This observational study aims to investigate the impact of body composition on the absorption, distribution, and metabolism of anesthetic drugs, as well as on the incidence of complications in overweight and obese patients. The primary research question is whether specific body composition parameters in this population influence drug pharmacokinetics and complication rates. By integrating pharmacokinetic parameters, adverse drug reactions (ADRs), and clinical complications, the study will analyze variations in sufentanil kinetics under different body composition conditions. Under the guidance of research personnel, participants will undergo non-invasive body composition assessment using the nBody S10 analyzer. Key metrics collected will include, but are not limited to, mineral content, muscle mass, lean body mass (LBM), total body weight, and body fat percentage (BFP).

Inclusion Criteria:

1. Aged 18-65 years with ASA physical status I-III
2. Participants were divided into a normal control group (18.5 < BMI < 23.9 kg/m²) and an experimental group (BMI > 24 kg/m²)
3. Voluntary participation with written informed consent approved by the Ethics Committee
4. No cognitive or verbal communication impairments, with the ability to fully cooperate with the study procedures

Exclusion Criteria:

• 1: Severe organ dysfunction, including severe hepatic or renal insufficiency, unstable coronary syndrome, uncontrolled hypertension, and other severe cardiovascular diseases

  2: History of chronic pain or long-term use of opioids/sedatives; preoperative use of potent CYP3A inhibitors or inducers

  3: Contraindications to body composition measurement via Bioelectrical Impedance Analysis (BIA), including abdominal wall stoma, massive ascites, limb amputation/absence, and presence of cardiac pacemakers or implantable cardioverter-defibrillators (ICDs)

  4: Women who were pregnant or breastfeeding were excluded from the study

  5: Known hypersensitivity or allergy to study medications

  6: Any other condition deemed by the investigator to make the patient unsuitable for participation, including but not limited to severe psychiatric disorders or legal restrictions

Eligible participants were adults aged 18 to 65 years with an ASA physical status of I-III and a body mass index (BMI) greater than 24 kg/m², who were scheduled to undergo surgery under general anesthesia.

There is not a plan to make IPD available.