The Improvement of Low-dose Esketamine on Postoperative Depression in Patients Undergoing Bariatric Surgery With Preoperative Depression

Inclusion Criteria: * Age ≥18 years old and \<65 years old * Patients with a BMI greater than 35 kg/m\^2 * Hamilton Depression score ≥7 points * Planned to undergo elective laparoscopic sleeve gastrectomy Exclusion Criteria: * ASA ≥ grade IV * Those who have had or are currently suffering from mental disorders other than anxiety and depression, such as schizophrenia, bipolar disorder, organic mental disorders, etc. * Those who are unable to cooperate in completing the scale assessment * Have received ketamine/esketamine treatment, or are allergic to ketamine/esketamine * Clarify ischemic cardiomyopathy or severe liver and kidney dysfunction (Child pugh grade C, CKD stage G5) * People with opioid dependence and those who have been taking various types of painkillers for a long time (more than 3 months) * Participate in other research