Effectiveness of Combined Erector Spinae and Pecto-intercostal Fascial Plane Blocks Versus Thoracic Paravertebral Block in Perioperative Pain in Modified Radical Mastectomy

patients scheduled for modified radical mastectomy and axillary dissection under general anesthesia (GA) will be included in the study. The patients will be randomly allocated by a computer-generated table into one of the two study groups.Thoracic paravertebral block group (TPV group) and combined erector spinae and pecto-intercostal fascial plane blocks group (ES-PI group). 0.25% bupivacaine and 1 mg dexamethasone will be injected with different volumes in each block. The first time to ask for rescue analgesia post-operatively will be measured. Using MedCalc Software version 14 (MedCalc Software bvba, Ostend, Belgium), 24 patients (12 patients per group) were calculated for a relative difference of 10% (0.635 hours) in the time to first analgesic request between both groups, with a study power of 95% and an alpha error of 0.05. This number will be increased to 30 patients (15 patients per group) to compensate for possible dropouts. Analysis of data will be performed using the Statistical Package for Social Science (SPSS) software, version 21 for Microsoft Windows (SPSS Inc., Chicago, iL, USA). Categorical data will be reported as numbers and percentages and will be analyzed using the chi-squared test. Continuous data will be checked for normality using the Kolmogorov-Smirnov test. Normally distributed data will be presented as means (standard deviations) and will be analyzed using the unpaired student t-test. Skewed data will be expressed as medians(quartiles) and will be analyzed using the Mann Whitney U test. For repeated measures, a two-way repeated measures ANOVA will be used to evaluate block (between-groups factor) and time (repeated measures)". Post-hoc pairwise comparison will be performed using the Bonferroni test. A P value of 0.05 or less will be considered significant.