Determination of the Optimal Inspiratory Pressure to Decrease Incidence of Gastric Insufflation With Adequate Ventilation During Facemask Ventilation in Morbidly Obese Patients

Ultrasound-Guided Optimization of Inspiratory Pressure During Facemask Ventilation in Morbidly Obese Patients to Prevent Gastric Insufflation: A Randomized Clinical Trial

The goal of this randomized clinical trial is to optimize the inspiratory pressure during facemask ventilation (FMV) in morbidly obese patients (BMI ≥40 kg/m²), to ensure adequate ventilation while minimizing the risk of gastric insufflation by real-time ultrasound guidance

Morbid obesity, defined as a body mass index (BMI) ≥ 40 kg/m², presents significant challenges during the management of the airway and ventilation under general anesthesia. One of the critical issues is the increased risk of gastric insufflation during facemask ventilation (FMV), which can lead to pulmonary aspiration, reduced lung compliance, and impaired oxygenation. Therefore, optimizing inspiratory pressure to ensure adequate ventilation while minimizing the risk of gastric insufflation is paramount in this population.

Ultrasound imaging has emerged as a valuable, non-invasive tool for real-time assessment of gastric content and volume. Recent studies have demonstrated the utility of gastric ultrasonography in detecting gastric insufflation during positive pressure ventilation. By visualizing the antrum and measuring the cross-sectional area , anesthesiologists can identify even small volumes of air entering the stomach, which might not be clinically apparent.

Inclusion Criteria:

• Adult patients (18-65 years old) scheduled for elective surgery under general anesthesia requiring facemask ventilation.

  • Morbid obesity (BMI ≥40 kg/m²).
  • American Society of Anesthesiologists (ASA) physical status II-III.
  • Normal upper gastrointestinal anatomy (no history of gastric surgery, esophageal strictures, or hiatus hernia).
  • Fasted for at least 6 hours for solids and 2 hours for fluids (standard preoperative fasting guidelines).

Exclusion Criteria:

• • Emergency surgery (due to inability to ensure proper fasting or preoperative assessment).

  • Known or suspected difficult airway (Mallampati class IV, limited neck mobility, or history of difficult intubation).
  • Gastroesophageal reflux disease (GERD) or high aspiration risk (e.g., pregnancy, symptomatic hiatal hernia).
  • Contraindications to facemask ventilation (facial trauma, beard/mask seal interference).
  • Severe cardiopulmonary disease (e.g., severe COPD, pulmonary hypertension, or unstable angina).
  • Neuromuscular disorders affecting respiratory function.
  • Refusal to participate or inability to provide informed consent.