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ORI-Guided FiO₂ Titration in Prone Spine Surgery: Impact on Postoperative Atelectasis Assessed by Lung Ultrasound
Sponsor: Ankara Etlik City Hospital
Summary
Atelectasis is a frequent pulmonary complication after general anesthesia, often triggered by preoxygenation and intraoperative hyperoxia. High inspiratory oxygen fractions (FiO₂) can promote absorption atelectasis, ventilation-perfusion mismatch, hemodynamic alterations, and oxidative injury. This study evaluates the effect of two intraoperative oxygen management strategies-oxygen reserve index (ORI)-guided FiO₂ titration versus fixed 50% FiO₂-on postoperative atelectasis in patients undergoing thoracolumbar spine surgery under general anesthesia. Atelectasis severity will be assessed using lung ultrasonography (LUS), scored across 12 thoracic regions (0-3 per region, total 0-36), while respiratory function changes will be examined via preoperative and 24-hour postoperative spirometry (FVC, FEV₁, FEV₁/FVC). Because postoperative spirometry may be influenced by pain, Numeric Rating Scale (NRS) scores will be recorded to help distinguish true restrictive patterns from pain-limited respiratory effort. The study aims to determine whether ORI-guided FiO₂ titration can reduce postoperative atelectasis and improve respiratory outcomes compared with a fixed FiO₂ approach.
Official title: Oxygen Reserve Index-Guided FiO₂ Titration in Prone Spine Surgery: Impact on Postoperative Atelectasis Assessed by Lung Ultrasound
Key Details
Gender
All
Age Range
18 Years - 80 Years
Study Type
INTERVENTIONAL
Enrollment
74
Start Date
2026-03-15
Completion Date
2026-11-30
Last Updated
2026-01-29
Healthy Volunteers
No
Conditions
Interventions
Titrated Oxygen
This intervention is distinguished by the use of real-time Oxygen Reserve Index (ORI) monitoring to guide individualized intraoperative FiO₂ titration. Unlike fixed-FiO₂ strategies commonly used in anesthesia practice, this protocol continuously adjusts FiO₂ based on ORI values measured with the Masimo Rad-97 device. FiO₂ is increased or decreased in increments of 0.05 according to predefined ORI thresholds to maintain patients within a targeted normoxemic range. The intervention is entirely noninvasive and integrates standardized lung ultrasound (LUS) assessments and spirometry to evaluate postoperative aeration loss and respiratory function. This dynamic, physiology-based oxygen management approach differentiates the intervention from routine fixed-oxygen administration used in other clinical studies.
Fixed oxygen
This intervention uses a standard, non-individualized oxygen administration approach in which FiO₂ is maintained at a constant 50% throughout the entire surgical procedure. After preoxygenation with 80% FiO₂ for 3 minutes, the FiO₂ is set at 0.50 immediately after intubation and is not modified in response to patient physiology or ORI measurements. PEEP is fixed at 5 cmH₂O, and a standardized alveolar recruitment maneuver is applied at the beginning of surgery. This fixed-FiO₂ strategy differs from the ORI-guided titration group by avoiding dynamic oxygen adjustments and reflects conventional intraoperative oxygen management commonly used in clinical practice.