A clinical trial to study a technique of pain relief with different drugs for patients undergoing breast cancer surgery

INTERVENTION: Intervention1: Single shot paravertebral block; Group A: 0.25% bupivacaine 0.3ml/kg + ketamine 0.5mg/kg Control Intervention1: Single shot paravertebral block; Group B: 0.25% bupivacaine 0.3ml/kg CONDITION: Breast cancer patients undergoing Modified Radical Mastectomy PRIMARY OUTCOME: Intra‐operative fentanyl consumption, Post operative morphine consumption, Post operative pain scores‐‐‐‐‐‐Timepoint: during surgery, at 0,2,6,12 and 24 hours in the post operative period SECONDARY OUTCOME: Post operative nausea and vomiting, pruritus, urinary retention, pnemothorax, respiratory depression‐‐‐‐‐‐Timepoint: 24 hours post operative period INCLUSION CRITERIA: Breast cancer patients undergoing modified radical mastectomy, under 60 years of age, belonging ASA physical status 1 and 2