Effectiveness of ultrasound-guided Continuous Unilateral Erector Spinae Plane Block for Postoperative Analgesia in Modified Radical Mastectomy: A Randomised Clinical Study

Introduction: Modified Radical Mastectomy (MRM) can cause postoperative pain, which is often difficult to relieve due to the complex innervation of the breast. This may lead to chronic pain syndrome if not managed adequately. Continuous Erector Spinae Plane (ESP) block could be useful as it provides analgesia over a wide range of dermatomes and avoids opioidrelated adverse events. Aim: To evaluate the effectiveness of unilateral continuous ESP block in providing postoperative analgesia in MRM. Materials and Methods: A prospective randomised clinical study was conducted involving 56 females scheduled for MRM in Government Medical College, Kozhikode, Kerala, India. They were divided into two groups. Group E (n=28) received an ultrasound-guided ESP block using inj. Ropivacaine 0.5% 20 mL and an indwelling catheter was inserted in the plane. Group I (n=28) received local infiltration around the incision with 20 mL of 0.2% Ropivacaine. Postoperatively, patients in Group E received an infusion of Inj. Ropivacaine 0.2% at 5 mL/hr for 24 hours through the catheter. Postoperative pain was assessed using the Numerical Rating Scale (NRS). The time to the first rescue analgesic and the cumulative dose of rescue analgesic over 24 hours were recorded. The incidence of nausea or vomiting and haemodynamic parameters were also recorded. The Student’s t-test was used to determine the significance of parameters on a continuous scale, while the Fisher’s exact test/ Chi-square test was employed for categorical variables. Results: The mean NRS pain scores were significantly lower in Group E (p-value <0.001) at all time intervals. Group I required rescue analgesia earlier than Group E (p-value <0.001). The mean cumulative dose of rescue analgesics in 24 hours was significantly lower in Group E (p-value <0.001). The incidence of postoperative nausea or vomiting at six hours and 12 hours was significantly lower in Group E. Conclusion: Unilateral continuous ESP block is an effective technique for providing postoperative analgesia for patients undergoing MRM. It offers a longer duration of analgesia, a lesser requirement for postoperative rescue analgesics and a reduced incidence of nausea and vomiting.