Brachial plexus block allows patients to remain conscious and mobile during surgery, significantly reducing the risk of aspiration in full-stomach cases compared to general anaesthesia. It also minimizes common adverse effects like postoperative nausea, vomiting, pulmonary complications (e.g., atelectasis), hypotension, ileus, and deep vein thrombosis. ^[1–4] This technique is particularly beneficial for patients with cardiopulmonary disease, diabetes, or chronic illnesses due to minimal hemodynamic disturbance and reduced surgical stress.

Peripheral nerve blocks, including brachial plexus block, offer sympathetic blockade, improving regional blood flow, reducing vasospasm, edema, tissue hypoxia, and enhancing pain control—especially useful in hand and reconstructive surgeries.

Several approaches target the brachial plexus at various anatomical levels, including interscalene, parascalene, subclavian perivascular, supraclavicular, infraclavicular, and axillary. ^[5] The supraclavicular and subclavian approaches provide more complete blockade, while axillary may spare the shoulder and interscalene may miss the ulnar distribution. ^[6] The supraclavicular route is particularly effective, offering a dense, predictable block at the trunk level—ideal for upper limb surgeries.

While local anaesthetics remain foundational, concerns over toxicity and limited duration have prompted the use of adjuvants. Bupivacaine-lignocaine combinations are commonly used for their rapid onset and prolonged action (3–8 hours). ^[7] Adjuvants like epinephrine, midazolam, neostigmine, hyaluronidase, ketamine, and bicarbonate have been studied, though often limited by side effects or inconsistent outcomes. ^[8–10] Opioids such as fentanyl and α2-agonists like clonidine have shown more promise by enhancing block quality and duration, while reducing the required anaesthetic dose and associated toxicity. ^[11,12]

The present study aims to evaluate and compare the efficacy of fentanyl and clonidine as adjuvants to a standard combination of bupivacaine and lignocaine in supraclavicular brachial plexus block. The primary focus is to assess improvements in block quality, duration of analgesia, and overall anaesthetic efficiency.

The study was conducted in the Department of Anesthesiology, S.M.S Medical College, Jaipur. This randomized double-blind controlled study included 135 Patients (age 20-50 years) undergoing elective surgery of upper limb. Due permission from the institutional ethical committee and review board and written informed consent of patient had been obtained.

Study design- A Prospective, Randomized, Double Blind Hospital based Controlled study.

Sample Size-45 patients in each group.

Inclusion Criteria: 1) Patients of either sex 2) Age group between 20 and 50 years 3) Body weight 50 to 70 kg. 4) Patients belonging to ASA class-I and II 5) Patients undergoing elective surgical procedure on upper limb of duration 1-4 hrs.

Exclusion Criteria: 1) Patients not willing to participate in the study.2) Uncooperative patients.3) Local pathology at the site of injection or disability limiting the performance of block. 4) History of convulsion, allergy to the drugs used, bleeding disorder, severe neurological deficit. 5) Patient with history of respiratory, cardiac, hepatic or renal disease (necessitating classification in ASA Class III or above). 6) Inadequate block necessitating institution of general anaesthesia for continuation of surgical procedure.

Pre anaesthetic check-up was done a day before the surgery that included. 1)  Complete history of patient including any known drug allergy. 2)  General and systemic examination and local examination of supraclavicular area was done. 3)  Pulse rate, blood pressure, respiratory rate and weight of the patient were noted.

Investigations: Hematological – Hb%, TLC, DLC, BT,CT, Fasting / Random blood sugar,Blood Urea, Serum Creatinine, Chest X ray, ECG.Informed consent was obtained for performance of block after complete explanation about the study protocol and the procedure.The patients were randomly allocated into one of the three predefined groups by chit in box method. The medications were prepared by another person so that patient and the person administering the block and doing the evaluation were blinded.

Group I (n= 45) received Bupivacaine 0.5% 10ml + Lignocaine 2% 6ml.,

Group II (n= 45) received Bupivacaine 0.5% 10ml + Lignocaine 2% 6ml + Fentanyl 50 mcg.,

Group III (n= 45) received Bupivacaine 0.5% 10ml + Lignocaine 2% 4ml + Clonidine 75 mcg. Total volume in all the groups was made upto 30 ml with normal saline.

PROCEDURE: Fasting status, consent, PAC were checked, and intravenous access secured. Patients did not receive any premedication. The patient was placed in the supine position a wedge was placed below shoulders, with the head turned away and the ipsilateral arm adducted. The landmarks interscalene groove, mid-point of the clavicle and subclavian artery were identified. The area was painted with povidone iodine 10%, under all aseptic precautions a skin wheal was raised with a local anaesthetic (Inj. Lignocaine2%) 1.5 to 2.0 cm posterior to midpoint of the clavicle with 23G hypodermic needle. Next, a 22G, 50 mm needle was passed through the same point in a caudal, slightly medial and posterior direction, until either a paresthesia was elicited or the first rib was encountered. If the first rib was encountered, the needle was walked over the first rib until a paresthesia was elicited either in the hand or arm. After eliciting paresthesia and negative aspiration for blood, one millilitre of the test solution was injected to test for inadvertent intravascular placement of the needle. All subjects were observed for possible intravascular placement for approximately 1 minute following the injection of the test solution, and then the remaining 29 mL of the anaesthetic was administered in 5-mL increments following repeated aspiration. After performance of nerve block patients were evaluated for onset of sensory block every 1 minute. The sensory block was assessed by pin prick with 25 gauge hypodermic needle. The sensory onset was defined as the loss of pain to pin prick in skin dermatomes C4-T2. Motor blockade was checked by Modified Bromage scale. The sensory blockade and motor blockade were checked every minute till the block was established. The onset times of sensory and motor block were noted. Heart rate, non-invasive blood pressure and SPO₂ were measured every 5 minutes for first 15 minute and thereafter every 15 minutes.

Postoperatively heart rate, noninvasive blood pressure, VAS and Bromage Score were recorded at 0 min, 30 min, 1 hr, 3 hr, 6 hr, 12 hr, 18 hr and 24 hr.             Rescue analgesic (Inj Tramadol 100mg IV) was administered at VAS score > 4 and the time was noted.

Time of return of complete motor power was recorded.

Analysis of data–Data was analyzed using unpaired student “t” test for data on ratio and interval scale whereas data on ordinal and nominal scales were compared using Mann Whitney’s U test and Chi Square test respectively. A “p” value of less than 0.05 was considered significant.           End point of study – Compete recovery of motor and sensory block.

DRUGS AND EQUIPMENT:

Weighing machine,Sphygmomanometer to monitor blood pressure, ECG monitor and electrods, pulse oximeter,IV cannula, IV infusion sets and IV fluids (Ringer lactate).Pair of sterile gloves, Betadine, sponge holding forceps, sterile gauze pieces, sterile sheets, sterile gown,Disposable syringe of 20cc, 10cc and 2cc each,23 gauge needle for local infiltration, A 22 gauge 2 inch needle for performing Supraclavicular brachial plexus block,A 25 gauge sterile needle for testing pin prick,Anaesthesia work station, laryngoscopes, cuffed Endotracheal tubes (size 7 to 8.5), suction apparatus, suction catheter 14 and 16 FG, defibrillator etc.

Emergency drugs: Atropine, Adrenaline, Dopamine, Dobutamine, Isoprenaline, Hydrocortisone, Dexamethasone, Sodium bicarbonate, Calcium-gluconate, Potassium-chloride, Xylocard, Digoxin, Nitroglycerine, Deriphylline, Avil, Furosemide, Ranitidine, Metoclopramide, Phenytoin, Diazepam, midazolam, intralipid 20%.

Study drugs: Inj. Bupivacaine 0.5%, Inj. Lignocaine 2%,Inj. Fentanyl , Inj. Clonidine

SENSORY BLOCK: 0 –No block,1 –Partial block (Touch sensation only).,2 –Compete block (Not even touch sensation).

MOTOR BLOCK: (modified Bromage scale) : 0 - Able to raise the extended arm to 90° for a full 2 seconds,1- Able to flex the elbow and move the fingers but unable to raise the  extended arm,2 - Unable to flex the elbow but able to move the fingers; and 3 - Unable to move the arm, elbow, or fingers.

VISUAL ANALOGUE SCORE: Scale for grading severity of pain. Graded from 0 -10. 0 being no pain at all and 10 being worst pain imaginable.

SEDATION SCORE

1- Awake and alert, 2- Sedated, responding to verbal stimulus ,3- Sedated, responding to mild physical stimulus,4- Sedated, responding to moderate or severe physical stimulus,5- not arousable.

Table-1 shows the mean age (years), mean body weight (Kgs), sex ratio, baseline Clinical Variables & mean duration of surgery in the three groups.  These parameters were comparable in all the groups and no statistical difference was observed.(P>0.05)

Table-1:  Clinico-demographic Profile

As showing in table-2, the mean onset of sensory block for Group I was 4.44±1.235 (min) for Group II was 3.69±1.104 (min) and for Group III - 2.87±0.786 (min) and the difference was found to be statistically very significant between all the groups (p < 0.001). The mean onset of motor block for Group I was 4.78±1.428 (min) for Group II was 3.87±1.079 (min) and for Group III - 4.82±1.787 (min) and the difference was found to be statistically significant between Group I and Group II (p < 0.05) but was not significant between Group I and Group III and Group II and Group III (p > 0.05). In group I grade II block was achieved in 22 out of 45 patients, in group II 21 out of 45 patients achieved grade II block and in group III 30 out of 45 patients had grade II sensory block. 23 patients in Group I, 24 patients in Group II and 15 patients in Group III had only touch sensation and no response to any painful stimulus (grade 1 sensory block). Chi square test applied between the groups and found statistically not significant (p > 0.05). The mean duration of sensory block in Group I was 222.56±50.222 (min), in Group II 340.11±53.369 and Group III was 466.20±97.028 (min).  By using ANOVA test the p value was < 0.001 between all the groups which was statistically significant. The mean duration of motor block in Group I was 208.67±40.261 (min), in Group II 338.78±52.550 and Group III was 402.22±82.031 (min).The p value was <0.001 between the Groups and found to be statistically significant.The mean time of rescue analgesia in Group I was 256.78±41.288 (min), in Group II 455.44±75.301 and Group III was 619.33±72.344 (min).The p value was <0.001 between the Groups and found to be statistically significant.

Table 2: Onset of Block

Table-3 shows intraoperative mean heart rate with standard deviation at various time points during surgery. Turkey’s test applied between the groups upto 60 minutes and found significant difference between group I and group III at 45 minutes and 60 minutes (p <0.05). From 75 – 135 minute time point scheffe’s test applied and found significance difference at 75, 90 and 105 minute time point between group I and group III (p < 0.05).

Table -3 : Effect on Heart Rate (Mean + S.D.)

Table-4 shows intra-operative mean systolic blood pressure with standard deviation at various time points during surgery. Turkey’s test applied between the groups up to 60 minutes and found significant difference between group I and III and group II and III from 15 minute time point to 60 minute time point (p <0.05). From 75 – 135 minute time point scheffe’s test applied and found significance difference at 75, 90, 105 and 120 minute time point between group I and III and group II and III (p < 0.05).

Table 4: Effect on Systolic BP  (Mean + S.D.)

Table-5 shows intraoperative mean diastolic blood pressure with standard deviation at various time points during surgery. ANOVA test applied between the groups and found significant difference only at 90 minute time point. It was found that the difference was between group II and group III after applying Scheffe’s test (p < 0.05). 

Table 5- Effect on Diastolic BP (Mean + S.D.)

Table-6 shows intraoperative mean respiratory rate with standard deviation at various time points during surgery. Turkey’s test applied between the groups up to 60 minutes and found significant difference between group I and III and group II and III from 30 minute time point to 60 minute time point (p <0.05). From 75 – 135 minute time point scheffe’s test applied and found significance difference at 75, 90 and 105 minute time point between group I and III and group II and III (p < 0.05) and between group II and group III at 120 minute time point.

Table -6: Effect on Respiratory Rate (Mean + S.D.)

Intra-operative mean saturation levels showed no significant differences between the groups. There were slightly higher sedation score in group III compare to II & I GROUPS.

During the postoperative period, hemodynamic variables remained largely stable without significant variations. There were slightly higher sedation score in group III at o min, 30 minute and 1 hour postoperative.

Table 7: Visual Analogue Score (No. of Patients)

Table-7 shows the distribution of pain scores (VAS) in the groups at different time points. All the groups had 0 pain score in the post operative period at 0, 30 min, 1 hr and 3 hrs.  At 6 hrs. Group I recorded 3 patients with mild pain (VAS 0-3), 41 patients with moderate pain (VAS 4-6) and 1 patient with severe pain (VAS 7-10). Group II recorded 11 patients with mild pain, 34 patients with moderate pain. While in Group III 38 patients recorded with mild pain and 7 patients with moderate pain. At 12 hrs. Group I recorded 14 patients with mild pain, 30 patients with moderate pain and 1 patient with severe pain. Group II recorded 5 patients with mild pain, 38 patients with moderate pain and 2 with severe pain. While in Group III 26 patients recorded with mild pain and 19 patients with moderate pain. At 18 hrs. Group I recorded 9 patients with mild pain, 26 patients with moderate pain and 10 patients with severe pain. Group II recorded 13 patients with mild pain, 23 patients with moderate pain and 9 with severe pain, While in Group III 24 patients recorded with mild pain, 20 patients with moderate pain and 1 patient with severe pain. At 24 hrs, Group I recorded 14 patients with mild pain, 28 patients with moderate pain and 3 patients with severe pain. Group II recorded 13 patients with mild pain, 22 patients with moderate pain and 10 with severe pain. While in Group III 21 patients recorded with mild pain, 18 patients with moderate pain and 6 patients with severe pain.

In present study an attempt has been made to assess the efficacy of Fentanyl and Clonidine as adjunct to local anaesthetic mixture (Lignocaine and Bupivacaine) in Brachial plexus block (Supraclavicular approach) in terms onset time, duration of analgesia. Haemodynamic variables and rescue analgesic requirement in first 24 hours was also studied.

The mean age and weight of patients were comparable in all the groups. The male: female ratio was 75.55: 24.44. More number of males in all groups reflects the higher risk of trauma in males. No statistical significance was noted between the groups regarding duration of surgery.  Onset of Sensory Block: The onset of sensory block was significantly earlier in the clonidine group (2.87 ± 0.786 min; CI: 2.554–3.179), followed by the fentanyl group (3.69 ± 1.104 min; CI: 3.377–4.001), and latest in the control group (4.44 ± 1.235 min; CI: 4.132–4.752) (p < 0.05). This aligns with findings by Antonucci S (2001),^[13] who reported shorter onset times in groups receiving clonidine (12 ± 4 min), tramadol (14 ± 8 min), and sufentanil (11 ± 7 min) compared to control (20 ± 11 min). Similarly, Sukran Geze et al. (2012) ^[14] observed faster onset in the fentanyl group (7 ± 3.73 min) versus control (9 ± 4.45 min; p < 0.001). Chakraborty et al. (2011)^[¹⁵^] reported shorter onset in the clonidine group (6.2 ± 0.78 min) compared to control (8.7 ± 1.01 min), consistent with Gabriella Iohom (2005),^[16] who found reduced onset time with clonidine (21.3 ± 7.2 min) versus placebo (24.7 ± 5.5 min). A meta-analysis by Popping DM (2009)^[17] also confirmed an earlier onset with clonidine (12.8 min) compared to controls (15 min). Conversely, Vinoles M et al. (1991)^[18] reported no significant difference in onset time when 10 µg fentanyl was added to mepivacaine in axillary blocks.

Onset of Motor Block: Onset of motor block was earlier in fentanyl group (3.87±1.079 min, CI- 3.43 – 4.29) than in control group (4.78±1.428 min, CI- 4.34 – 5.20) and clonidine group (4.82±1.787 min, CI- 4.39 – 5.25). There was no statistically significant difference in onset time of motor block in clonidine and control groups. In the study of Sukran Geze et al (2012)^[14] the mean onset time of motor block was earlier in fentanyl group (10+6.68) as compared to control (11+3.73). Daniel M. ^Popping[17] found that clonidine had no significant impact on onset time of motor block (WMD -0.38 min, 95% CI -3.14 to 2.38, p = 0.79). In our study we also found that the mean onset time of motor block was not significant between clonidine group (4.82±1.787 min) and control group (4.78±1.428 min). Karakaya and colleagues (2001)^[19] evaluated the effect of adding fentanyl (2.5 microgram/ml) to 40 ml of 0.25% bupivacaine in axillary brachial plexus blockade. They observed no statistically significant difference in time of onset of motor and sensory block than in those with bupivacaine alone. However the drugs and criteria selected for onset of motor block was different from this study.

Duration of Sensory and motor Block: The mean duration of sensory blockade, in the study was 466.20±97.028 min (CI- 445.49 – 486.90) with clonidine, 340.11±53.369 min (319.41 – 360.81) with fentanyl and 222.56±50.222 min (CI- 201.85 – 243.25) with plane local anaesthetic mixture, which was statistically significant between all the three groups (p < 0.001). Gabriella Iohom(2005)^[16] in his study, found that the duration of sensory block was longer in clonidine group compared with placebo 275 ± 75 versus 163 ±57; P= 0.04, these observation were similar to our study. In a study conducted by Henri Iskandar ^[20] the median sensory block was 235 min (195–250) in the clonidine group, compared with 150 min (135–160) in the control group. Giovanni Cucchiaro et al ^[21] in his study on children using 0.25% bupivacaine found significant prolongation of duration of sensory block with clonidine group 1140 min compared to control 840 min. Shirish G. Chavan et al (2011)^[22] in his study found that the mean duration of sensory block was longer in fentanyl group (623+96 min), compared to control group (450+79 min), these observation were similar to our study. Nishikawa K et al (2000)^[23] observed that addition of fentanyl 100 microgram to 40 ml of 1.5% lignocaine with 1:200000 adrenaline increases the success rate of sensory blockade for radial and musculocutaneous nerves.

The mean duration of motor blockade, in the study was 402.22±82.031 min (CI- 384.27 – 420.16) with clonidine, 338.78±52.550 min (CI- 320.83 – 356.72) with fentanyl and 208.67±40.261 min (CI- 190.72 – 226.61) with plane local anaesthetic mixture, which were statistically significant between all the three groups (p < 0.001).In the meta-analysis conducted by Daniel M. Popping,^[17] the average duration of motor block was 405 min (range, 122–728) in control group. Clonidine significantly prolonged the duration of block to 546 min. According to study conducted by Wolfgang Erlacher et al, ^[24] the duration of blockade in the bupivacaine group was 728 min in control, and in comparison clonidine group had 972 min, which are matching well with our study. Karakaya and colleagues (2001)^[19] in their study found that the mean duration of motor block was longer in bupivacaine-fentanyl group (10.7 hours) than bupivacaine alone group (4.9 hours). Similar finding were observed by Sukran Geze et al ,^[14] the duration of mean motor block in their study was 7+2.57 hours and 4+1.14 hours for fentanyl and control group respectively. Chakraborty et al (2011)¹⁵ observed prolonged duration of sensory and motor block with clonidine group as compare to control. In their study the mean duration of sensory block in clonidine and control group were 279.1+28.98 min and 116.0+17.16 min respectively, and mean duration of motor block was 330.4+31.68 min in clonidine group and 144.8+17.31 min in control group.

Duration of analgesia (Time of rescue analgesia): In our study, the mean duration of analgesia (time to first rescue dose) was significantly longer in the clonidine group (619.33±72.344 min, CI: 500.21–639.45) compared to the fentanyl group (455.44±75.301 min, CI: 436.32–474.56) and control group (256.78±41.288 min, CI: 237.66–275.89), with statistically significant differences among all groups. Murphy et al.^[25] reported clonidine extended analgesia to 492 min, nearly double that of placebo (260 min). Similarly, Popping^[17] observed increased duration with clonidine (584 min) over control (461 min), aligning with our findings. Chakraborty et al. (2011)^[15] also reported longer analgesia in the clonidine group (415±38.18 min) versus control (194.2±28.74 min). Nishikawa et al. (2000)^[23] found significantly longer analgesia with axillary fentanyl (295±85 min) than lignocaine alone (215±78 min) or IV fentanyl (210±62 min). Karakaya et al. (2001) ^[19] and Chavan et al. (2011)^[22] similarly noted that adding fentanyl to local anaesthetic prolonged analgesia in brachial plexus blocks. Conversely, morphine and sufentanil showed no added benefit. Racz et al. (1991)^[26] found morphine did not affect onset or quality of analgesia, and Bouaziz et al. (2000)^[27] reported sufentanil added to mepivacaine had no impact on block characteristics. These discrepancies likely stem from variations in opioid type (dose, lipid solubility, pKa), local anaesthetic pH, and block technique (interscalene, supraclavicular, axillary).

Side effects

In our study, sedation scores were higher in the clonidine group, consistent with Chakraborty et al.,^[15] likely due to partial vascular uptake and central action of clonidine. The sedation was mild, desirable, and self-limited due to clonidine’s lipophilicity. No patient required airway assistance. A significant reduction in systolic and diastolic blood pressure was observed in the clonidine group without hypotension (>20% drop), aligning with Eisenach et al.^[28] and Culebras et al.^[29] Pulse rate also decreased, but no clinical bradycardia (<60/min) occurred. One patient in the fentanyl group experienced nausea and vomiting postoperatively, likely of gastrointestinal origin. No cases of local anaesthetic toxicity, puncture site inflammation, or nerve injury were noted. Patient acceptance was high, with no postoperative complications. Ultrasound-guided and nerve stimulator-assisted blocks offer more precision by directly visualizing nerve structures and drug deposition, reducing risks like nerve injury or pneumothorax seen with blind techniques. Though we observed no such complications, these advanced methods enhance success rates and reduce variability in analgesic duration. While nerve stimulators are easier to use, ultrasound requires expertise and equipment.

Addition of both fentanyl (50 mcg) and clonidine (75 mcg) to local anaesthetic mixture for supraclavicular brachial plexus block is highly effective in prolongation of duration of anaesthesia and analgesia. So the patient remains comfortable in the postoperative period with considerable therapeutic benefit and without any potential side effects.

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