This is a prospective, randomized, parallel-group clinical trial designed to evaluate the effects of high-flow nasal oxygen therapy (HFNOT) versus conventional oxygen mask (COM) on perioperative hypoxia in patients undergoing video-assisted thoracoscopic (VATS) pericardial window procedures under sedoanalgesia. The pericardial window procedure, indicated for diagnostic and therapeutic drainage of pericardial effusion, is traditionally performed under general anesthesia. However, the use of non-intubated VATS with sedoanalgesia has gained popularity due to reduced morbidity, shorter recovery, and avoidance of complications associated with general anesthesia, especially in elderly and comorbid patients.

During non-intubated VATS, the occurrence of hypoxia and hemodynamic instability may be exacerbated by procedural pneumothorax and underlying cardiac pathology. High-flow nasal oxygen therapy may provide physiological benefits in this setting by reducing airway resistance, improving alveolar ventilation, and minimizing dead space.

The primary outcome of the study is to compare the incidence of perioperative hypoxia between HFNOT and COM groups. Secondary outcomes include patient comfort, intraoperative oxygenation profiles, hemodynamic stability, and recovery parameters. The trial will be conducted at a single academic center with eligible patients randomized into two treatment arms.

Pericardial effusion may require therapeutic or diagnostic drainage by pericardiocentesis or creation of a surgical "pericardial window." Video-assisted thoracoscopic surgery (VATS) is the preferred minimally invasive approach, but standard practice employs general anesthesia with tracheal intubation. Since the late 1980s, non-intubated VATS (NI-VATS) performed under sedoanalgesia with regional blocks has gained acceptance, offering lower morbidity, shorter recovery, and avoidance of postoperative pulmonary complications-advantages that are especially valuable in elderly or comorbid patients who are at risk of hypotension or cardiac arrest during induction.

During NI-VATS, iatrogenic pneumothorax and underlying cardiac pathology can precipitate perioperative hypoxia. Conventional oxygen delivery (facemask or low-flow nasal cannula at ≤15 L min-¹) may be insufficient. High-flow nasal oxygen therapy (HFNOT) delivers warmed, humidified gas at up to 70 L min-¹ and FiO₂ 0.21-1.00, matching or exceeding peak inspiratory flow, reducing airway resistance, washing out nasopharyngeal dead space, and improving alveolar ventilation. Perioperative data on HFNOT in NI-VATS remain limited.

In this study, the primary objective is to compare the incidence of intraoperative hypoxia (defined as SpO₂ < 92%) in patients receiving high-flow nasal oxygen therapy (HFNOT) versus a conventional oxygen mask (COM) during sedoanalgesia-guided non-intubated video-assisted thoracoscopic (NI-VATS) pericardial window procedures.

Secondary objectives include the comparison of oxygen saturation trends and nadir SpO₂ values; hemodynamic stability (heart rate and mean arterial pressure); arterial blood gas parameters (pO₂, pCO₂, pH, lactate, and base excess); regional cerebral oxygen saturation (NIRS); procedural and recovery times; postoperative pain scores (VAS); the need for intensive care unit admission; length of hospital stay; and the incidence of pulmonary or cardiovascular complications.

Inclusion Criteria:

• Adults aged 18 to 75 years
• Scheduled for elective video-assisted thoracoscopic pericardial window procedure under sedoanalgesia
• ASA Physical Status Classification I-III
• Able and willing to provide written informed consent

Exclusion Criteria:

• Age <18 or >75 years
• ASA Physical Status ≥ IV
• Body Mass Index (BMI) > 30 kg/m²
• Need for inotropic support at enrollment
• Preoperative hemodynamic instability
• Symptomatic respiratory disease (e.g., pneumonia, nasal congestion, asthma attack)
• Diagnosed neuromuscular disorder
• Diagnosed tracheal stenosis
• Local infection at the site of regional block application
• Coagulopathy or bleeding diathesis
• Pregnancy
• Patients refusing sedoanalgesia
• Patients refusing study participation
• Conversion to general anesthesia or use of supraglottic airway intraoperatively

The study protocol and statistical analysis plan may be shared upon reasonable request.

Data will be available after the publication of the study results in a peer-reviewed journal.

Data will be available upon publication of the study results.