Inclusion Criteria:  Subject is scheduled to undergo Laparoscopic Bariatric Surgery Subject's American Society of Anesthesiologists physical status is I-III. BMI>35kg/m2 The subject's parent/legally authorized guardian has given written informed consent to participate  Exclusion Criteria:  Subject has a diagnosis of renal or liver failure. Subject has a diagnosis of mental illness Subject is allergy and contraindication to Ropivacaine. Subject has a history of chronic pain, a history of alcohol or opioid abuse, pre-existing therapy with opioids, intake of any analgesic drug within 48 hours before surgery. Subject has any contraindication for the use of patient-controlled analgesia (PCA). Subject is pregnant or breast-feeding.