European Journal of Cardiovascular Medicine

Effective management of postoperative pain is crucial in enhancing patient recovery, minimizing complications, and improving overall surgical outcomes. Inadequately managed postoperative pain can lead to adverse physiological and psychological effects, including delayed mobilization, increased morbidity, and the development of chronic pain syndromes¹.

Regional anesthesia techniques have gained prominence as effective alternatives to systemic analgesics. Among these, the Transverse Abdominis Plane (TAP) block has emerged as a reliable method for providing analgesia to the anterior abdominal wall by targeting the thoracolumbar nerves located in the fascial plane between the internal oblique and transversus abdominis muscles².

The TAP block has been shown to reduce postoperative opioid requirements and enhance patient comfort, especially in lower abdominal surgeries³. The choice of local anesthetic significantly influences the efficacy and duration of the block. Bupivacaine, a widely used long-acting amide local anesthetic, provides effective analgesia but is associated with potential cardiotoxicity at higher plasma levels.

Ropivacaine, the pure S-enantiomer of Bupivacaine, offers several advantages including a better safety profile, reduced cardiotoxicity, and less motor blockade. Previous studies have demonstrated the superior efficacy and prolonged duration of analgesia with Ropivacaine in TAP blocks compared to Bupivacaine^4-6.

This study aims to compare the analgesic efficacy and safety of 0.25% Bupivacaine versus 0.5% Ropivacaine when used in TAP blocks for patients undergoing abdominal surgeries under general anesthesia. The evaluation includes duration of analgesia, time to first rescue analgesic, pain scores, hemodynamic changes, and associated complications.

Study Design and Setting

This was a prospective, randomized, single-blinded, controlled interventional study conducted over a period of one year in the Department of Anaesthesiology at Government General Hospital, Anantapuramu, Andhra Pradesh, India.

Study Population

A total of 60 adult patients, aged between 18 and 60 years, of American Society of Anesthesiologists (ASA) physical status I and II undergoing elective abdominal surgeries under general anesthesia were enrolled and randomized into two groups of 30 patients each.

Inclusion Criteria

Patients aged 18–60 years

ASA physical status I or II

Body weight between 50–75 kg

Undergoing elective abdominal surgeries under general anesthesia

Provided written informed consent

Exclusion Criteria

Known allergy to local anesthetics

Coagulation abnormalities

Infection at the site of injection

Inability to comprehend the Visual Analog Scale (VAS)

Pregnant women

Randomization and Blinding

Patients were randomly allocated into two groups using a computer-generated random number table:

Group B (Bupivacaine group): Received 15 ml of 0.25% Bupivacaine on each side

Group R (Ropivacaine group): Received 15 ml of 0.5% Ropivacaine on each side

The patients were blinded to the group allocation.

Anesthetic Protocol

All patients underwent a pre-anesthetic check-up and were educated on the VAS pain scale (0 = no pain; 10 = worst imaginable pain). Standard fasting protocols were followed.

Upon arrival in the operating room, baseline monitoring included pulse rate (PR), non-invasive blood pressure (NIBP), electrocardiogram (ECG), respiratory rate (RR), end-tidal CO₂, and SpO₂.

Anesthesia induction was done using Inj. Glycopyrrolate (10 mcg/kg IV), Inj. Fentanyl (2 mcg/kg IV), and Inj. Propofol (2–2.5 mg/kg IV). Muscle relaxation was achieved with Inj. Vecuronium (0.1 mg/kg IV), followed by orotracheal intubation.

Maintenance was with sevoflurane (1–1.2 MAC), nitrous oxide (66%), and oxygen (33%). Additional fentanyl (1 mcg/kg) was administered as needed intraoperatively.

At the conclusion of surgery, TAP block was administered under landmark guidance as per group allocation. Neuromuscular blockade was reversed with Inj. Neostigmine (0.05 mg/kg) and Inj. Glycopyrrolate (0.01 mg/kg), followed by extubation and transfer to the postoperative recovery unit.

Postoperative Assessment

Pain was assessed using the VAS scale at regular intervals until 800 minutes postoperatively. Rescue analgesia (Inj. Paracetamol 15–20 mg/kg IV) was administered when VAS >3. If pain persisted after 30 minutes, Inj. Tramadol (50–100 mg IV) was given.

Parameters Monitored 

Primary outcomes:

Duration of effective analgesia (time from TAP block to VAS >3)

Time to first rescue analgesia

Secondary outcomes:

VAS scores at predefined intervals

Hemodynamic variables (HR, SBP, DBP, MAP, SpO₂)

Frequency of rescue analgesia

Complications (if any)

Hemodynamic parameters and VAS scores were recorded at baseline, 5, 10, 15, 20, 25, 30, 45, 60, 75, 90, 105, 120, 180, 240, 300, 360, 420, 480, 540, 600, 660, 720, and 800 minutes postoperatively.

Statistical Analysis

Data were analyzed using appropriate statistical tests. Quantitative data were presented as mean ± standard deviation (SD) and compared using the Student’s t-test. Categorical variables were analyzed using Chi-square test. A p-value <0.05 was considered statistically significant.

Ethical Considerations

The study was approved by the Institutional Ethics Committee of Government Medical College and Government General Hospital, Anantapuramu, Andhra Pradesh, India, on 11-08-2022 (IEC No: 19-08-2022, GMC-GGH). Informed written consent was obtained from all participants after providing a detailed explanation of the study objectives and procedures.

A total of 60 patients undergoing elective abdominal surgeries under general anesthesia were enrolled and randomly assigned into two equal groups receiving either 0.25% Bupivacaine or 0.5% Ropivacaine for Transverse Abdominis Plane (TAP) block.

Demographic and Baseline Characteristics

There was no statistically significant difference between the Bupivacaine and Ropivacaine groups in terms of age, sex distribution, ASA status, or mean body weight. The mean age was 40.13 ± 12.63 years in the Bupivacaine group and 44.16 ± 10.91 years in the Ropivacaine group (p = 0.34). Gender distribution was comparable (43.3% males in Bupivacaine vs. 60% in Ropivacaine, p = 0.20), as was ASA physical status (p = 0.60) and mean weight (p = 0.97) (Table 1).

Table 1: Demographic Characteristics of Study Participants

Figure 1. Demographic Characteristics of Study Participants

Duration of Analgesia and Rescue Analgesic Requirement

The total duration of analgesia was significantly longer in the Ropivacaine group (725.33 ± 18.89 minutes) compared to the Bupivacaine group (408 ± 14.10 minutes), with a p-value of 0.001. Similarly, the mean time to first rescue analgesia was delayed in the Ropivacaine group (735.33 ± 18.89 minutes vs. 417.67 ± 15.01 minutes; p = 0.001). No complications were reported in either group (Table 2).

Table 2: Analgesia Duration and Rescue Requirements

Figure 2. Analgesia Duration and Rescue Requirements

Pain Intensity Based on VAS Scores

Postoperative pain was assessed using the Visual Analog Scale (VAS) at various intervals. Statistically significant differences in VAS scores were observed at multiple key time points, particularly after 480 minutes, favoring the Ropivacaine group. At 540 minutes, the VAS score was 3.23 ± 0.90 in the Bupivacaine group versus 0.60 ± 0.50 in the Ropivacaine group (p < 0.001). Even at 800 minutes, pain scores remained significantly lower in the Ropivacaine group (2.43 ± 1.01 vs. 4.87 ± 1.36; p < 0.001) (Table 3).

Table 3: VAS Scores at Key Time Intervals

Figure 3. VAS Scores at Key Time Intervals

Hemodynamic Parameters

Heart rate and blood pressure were monitored at regular intervals. The Ropivacaine group consistently demonstrated lower heart rates than the Bupivacaine group, with significant differences noted at 5-, 10-, 15-, and 25-minutes post-block. For example, at 10 minutes, the mean heart rate was 79.13 bpm in the Ropivacaine group compared to 83.47 bpm in the Bupivacaine group (p = 0.006).

Systolic and diastolic blood pressures were also lower in the Ropivacaine group at certain time points. At 25 minutes post-block, the systolic blood pressure was 108.20 mmHg in the Ropivacaine group versus 115.40 mmHg in the Bupivacaine group (p = 0.008), and the diastolic pressure was 66.60 mmHg versus 70.47 mmHg respectively (p = 0.027) (Table 4).

Table 4: Hemodynamic Parameters at Selected Time Points

This randomized controlled trial evaluated the efficacy of 0.25% Bupivacaine versus 0.5% Ropivacaine in Transverse Abdominis Plane (TAP) block for postoperative analgesia in patients undergoing abdominal surgeries under general anesthesia.

Baseline demographic characteristics, including age, gender, ASA status, and weight, were statistically comparable between the two groups, thereby minimizing confounding variables and enhancing the internal validity of the study.

The duration of analgesia was significantly longer in patients who received Ropivacaine (725.33 ± 18.89 minutes) compared to those who received Bupivacaine (408 ± 14.10 minutes), with a highly significant p-value (p=0.001). Similarly, the time to first rescue analgesia was significantly delayed in the Ropivacaine group (735.33 ± 18.89 minutes vs. 417.67 ± 15.01 minutes; p=0.001), confirming the prolonged analgesic efficacy of Ropivacaine. These findings align with previous studies that demonstrated the superior pharmacokinetic and analgesic profile of Ropivacaine in TAP blocks7-9.

Postoperative pain scores (VAS) were consistently lower in the Ropivacaine group across various time intervals, with statistically significant differences noted between 10 and 800 minutes (Table 3). At 540 minutes postoperatively, the VAS score in the Bupivacaine group was 3.23 ± 0.90, compared to 0.60 ± 0.50 in the Ropivacaine group (p<0.001), highlighting its enhanced analgesic effectiveness10-11.

Hemodynamic parameters such as heart rate and blood pressure remained within normal physiological ranges for both groups. However, the Ropivacaine group showed statistically lower values at select intervals post-block, particularly at 5, 10, 15, and 25 minutes (Table 4), indicating a more stable perioperative autonomic profile, though not clinically alarming12-13.

Importantly, no complications were observed in either group throughout the study period. This confirms the favorable safety profile of both agents, especially Ropivacaine, which has demonstrated lower cardiotoxicity and reduced motor block compared to Bupivacaine¹⁴.

Limitations

The study was limited by the use of the landmark technique rather than ultrasound guidance, which may affect the precision of TAP block placement. Additionally, only a single dose of local anesthetic was used, without adjuncts or catheter-based techniques, which could influence the duration of analgesia.

This study demonstrates that 0.5% Ropivacaine is significantly more effective than 0.25% Bupivacaine when used in a Transverse Abdominis Plane (TAP) block for postoperative analgesia in patients undergoing abdominal surgeries. Ropivacaine provided a longer duration of analgesia, delayed the need for first rescue analgesia, and resulted in lower pain scores, without any reported complications. Hemodynamic parameters remained stable in both groups, with no adverse effects noted. Given its superior analgesic profile and safety, Ropivacaine appears to be a more advantageous choice for TAP blocks in abdominal surgeries. Future studies with larger sample sizes and ultrasound guidance may further validate these findings.

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