With increasing life expectancy, the geriatric population continues to grow. According to the Turkish Statistical Institute (TÜİK), the average life expectancy in Turkey between 2021 and 2023 is 77.3 years. As the number of elderly surgical patients rises, optimizing anesthesia care is critical to reducing complications and improving clinical outcomes. In elderly patients with severe aortic stenosis, traditional surgical aortic valve replacement poses a high risk of complications. Consequently, Transcatheter Aortic Valve Implantation (TAVI) has emerged as a preferred, less invasive alternative. Due to technological advancements and shorter procedure durations, TAVI is increasingly performed under sedation rather than general anesthesia. However, sedation carries risks, including hypoxemia and hypoventilation, primarily due to sedative-induced respiratory depression.

Pulse oximetry, the traditional monitoring method, measures only peripheral oxygen saturation and does not provide early detection of apnea or hypoventilation. Therefore, monitoring end-tidal carbon dioxide (EtCO₂) during sedation has gained importance. The American Society of Anesthesiologists (ASA) recommends EtCO₂ monitoring during sedation. However, obtaining accurate EtCO₂ values via nasal cannulas is technically challenging. Open sampling ports and high oxygen flow rates can cause dilution or loss of exhaled CO₂, resulting in inaccurate readings.

The SuperNO₂VA™ nasal mask (Vyaire Medical, USA) addresses these limitations with an integrated CO₂ sampling port and the ability to provide positive airway pressure. This facilitates more accurate EtCO₂ monitoring and better ventilatory support compared to standard nasal cannulas. Prior studies have demonstrated that the SuperNO₂VA mask significantly reduces the risk and severity of hypoxia in high-risk patients during sedated endoscopic procedures. It prevents upper airway collapse and increases ventilated lung surface area, without causing clinically significant hypercapnia or CO₂ retention.

This study aims to compare the incidence of hypoxia in patients aged 65 years and older undergoing TAVI under sedation using either the SuperNO₂VA nasal mask or a conventional nasal oxygen mask. Secondary outcomes include the evaluation of intraoperative hypercapnia or hypocapnia and the assessment of postoperative respiratory complications.

The continuous increase in life expectancy has led to steady growth in the geriatric population. According to the Turkish Statistical Institute (TÜİK), the average life expectancy in Turkey from 2021 to 2023 is 77.3 years. In surgical geriatric patients, optimizing anesthesia care strategies is essential to reduce complications and enhance clinical outcomes. In patients with severe aortic stenosis, traditional surgical aortic valve replacement is associated with a high risk of complications. As a result, Transcatheter Aortic Valve Implantation (TAVI) has gained popularity. The anesthetic approach to TAVI varies based on surgical preference, procedural volume, echocardiography type, and team experience. Recent technological advancements and shorter procedural durations have made sedation-based anesthesia a preferred option. However, sedation may result in complications such as hypoxemia and hypoventilation due to central respiratory depression from sedative agents. Pulse oximetry, a conventional respiratory monitoring method, measures only peripheral oxygen saturation and may delay the detection of hypoventilation or apnea. In sedated patients receiving supplemental oxygen, measuring exhaled carbon dioxide (CO2) becomes essential. The American Society of Anesthesiologists (ASA) has endorsed the use of end-tidal capnography (EtCO2) as a standard for monitoring sedation. While capnography surpasses pulse oximetry in detecting hypoventilation and apnea, accurate EtCO2 measurement during deep sedation remains technically challenging due to dilution of exhaled gases from open nasal cannula sampling ports and high oxygen flow rates. The SuperNO2VA™ nasal mask (Vyaire Medical, USA) is an innovative device designed to overcome these challenges. It features an integrated CO2 sampling port and provides positive airway pressure, thereby allowing for accurate EtCO2 measurement and improved respiratory support compared to standard nasal oxygen masks. Prior research has shown that the SuperNO2VA mask significantly reduces both the frequency and severity of hypoxia in high-risk patients undergoing sedated endoscopic procedures. This device also helps prevent upper airway collapse and enhances lung ventilation. Importantly, its use has not been associated with clinically significant hypercapnia or CO2 retention. The objective of this study is to compare the incidence of hypoxia in patients over 65 years of age undergoing TAVI under sedation, using either the SuperNO2VA nasal mask or a standard nasal oxygen mask. In minimally invasive procedures such as TAVI in the geriatric population, accurate evaluation of hypoxia and hypercapnia is critical. Traditional oxygen delivery methods may be insufficient in preventing hypoxia and predicting CO2 disturbances. Based on previous studies, it is hypothesized that the SuperNO2VA mask will reduce hypoxia and improve detection of hypo/ hypercapnia via continuous EtCO2 monitoring. No specific risk is anticipated for participants in this study. A prospective, randomized controlled trial is planned, enrolling 100 patients via computer generated randomization in a 1:1 ratio (SuperNO2VA group: 50; control group: 50). In patients undergoing TAVI under sedation without endotracheal intubation, the SuperNO2VA group will receive oxygen via the nasal mask delivering positive airway pressure, while the control group will receive oxygen through a standard nasal mask. Oxygen flow will be adjusted to maintain SpO2

• 92%. All parameters will be prospectively recorded by the clinical staff and investigators from the Department of Anesthesiology and Reanimation at Ankara Bilkent City Hospital. Study participation will be terminated for any patient in the event of withdrawal, intraoperative intubation, or serious adverse events such as laryngospasm. This study will be conducted in accordance with the Declaration of Helsinki and Good Clinical Practice (GCP) guidelines. Written informed consent will be obtained from all participants, who will retain the right to withdraw from the study at any time without providing a reason.

Preoperative parameters to be assessed:

Age and sex Height, weight, Body Mass Index (BMI) ASA Physical Status Classification Comorbidity evaluation Smoking history ARISCAT score parameters

Intraoperative parameters to be assessed:

Duration of anesthesia Occurrence of complications (e.g., need for intubation, resuscitation, bronchospasm) Incidence of hypoxia (SpO2 < 90% for >10 seconds) Continuous EtCO2 monitoring Arterial blood gas measurements (PaO2, PaCO2) Peripheral oxygen saturation (SpO2) will be monitored continuously and recorded throughout the preoperative, intraoperative, and postoperative periods, totaling 12 hours. Data will be analyzed using SPSS version 27 (IBM Corporation, Armonk, NY, USA). Descriptive statistics will summarize baseline characteristics. The incidence of hypoxia between groups will be compared using Fisher's Exact Test. Multivariate logistic regression will be used to identify factors associated with hypoxia or hypercapnia. Statistical significance will be defined as p < 0.05.

Inclusion Criteria:

• Patients aged 65 years and older who are scheduled for TAVI under sedation will be included in the study.

Exclusion Criteria:

• History of prolonged intubation
• History of tracheostomy
• Patients who are planned to undergo endotracheal intubation during the procedure
• Patients undergoing TAVI under local anesthesia