Laryngeal Edema Assessment by Cuff Leak Test and Ultrasound in ICU Patients and Its Relationship With Weaning Success

Endotracheal intubation is one of the life-saving procedures used to support the respiratory system of critically ill patients on mechanical ventilation. In intubated patients, mechanical ventilation support is frequently applied in conditions such as acute respiratory failure or acute exacerbation of chronic respiratory failure where adequate oxygenation and/or ventilation cannot be achieved, loss of consciousness or airway reflexes, upper airway obstruction, and advanced life support in cardiac arrest; with the aim of improving gas exchange, reducing the work of breathing, or maintaining airway patency (1).

Airway complications may occur as a result of mechanical effects such as friction between the endotracheal tube and anatomical structures and prolonged compression. Prolonged intubation may cause partial airway obstruction, which can lead to laryngeal edema and post-extubation stridor (2). In patients receiving mechanical ventilation for 4 days or longer, mucosal ulcerations and laryngeal edema can be observed in almost all cases (3). Factors associated with post-extubation edema include advanced age, female gender, endotracheal tube size, presence of a cuffed endotracheal tube, prolonged duration of intubation, underlying airway disease, traumatic intubation, tracheal aspiration, tube mobility, and patient resistance to the tube (4). This may lead to sore throat, cough, dysphonia, dysphagia, and even respiratory failure requiring reintubation due to airway narrowing. Consequently, laryngeal edema in intensive care units (ICUs) is associated with longer durations of mechanical ventilation, increased hospital stay, higher morbidity and mortality, and significant economic costs (5).

"Weaning" is defined as the gradual reduction and discontinuation of mechanical ventilation support (6). The weaning process begins with the resolution of the cause of respiratory failure and results in the patient eventually breathing spontaneously. Weaning trials may fail due to increased work of breathing, laryngeal edema caused by prolonged intubation, electrolyte imbalances, malnutrition, hypothyroidism, major organ failure, and critical illness neuropathy (6).

Laryngeal edema causing post-extubation respiratory distress is usually the result of edema in the subglottic region and vocal cords (7). Examination of the vocal cords is typically performed using direct or indirect laryngoscopy. However, the presence of the endotracheal tube before extubation prevents direct visualization of the upper airway, making it difficult to detect laryngotracheal injury and edema.

The endotracheal tube cuff leak test is one of the most commonly used non-invasive and easily applicable bedside methods to assess airway anatomy and patency before extubation (6,8).

In recent years, ultrasound evaluation of the airway has emerged as an alternative to the cuff leak test for detecting laryngeal edema (6). Assessment of the larynx with airway ultrasound before extubation provides a fast, safe, real-time, bedside, and non-invasive method that helps predict the potential for post-extubation laryngeal edema. Using airway ultrasound, the air column passing between the vocal cords can be visualized, and its width is defined as the "laryngeal air column width" (9). Dynamic changes in the laryngeal air column during cuff deflation and inflation can be easily evaluated. Changes in air column dimensions reflect alterations in air leakage and airflow around the endotracheal tube (8). The "laryngeal air column width difference," defined as the difference between measurements taken with the cuff deflated and inflated, is important in detecting laryngeal edema (6).

In this prospective observational study, we aimed to investigate the relationship between weaning success and the endotracheal tube cuff leak test and ultrasound-measured laryngeal air column width difference in patients who were intubated for 24 hours or more in the ICU and planned for weaning. Our secondary objectives were to evaluate the presence of post-extubation stridor, sore throat, dysphonia, and dysphagia.

Inclusion criteria

• Patients who have been intubated and receiving invasive mechanical ventilation for at least 24 hours in the Intensive Care Unit of Fatih Sultan Mehmet Training and Research Hospital and who are considered by the intensive care physician to be ready for weaning from mechanical ventilation:
• Patients over 18 years of age
• Patients who have given their voluntary consent

Exclusion criteria

• Patients under 18 years of age
• Patients with a history of oral cavity surgery such as direct laryngoscopy and biopsy, microlaryngoscopic surgery, tonsillectomy, adenoidectomy, soft palate, oropharynx, hypopharynx, larynx and trachea,
• Patients with a history of allergy, asthma, reflux, upper respiratory tract viral or fungal infections, and cancer surgery,
• Patients who received radiotherapy to the neck region, or who had more than one intubation attempt in the previous year,
• Tracheostomized patients, patients with upper respiratory tract obstruction, vocal cord paralysis, and patients with stridor clinical picture before intubation,
• Patients for whom voluntary consent cannot be obtained