Gastric Insufflation
Conditions
Brief summary
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
Detailed description
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.
Interventions
DEVICE"Ultrasound-Guided Optimization of Inspiratory Pressure During Facemask Ventilation"
Description: Group A will be subjected to an inspiratory pressure of 10 cmH₂O. A curvilinear ultrasound probe will be placed in the epigastric region to visualize the antrum. Baseline gastric ultrasound will be performed to confirm an empty stomach. During FMV, ultrasound images will be obtained at 30, 60, and 90 seconds. Gastric insufflation will be detected by the change in gastric cross-sectional area (ΔCSA).
Sponsors
Benha University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Outcomes Assessor)
Intervention model description
•"Face mask ventilation with isoflurane for 90 seconds assisted by oropharyngeal or nasopharyngeal airway before endotracheal intubation. The inspiratory pressure will be adjusted according to the 4 groups at (10-15-20-25 cmH₂O) and set on the anesthesia ventilator (PEEP = 5 cmH₂O). Ventilation will be pressure-controlled with FiO₂ 100%, RR = 14 breaths/min, I:E = 1:2. The study inspiratory pressure refers to the set inspiratory pressure above PEEP (i.e., set PIP). 1. A curvilinear ultrasound probe (2-5 MHz) will be placed in the epigastric region to visualize the antrum. 2. Baseline gastric ultrasound will be performed to confirm an empty stomach (cross-sectional area of the antrum \<3.4 cm²). 3. During FMV, ultrasound images will be obtained at 30 s, 60 s, and 90 s. Gastric insufflation is defined as any of the following: Appearance of air artifacts ("comet tail" or "ring-down" artifacts). Increase in antral cross-sectional area ≥3.4 cm². ΔCSA (cross-sectional area) \>30%."
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
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.
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Incidence of Gastric insufflation (ultrasound-confirmed) during FMV | At 30 seconds, 60 seconds, and 90 seconds after induction |
Secondary
| Measure | Time frame |
|---|---|
| Tidal volume (mL/kg ideal body weight) and peak inspiratory pressure | at 30, 60, and 90 seconds of facemask ventilation (FMV) |
| Oxygen saturation (SpO₂) | At baseline and 30 seconds, 60 seconds, and 90 seconds during FMV |
| End tidal CO2 | At baseline and 30 seconds, 60 seconds, and 90 seconds during FMV |
| Antral cross-sectional area | at baseline (15 minutes before induction) and 30, 60, 90 seconds during FMV. |
| Heart rate | At baseline, 30, 60, 90 seconds during facemask ventilation and one minute after endotracheal tube placement |
| Mean arterial blood pressure | At baseline, 30, 60, 90 seconds during facemask ventilation and one minute after endotracheal tube placement |
| Hypoxia occurrence | Monitored continuously from induction of anesthesia till one minute after endotracheal intubation |
| Aspiration events | Continuously monitored, intraoperatively and postoperatively (24-hour follow-up). |
Countries
Egypt
Contacts
CONTACTmohamed a mustafa, MSC
CONTACTalaa b mohamed, MBBCH
Outcome results
None listed