Comparison of Epidural Infusion of 0.1% Ropivacaine and 0.2% Ropivacaine for Postoperative Analgesia using Elastomeric Pump in Abdominal Hysterectomies: A Randomised Controlled Trial

Introduction: Epidural analgesia is a common and one of the standard modes of postoperative analgesia for surgeries involving the lower abdomen and lower extremities. The duration of action of Ropivacaine is longer and is favoured for its sensory block with minimal motor impairment, yet the optimal concentration for analgesia and adverse effects remains unclear. Aim: To compare the efficacy and safety of 0.1% Ropivacaine with Fentanyl 2 mcg/mL versus 0.2% Ropivacaine with Fentanyl 2 mcg/mL for postoperative pain relief using an elastomeric pump in abdominal hysterectomy patients. Materials and Methods: This was a double-blinded, randomised controlled trial conducted at the Department of Anaesthesia, SRM Medical College Hospital and Research Institute, Kattankulathur, Tamil Nadu, India, from August 2023 to December 2024. Patients who were undergoing abdominal hysterectomy as elective surgeries with American Society of Anaesthesiologists (ASA) physical status grading as I, II, or III from 35 years to 65 years were included. The study was conducted on 100 patients, who were divided into two groups: Group R1 (0.1% Ropivacaine with 2 mcg/mL Fentanyl) and Group R2 (0.2% Ropivacaine with 2 mcg/mL Fentanyl) as a continuous epidural infusion at 5 mL/hour via elastomeric pump for 48 hours postoperatively. Visual Analogue Scale (VAS) was used to assess the intensity of pain at rest, on movement and while coughing at regular intervals. Motor blockade was evaluated with the modified Bromage scale. Haemodynamic parameters were monitored, and rescue analgesia was provided with intravenous (i.v.) Paracetamol or Tramadol as required. An Unpaired t-test was used to compare continuous variables. Results: Between groups R1 and R2, demographic characteristics such as age, weight, height, Body Mass Index (BMI), baseline pulse rate, baseline Systolic Blood Pressure (SBP), and baseline Diastolic Blood Pressure (DBP) were comparable. At 30 min, 45 min and 1 hour, the heart rate was lower in group R2 (p-value <0.0001). At 15 min and 12 hours, group R2 had a lower Mean Arterial Pressure (MAP) (p-value=0.0005, p-value=0.0089) in contrast to group R1. VAS scores were comparable between the two groups, except at 24 hours, which was lower in group R2 (p-value=0.0232). Group R2 had significantly lower VAS scores during movement and cough. Significant motor blockade was observed in group R2 (p-value <0.05). Group R2 required fewer rescue analgesics (p-value <0.05). Conclusion: Ropivacaine (0.1%) provided adequate pain relief at rest. While on movement and coughing, 0.2% Ropivacaine had lower VAS scores with comparable haemodynamic stability between both groups. Motor blockade was more with 0.2% Ropivacaine.