Perineural versus intravenous clonidine as an adjuvant to Bupivacaine in supraclavicular Brachial plexus block

Abstract

Background: Clonidine has been used as an adjuvant in Brachial plexus block (BPB) to enhance its quality and duration. However, whether, clonidine in BPB acts perineurally or via systemic absorption is not entirely clear. Methods: Ninety-three patients of either sex, ASA I and II, aged 18-70 years, undergoing lower end humerus fracture fixation were included in the study. Patients were randomized into 3 groups. All the patients received brachial plexus block using nerve stimulator with 28 ml 0.5% Bupivacaine and 2 ml of NS/NS with clonidine. In the first group (Bc) 2 mcg/kg of clonidine was added to the anaesthesia solution and 10 ml of NS was injected intravenously; second group (Bivc) received clonidine 2 mcg/kg diluted up to 10 ml by intravenous route with 28 ml of 0.5% Bupivacaine and 2 ml of NS in the block; third group (B) received 28 ml of 0.5% Bupivacaine with 2 ml of NS in the block and 10 ml of NS intravenously, as placebo. Onset and duration of sensorimotor block, hemodynamic variables, duration of analgesia, level of sedation and adverse effects were noted. Results: Onset of sensory blockade was faster in group Bc (7 ± 0.720 min) compared to group B (11.46 ± 1.138 min) and Bivc (11.46 ± 1.170 min) (p < 0.001). Onset of motor block was faster in group Bc (16.43 ± 1.136 min) compared to group B (22.75 ± 1.456 min) and Bivc (22.25 ± 1.295 min) (p < 0.001). The mean durations of analgesia were recorded as 1160.71 ± 53.259 min in group Bc, 454.64 ± 14.07 min in Group Bivc and 442.50 ± 18.634 min in group B. Conclusion: Addition of clonidine 2mcg/kg to 28 ml of 0.5% bupivacaine in brachial plexus blocks results in a faster onset, increased duration of block and longer postoperative pain relief when compared to bupivacaine alone. These advantages are not observed when the same dose of clonidine is injected intravenously.

A prospective, randomized, double blind, systemic controlled trial to compare analgesic efficacy of clonidine and fentanyl in supraclavicular block with 0.75% ropivacaine

“…The results of the present study are similar to those reported earlier studies by Baj et al (2013), 3 Ahmed NU et al (2011), 10 Kohli et al (2013), 11 Jaiswal et al (2013) 12 V. Bedi et al (2017) 9 who found that the significant prolongation of mean total duration of sensory and motor block occured in which clonidine given perineurally. Time to first rescue analgesia (duration of analgesia) Mean duration of analgesia was longest in perineural clonidine group C (8.12±1.22 hrs) in comparison to group A (statistically significant p value 0.001) and it might be due to that clonidine enhance sensory and motor nerve blockade by three possible mechanism: (1) clonidine block conduction of C and A delta fibers and increase potassium conductance and intensifies conduction block of local anaesthetics, (2) clonidine may cause local vasoconstriction thereby reducing vascular removal of local anaesthetic surrounding neural structures, and (3) primary spinal site of action of alpha 2 adrenergic agonist for analgesia and a mutifactorial mechanism of action enhancing peripheral or intraspinal blockade from local anaesthetics.…”

“…Our findings corroborate by Singelyn et al (1992) 17 and V. Bedi et al (2017). 9 Mean VAS Score in present study remained less than 4 throughout the study period showing adequate postoperative analgesia in the all the four groups. Overall value of mean VAS score was significantly more in group A (1.88±0.13) as compared to group C (1.33±0.22).…”

“…These result also supported by a study done by Bedi et al (2017). 9 The duration of sensory and motor blockade was highest in perineural clonidine group C (7.41±1.00 and 6.79±0.86 hrs respectively) as compared to perineural fentanyl group A (6.19±1.22 and 6.21±0.53 hrs respectively), and it was statistically significant (p = 0.003 and p<0.0474).…”

“…13 Our findings correlated with those of Kulkarni et al (2012) 14 and El Saied et al (2000), 15 Bedi et al (2017). 9 When compared, duration of analgesia of Group A (7.41±1.00 hrs) from Group B (7.35±0.93 hrs), it was found that there was statistically insignificant difference between these groups (p>0.05). it might be due to mechanism of action of fentanyl both on peripheral nerves and dorsal nerve root when it is administered as an adjuvents (fentanyl may diffuse through brachial plexus sheath to extradural or subarachnoid space to dorsal horn) and central action on dorsal horn when administered systemically.…”

Alpha2‐receptor agonists as adjuvants for brachial plexus nerve blocks—A systematic review with meta‐analyses

“…Thirty-three trials compared clonidine in doses of 30-180 µg with placebo in 1975 patients, 12−44 three of the trials included a systemic clonidine group. 14,21,39 Fifty-six trials compared dexmedetomidine in doses of 30-100 µg with placebo in 3243 patients, 5,31,42,45−94 six of the 53 trials included a systemic dexmedetomidine group. 45,[63][64][65]78,80 Nineteen trials compared dexmedetomidine with clonidine in 1130 patients.…”