European Journal of Cardiovascular Medicine

Brachial plexus block provides a useful alternative to general anesthesia for upper limb surgery. It provides complete muscle relaxation, stable hemodynamics. Brachial plexus blockage eliminates requirement for intraoperative opioids and reduces the need for postoperative opioids, offering better pain control. This leads to improved patient & surgeon satisfaction, quicker recovery and shorter hospital stay.

Axillary block, Supraclavicular block, Infraclavicular block, Interscalene block are some of brachial plexus block. The most popular method for administrating brachial plexus block is the Supraclavicular technique. It is ‘Spinal of the arm’. It delivers dense block distal to elbow, easier to implement with good quality and higher success rate because availability of variety of tools such as nerve stimulator, ultrasound technology. (1)

For brachial plexus block, various local anesthetics are used singly or in combination with adjuvants. Use of adjuvants along with local anesthetics result in early onset of action, decrease risk of LA toxicity and longer duration of blockage.

Dexmedetomidine is a highly selective α2 adrenoreceptor agonist with sympatholytic, sedative, hypnotic, anxiolytic, analgesic, anti-shivering, cardio-respiratory stability and neuroprotective properties through inhibition of neurotransmitter release.(2)  Research on supraclavicular brachial plexus block found that Dexmedetomidine considerably reduces the time it take for sensory and motor block onset and lengthens duration of both sensory and motor blockage. (3)

According to Rajkhowa T et al. (2016), opioids like Fentanyl mainly act at the central and/or spinal levels by activating mu receptors. Fentanyl is known to act as an adjuvant to prolong the action of local anesthetics. (4)

Very few studies are available who compare effect of Dexmedetomidine and Fentanyl as an adjuvant with Lignocaine and Bupivacaine combination using Peripheral nerve stimulator for supraclavicular block. Comparison of newer adjuvant Dexmedetomidine and time-tested Fentanyl, mixture of local anesthetics, that makes our study unique.

In a tertiary medical college and hospital, this cross sectional and observational comparative study was conducted on 80 patients who were having elective forearm orthopedic surgeries with ASA 1 & 2, age 18-45 years, BMI <25, surgical duration of 2 hours and who have given written informed consent. Patients with pediatric and geriatric (<18 years and >45 years), high risk category (ASA 3,4,5), history of allergy to local anesthetic or any other drugs, coagulopathy, systemic diseases, pregnant females or poly trauma patients were excluded.

After obtaining permission from Institutional Ethical committee of the GMERS medical college and hospital, Dharpur, patan, Gujarat, 80 patients were randomly allocated to two groups by computer based random method. After pre-operative anesthesia checkup, all routine baseline investigations (like CBC, urea, creatinine, blood sugar, blood group, ECG, CXR) were done. On the day of surgery, after proper explanation of study protocol to patients, basic monitors like ECG, NIBP, Spo2 were attached. Pre medication done with inj.glycopyrollate 4-8 µg/kg iv. Inj.ondasatron 4mg iv.

Supraclavicular block was performed using classic approach. The point of needle entry was about 1inch lateral to insertion of lateral head of Sternocleidomastoid. Palpating the subclavian artery at the site confirms landmark. After local infiltration of 1 ml of 1% lignocaine, nerve stimulation was started using insulating needle with intensity of 20 mA and pulse width of 100 microseconds. The needle is inserted at 300 caudally to anteroposterior plane, then posteriorly and laterally. The goal was to bring the tip of needle in proximity of the lower trunk which is manifested by a twitch of fingers at 0.5 mA current strength.

After negative aspiration of blood, drug injected according to 2 groups.

Group D: Inj. Lignocaine 2% 10 ml + Inj. Bupivacaine 0.5% 20 ml + Inj. Dexmedetomidine 1 µg/kg

Group F: Inj. Lignocaine 2% 10 ml +Inj. Bupivacaine 0.5% 20 ml + Inj. Fentanyl 1 µg/kg

Monitoring Parameters:

Following Parameters were observed and recorded at 0min, 5min, 10min, 15min, 30 min, 1hr, 1.5 hr, 2hr. 4hr, 6hr, 8hr, 10hr, 12hr

1> Sensory block- onset and duration

2>Motor block-onset and duration

3>Hemodynamic Parameters- Heart rate, Systolic blood Pressure, Diastolic Blood Pressure

4>Respiratory Parameters- Respiratory rate, SpO2

5> Sedation score- As per modified Ramsay Sedation Score

6>Intra/postoperative complication- like Bradycardia/ Tachycardia, Hypotension/Hypertension, Nausea/vomiting, Respiratory depression, pruritus

7>Rescue Analgesia – it was given with inj.diclofenac sodium 75mg iv when Visual analogue score was >= 4.

Table1: Demographic data

This table shows demographic data of both groups. Both groups are comparable in respect of age, weight, gender (unintentionally male predominance) and ASA grade. There was no statistically significant difference. (p > 0.05).

Table 2: Onset of Sensory block and motor block (Mean ± SD)

Table 3: Duration of sensory and motor block (Mean ± SD)

Table 4: Rescue Analgesia (Mean ± SD)

As per Table 4, the mean time of requirement of Rescue Analgesia in group D was longer compared to Group F which was statistically significant difference.

Table 5: Complications / adverse effects

1> Demographic Data

In this study, we have included individuals between age of 18 to 45 with ASA 1 &2 . Gender is comparable in both groups with unintentional male dominance. Demographic parameters in terms of age, weight and ASA grading were comparable and not significant difference.

2> Type of anesthesia and surgery

In this study, we have used classic approach of supraclavicular block using nerve stimulator for forearm surgery. Peripheral nerve stimulator allows better localization of brachial plexus compared to landmark guided technique. Though use of ultrasonography to localize brachial plexus has revolutionized the field of regional anesthesia, above facility was not available at our department, so we have used PNS.

Swaro et al,(5), Farooq et al.(6) utilized same technique  for supraclavicular block using PNS.

3>Combination of Lignocaine and Bupivacaine

Our study is mainly emphasis on adjuvants effects, therefore we have used time tested and proven Lignocaine and Bupivacaine combination. Almasi R et al. (6), Mustafa A et al. (7) also used Lignocaine and Bupivacaine combination in supraclavicular block in forearm surgeries and concluded that early onset was achieved by Lignocaine and long duration is benefited by Bupivacaine.

4> Dose of Dexmedetomidine and Fentanyl

Antinociception effect of Dexmedetomidine is provided by peripheral α receptors. The inhibitory action of α2 receptor agonist is expressed by hyperpolarization of cell membrane which keeps the nerve from returning from a hyperpolarized state to resting membrane potential for recurrent firing, is responsible for the longer analgesic action of peripheral perineural Dexmedetomidine (3)(9).

 Fentanyl can directly bind to opioid binding sites on primary afferent tissue (dorsal roots). It can diffuse from brachial plexus sheath to opioid receptors of epidural and subarachnoid space. Thirdly, it can also potentiate local anesthetic action via peripheral uptake.

Sawaro et al. (5) studied effect Fentanyl and Dexmedetomidine in supraclavicular block. They used Fentanyl 50 μg, Dexmedetomidine 50 μg along with Bupivacaine 30ml. The characteristics for anaesthesia and analgesia were assessed in both groups. Gandhi et al. (10) and Kathuria et al. (3) that used Dexmedetomidine at doses ranging from 30 to 50 μg and found similar effects.

5> Characteristic of Block

Onset of sensory block and motor block were significantly faster in group D than in group F. Duration of sensory block and motor block were higher in group D as compared to group F.

Ø  in our study, duration of rescue analgesia was longer in group D (713.2 ± 37.53 minutes) as compared to group F (9.18 ± 0.72 minutes, p < 0.001).

Swaro et al. (5)    also concluded the similar results. Agrawal et al. (11) studied effect of 30 ml bupivacaine with 100 µg dexmedetomidine and found similar results.

6> Hemodynamic Parameters

In present study, Heart Rate, Systolic Blood Pressure, Diastolic Blood Pressure were all maintained in both groups except bradycardia was found in 11 patients in Group D intraoperatively during1-1.5 hours.

Agrawal et al. (11)      studied that bradycardia and hypotension are reflex response to transient hypertensive response and it is due to postsynaptic activation of α2 receptors that inhibits sympathetic response.

7> Respiratory Parameters

At this much dose, no episode of respiratory depression or hypoxemia was observed in any patients intraoperatively or 24 hours post operatively.

8> Sedation

In our study, Group D had a higher sedation score compared to Group F.13 patients in Group D were found to have a sedation score of 3. This outcome coincided with study of Bajwa et al. (12), , Gupta K et al. (13). Major sedative and antinociceptive effects of Dexmedetomidine are attributable to its stimulation of the α2 adrenoceptors in the locus coeruleus. Dexmedetomidine has peculiar property of “arousable sedation” that is effective to prevent respiratory depression, hypoxia and hypoventilation (14).

9> Complications

In our study, Bradycardia which was noted between 1-1.5 hours intraoperatively in Group D, which was asymptomatic. In Group F, Nausea/Vomiting and Pruitus were noted in 1 patient each. Nausea/Vomiting was treated with inj.ondansatron 4mg iv. Pruitus was treated with reassurance and inj.chlorpheniramine

In this study, an attempt was made to compare the two drugs as adjuvants -

Dexmedetomidine & Fentanyl via Supraclavicular block for forearm surgeries.

Thus, Dexmedetomidine shortens the onset time and prolongs the duration of sensory & motor block with stable cardiorespiratory parameters as well as provides better post-operative analgesia without any significant side effects, which all contribute to excellent quality of block as compared with Fentanyl when used as an adjuvant to Lignocaine and Bupivacaine combination in supraclavicular brachial plexus block.

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