Oxygen Reserve Index-Guided FiO₂ Titration in Prone Spine Surgery: Impact on Postoperative Atelectasis Assessed by Lung Ultrasound
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 发起方
- 入组人数
- 74
- 主要终点
- Change in Total Lung Ultrasound (LUS) Score
研究概览
简要总结
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.
详细描述
Atelectasis is one of the most common pulmonary complications following general anesthesia, and both preoxygenation and intraoperative hyperoxia are major contributing factors. Hyperoxia can lead to absorption atelectasis, ventilation-perfusion mismatch, cerebral and coronary vasoconstriction, decreased cardiac output, and oxidative tissue injury caused by reactive oxygen species. The use of a high inspiratory oxygen fraction (FiO₂) during general anesthesia, particularly in prolonged surgeries, increases the risk of absorption atelectasis.
This study aims to investigate the impact of different intraoperative oxygen management strategies-oxygen reserve index (ORI)-guided FiO₂ titration versus fixed 50% FiO₂-on the development of postoperative atelectasis in patients undergoing thoracolumbar spine surgery under general anesthesia. The presence and severity of atelectasis will be assessed using lung ultrasonography (LUS), and changes in respiratory function will be evaluated objectively through spirometry measurements.
Lung ultrasonography will be performed by the same experienced and certified anesthesia practitioner for both groups. LUS assessment will be conducted in 12 regions (superior and inferior zones along the anterior, lateral, and posterior lines of each hemithorax). Each region will be scored from 0 to 3 according to the degree of aeration:
0 = normal aeration (A-lines predominance, <2 B-lines);
- = mild loss of aeration (≥3 well-defined B-lines);
- = moderate loss of aeration (multiple coalescent B-lines or "white lung");
- = severe loss of aeration (subpleural or complete consolidation with air bronchograms).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Screening
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 80 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Adults aged 18 to 80 years
- •Patients with an ASA physical status of I, II, or III
- •Individuals with a body mass index (BMI) between 18 and 35 kg/m²
排除标准
- •History of or active upper or lower respiratory tract infection within the past month
- •Pulmonary emphysematous/bullous disease or COPD
- •Pre-existing significant atelectasis or consolidation (Preoperative LUS showing a score of 3 consolidation or ≥2 regions with a score ≥2)
- •Severe obstructive sleep apnea requiring CPAP therapy
- •NYHA class III-IV heart failure, EF <35%, or severe valvular disease
- •Severe arrhythmia or hemodynamic instability requiring high-dose vasopressors
- •Body mass index (BMI) >35 kg/m²
- •Severe anemia (Hb <9 g/dL) or polycythemia (Hb >18 g/dL)
- •Non-diagnostic or unclear preoperative lung ultrasound images
- •Preoperative SpO₂ ≤ 94%
- •Inability to apply the sensor due to finger deformity, or inadequate signal caused by digital hypoperfusion
研究组 & 干预措施
Group 1-ORI-Guided FiO₂ Titration Group
Patients will receive 80% FiO₂ for 3 minutes before induction. After intubation, FiO₂ will be set to 50% and titrated to keep the Oxygen Reserve Index (ORI) between 0.00-0.05 using the Masimo Rad-97. If ORI ≥0.05 for ≥5 min, FiO₂ will be reduced by 0.05; if ORI stays within 0-0.05 for ≥5 min, FiO₂ will be maintained; if ORI = 0 with SpO₂ <95%, FiO₂ will be increased by 0.05. The target PaO₂ is 80-120 mmHg. PEEP will be fixed at 5 cmH₂O, and a standard recruitment maneuver will be applied at surgery start. The protocol continues throughout the operation. Only noninvasive methods (ORI, LUS, spirometry) will be used. Both groups will have preoperative LUS and spirometry. Postoperative LUS will be repeated at 30 minutes and spirometry at 24 hours for comparative assessment.
干预措施: Titrated Oxygen (Procedure)
Group 2- Fixed FiO₂
Patients will undergo preoxygenation with 80% FiO₂ for 3 minutes prior to induction. After endotracheal intubation, FiO₂ will be maintained at 50% and continued unchanged throughout the surgical procedure. Positive end-expiratory pressure (PEEP) will be set at 5 cmH₂O, and a standard alveolar recruitment maneuver will be applied to all patients at the beginning of surgery.
The intervention will be continued throughout the surgical procedure. Only noninvasive monitoring (ORI measurement), lung ultrasonography (LUS), and spirometry will be performed in this study. In both groups, preoperative spirometry and lung ultrasonography will be conducted. Postoperatively, lung ultrasonography will be repeated at the 30th minute, and spirometry will be repeated at the 24th hour to allow for comparative analysis.
干预措施: Fixed oxygen (Procedure)
结局指标
主要结局
Change in Total Lung Ultrasound (LUS) Score
时间窗: Baseline (Preoperative) and 30 Minutes After Extubation
The primary outcome of the study is the change in the total Lung Ultrasound (LUS) score obtained using a standardized 12-zone lung ultrasound protocol. Each hemithorax was evaluated in six regions-anterior, lateral, and posterior lines, each divided into superior and inferior zones-resulting in a total of 12 assessed areas. Each zone was scored from 0 to 3 based on the degree of aeration, yielding a total score ranging from 0 to 36, with higher scores indicating greater aeration loss and atelectasis. Accordingly, the difference between the preoperative LUS score and the LUS score measured at 30 minutes after extubation was defined as the primary endpoint of the study.
次要结局
- Change in Forced Vital Capacity (FVC)(Baseline (Preoperative) and Postoperative 24th Hour)
- Change in Forced Expiratory Volume in 1 Second (FEV1)(Baseline (Preoperative) and Postoperative 24th Hour)
- Change in FEV1/FVC Ratio(Baseline (Preoperative) and Postoperative 24th Hour)
研究者
Sıla Soytaş
Principal Investigator
Ankara Etlik City Hospital