Regional anaesthesia is an essential component of modern anaesthetic practice, offering distinct advantages over general anaesthesia, particularly in infra-umbilical surgeries. It provides superior postoperative analgesia, reduces opioid requirements, facilitates early mobilisation, and lowers the incidence of pulmonary complications such as atelectasis and hypoxia, while improving overall patient satisfaction ^1-3. Neuraxial techniques, especially spinal and epidural anaesthesia, are most commonly employed as they ensure effective sensory and motor blockade with stable intraoperative haemodynamics ⁴.

Spinal anaesthesia is simple, rapid in onset, and produces dense blockade but is limited by fixed dosing and relatively short duration, making it less suitable for prolonged procedures ⁵. Epidural anaesthesia, though technically more demanding and slower in onset, allows incremental dosing and continuous infusion, offering flexibility, prolonged analgesia, and superior haemodynamic stability ^6,7.

Ropivacaine, a long-acting amide local anaesthetic, is increasingly favoured in epidural practice due to its reduced cardiotoxicity and motor-sparing effect compared with bupivacaine ^8,9. At 0.75% concentration, it provides adequate sensory blockade for infra-umbilical surgery while allowing earlier postoperative mobilisation ¹⁰. The addition of adjuvants further improves analgesic quality and duration ¹¹.

Fentanyl, a μ-opioid receptor agonist, acts synergistically with local anaesthetics to provide rapid analgesia with minimal motor block but may cause pruritus, nausea, or respiratory depression ^12,13. Clonidine, an α2-adrenergic agonist, prolongs sensory blockade and provides sedation without respiratory compromise, though it may induce hypotension and bradycardia^14–16.

Comparative studies of these agents with ropivacaine remain limited. This study aims to evaluate the efficacy, haemodynamic effects, and side-effect profiles of fentanyl versus clonidine as adjuvants to 0.75% ropivacaine in epidural anaesthesia for infra-umbilical surgeries.

Aim Of the Study

The aim of this study is to compare the analgesic efficacy and duration of analgesia between fentanyl and clonidine when used as adjuvants to epidural ropivacaine in patients undergoing Infra-umbilical surgeries.

Objectives Of the Study

To evaluate and compare the following parameters between epidural Ropivacaine 0.75% combined with Clonidine and Ropivacaine 0.75% combined with Fentanyl:

• Onset of analgesia
• Time to achieve maximum sensory blockade
• Time to achieve complete motor blockade
• Duration of analgesia
• Hemodynamic parameters
• Incidence of side effects

This prospective, randomized, single-blind comparative study was conducted at a tertiary care hospital after obtaining Institutional Ethical Committee approval. The objective was to compare the analgesic efficacy and duration of analgesia of fentanyl and clonidine as adjuvants to 0.75% ropivacaine administered epidurally in patients undergoing infra-umbilical surgeries.

Study design and population: The study was carried out between July 2023 and December 2024 in 60 patients of either sex, aged 18–60 years, belonging to ASA physical status I or II, scheduled for elective infra-umbilical surgeries. All patients underwent pre-anaesthetic evaluation and provided written informed consent.

Exclusion criteria included patients with significant cardiac, renal, hepatic, or neurological disease, pregnancy, spinal deformity, allergy to study drugs, or those receiving anaesthesia other than epidural.

Randomisation and groups: Patients were allocated into two equal groups (n=30 each) using an odd–even day method:

• Group F:75% ropivacaine 15 ml + fentanyl 75 μg
• Group C:75% ropivacaine 15 ml + clonidine 30 μg

Procedure: Under aseptic precautions, an epidural catheter was placed at the L2–L3 interspace using an 18G Tuohy needle and the loss-of-resistance technique. After test dosing, the study drug was administered. Standard monitoring (ECG, NIBP, SpO₂) was applied, and patients were preloaded with Ringer lactate.

Parameters assessed included onset and maximum level of sensory block (pinprick method), onset and duration of motor block (Modified Bromage scale), time to two-segment regression, duration of analgesia (time to first rescue analgesic request, NRS ≥3), hemodynamic parameters (HR, SBP, DBP, MAP), and incidence of side effects.

Emergency resuscitation equipment, oxygen, intravenous fluids, and essential drugs were kept ready throughout the procedure

Data collection & Analysis: The data will be collected on Microsoft Excel Sheet and subjected to appropriate Descriptive statistics and inferential statistics

Demographic Distribution of the study subjects:

30 study subjects were randomly allotted to each study group randomly while maintaining the homogeneity (p>0.05)

Table 1: Distribution of the study subjects

Time of onset of sensory block:

Table 2: Time of onset of Sensory Block

In the present study we observed that There was no significant difference between mean time to sensory block but Clonidine trends towards faster onset.

Highest Level Achieved:

Highest Level of block achieved was assessed by the pin prick method and noted.

Table 3: Highest Level Achieved

Fig 1: Highest Level Achieved

In our study Highest level of sensory loss achieved was T4 in subjects receiving Fentanyl whereas in subjects receiving Clonidine highest level was T6.

Time of onset of complete motor Block (in Min)

Time of onset of motor Block was assessed using modified Bromage scale.

Table 4: Time of onset of complete motor Block

In the present study There was no significant difference between mean time to Motor block but Trends toward faster motor block with Fentanyl (p = 0.08)

Two-Segment Regression Time (min):

Time required for block to regress by to dermatomal segments is as follows

Table 5: Two-Segment Regression Time

Study does not reveal any significant difference in 2 Segment Regression time between the two drugs. (p = 0.12)

Complete Motor Reversal

Time required for complete reversal of motor block was marked once patients Modified Bromage Scale score is 3.

Table 6: Complete Motor Reversal

There is a statistically significant difference between the Clonidine and Fentanyl groups in the time for complete motor reversal (p < 0.05), with Fentanyl group having a longer mean reversal time.

Duration of Effective Analgesia

Duration of effective analgesia was assessed using NRS scale and rescue analgesia given after NRS 3 and above.

Table 7: Duration of Effective Analgesia

Fig 2: Duration of Effective Analgesia

Study shows that Clonidine provides significantly longer analgesia than Fentanyl. (p = 0.03)

MAP Trends at Key Time Intervals (mmHg)

MAP Trend recorded at intervals of 0,2,5,10,15,30,45,60,90 and 120 minutes following shows the time intervals.

Table 8: MAP Trends at Key Time Intervals

Fig 3: MAP Trends at Key Time Intervals

At baseline (0 min), there was no significant difference in MAP between the groups (p = 0.277), indicating comparable hemodynamic status. From 2 to 30 minutes, the clonidine group demonstrated significantly higher MAP values (p < 0.01), suggesting better preservation during the early intraoperative period. Between 30 and 60 minutes, although MAP remained higher with clonidine, a steeper decline was observed, leading to convergence of values between the groups. At 90 minutes, no significant difference was noted (p = 0.061). However, by 120 minutes, clonidine showed a significant drop in MAP compared to fentanyl (p = 0.034). Overall, fentanyl was associated with a more gradual decline and stable hemodynamics, whereas clonidine produced a slightly faster and prolonged reduction in MAP, though this was manageable and did not require aggressive intervention.

Pulse Rate Trends at Key Time Intervals:

Pulse rate trend recorded at intervals of 0,2,5,10,15,30,45,60,90 and 120 minutes following shows the time intervals

Table 9: Pulse Rate Trends at Key Time Intervals

Fig 4: Pulse Rate Trends at Key Time Intervals

At baseline, there was no significant difference in pulse rate between the groups (p = 0.524), indicating comparable hemodynamic status. From 2 to 30 minutes, a slightly steeper decline was noted in the clonidine group, while the fentanyl group showed a gradual fall, though the difference was not statistically significant (p = 0.342). Between 30 and 90 minutes, both groups demonstrated a gradual reduction in pulse rate without significant variation (p = 0.640). By 120 minutes, pulse rates plateaued in both groups, again with no significant difference.

Complications:

Most common complication in both the groups was hypotension seen in 2 patients in clonidine group while in Fentanyl group 3 patients had hypotension. Bradycardia was observed in 2 patients in clonidine group. Only 1 case of nausea and vomiting was found in Fentanyl group. No significant differences (p > 0.05) for all comparisons, (Fisher’s Exact Test). The incidence of hypotension in Fentanyl group was found to be more than clonidine group which may be attributed to higher level of block achieved in Fentanyl group rather than adjuvant effect.

This prospective randomized study compared clonidine and fentanyl as adjuvants to 0.75% ropivacaine administered epidurally in patients undergoing infra-umbilical surgeries. The primary endpoints were analgesic efficacy, onset and duration of sensory and motor block, hemodynamic stability, and incidence of side effects.

Demographic Profile

The two groups were comparable in terms of demographic variables, ASA physical status, and BMI (p > 0.05), confirming effective randomization. Most patients were middle-aged with a predominance of ASA I–II, thereby minimizing confounding factors. These findings parallel those of Bajwa et al. (2010)¹⁶, who reported similar baseline characteristics when comparing clonidine and fentanyl with ropivacaine.

Sensory Block Characteristics

The onset of sensory block was slightly faster with clonidine (10.2 ± 3.1 min) compared to fentanyl (11.0 ± 2.8 min), although not statistically significant (p = 0.28). Both groups achieved adequate block levels for infra-umbilical surgeries. The earlier onset with clonidine can be explained by its α2-adrenergic receptor–mediated vasoconstrictive and antinociceptive actions. Fentanyl, via μ-opioid receptor activation, provided robust analgesia but with slightly delayed onset. These results align with Bajwa et al. (2010)¹⁶ and Baptista et al. (2008)¹⁷, who also reported marginal differences in onset, with clonidine producing more consistent dermatomal spread.

Two-segment regression was significantly prolonged in the clonidine group (128.5 ± 21.2 min vs 111.7 ± 18.6 min, p = 0.01). This confirms clonidine’s ability to extend sensory block by reducing nociceptive transmission and prolonging local anesthetic action, consistent with Gupta et al. (2017)¹⁸ and Baptista et al. (2008)¹⁷.

Motor Block Characteristics

Motor block onset was slightly faster in the fentanyl group (19.8 ± 5.0 min) than with clonidine (22.1 ± 5.2 min), though not statistically significant (p = 0.08). Importantly, motor block regression was earlier in the clonidine group (227.3 ± 47.7 min vs 254 ± 41.2 min, p = 0.023), allowing faster postoperative mobilization. This is desirable in enhanced recovery protocols. Our findings echo Gupta et al. (2017)¹⁸, who reported earlier recovery with clonidine despite similar block intensity.

Duration of Analgesia

Clonidine significantly prolonged analgesia (320.4 ± 60.2 min) compared to fentanyl (290.5 ± 50.7 min, p = 0.03). This superior analgesic effect reflects clonidine’s synergistic action with local anesthetics, enhancing both presynaptic and postsynaptic inhibition of nociceptive transmission. Our results are consistent with Baptista et al. (2008)¹⁷ and Gupta et al. (2017)¹⁸, who also reported longer analgesic duration with clonidine. Fentanyl, though effective, provided shorter-lasting relief due to faster redistribution, as highlighted in previous studies (Bajwa et al., 2010¹⁶; Soni et al., 2016¹⁹).

Hemodynamic Effects

Both groups maintained acceptable hemodynamic stability. The clonidine group showed a significant decline in MAP after 15 minutes, maximal at 120 minutes (p = 0.034). This is explained by clonidine’s sympatholytic action leading to vasodilation and reduced norepinephrine release. Despite the decline, hypotension was manageable and did not require vasopressor support. Similar results were reported by Soni et al. (2016)¹⁹ and Bajwa et al. (2010)¹⁶.

In contrast, the fentanyl group maintained more stable MAP, reflecting its neutral effect on vascular tone. This profile makes fentanyl preferable in patients with cardiovascular comorbidities.

Pulse rate trends showed a gradual reduction in the clonidine group, with mild bradycardia in 2 patients, not requiring treatment. The fentanyl group demonstrated stable heart rates throughout. These findings agree with Baptista et al. (2008)¹⁷ and Gupta et al. (2017)¹⁸, who noted clonidine-induced bradycardia as predictable but clinically insignificant.

Complications

Overall complication rates were low. Hypotension was seen in 2 patients in the clonidine group and 3 in the fentanyl group, managed with fluids or mephentermine. Bradycardia occurred only in clonidine patients, consistent with its pharmacology.

Opioid-related side effects were minimal: one patient in the fentanyl group reported nausea and pruritus, both self-limiting. No cases of respiratory depression occurred in either group, confirming the safety of the doses used. Sedation with clonidine was mild and not clinically significant. These findings align with previous reports by Bajwa et al. (2010)¹⁶, Visalyaputra et al. (2005)²⁰, and Shukla et al. (2022)²¹.

Clinical Implications

Clonidine, as an epidural adjuvant, provides longer-lasting analgesia, denser sensory block, and earlier motor recovery, but is associated with predictable hypotension and bradycardia. Fentanyl offers more hemodynamic stability and quicker onset of motor block but with shorter analgesic duration and opioid-related side effects.

Thus, clonidine is advantageous in surgeries requiring prolonged analgesia and early mobilization, while fentanyl may be preferred in patients with cardiovascular concerns. Careful patient selection, vigilant monitoring, and dose titration are essential to optimize outcomes with either agent.

This prospective, randomized clinical study compared the analgesic efficacy, block characteristics, hemodynamic trends, and side effect profiles of clonidine and fentanyl when used as adjuvants to 0.75% ropivacaine administered via the epidural route in patients undergoing Infra-umbilical surgeries.

The key findings of the study are:

• Both clonidine and fentanyl effectively enhanced epidural analgesia, providing satisfactory intraoperative anesthesia and postoperative pain control.
• Clonidine demonstrated a significantly longer duration of analgesia, with earlier motor block regression and minimal opioid-related side effects, making it favorable for procedures requiring prolonged pain relief and early ambulation.
• Fentanyl produced a faster onset of motor block and maintained greater hemodynamic stability, making it a better choice in patients with cardiovascular concerns or when a more rapid onset is clinically desirable.
• Hemodynamic changes were more pronounced in the clonidine group, with mild hypotension and bradycardia, though all were clinically manageable.
• Complications were infrequent and mild in both groups, with no serious adverse events reported. Inadequate motor block occurred only in the fentanyl group but did not require conversion to general anesthesia.

Overall, the study concludes that clonidine is a more effective adjuvant in terms of analgesic duration and recovery profile, whereas fentanyl offers better cardiovascular stability. The choice between the two should be tailored to patient comorbidities, surgical duration, and desired recovery profile.

This study adds to the growing body of evidence supporting the individualized selection of epidural adjuvants to optimize perioperative outcomes and enhance patient satisfaction.

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