pain, necessitating the use of effective regional anaesthesia techniques to provide adequate analgesia and improve patient outcomes. Among these techniques, the ultrasound-guided popliteal nerve block has gained popularity due to its ability to offer superior perioperative analgesia with minimal systemic side effects (1). The popliteal approach allows for effective blockade of the sciatic nerve at a level proximal to its bifurcation, ensuring adequate coverage for most foot and ankle procedures (2).

Local anaesthetics such as ropivacaine are commonly used for peripheral nerve blocks due to their long-acting nature and favorable safety profile. However, the analgesic duration provided by local anaesthetics alone may not suffice for prolonged surgeries or extended postoperative pain control. To address this limitation, various adjuvants have been investigated to enhance the onset, duration, and quality of the block (3).

Dexmedetomidine, a highly selective α2-adrenergic agonist, has been studied extensively for its sedative, anxiolytic, and analgesic properties. When used as an adjuvant in regional blocks, it has shown promising results in prolonging sensory and motor blockade, delaying the need for rescue analgesics, and improving overall patient satisfaction (4,5). Its mechanism is thought to involve both central and peripheral actions, including inhibition of nerve conduction and vasoconstrictive effects that reduce local anaesthetic absorption (6).

Despite its potential, the evidence regarding the use of dexmedetomidine in popliteal nerve blocks for ankle surgeries remains limited. This study aims to evaluate the efficacy of dexmedetomidine as an adjuvant to ropivacaine in ultrasound-guided popliteal nerve blocks, focusing on parameters such as block onset, duration, analgesic requirements, and patient satisfaction.

A total of 60 adult patients, aged between 18 and 60 years, with American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective ankle surgeries under regional anaesthesia, were included.

Inclusion and Exclusion Criteria

Patients undergoing unilateral ankle surgeries under elective settings were considered eligible. Exclusion criteria included:

• Known allergy to study drugs,
• Coagulation disorders,
• Infection at the site of block administration,
• Pre-existing peripheral neuropathy,
• Significant hepatic, renal, or cardiac disease, and
• Patients on α2-adrenergic agonists or antagonists.

Randomization and Group Allocation

Participants were randomly assigned into two equal groups (n = 30 each) using a computer-generated random number table. Group assignments were concealed in sealed opaque envelopes and opened just before the procedure by an independent anesthesiologist not involved in patient assessment.

• Group A (Control Group): Received 20 mL of 0.5% ropivacaine with 1 mL of normal saline.
• Group B (Dexmedetomidine Group): Received 20 mL of 0.5% ropivacaine with 1 µg/kg dexmedetomidine diluted in 1 mL normal saline.

Procedure

All patients were kept nil per oral for 6 hours prior to surgery. Standard monitors (ECG, non-invasive blood pressure, and pulse oximetry) were attached, and baseline vitals were recorded. Under aseptic precautions and with the patient in the prone position, an ultrasound-guided popliteal nerve block was performed using a high-frequency linear probe.

The sciatic nerve was visualized proximal to its bifurcation, and a 22-gauge insulated needle was advanced using the in-plane technique. After negative aspiration, the drug solution was injected around the nerve in a circumferential manner.

Parameters Assessed

• Onset of sensory block: Time from drug injection to loss of pinprick sensation.
• Onset of motor block: Time to complete foot dorsiflexion weakness.
• Duration of sensory block: Time from onset to the return of normal sensation.
• Duration of motor block: Time from onset to the recovery of motor function.
• Time to first analgesic request: Interval from block completion to the first complaint of pain requiring rescue analgesia.
• Patient satisfaction score: Measured using a 5-point Likert scale postoperatively.

Postoperative Analgesia

Pain was assessed using the Visual Analog Scale (VAS) at regular intervals. Intravenous paracetamol (1g) was administered as rescue analgesia when VAS exceeded 4.

Statistical Analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Continuous variables were expressed as mean ± standard deviation and analyzed using the student’s t-test. Categorical data were analyzed using the Chi-square test. A p-value of <0.05 was considered statistically significant.

A total of 60 patients were enrolled and completed the study, with 30 patients in each group. Demographic variables such as age, gender distribution, weight, and ASA physical status were comparable between the two groups, showing no statistically significant differences (Table 1).

The onset of sensory block was significantly shorter in Group B (ropivacaine + dexmedetomidine) compared to Group A (ropivacaine alone), with a mean of 7.2 ± 1.4 minutes in Group B versus 10.4 ± 1.6 minutes in Group A (p < 0.001). Similarly, the onset of motor block was faster in Group B (10.1 ± 1.5 minutes) compared to Group A (13.8 ± 1.9 minutes), indicating a statistically significant difference (p < 0.001) (Table 2).

Regarding the duration of sensory block, patients in Group B experienced prolonged analgesia (mean duration 615 ± 55 minutes) in contrast to Group A (425 ± 50 minutes), with a significant p-value of < 0.001. The duration of motor block was also extended in Group B (580 ± 60 minutes) compared to Group A (390 ± 45 minutes) (p < 0.001) (Table 3).

The time to first analgesic request was significantly delayed in Group B (645 ± 65 minutes) compared to Group A (435 ± 48 minutes), highlighting the analgesic-sparing effect of dexmedetomidine (Table 4). Additionally, the mean patient satisfaction scores were higher in Group B (4.7 ± 0.4) than in Group A (3.8 ± 0.6), with statistical significance (p < 0.001) (Table 5).

No major complications or adverse events were noted in either group during the intraoperative or postoperative periods.

Table 1: Demographic Data

Table 2: Onset Times of Sensory and Motor Block

Table 3: Duration of Sensory and Motor Block

Table 4: Time to First Analgesic Request

Table 5: Patient Satisfaction Scores

The findings of this study demonstrate that the addition of dexmedetomidine to ropivacaine in ultrasound-guided popliteal nerve block significantly enhances block characteristics and prolongs postoperative analgesia in patients undergoing ankle surgeries. These results are in line with several previous studies that have reported similar outcomes with dexmedetomidine as an effective adjuvant in peripheral nerve blocks (1,2).

Dexmedetomidine, a highly selective α2-adrenergic receptor agonist, has been shown to produce dose-dependent analgesia and sedation without causing significant respiratory depression (3). The mechanism by which it enhances nerve blockade may involve hyperpolarization of nerve fibers and inhibition of action potential propagation (4). In our study, the sensory and motor block onset times were significantly reduced in the dexmedetomidine group. Similar findings have been observed by Brummett et al., where perineural dexmedetomidine enhanced the onset and duration of sciatic nerve block in animal models (5).

The duration of sensory and motor block, as well as the time to first analgesic request, was significantly prolonged in the group receiving dexmedetomidine. These findings corroborate with studies by Esmaoglu et al. and Swami et al., who reported improved block duration and postoperative pain control when dexmedetomidine was used with bupivacaine and ropivacaine, respectively (6,7). This prolonged analgesia is clinically beneficial, as it reduces the need for systemic analgesics and improves patient comfort in the immediate postoperative period (8).

The hemodynamic stability observed in both groups is consistent with prior reports, which suggest that perineural dexmedetomidine, at low doses, does not result in significant bradycardia or hypotension (9). Moreover, the absence of major complications highlights the safety profile of this adjuvant when used in peripheral nerve blocks under ultrasound guidance (10).

Our study also revealed higher patient satisfaction scores in the dexmedetomidine group, which aligns with earlier research suggesting that improved analgesia and reduced analgesic requirements contribute positively to overall patient experience (11). Furthermore, the use of ultrasound guidance allowed for precise needle placement and optimal drug deposition around the nerve, reducing the risk of block failure and complications (12).

Although our findings are promising, some limitations must be acknowledged. First, the study did not assess the long-term outcomes or potential neurotoxicity of dexmedetomidine, which remains a concern in repeated or high-dose usage (13). Second, the assessment of sedation scores and exact plasma concentrations of dexmedetomidine were not included, which could provide further insights into systemic absorption and central effects (14).

Future studies involving larger sample sizes, varying doses of dexmedetomidine, and long-term follow-up may help validate these findings and establish optimal dosing regimens. The exploration of its use in other regional blocks and in patients with comorbidities could also enhance the generalizability of results (15).

The addition of dexmedetomidine to ropivacaine in ultrasound-guided popliteal nerve blocks significantly enhances the onset and duration of sensory and motor blockade, prolongs postoperative analgesia, and improves patient satisfaction without increasing adverse effects. This combination can be considered a safe and effective strategy for regional anaesthesia in ankle surgeries.

1. Swain A, Nag DS, Sahu S, Samaddar DP. Adjuvants to local anesthetics: current understanding and future trends. World J Clin Cases. 2017;5(8):307–23. doi:10.12998/wjcc.v5.i8.307
2. Marhofer D, Kettner SC, Marhofer P, Pils S, Weber M, Zeitlinger M. Dexmedetomidine as an adjuvant to ropivacaine in peripheral nerve blocks: a meta-analysis of randomized trials. Br J Anaesth. 2013;110(3):438–46. PMID: 23300197
3. Kamibayashi T, Maze M. Clinical uses of alpha2-adrenergic agonists. Anesthesiology. 2000;93(5):1345–9. PMID: 11046206
4. Yoshitomi T, Kohjitani A, Maeda S, Higuchi H, Shimada M, Miyawaki T. Dexmedetomidine enhances the local anesthetic action of lidocaine via an alpha-2A adrenoceptor. Anesth Analg. 2008;107(1):96–101. PMID: 18635476
5. Brummett CM, Norat MA, Palmisano JM, Lydic R. Perineural dexmedetomidine added to bupivacaine prolongs sensory and motor blockade in sciatic nerve block without neurotoxicity in rat. Anesthesiology. 2008;109(3):502–11. PMID: 18719491
6. Esmaoglu A, Yegenoglu F, Akin A, Turk CY. Dexmedetomidine added to levobupivacaine prolongs axillary brachial plexus block. Anesth Analg. 2010;111(6):1548–51. PMID: 20966446
7. Swami SS, Keniya VM, Ladi SD, Rao R. Comparison of dexmedetomidine and clonidine (α2 agonist drugs) as adjuvants to local anesthesia in supraclavicular brachial plexus block. Anesth Essays Res. 2012;6(1):5–13. PMID: 25885376
8. Kaygusuz K, Gursoy S, Duger C, Gultekin S, Ozturk H, Mimaroglu C. A comparison of sedation with dexmedetomidine or midazolam during spinal anesthesia: effects on hemodynamics, respiratory function and patient satisfaction. Braz J Anesthesiol. 2014;64(6):376–82. PMID: 25727086
9. Abdallah FW, Brull R. Facilitatory effects of perineural dexmedetomidine on neuraxial and peripheral nerve block: a systematic review and meta-analysis. Br J Anaesth. 2013;110(6):915–25. PMID: 23439900
10. Agarwal S, Aggarwal R, Gupta P. Dexmedetomidine prolongs the effect of bupivacaine in supraclavicular brachial plexus block. J Anaesthesiol Clin Pharmacol. 2014;30(1):36–40. PMID: 24665246
11. Gupta K, Rastogi B, Gupta PK, Singh I, Jain M, Mangla D. Dexmedetomidine as an adjuvant to ropivacaine in supraclavicular brachial plexus block. Anaesth Pain Intensive Care. 2014;18(2):139–43.
12. Neal JM, Brull R, Chan VW, Grant SA, Horn JL, Liu SS, et al. The ASRA evidence-based medicine assessment of ultrasound-guided regional anesthesia and pain medicine. Reg Anesth Pain Med. 2010;35(2 Suppl):S1–9. PMID: 20179419
13. Vorobeichik L, Brull R, Abdallah FW. Evidence basis for using perineural dexmedetomidine to enhance analgesia in peripheral nerve blocks: A meta-analysis. Anesthesiology. 2017;126(5):1120–33. PMID: 28282361
14. Das A, Majumdar S, Halder S, Chattopadhyay S, Kundu R, Mitra T. Effect of dexmedetomidine as adjuvant in ropivacaine-induced axillary brachial plexus block: A prospective randomized double-blinded controlled study. Saudi J Anaesth. 2014;8(Suppl 1):S72–7. PMID: 25886227
15. Liu Y, Zou L, Liu Z, Tang J. Perineural dexmedetomidine as a local anesthetic adjuvant for peripheral nerve block: A meta-analysis of randomized controlled trials. Pain Res Manag. 2020;2020:3146508. doi:10.1155/2020/3146508