A comparative study of analgesic efficacy of ultrasound-guided serratus anterior plane block versus landmark-guided thoracic paravertebral block for modified radical mastectomy under general anesthesia

Abstract

Background: Postoperative pain is a common sequel of modified radical mastectomy (MRM) and, when left unrelieved may progress to chronic pain syndrome known as persistent pain after breast cancer surgery. With increased breast cancer survival seen in recent years, it has become increasingly important to recognize and implement the best modalities of pain-relieving treatment. Aims: The aim of the study was to compare the analgesic efficacy of ultrasound (US)-guided serratus anterior plane block (SAPB) and conventional anatomical landmark-guided thoracic paravertebral block (TPVB) for MRM in terms of time to first request for rescue analgesia and other associated characteristics in terms of time taken to perform both blocks (in minutes), intraoperative fentanyl consumption, Visual Analog Scale (VAS) score and morphine consumption on the 1st postoperative day, intraoperative and postoperative hemodynamics (heart rate and mean arterial pressure), and complications of either block techniques. Settings and Design: This study was conducted at a single-center tertiary care hospital in the form of parallel-group randomized controlled trial (RCT), which was based on computer-generated randomization. Materials and Methods: This RCT was conducted on 78 adult females posted for MRM. After intubation, patients were administered a single-shot injection of either TPVB at T4 (Group T, n = 39) or SAPB between the 4th and 5th ribs (Group S, n = 39) with 20 ml of 0.5% bupivacaine. Time to first rescue analgesic, morphine consumption in patient-controlled analgesia pump, VAS score, intraoperative hemodynamics, and adverse effects were recorded. Statistical Analyses: All raw data were entered into a Microsoft Excel spreadsheet and analyzed using the appropriate statistical methods using SPSS (version 27.0; SPSS Inc., Chicago, IL, USA). Data were expressed in mean ± standard deviation (SD), and P < 0.05 was considered statistically significant. Data were summarized by routine descriptive statistics, namely mean and SD for numerical variables that are normally distributed, the median and interquartile range for skewed numerical variables, and counts and percentages for the categorical variables. Numerical variables were compared between the groups by Student's independent sample t-test, when normally distributed and by Mann–Whitney U-test when skewed. Results: The duration of analgesia was significantly longer in the TPVB group as compared to the SAPB group (7.77 ± 1.317 h vs. 6.59 ± 1.174 h, P < 0.05). The postoperative 24 h morphine consumption (mean ± SD) was also significantly higher in the SAPB group as compared to the TPVB group (7.03 ± 1.135 mg vs. 5.74 ± 1.21 mg, P < 0.05). Conclusion: Preincisional conventional anatomical landmark-guided TPVB is significantly superior to preincisional US-guided SAPB in terms of duration of analgesia and overall morphine consumption in post-MRM patients.