European Journal of Cardiovascular Medicine

Epidural anesthesia is a widely used technique for intraoperative and postoperative pain management in lower abdominal and lower limb surgeries¹. Ropivacaine, a long-acting amide local anesthetic, is favored for its favorable safety profile, reduced cardiotoxicity, and motor-sparing properties^2,3. However, its efficacy in terms of sensory and motor blockade can be enhanced by the addition of adjuvants⁴.

Dexmedetomidine, a highly selective alpha-2 adrenergic agonist, has emerged as an effective adjuvant in regional anesthesia⁵. It provides sedative, anxiolytic, and analgesic effects while reducing the requirement for local anesthetics. Its mechanism involves hyperpolarization of nerve fibers, leading to prolonged sensory and motor blockade^6,7. Additionally, Dexmedetomidine improves hemodynamic stability and minimizes the incidence of side effects such as hypotension and bradycardia⁸.

The combination of Ropivacaine and Dexmedetomidine for epidural anesthesia has shown synergistic effects, resulting in improved quality and duration of anesthesia^4,6. However, limited studies have comprehensively compared this combination to Ropivacaine alone for postoperative analgesia, particularly in the context of lower abdominal surgeries.

This study aims to evaluate and compare the efficacy, safety, and hemodynamic effects of 0.75% Ropivacaine alone versus 0.75% Ropivacaine combined with Dexmedetomidine for postoperative analgesia in patients undergoing lower abdominal surgeries. By analyzing parameters such as the onset, intensity, and duration of sensory and motor blockades, sedation scores, and hemodynamic stability, the study seeks to determine the potential benefits of this combination.

Study Design and Setting

This randomized controlled trial was conducted over 18 months from November 2020 to May 2022 at the Konaseema Institute of Medical Sciences, a tertiary care hospital in Amalapuram, Andhra Pradesh, India. Ethical committee approval was obtained before the commencement of the study, and written informed consent was collected from all participants.

Study Population

The study included adult patients aged 18–60 years, classified as ASA grade I or II, scheduled for elective lower abdominal surgeries. Patients with obesity (BMI >30), pregnancy, lactation, emergency surgeries, uncontrolled diabetes or hypertension, coagulopathy, spinal deformities, neurological or cardiac disorders, or known allergies to the study drugs were excluded.

Sample Size

Based on a prior study, a sample size of 61 patients per group was calculated to achieve 80% power and 5% significance, accounting for a 10% non-response rate.

Randomization

Patients were randomly allocated into two groups (Group R and Group RD) using a computer-generated randomization list:

Group R: Received 0.5% Ropivacaine (20 ml) diluted with 1 ml distilled water.

Group RD: Received 0.5% Ropivacaine (20 ml) combined with Dexmedetomidine (50 mcg diluted in 1 ml distilled water).

Procedure

All patients underwent a standardized pre-anesthetic evaluation and were premedicated with oral Alprazolam (0.5 mg) the night before surgery. On the day of surgery, patients were preloaded with 500 ml of Ringer's lactate before the epidural procedure.

Epidural anesthesia was administered at the L2–L3 or L3–L4 interspinous space using an 18G Tuohy needle under aseptic conditions. A catheter was placed in the epidural space, and a test dose of 3 ml of 2% Lignocaine with 1:200,000 adrenaline was administered to confirm the placement. The study drugs were then injected according to group allocation.

Data Collection

The following parameters were recorded:

Onset of sensory blockade: Time to achieve loss of pinprick sensation at T10.

Onset of motor blockade: Time to achieve Bromage scale grade 1.

Duration of sensory blockade: Time from drug injection to the resolution of sensory block at T10.

Duration of motor blockade: Time from drug injection to complete motor recovery (Bromage scale grade 0).

Sedation scores: Assessed using a five-point sedation scale.

Hemodynamic parameters: Heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) recorded at baseline and at regular intervals during and after the procedure.

Adverse effects: Incidence of hypotension, bradycardia, nausea, vomiting, or other complications.

Statistical Analysis

Data were entered in Microsoft Excel and analyzed using SPSS software (version 23). Descriptive statistics were used for demographic data, while independent t-tests and chi-square tests were applied to assess differences between the groups. A ppp-value <0.05 was considered statistically significant. Results were presented as mean ± standard deviation for continuous variables and as percentages for categorical variables.

Demographic Data

The age distribution among the study participants was similar between the two groups, with no significant differences observed across the age categories (Table 1). Male participants predominated in Group R (77.0%) compared to Group RD (60.6%), while female representation was higher in Group RD (39.3%) than in Group R (22.9%). However, the overall sex distribution difference was not statistically significant (p=0.09) (Table 1). The mean weight (p=0.12) and height (p=0.09) were also comparable between the two groups.

Table 1: Demographic Data

Figure No:1. Onset and Duration of Blocks (Group R vs Group RD)

Onset and Duration of Blocks

The onset of both sensory and motor blocks was significantly faster in Group RD compared to Group R, with mean onset times of 6.1±2.5 minutes vs. 11.1±3.1 minutes (p=0.009) for sensory block and 10±2.5 minutes vs. 17±3.1 minutes (p=0.005) for motor block (Table 2).

The duration of sensory block (349±52 minutes in Group RD vs. 196±12.5 minutes in Group R, p=0.007) and motor block (240±12 minutes in Group RD vs. 150±34 minutes in Group R, p=0.002) was significantly longer in Group RD (Table 2).

Table 2: Onset and Duration of Blocks

Figure No:2 Maximum Sensory Level Achieved

Sensory and Motor Blockade Characteristics

The maximum sensory level achieved was not significantly different between the two groups (p=0.23) (Table 3). However, Group RD exhibited significantly more intense motor blockade, with a higher proportion of patients achieving Bromage 4 (34.4%) compared to Group R (0%) (p=0.002) (Table 3). Additionally, no patients in Group RD remained at Bromage 2, whereas 40.9% of patients in Group R did (p=0.002).

Table 3: Sensory and Motor Blockade Characteristics

Figure No:3. Grade of Motor Blockade

Sedation Scores

Group RD exhibited significantly higher sedation scores compared to Group R (p=0.004) (Table 4). Most patients in Group RD achieved a sedation score of S3 (75.4%), while the highest score in Group R was S2 (67.2%).\

Table 4: Sedation Scores

Figure No:4. Sedation Scores (Group R vs Group RD)

Hemodynamic Parameters

The baseline heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were comparable between the two groups (p=0.12, p=0.09, and p=0.6, respectively). During the subsequent time intervals, there were no statistically significant differences in heart rate (p=0.837), SBP (p=0.379), or DBP (p=0.640) between the groups (Table 5). Both groups maintained hemodynamic stability throughout the study period.

Table 5: Hemodynamic Parameters

Side Effects

No significant side effects, such as hypotension or bradycardia, were observed in either group. Both regimens demonstrated a favorable safety profile.

Epidural anesthesia is an essential component of perioperative pain management, particularly in lower abdominal surgeries. This study evaluated the efficacy and safety of Ropivacaine combined with Dexmedetomidine versus Ropivacaine alone for epidural anesthesia. The findings demonstrate that adding Dexmedetomidine significantly enhances the anesthetic and analgesic effects of Ropivacaine without compromising hemodynamic stability or increasing adverse effects.

Onset of Sensory and Motor Blockade

The onset of sensory and motor blockades was significantly faster in the Ropivacaine-Dexmedetomidine group (Group RD) compared to the Ropivacaine-only group (Group R). This is consistent with results reported by Kaur et al., who observed accelerated nerve blockade onset with alpha-2 agonists due to their synergistic action, which enhances local anesthetic effects by hyperpolarizing nerve fibers¹⁰. Similarly, Emam et al. also found Dexmedetomidine to be effective in reducing block onset times when used with local anesthetics⁸.

Duration of Sensory and Motor Blockade

The prolonged duration of sensory and motor blockades in Group RD highlights the efficacy of Dexmedetomidine as an adjuvant. Dexmedetomidine reduces neurotransmitter release and inhibits C-fiber conduction, resulting in prolonged analgesia. This finding aligns with studies by Gujral et al. and Zeng et al., who demonstrated significant prolongation of sensory and motor blockade with the addition of Dexmedetomidine to local anesthetics^9,11.

Intensity of Motor Blockade

Group RD exhibited more intense motor blockade, with a higher proportion of patients achieving Bromage grade 4. This intensified blockade is likely due to Dexmedetomidine’s presynaptic and postsynaptic actions on alpha-2 adrenergic receptors, which potentiate the effects of Ropivacaine. Kaur et al. and Ravipati et al. similarly reported enhanced motor blockade with Dexmedetomidine as an adjuvant^10,12.

Sedation

Higher sedation scores in Group RD reflect the central sedative action of Dexmedetomidine, mediated by its alpha-2 adrenoceptor effects in the locus coeruleus. Such sedation reduces the need for supplemental sedatives, which is beneficial for long-duration surgeries. Comparable findings were reported by Qureshi et al. and Soni, who highlighted the sedative advantages of Dexmedetomidine in epidural anesthesia^13,14.

Hemodynamic Stability

Hemodynamic parameters, including heart rate and blood pressure, remained stable in both groups. The absence of significant hypotension or bradycardia in Group RD aligns with the findings of Wan et al., who demonstrated that Dexmedetomidine at appropriate doses does not adversely affect hemodynamic stability¹⁵.

Safety Profile

No significant side effects, such as hypotension, bradycardia, nausea, or vomiting, were observed in either group. This favorable safety profile reinforces the reliability of Dexmedetomidine as an adjuvant. Bajwa et al. also reported similar safety outcomes in their study on Dexmedetomidine with Ropivacaine⁸.

Clinical Implications

The combination of Ropivacaine and Dexmedetomidine provides faster onset, prolonged duration, and enhanced intensity of sensory and motor blockades, along with better sedation, making it an effective option for epidural anesthesia in lower abdominal surgeries. These findings are supported by studies such as those by Gujral et al. and Zeng et al., emphasizing the utility of this combination in achieving superior perioperative analgesia^9,11.

Limitations

This study was limited to ASA grade I and II patients undergoing elective lower abdominal surgeries. Further research is needed to evaluate the efficacy and safety of this combination in high-risk patients and other surgical procedures.

The addition of Dexmedetomidine to Ropivacaine for epidural anesthesia significantly improved the onset, intensity, and duration of sensory and motor blockades compared to Ropivacaine alone. The mean onset times for sensory and motor blockades were faster, and the durations of sensory and motor blockades were markedly prolonged in the Ropivacaine-Dexmedetomidine group. Patients in this group also achieved higher sedation scores, indicating enhanced comfort during the perioperative period. Hemodynamic parameters remained stable in both groups, and no significant side effects, such as hypotension or bradycardia, were observed. These findings suggest that Ropivacaine combined with Dexmedetomidine is a safe and effective regimen for epidural anesthesia in lower abdominal surgeries, offering improved anesthetic and analgesic outcomes.

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