This prospective observational study aims to validate the BBCMADE nomogram (Body Mass Index, Brain infarction, Cirrhosis, Male sex, Age, Diabetes, Esophageal reflux) for predicting high-risk gastric content in patients undergoing elective sedative gastrointestinal endoscopy in a Turkish population. Nomogram-predicted risk scores will be compared against the gold standard - endoscopically measured gastric volume and content. High-risk gastric content is defined as gastric volume ≥25 mL, pH <2.5, or presence of solid content. The nomogram is a non-invasive, web-based, easily applicable screening tool that requires no additional training or equipment, and may contribute to safer anesthesia management by identifying high-risk patients prior to the procedure.

Pulmonary aspiration of gastric contents accounts for 10-30% of anesthesia-related deaths. Standard fasting guidelines do not guarantee adequate gastric emptying in all patients. The BBCMADE nomogram, developed and validated by Yan et al. (2024) in a Chinese population, demonstrated high discriminatory power for predicting high-risk gastric residual content in outpatients undergoing sedative GI endoscopy. This study will prospectively evaluate its validity in a Turkish population (n=533).

The seven predictor variables (BMI, history of cerebral infarction, cirrhosis, male sex, age, diabetes, gastroesophageal reflux) will be recorded preoperatively and entered into the web-based nomogram interface. Endoscopic gastric volume measurement will serve as the gold standard. Discriminatory performance will be assessed by AUROC. Secondary analyses will include sensitivity, specificity, PPV, NPV, and subgroup analyses.

Sample size: 533 patients (prevalence ~13%, α=0.05, power=95%, 15% dropout allowance; calculated using G*Power 3).

Inclusion Criteria:

• Age 18 years or older
• ASA physical status I-III
• Scheduled for elective gastrointestinal endoscopy under sedoanalgesia
• Deemed suitable for out-of-OR anesthesia by the anesthesiology outpatient clinic
• Provision of written informed consent

Exclusion Criteria:

• Age under 18 years
• Pregnancy or suspected pregnancy
• ASA physical status IV or higher
• Emergency procedures
• Unable or unwilling to provide informed consent
• History of upper airway obstructive pathology or difficult airway
• Not eligible for out-of-OR anesthesia
• Known hypersensitivity to anesthetic agents

Consecutive adult patients presenting for elective sedative gastrointestinal endoscopy at Bursa Yuksek Ihtisas Training and Research Hospital

Individual participant data will not be shared. This is a single-center observational study conducted at a public hospital. Data sharing is not planned due to institutional privacy regulations and the absence of external funding requiring data sharing.