Preoperative Gastric Ultrasound to Assess Stomach Contents and Aspiration Risk in Patients With Diabetes

This is a prospective, observational, single-center study to be conducted at the University of Health Sciences Gazi Yasargil Training and Research Hospital. Approximately 130 adult patients (aged 18-80 years, ASA physical status I-III) with type 1 or type 2 diabetes mellitus scheduled for elective surgery under general anesthesia will be enrolled after written informed consent.

Each patient will be assessed at a single time point in the preoperative holding area before induction of anesthesia. Gastric ultrasound will be performed in the supine and right lateral decubitus positions. The anteroposterior and craniocaudal diameters of the gastric antrum will be measured, and the antral cross-sectional area (CSA) will be calculated. Gastric volume (GV) will be estimated using the Perlas formula \[GV (mL) = 27 + 14.6 x CSA - 1.28 x age\] and normalized to body weight (mL/kg). Gastric content will be classified according to the Perlas grading system (Grade 0-2). Patients with Perlas Grade 2 and/or GV \>1.5 mL/kg will be classified as having high aspiration risk.

Demographic data, diabetes-related clinical parameters (type and duration of diabetes, HbA1c, fasting blood glucose, insulin and oral antidiabetic use), details of GLP-1 receptor agonist use (drug, dose, frequency, and time since last dose), preoperative fasting durations, and gastroparesis symptoms assessed with the Gastroparesis Cardinal Symptom Index (GCSI) will be recorded by a second investigator.

To minimize measurement bias, the ultrasound examination will be performed by a single trained anesthesiologist blinded to the patients' clinical data, while the investigator collecting clinical data will be blinded to the ultrasound findings.

Patients will be followed for 24-48 hours postoperatively through medical records for postoperative nausea and vomiting, fever, cough, dyspnea, pulmonary infiltrates on chest radiography, and clinical signs of aspiration pneumonia.

Factors associated with high aspiration risk will be analyzed using univariable and multivariable logistic regression. Correlations between gastric volume and HbA1c, diabetes duration, fasting duration, and GCSI score will be assessed using Pearson or Spearman correlation.

dult patients (18-80 years, ASA physical status I-III) with type 1 or type 2 diabetes mellitus scheduled for elective surgery under general anesthesia, who will undergo a single preoperative gastric ultrasound assessment and 24-48 hours of postoperative follow-up for clinical signs of aspiration.

Diagnostic Test: Preoperative Gastric Ultrasound

Bedside gastric ultrasound performed in the supine and right lateral decubitus positions in the preoperative holding area before induction of anesthesia. The antral cross-sectional area will be measured, gastric volume will be calculated using the Perlas formula and normalized to body weight (mL/kg), and gastric content will be classified using the Perlas grading system. The examination is non-invasive and part of a single assessment; no drug or treatment is administered.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Gastric ultrasound will be performed in both the supine and right lateral decubitus positions. Gastric volume will be estimated from the antral cross-sectional area measured in the right lateral decubitus position using the Perlas formula \[GV (mL) = 27 + 14.6 x CSA - 1.28 x age\] and normalized to body weight (mL/kg). The distribution of residual gastric volume will be reported as mean, standard deviation, median, interquartile range, and minimum-maximum values.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Proportion of patients classified as having high aspiration risk, defined as Perlas Grade 2 (fluid visible in both supine and right lateral decubitus positions) and/or gastric volume \>1.5 mL/kg. Prevalence will be reported with 95% confidence interval

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Correlation between preoperative HbA1c level (%) and weight-normalized gastric volume (mL/kg), assessed using Pearson or Spearman correlation coefficient.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Correlation between duration of diabetes mellitus (years) and weight-normalized gastric volume (mL/kg), assessed using Pearson or Spearman correlation coefficient.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Weight-normalized gastric volume (mL/kg) compared between GLP-1 receptor agonist users and non-users. Among users, gastric volume will be compared between patients whose last dose was taken ≤7 days and \>7 days before the preoperative assessment

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Weight-normalized gastric volume (mL/kg) compared between patients using and not using insulin therapy.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Correlation between preoperative solid and clear fluid fasting durations (hours) and weight-normalized gastric volume (mL/kg), assessed using Pearson or Spearman correlation coefficient.

Plazo: Preoperatively, before induction of anesthesia (single assessment)

Correlation between total GCSI score (range 0-5, higher scores indicate more severe gastroparesis symptoms) and weight-normalized gastric volume (mL/kg), assessed using Pearson or Spearman correlation coefficient.

Plazo: Up to 48 hours after surgery

Number of patients developing clinical signs of pulmonary aspiration (fever, cough, dyspnea, new pulmonary infiltrate on chest radiography) or aspiration pneumonia, and postoperative nausea and vomiting, assessed from medical records.

Distribution of Residual Gastric Volume Assessed by Preoperative Gastric Ultrasound, Aspiration Risk, and Related Factors in Diabetic Patients Undergoing Elective Surgery: A Prospective Observational Study