Inclusion criteria  Patients with American Society of Anesthesiologists (ASA) physical status 1-3 -- scheduled for VATS .  Exclusion Criteria:  ≤20 or ≥80 years old. Refusing to participate in the study . History of allergy to the medications used in the study. Contraindication to regional anesthesia (including coagulopathy and local infection). Severe hepatic impairement (serum protein < 3g/dl and serum bilirubin > 3mg/dl) . Renal dysfunction (as determined by creatinine levels greater than 2mg/dl or predicted creatinine clearance (CLcr)<50ml/min). Psychiatric disorder. Pregnancy. Body mass index (BMI) ≥40 or ≤18 kg/m2.