Inclusion Criteria:  Body mass index>35 kg/m2 The American Society of Anaesthesiologists (ASA) physical status class II III Patients who will undergo an elective laparoscopic sleeve gastrectomy (LSG)  Exclusion Criteria:  refusal to participate allergy to the study drugs chronic kidney disease (creatinine>150 μmol/L) mental illness liver, respiratory or oncological disease, cardiac dysfunction (ejection fraction <40%), uncontrolled hypertension, preoperative analgesic use, chronic pain, history of alcohol or drug addiction