Laparoscopic abdominal surgery has become the standard of care for many surgical procedures due to its well-established benefits including reduced tissue trauma, decreased postoperative pain, shorter hospital stays, faster recovery, and improved cosmetic outcomes. However, postoperative pain remains a significant concern, arising from multiple sources including parietal peritoneal stretch, visceral irritation, diaphragmatic irritation from residual carbon dioxide, and referred shoulder pain.^1-3

Effective postoperative pain management is crucial for early mobilization, enhanced recovery, and patient satisfaction. While systemic opioids have traditionally been used, their adverse effects such as nausea, vomiting, sedation, respiratory depression, and delayed bowel motility have prompted the search for alternative, opioid-sparing analgesic techniques.⁴

Intraperitoneal instillation of local anesthetics has emerged as a simple, cost-effective, and safe technique for managing postoperative pain following laparoscopic procedures.⁵ Among the various local anesthetics available, ropivacaine has gained widespread acceptance due to its favorable pharmacological profile. Ropivacaine is a pure S-enantiomer amide local anesthetic that provides effective sensory blockade with significantly reduced cardiotoxicity and neurotoxicity compared to its predecessor bupivacaine.^6,7 The reduced cardiotoxicity of ropivacaine is attributed to its weaker binding affinity for cardiac sodium channels and its stereoselective properties.⁸

When administered intraperitoneally, ropivacaine acts locally on peritoneal nociceptors, inhibiting sodium channel conductance and preventing the initiation and propagation of action potentials in afferent nerve fibers. This results in effective analgesia for both visceral and somatic components of postoperative pain.⁹ The drug is gradually absorbed from the peritoneal surface through mesothelial cells and diaphragmatic lymphatics, providing sustained local effect without high plasma peaks.¹⁰

Despite the growing body of evidence supporting the analgesic efficacy of intraperitoneal ropivacaine, comprehensive data regarding its hemodynamic safety profile when administered through this route remains limited. Previous studies have primarily focused on analgesic outcomes, with hemodynamic parameters often reported as secondary observations.^11-13

The present study was therefore designed to specifically evaluate the hemodynamic stability associated with intraperitoneal instillation of 0.375% ropivacaine compared with placebo in patients undergoing laparoscopic abdominal surgery, with the hypothesis that ropivacaine would not produce significant hemodynamic alterations.

MATERIALS AND METHODS

Study Design and Setting

This was a prospective, randomized, double-blind, placebo-controlled comparative study conducted at Basaveshwara Medical College and Hospital, Chitradurga, over a period from February 2024 to August 2025. The study was approved by the Institutional Ethical Committee (IEC No: 197/23-24) and was registered with the institutional clinical trial registry. The study was conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice guidelines. Written informed consent was obtained from all participants prior to their enrollment.

Study Population

A total of 60 patients of either sex, aged 18-60 years, with body weight between 50-80 kg, and classified as American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective laparoscopic abdominal surgery under general anesthesia, were included in the study.

Inclusion Criteria:

• Patients willing to participate in the study
• ASA Grade I and II patients scheduled for elective laparoscopic abdominal surgery
• Age between 18-60 years of either sex
• Weight between 50-80 kg

Exclusion Criteria:

• Patients with severe systemic diseases
• Patients with morbid obesity, heart block, hepatorenal disturbances
• Patients converted to open surgery
• History of chronic use of analgesics
• History of hypersensitivity to ropivacaine
• Pregnancy

2.3 Sample Size Calculation

Sample size was calculated based on published data from a previous study,¹¹ considering the anticipated difference in pain scores between groups. Assuming Type I error of 5% and Type II error of 20% (power of 80%), with a clinically significant decrease in pain score of 25%, the calculated sample size was 27 patients per group. To account for potential dropouts, the final sample size was rounded to 30 patients in each group.

Randomization and Blinding

Patients were randomly allocated into two groups of 30 each using computer-generated random numbers. The allocation sequence was concealed in sequentially numbered, opaque, sealed envelopes. Both the patients and the investigator responsible for recording hemodynamic parameters and assessing outcomes were blinded to group allocation.

Group R (n=30): Received intraperitoneal instillation of 20 ml of 0.375% ropivacaine (75 mg).

Group S (n=30): Received intraperitoneal instillation of 20 ml of 0.9% normal saline as placebo.

The study drug was prepared by an independent anesthesiologist not involved in patient assessment, ensuring blinding. The total dose of ropivacaine (75 mg) was calculated to remain below the maximum recommended dose of 3 mg/kg in all patients.

Preoperative Preparation

All patients underwent a thorough preanesthetic evaluation one day prior to surgery, including detailed history, clinical examination, airway assessment using Mallampati grading, and baseline investigations (complete hemogram, blood glucose, renal function tests, liver function tests, urine analysis, 12-lead ECG, and chest X-ray). Patients were instructed to fast according to ASA nil per oral guidelines. Premedication with Tab Alprazolam 0.25 mg and Tab Pantoprazole 40 mg was given orally the night before surgery.

Anesthesia Protocol

On the day of surgery, patients were shifted to the operation theater and connected to a multichannel monitor (Philips IntelliVue) for continuous monitoring of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), end-tidal carbon dioxide (EtCO₂), oxygen saturation (SpO₂), and electrocardiogram (ECG - Lead II). Baseline readings were recorded by the blinded anesthesiologist.

An 18G intravenous cannula was secured, and preloading with crystalloid solution was initiated. Patients were premedicated with IV Glycopyrrolate 0.2 mg and IV Fentanyl 2 mcg/kg. After preoxygenation with 100% oxygen for 3 minutes, general anesthesia was induced with IV Propofol 2 mg/kg and IV Suxamethonium 2 mg/kg to facilitate endotracheal intubation. An appropriately sized cuffed endotracheal tube was inserted under direct laryngoscopy, and bilateral air entry was confirmed along with end-tidal capnography. Anesthesia was maintained with a mixture of oxygen, nitrous oxide, isoflurane, and Vecuronium.

Laparoscopic surgeries were performed according to standard surgical and anesthesia protocols. Pneumoperitoneum was achieved using non-humidified and non-heated carbon dioxide, with intra-abdominal pressure maintained between 12-14 mmHg. All patients received IV Paracetamol 15 mg/kg 30 minutes prior to extubation.

Intervention

At the end of the surgical procedure, before removal of the trocars, the study drug (20 ml of either 0.375% ropivacaine or normal saline) was injected intraperitoneally with the patient in Trendelenburg's position to facilitate dispersion of the drug solution in the subhepatic region.

Data Collection and Outcome Measures

Primary Outcome Measures:

• Comparison of hemodynamic parameters (HR, SBP, DBP, MAP, SpO₂, and temperature) between the two groups at various time intervals

Secondary Outcome Measures:

• Incidence of adverse effects (hypotension, bradycardia, arrhythmias, respiratory depression, nausea, vomiting)

Hemodynamic parameters were recorded at the following time points:

Baseline: Before induction of anesthesia

After Drug Instillation: 1, 2, 5, 8, and 10 minutes after intraperitoneal instillation

Postoperatively: 0 hours (immediately after surgery), 0.5 hours, 1 hour, 2 hours, and then at 2-hourly intervals up to 24 hours (4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 hours)

All recordings were performed using the same monitoring equipment and by the same blinded investigator to minimize measurement bias. Any episodes of hemodynamic instability, defined as hypotension (SBP < 90 mmHg or > 30% decrease from baseline), bradycardia (HR < 50 beats/min), or any arrhythmia requiring intervention, were recorded and managed according to standard protocols.

Statistical Analysis

Data were compiled using Microsoft Excel and analyzed using Statistical Package for Social Sciences (SPSS) version 20. Continuous variables were expressed as mean ± standard deviation (SD) and analyzed using the independent samples t-test after checking for normality of distribution. Categorical variables were expressed as frequencies and percentages and analyzed using the Chi-square test. A p-value of < 0.05 was considered statistically significant, and p < 0.001 was considered highly significant.

RESULTS

A total of 60 patients completed the study, with 30 patients in each group. Both groups were comparable with respect to demographic characteristics and baseline parameters, confirming successful randomization.

Table 1: Demographic Characteristics

Statistical comparison using unpaired t-test for continuous variables and Chi-square test for categorical variables. P < 0.05 considered significant.

There were no statistically significant differences between the groups in terms of age (p = 0.7612), weight (p = 0.6899), gender distribution (p = 0.793), or ASA grade distribution (p = 0.786). This homogeneity is crucial for ensuring that any differences observed can be attributed to the intervention rather than demographic variations.

Table 2: Baseline Hemodynamic Parameters

Baseline hemodynamic parameters recorded before induction of anesthesia were comparable between both groups, with no statistically significant differences observed (p > 0.05).

Table 3: Comparison of Heart Rate (beats/min) - Selected Time Points

Values expressed as Mean ± SD. P < 0.05 considered significant.

Heart rate was monitored throughout the study period. Both groups showed a gradual decline in heart rate from baseline during the immediate postoperative period, which was expected due to the effects of anesthesia and surgical stress resolution. There were no statistically significant differences in heart rate between the two groups at any time point (p > 0.05 for all measurements).

Table 4: Comparison of Systolic Blood Pressure (mmHg) - Selected Time Points

Values expressed as Mean ± SD. P < 0.05 considered significant.

Systolic blood pressure remained stable in both groups throughout the observation period. While there was a slight decline from baseline in both groups following drug instillation, the values remained within clinically acceptable ranges. No statistically significant differences were observed between the groups at any time point.

Table 5: Comparison of Diastolic Blood Pressure (mmHg) - Selected Time Points

Values expressed as Mean ± SD. P < 0.05 considered significant.

Diastolic blood pressure trends mirrored those of systolic blood pressure, remaining stable throughout the study period. No significant differences were observed between the ropivacaine and placebo groups at any measured time interval (p > 0.05 for all comparisons).

Table 6: Comparison of Mean Arterial Pressure (mmHg) - Selected Time Points

Mean arterial pressure, a comprehensive indicator of tissue perfusion, remained stable and comparable between both groups at all time points. The MAP values gradually declined from baseline during the postoperative period and then recovered, with no significant intergroup differences (p > 0.05 for all measurements).

Table 7: Comparison of Oxygen Saturation (%) - Selected Time Points

Values expressed as Mean ± SD. P < 0.05 considered significant.

Oxygen saturation remained consistently above 99% in both groups at all time points, reflecting adequate oxygenation throughout the perioperative period. No statistically significant differences were observed between the groups (p > 0.05 for all measurements), confirming that intraperitoneal ropivacaine does not impair respiratory function.

Table 8: Comparison of Body Temperature (°C) - Selected Time Points

Body temperature remained stable throughout the perioperative period in both groups, with no significant intergroup differences (p > 0.05 for all measurements). The mean temperatures ranged from 36.81°C to 37.04°C, within the normal physiological range.

DISCUSSION

The primary objective of this study was to evaluate the hemodynamic stability following intraperitoneal instillation of 0.375% ropivacaine compared with placebo in patients undergoing laparoscopic abdominal surgery. Our findings demonstrate that intraperitoneal ropivacaine does not produce significant hemodynamic alterations when compared with placebo, establishing it as a safe technique for postoperative analgesia.

The results of this study clearly demonstrate that all hemodynamic parameters—heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, oxygen saturation, and body temperature—remained stable and comparable between the ropivacaine and placebo groups throughout the entire 24-hour observation period. No statistically significant differences were observed at any measured time interval (p > 0.05 for all parameters).

This finding is consistent with the known pharmacological profile of ropivacaine. Ropivacaine is a pure S-enantiomer amide local anesthetic that was specifically developed as a safer alternative to bupivacaine.⁶ The reduced cardiotoxicity of ropivacaine is attributed to its lower affinity for cardiac sodium channels, resulting in less myocardial depression, fewer conduction disturbances, and a lower risk of arrhythmias.^8,14

Several studies have supported the cardiovascular safety of ropivacaine. Scott et al. demonstrated that ropivacaine has a significantly wider margin of safety between its central nervous system and cardiovascular toxic doses compared to bupivacaine.¹⁵ Similarly, Knudsen et al. reported that ropivacaine produced less cardiac toxicity in animal models.¹⁶

When administered intraperitoneally, ropivacaine undergoes gradual absorption from the peritoneal surface, resulting in moderate plasma concentrations that do not reach toxic levels.¹⁰ The absorption occurs through mesothelial cells and diaphragmatic lymphatics, with peak plasma concentrations occurring approximately 30-60 minutes after instillation.¹⁷ The moderate absorption profile explains why intraperitoneal administration does not result in the high plasma peaks associated with intravascular injection.

Our findings are consistent with previous studies that evaluated the hemodynamic effects of intraperitoneal local anesthetics. Labaille et al. studied the clinical efficacy and pharmacokinetics of intraperitoneal ropivacaine for laparoscopic cholecystectomy and reported no significant hemodynamic changes.¹⁷ Similarly, Kim et al. evaluated intraperitoneal ropivacaine and found stable hemodynamics with no adverse effects.¹⁸

Neha T. Das and Charulata Deshpande, in their comparative study of intraperitoneal bupivacaine and ropivacaine, reported that ropivacaine provided superior analgesia without significant hemodynamic effects.¹¹ The absence of hemodynamic changes in their study, as in ours, supports the safety profile of ropivacaine.

Sharan et al., comparing intraperitoneal bupivacaine and ropivacaine for postoperative analgesia in laparoscopic cholecystectomy, found lower heart rates and blood pressure values in the ropivacaine group but concluded that these were clinically insignificant.¹³ The ropivacaine group in their study had values within normal ranges, and the differences were not clinically meaningful.

Dinesh Singh et al. evaluated the effect of intraperitoneal ropivacaine for postoperative pain management and reported stable hemodynamics with no adverse effects.¹⁹ These findings corroborate our results.

CONCLUSION

Intraperitoneal instillation of 0.375% ropivacaine (75 mg) at the end of laparoscopic abdominal surgery demonstrates excellent hemodynamic stability, with no statistically significant differences in heart rate, blood pressure, mean arterial pressure, oxygen saturation, or body temperature when compared with placebo over a 24-hour observation period. All hemodynamic parameters remained within clinically acceptable ranges, and no adverse effects such as hypotension, bradycardia, arrhythmias, or respiratory depression were observed in either group. These findings confirm that intraperitoneal ropivacaine is a safe technique with a favorable cardiovascular safety profile, making it a reliable and effective option for postoperative analgesia in ASA I and II patients undergoing laparoscopic abdominal surgery, with the added benefit of avoiding opioid-related complications.

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