mL morphine can reduce the incidence and severity of intraoperative and postoperative shivering after spinal anesthesia for patients undergoing cesarean section without increasing other side effects.[16]

Opioids are still currently being used as adjuvants to intrathecal blocks as side effects are minimal, and they can be safely used in the elderly as well as pregnant patients and ease of availability makes them a practical choice.[1718192021222324252627] Previous systematic reviews have evaluated the safety and efficacy of intrathecal opioids (Fentanyl) as adjuvants for spinal anesthesia.[171819] A study conducted by Wang and et al. on the effects of intrathecal bupivacaine and bupivacaine plus fentanyl in elderly patients undergoing total hip arthroplasty showed that although the quality of anesthesia was the same, the fentanyl group showed less use of ephedrine for stable hemodynamics and a longer duration for postoperative analgesic use.[19] Ravindran et al. studied two doses of intrathecal buprenorphine as an adjuvant to 0.5% hyperbaric bupivacaine for cesarean sections and concluded that the addition of 60 mcg provided longer duration of postoperative analgesia as compared to 45 mcg and reported no side effects on mother as well as fetus.[20] Rabiee et al. showed that use of intrathecal buprenorphine for cesarean sections prolonged duration of anesthesia and analgesia without any significant side effects on the mother as well as fetus.[21] Gupta et al. compared the effects of intrathecal dexmedetomidine with buprenorphine as adjuvant to bupivacaine in spinal anesthesia and found that intrathecal dexmedetomidine as compared to intrathecal buporenorphine causes prolonged anesthesia and analgesia with reduced need for sedation and rescue analgesics.[22] However, Dexmedetomidine was not as easily and universally available as compared to opioids at the time of the study. A comparative evaluation of anesthetic efficacy and hemodynamic effects of a combination of isobaric bupivacaine with buprenorphine versus isobaric levobupivacaine with buprenorphine for spinal anaesthesia by Ture et al. showed that the onset of sensory block was similar between both the groups.[23] Arora et al. compared the effects of intrathecal clonidine–bupivacaine, buprenorphine-bupivacaine, and bupivacaine alone and concluded that addition of buprenorphine as well as clonidine intrathecally potentiates duration of analgesia, sensory and motor block with buprenorphine having a long-lasting effect.[24] Singh et al. had compared the effects of intrathecal buprenorphine versus fentanyl as adjuvants to 0.75% Ropivacaine on the duration of spinal anesthesia. The study revealed that although the duration of motor block was the same, the duration of sensory block was prolonged and time to first analgesic dose was also prolonged. There were no adverse hemodynamic parameters or side effects as compared to the control group.[26] Gupta et al. had studied the effects of adding intrathecal fentanyl as an adjuvant to 0.75% isobaric ropivacaine for infraumbilical surgery under sub-arachnoid block. They found that the addition of fentanyl not only accelerated onset of sensory block but also prolonged the duration of analgesia.[27]

The limitations of this study are the heterogeneity of the surgical and orthopedic procedures and the lack of blinding of the observer. A further, larger, prospective-blinded study would be helpful.

CONCLUSION

In conclusion, the addition of both Buprenorphine 150 μg and Fentanyl 25 μg to 0.5% hyperbaric Bupivacaine 15 mg enhance the quality and duration of sensory block for spinal anesthesia providing better postoperative analgesia, while decreasing the incidence of complications associated with each drug alone. Intrathecal Fentanyl 25 μg with 0.5% Bupivacaine 15 mg combination provide rapid onset of sensory analgesia, but prolonged postoperative analgesia is provided by Buprenorphine 150 μg with Bupivacaine 15 mg combination. A larger prospective, randomized blinded study of patients undergoing a similar surgery would be helpful to further evaluate this topic.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.