Predicting Difficult Intubation in Bariatric Surgery: Comparison of El Ganzouri Risk Index and Airway Ultrasound

Background and Rationale

Airway management is a fundamental aspect of anesthesia practice and plays a critical role in ensuring patient safety during surgical procedures. Under general anesthesia, suppression of spontaneous breathing necessitates the secure maintenance of airway patency. Successful tracheal intubation is essential for the safe conduct of surgery; however, in some patients, intubation may be unexpectedly difficult. According to current definitions, difficult intubation is characterized by the inability to adequately visualize glottic structures using standard techniques, resulting in failure or the need for multiple attempts. Delayed or failed intubation following anesthesia induction can lead to serious complications, including hypoxemia, aspiration, bradycardia, and cardiac arrest. Therefore, accurate preoperative prediction of difficult intubation is of critical importance. Early identification of difficult airway cases allows for timely implementation of alternative techniques and airway devices, thereby reducing perioperative risks and complications.

Obesity has emerged as a major global health concern and represents a significant risk factor for difficult intubation. Bariatric surgery is indicated in individuals with a body mass index (BMI) ≥40 kg/m² or ≥35 kg/m² in the presence of serious comorbidities, with the aim of reducing obesity-related metabolic, cardiovascular, and respiratory complications while improving quality of life. However, obese patients present unique challenges in airway management due to increased adipose tissue in the neck, reduced cervical-pharyngeal angles, and enlarged soft tissue structures. These anatomical factors impair visualization of laryngeal structures and may prolong intubation time, thereby increasing the risk of airway-related complications.

EGRI was developed as a comprehensive scoring system for predicting difficult intubation by incorporating multiple airway assessment parameters, including mouth opening, Mallampati classification, neck mobility, mandibular protrusion, upper incisors, thyromental distance, and a history of difficult intubation. Several studies have demonstrated the clinical utility and predictive value of EGRI in preoperative airway assessment.

Airway USG has recently gained attention as a non-invasive method for predicting difficult intubation. This technique enables real-time visualization of airway anatomy and allows measurement of parameters such as skin-to-epiglottis distance, skin-to-hyoid bone distance, skin-to-vocal cord distance, and tongue thickness. Previous studies suggest that USG may provide predictive accuracy comparable to or greater than that of traditional clinical indices, including EGRI. However, evidence regarding its use in patients undergoing bariatric surgery remains limited, underscoring the need for further investigation.

Direct laryngoscopy remains the standard technique for airway visualization during tracheal intubation. CL grading system, which ranges from Grade I (full view of the glottis) to Grade IV (no visible glottic structures), provides an objective assessment of intubation difficulty. In this study, CL score will be used as a reference standard to compare the predictive performance of EGRI and airway USG parameters in participants undergoing bariatric surgery.

Study Objectives

Patients scheduled for bariatric surgery are at increased risk of difficult intubation, necessitating the use of accurate and objective preoperative assessment tools. Traditional clinical scoring systems, such as EGRI, are practical and widely used; however, their predictive accuracy may be limited by subjectivity. Airway USG is an emerging, non-invasive technique that provides direct visualization of airway structures, but further investigation is required to establish its role in this patient population.

The primary objective of this study is to compare the predictive performance of EGRI and airway USG parameters in identifying difficult intubation in participants with obesity undergoing bariatric surgery. A secondary objective is to evaluate the association between preoperative airway assessment findings and intraoperative CL scores obtained during direct laryngoscopy.

By determining which assessment method demonstrates greater accuracy and reliability, this study aims to generate evidence that may contribute to improved preoperative airway evaluation and enhanced patient safety in bariatric surgery.

Study Design

This study is designed as a prospective observational clinical study. The primary aim is to compare EGRI and airway USG parameters in predicting difficult intubation in adult participants scheduled for bariatric surgery and to evaluate their association with CL scores obtained during direct laryngoscopy.

During the preoperative period, all participants will undergo airway assessment using both the EGRI scoring system and airway USG. Tracheal intubation will be performed under general anesthesia using direct laryngoscopy. The degree of intubation difficulty will be documented based on the anesthesiologist's observations, including CL grade, intubation time, and number of intubation attempts.

The collected data will be classified according to the presence or absence of difficult intubation. Statistical analyses will be performed to compare the predictive performance of EGRI scores and airway USG parameters and to evaluate their relationship with direct laryngoscopic findings.

Data Analysis

Data will be analyzed using appropriate statistical software. Participants will be categorized into two groups based on the presence or absence of difficult intubation, as determined by intraoperative findings.

Descriptive statistics will be used to summarize demographic and clinical characteristics. Continuous variables will be reported as mean ± standard deviation or median with interquartile range, depending on data distribution. Categorical variables will be presented as frequencies and percentages.

Appropriate statistical tests will be applied to compare EGRI scores and airway USG parameters between groups. Correlation analyses will be performed to evaluate the relationships among preoperative airway USG measurements, EGRI scores, and intraoperative CL grades.

The diagnostic performance of EGRI scores and airway USG parameters in predicting difficult intubation will be assessed using comparative statistical methods.

A p-value of <0.05 will be considered statistically significant.

Expected Outcomes

Primary Outcome:

To compare the diagnostic effectiveness of EGRI and airway USG parameters in predicting difficult intubation in adult participants scheduled to undergo bariatric surgery.

Secondary Outcome

To evaluate the association between EGRI scores and airway USG measurements and clinical variables, including intubation time, number of intubation attempts, and the occurrence of difficult intubation.