Comparação do efeito de dois métodos no edema laríngeo na inflação do manguito endotraqueal

Lumbar spine surgery is commonly performed in the prone position. Although the prone position provides optimal surgical exposure, it may be associated with several physiological and position-related complications. Increased intra-abdominal and intrathoracic pressures may affect venous return and hemodynamics, while compression of the face, neck, and upper airway may contribute to facial and laryngeal edema. In addition, displacement, obstruction, or kinking of the endotracheal tube may occur after positioning.

Endotracheal tube cuff pressure represents another potential contributor to airway morbidity. The recommended cuff pressure is generally 25-30 cmH₂O. Excessive cuff pressure may impair tracheal mucosal perfusion and contribute to mucosal injury and postoperative airway symptoms. In conventional clinical practice, cuff inflation is often performed by manual palpation of the pilot balloon, whereas cuff manometry allows objective measurement and adjustment of cuff pressure.

Ultrasonographic measurement of laryngeal air column width (ACW) provides a non-invasive method for assessing peri-extubation changes in the upper airway. In this study, ACW is measured after tracheal intubation and again before extubation, and the pre-extubation/post-intubation ACW ratio is used to assess perioperative changes suggestive of laryngeal edema.

This prospective observational study evaluates peri-extubation laryngeal edema in adult patients undergoing elective lumbar stabilization surgery in the prone position at Fatih Sultan Mehmet Training and Research Hospital. Participants are categorized according to the endotracheal tube cuff inflation technique used as part of routine anesthetic care: conventional pilot balloon palpation (Conventional group) or manometer-guided cuff inflation (Manometer group). No study-specific random allocation is performed, and the cuff inflation technique is determined as part of routine anesthetic practice rather than by the research protocol.

After standard monitoring and induction of general anesthesia, patients are intubated by direct laryngoscopy using an appropriately sized reinforced orotracheal tube. In the Conventional group, the endotracheal tube cuff is inflated manually according to the attending anesthesiologist's routine clinical practice, after which cuff pressure is measured using a cuff manometer and recorded. In the Manometer group, cuff pressure is adjusted to 25-30 cmH₂O using a cuff manometer. Thereafter, cuff pressure is measured and recorded at 30-minute intervals throughout the operation in both groups. In the Conventional group, cuff pressure is measured and recorded at these intervals without protocol-driven adjustment, whereas in the Manometer group, cuff pressure is readjusted to 25-30 cmH₂O when necessary.

Following intubation, laryngeal ACW is measured ultrasonographically in the transverse plane at the level of the cricothyroid membrane using a linear transducer. Patients are subsequently positioned prone with particular attention to avoiding pressure on the eyes, face, and neck. Mechanical ventilation is provided using volume-controlled ventilation with a tidal volume of 8 mL/kg, positive end-expiratory pressure of 5 cmH₂O, and a respiratory rate adjusted to maintain end-tidal carbon dioxide between 35 and 40 mmHg. General anesthesia is maintained with desflurane and remifentanil, with anesthetic agents titrated according to hemodynamic parameters and Patient State Index values. Routine hemodynamic and respiratory parameters are monitored and recorded throughout the procedure.

At the end of surgery, patients are returned to the supine position. Before extubation, laryngeal ACW is measured again using the same ultrasonographic technique. For ACW measurements, oral secretions are aspirated and the endotracheal tube cuff is deflated. After measurement, the cuff is reinflated to the appropriate pressure using a cuff manometer. The ACW ratio is calculated as the pre-extubation ACW divided by the post-intubation ACW.

After recovery from neuromuscular blockade and fulfillment of standard extubation criteria, patients are extubated and transferred to the post-anesthesia care unit. Postoperative airway-related symptoms, including cough, dyspnea, dysphagia, dysphonia, sore throat, and facial edema, are assessed during postoperative follow-up at 4, 8, and 24 hours after surgery.