Suspension laryngoscopy presents significant challenges for airway management due to the need to maintain adequate ventilation while providing optimal surgical exposure. Flow-controlled ventilation (FCV) is a novel ventilation mode that delivers constant inspiratory and expiratory flow using a narrow-lumen, cuffed endotracheal tube, potentially improving ventilation efficiency in shared-airway surgeries.

This prospective observational study aims to compare flow-controlled ventilation and conventional volume-controlled ventilation in patients undergoing elective suspension laryngoscopy. Respiratory mechanics, hemodynamic parameters, perioperative pulmonary function, and procedure-related complications will be evaluated to assess the feasibility and clinical performance of FCV in this surgical setting.

Suspension laryngoscopy is a shared-airway surgical procedure that requires optimal visualization of the operative field while maintaining adequate ventilation and oxygenation. Conventional ventilation strategies may be associated with increased airway pressures and limited surgical exposure due to the use of standard endotracheal tubes. Flow-controlled ventilation (FCV) is a ventilation mode characterized by constant inspiratory and expiratory flow, which may offer advantages in procedures requiring a narrow airway device.

This prospective, non-randomized, observational comparative study evaluates adult patients undergoing elective suspension laryngoscopy. The choice of ventilation strategy-flow-controlled ventilation or conventional volume-controlled ventilation-was based on the attending anesthesiologist's clinical preference, reflecting routine clinical practice. All patients provided written informed consent prior to participation.

In both groups, standardized anesthetic management was applied, and ventilation parameters were adjusted to maintain normocapnia and adequate oxygenation. Intraoperative respiratory mechanics, including airway pressures and lung compliance, were recorded at predefined intervals. Hemodynamic parameters were monitored throughout the procedure. Pulmonary function tests were performed preoperatively and postoperatively using a portable spirometry device. Perioperative complications were documented.

The primary objective of this study is to compare intraoperative respiratory mechanics between flow-controlled and volume-controlled ventilation during suspension laryngoscopy. Secondary objectives include the assessment of perioperative hemodynamic parameters, changes in pulmonary function, and procedure-related complications.

Inclusion Criteria:- Adult patients aged 18 to 65 years

• American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled for elective suspension laryngoscopy under general anesthesia
• Body mass index between 18 and 40 kg/m²
• Provision of written informed consent

Exclusion Criteria:- Severe cardiac, pulmonary, hepatic, or renal disease

• Inability to cooperate with pulmonary function testing
• Intraoperative hemodynamic instability or oxygen desaturation (SpO₂ <92%)
• Requirement for tracheostomy during the procedure

Adult patients aged 18 to 65 years scheduled for elective suspension laryngoscopy under general anesthesia were included. Eligible participants had an American Society of Anesthesiologists (ASA) physical status of I-III and a body mass index between 18 and 40 kg/m². All participants provided written informed consent prior to participation.

There is no plan to share individual participant data, as the study is an academic, single-center observational study and only aggregate data will be reported.