This study aims to compare two oxygenation strategies-laryngeal mask airway (LMA) ventilation and high-flow nasal cannula (HFNC)-during electroconvulsive therapy (ECT) in obese patients. Due to their physiological characteristics, obese patients are at increased risk of hypoxia during ECT under general anesthesia.

Adult patients with a body mass index (BMI) ≥30 who are scheduled to undergo ECT will participate. Each participant will receive both oxygenation strategies in a fixed alternating order during four consecutive ECT sessions. The procedures will follow standard anesthesia protocols.

During the ECT procedures and the 30-minute recovery period in the post-anesthesia care unit, we will monitor the occurrence of hypoxia (SpO₂ <92%), ventilator parameters, vital signs, postoperative confusion within 24 hours, and any reports of dental discomfort. This information will help assess the safety and clinical utility of each oxygenation method for obese patients receiving ECT.

Obesity is a known risk factor for perioperative hypoxia due to physiological changes such as increased airway resistance, reduced functional residual capacity, and elevated oxygen demand. These risks are amplified in patients undergoing electroconvulsive therapy (ECT) under general anesthesia, where periods of apnea can result in critical oxygen desaturation.

While laryngeal mask airways (LMAs) and high-flow nasal cannula (HFNC) therapy are both recommended strategies to maintain oxygenation during anesthesia, their comparative effectiveness in obese patients undergoing ECT has not been well established. LMAs provide direct airway access and enable positive pressure ventilation but carry a risk of dental trauma. HFNC offers a non-invasive alternative that may prolong safe apnea time, though its oxygenation efficacy during ECT remains unclear.

This study aims to evaluate the safety and effectiveness of LMA versus HFNC in preventing hypoxia during ECT in obese patients. Using a within-subject crossover design, each participant will receive both interventions in alternating ECT sessions. This trial will help determine the optimal airway management strategy for minimizing peri-procedural hypoxia in this high-risk population.

The outcome will be assessed during each ECT session as part of a crossover design. All participants will undergo both LMA and HFNC interventions in alternating sessions (LMA during sessions 1 and 3, HFNC during sessions 2 and 4). Oxygen support beyond the assigned method will be recorded when clinically indicated.

Inclusion Criteria:

• Age ≥ 18 years
• Patients scheduled to undergo ≥ 4 electroconvulsive therapy (ECT) sessions
• Body mass index (BMI) ≥ 30 kg/m² (WHO obesity classification)
• American Society of Anesthesiologists (ASA) physical status class I to III
• Provided written informed consent (by patient or legal guardian)

Exclusion Criteria:

• Patients under 18 years of age
• Patients with ASA class IV or V
• Patients with anticipated dental injury risk that precludes use of a laryngeal mask airway
• Patients or guardians who refuse participation