This prospective, randomized controlled trial evaluated the efficacy and safety of two anesthetic strategies-dexmedetomidine infusion and ultrasound-guided superior laryngeal nerve block (SLNB)-in patients undergoing non-intubated endoscopic laryngeal surgery under spontaneous breathing supported by Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE). The primary outcome was the arterial partial pressure of carbon dioxide (PaCO₂), measured at three time points: before oxygenation, at the end of surgery, and in the post-anesthesia care unit (PACU). Secondary outcomes included other arterial blood gas parameters, hemodynamic variables, and surgeon satisfaction scores.

Detailed Description:

This prospective, single-center randomized controlled trial was conducted to compare two anesthetic strategies-Dexmedetomidine infusion and ultrasound-guided bilateral superior laryngeal nerve block (SLNB)-for non-intubated endoscopic laryngeal surgery performed under spontaneous respiration with high-flow nasal oxygenation (THRIVE). The study was carried out at Kaohsiung Veterans General Hospital, Taiwan.

Patients aged 20 to 80 years scheduled for elective microlaryngeal surgery were enrolled and randomly assigned to either the Dexmedetomidine (Dex) group or the SLNB group. Both groups received total intravenous anesthesia (TIVA) with propofol and oxygenation via transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) to facilitate tubeless anesthesia. The Dex group received a loading dose of Dexmedetomidine (1 µg/kg over 10 minutes) followed by continuous infusion (1 µg/kg/h), while the SLNB group underwent bilateral ultrasound-guided nerve blocks with 1% lidocaine.

The primary outcome was the arterial partial pressure of carbon dioxide (PaCO₂) measured at three time points: before oxygenation (baseline), at the end of surgery, and 15 minutes after arrival in the post-anesthesia care unit (PACU). Secondary outcomes included arterial blood gas parameters (PaO₂, pH), intraoperative hemodynamic variables (HR, SBP, DBP, MAP), and surgeon satisfaction scores.

The goal of this study was to evaluate whether Dexmedetomidine, which offers both sedative and analgesic properties while preserving spontaneous breathing, could serve as a viable alternative to regional nerve block in the context of shared-airway surgery. Particular attention was given to the risk of carbon dioxide accumulation and respiratory acidosis associated with Dexmedetomidine.

This trial provides important insights into the safety and efficacy of two distinct anesthetic modalities for performing non-intubated endoscopic laryngeal surgery and contributes to the ongoing optimization of airway management strategies in tubeless anesthesia.

Inclusion Criteria:

• Subjects are between 20-80 years old.
• Patients undergoing endoscopic laryngeal surgery.
• Anesthesiologists rated ASA as between I and III.

Exclusion Criteria:

• Having drug dependence and drinking habits.
• Abnormal heart, liver and kidney function.
• Allergic reactions to narcotic drugs.
• Emergency surgery.
• pregnancy.
• Refuse to participate.
• BMI ≥ 35 kg/m2.