The 90% Effective Ventilation Pressure (EP90) for Esophageal Insufflation Avoidance During Anesthesia Induction

The 90% Effective Ventilation Pressure (EP90) for Esophageal Insufflation Avoidance During Anesthesia Induction: A Bias-Coin Design With Up-and-Down Sequential Allocation Trial

Exploring the 90% Effective Ventilation Pressure (EP90) for Esophageal Insufflation Avoidance During Anesthesia Induction: The aim is to determine the optimal ventilation pressure for esophageal insufflation avoidance during anesthesia induction and to explore its guiding significance for anesthesia management. The goal is to provide a more precise and personalized ventilation pressure setting standard for clinical anesthesia, thereby enhancing the safety of the anesthesia induction phase.

Study Overview

• Status: Recruiting
• Conditions: Airway Management; Induction of Anesthesia
• Intervention / Treatment: Other: Ultrasonic and inflation determination

Detailed Description

Pulmonary aspiration of gastric contents has been identified as one of the leading causes of anesthesia-related mortality. Even in fasting patients or those without known aspiration risks, such complications can still occur. In fact, in patients with unprotected airways during apnea, the introduction of air into the lungs during ventilation may become a potential trigger for gastric content aspiration. The entry of air can increase gastric pressure, leading to the reflux of gastric contents into the esophagus, which may subsequently result in hemodynamic instability and pulmonary failure. Therefore, airway management during anesthesia induction is crucial, particularly in the precise control of ventilation pressure, as it directly impacts the safety of the patient during surgery.

Previous studies have used gastric insufflation as the primary endpoint for evaluating the safety of ventilation pressures, often assessing the appearance of gastric gas in the stomach during mask ventilation. However, gastric insufflation typically occurs only after gas has passed through the esophagus and cardia, entering the gastric cavity-this process is a "terminal event" triggered by higher pressures. The esophagus, being structurally weaker than the stomach, is less tolerant to pressure. When gas first enters the esophagus, the cardia is not fully open, and if ventilation pressure continues to rise, it is easy to cause esophageal insufflation, further leading to gastric insufflation and even gastric content reflux. Since esophageal insufflation occurs earlier and has a lower pressure threshold, it can serve as a more sensitive indicator, providing an early warning to anesthesiologists about potential airway management issues.

To address this issue, determining the optimal ventilation pressure to avoid esophageal insufflation is particularly important. the 90% effective ventilation pressure (EP90) refers to the ventilation pressure that can avoid esophageal insufflation in 90% of cases, providing anesthesiologists with a quantitative reference for ventilation pressures.

This study employed a Sequential Allocation with Biased Coin Design (SABCD) trial, utilizing precise statistical methods to explore the EP90 for avoiding esophageal insufflation during anesthesia induction. The goal was to determine the optimal ventilation pressure for preventing esophageal insufflation during anesthesia induction and to explore its implications for anesthesia management. The ultimate aim is to provide a more precise and personalized ventilation pressure setting standard for clinical anesthesia, thereby enhancing the safety of the anesthesia induction phase.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Qinghe Zhou; Phone Number: 13732573379; Email: zqh10980@zjxu.edu.edu.cn

Study Locations

• China
  • Jiaxing, China
    • Recruiting
    • Affiliated Hospital of Jiaxing University
    • Contact: Qinghe Zhou

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age: 18-65 years, regardless of gender;
2. ASA classification: I-III;
3. Scheduled for elective general anesthesia surgery;
4. BMI: 18.0-28.0 kg/m²;
5. Preoperative fasting: Solid food >6 hours, liquid >2 hours;
6. Less than two from five criteria predicting difficult mask ventilation as described by Langeron et al.(Prediction of difficult mask ventilation. Anesthesiology 2000; 92:1229-36);
7. No severe underlying conditions such as heart, lung, liver, or kidney disease;
8. Signed informed consent and ability to cooperate with the study protocol.

Exclusion Criteria:

1. Pregnant or breastfeeding women;
2. History of upper gastrointestinal diseases such as gastroesophageal reflux disease, peptic ulcers, or hiatal hernia;
3. Recent (within 2 weeks) respiratory infections, chronic cough, similar symptoms, and other known or predictable respiratory system diseases;
4. Need for emergency surgery or airway obstruction after anesthesia induction requiring urgent intubation;
5. Inability to achieve adequate oxygenation during mask ventilation (e.g., SpO₂ < 92% for 30 seconds, unresponsive to treatment);
6. History of contraindications or allergies to study medications;
7. Inability to understand the study content or refusal to cooperate;
8. Oropharyngeal or facial pathology;
9. with an indwelling gastric tube, and who had previously undergone gastric surgery.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Ventilation Pressure; Anesthesia machine settings: pressure control mode, inspiratory-to-expiratory ratio of 1:2, respiratory rate of 15 breaths/min, 100% oxygen, no PEEP applied. Mask ventilation duration was standardized to 120 seconds, followed by tracheal intubation.

Other: Ultrasonic and inflation determination; Before induction, during ventilation, and after intubation, the anesthesiologist used a 7-14 MHz linear array probe for transverse (supraclavicular) positioning to monitor the left paratracheal esophageal region in real time. The main criterion for assessment was the absence of esophageal gas during ventilation, which was considered a positive response. If gas was detected entering the esophagus on ultrasound, it was recorded as a negative response. Additionally, the anesthesiologist performed a preoperative ultrasound examination of the gastric antrum to record baseline gastric antrum parameters. After successful tracheal intubation, a follow-up ultrasound of the gastric antrum was conducted to obtain postoperative gastric antrum parameters.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
EP90	The 90% effective ventilation pressure (EP90) for avoiding esophageal inflation refers to the minimum effective airway pressure (measured in cmH₂O) at which 90% of patients do not experience esophageal inflation during pressure-controlled mask ventilation during anesthesia induction.	Perioperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
EP95	The 95% effective ventilation pressure (EP95) for avoiding esophageal inflation refers to the minimum effective airway pressure (measured in cmH₂O) at which 95% of patients do not experience esophageal inflation during pressure-controlled mask ventilation during anesthesia induction.	Periprocedural
EP98	The 98% effective ventilation pressure(EP98) for avoiding esophageal inflation refers to the minimum effective airway pressure (measured in cmH₂O) at which 98% of patients do not experience esophageal inflation during pressure-controlled mask ventilation during anesthesia induction.	Periprocedural
Ventilation-related respiratory parameters	pulse oxygen saturation (SpO₂) was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Ventilation-related respiratory parameters	end-tidal carbon dioxide (EtCO₂) was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Ventilation-related respiratory parameters	end-tidal oxygen concentration (EtO₂) was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Ventilation-related respiratory parameters	minute leak volume was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Ventilation-related respiratory parameters	peak airway pressure (Ppeak) was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Ventilation-related respiratory parameters	tidal volume (Vt) was recorded at multiple time points during mask ventilation and 30/60/90/120 seconds after tracheal intubation.	Periprocedural
Incidence of complications Incidence of complications	Including gastric distension, signs of aspiration, failure rate of mask ventilation [such as pulse oxygen saturation (SpO₂) < 92% lasting for 30 seconds], intubation condition score (Cormack-Lehane classification), hypoxemia and other adverse events.	Periprocedural

Collaborators and Investigators

• Sponsor: Affiliated Hospital of Jiaxing University
• Investigators: Study Chair: Qinghe Zhou, Dr., Affiliated Hospital of Jiaxing University

Publications and helpful links

General Publications

• Langeron O, Masso E, Huraux C, Guggiari M, Bianchi A, Coriat P, Riou B. Prediction of difficult mask ventilation. Anesthesiology. 2000 May;92(5):1229-36. doi: 10.1097/00000542-200005000-00009.

Study record dates

Study Major Dates

• Study Start (Actual): September 29, 2025
• Primary Completion (Estimated): February 1, 2026
• Study Completion (Estimated): February 1, 2026

Study Registration Dates

• First Submitted: September 28, 2025
• First Submitted That Met QC Criteria: January 13, 2026
• First Posted (Actual): January 14, 2026

Study Record Updates

• Last Update Posted (Actual): January 14, 2026
• Last Update Submitted That Met QC Criteria: January 13, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Airway Management; Ventilation; Esophageal Insufflation; Bias-coin Design
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Respiration Disorders; Pathological Conditions, Signs and Symptoms; Respiratory Aspiration; Physical Phenomena; Radiation; Radiation, Nonionizing; Ultrasonic Waves; Sound; High-Energy Shock Waves
• Other Study ID Numbers: 2025-KY-396

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No