Effect of Positive End-Expiratory Pressure (PEEP) Level on Postoperative Oxygenation and Lung Aeration Assessed by Lung Ultrasound Monitoring: A Multicenter Randomized Controlled Trial (ULTRASVENT-2)
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 发起方
- 入组人数
- 360
- 试验地点
- 1
研究概览
简要总结
The purpose of this multicenter, randomized controlled trial (ULTRASVENT-2) is to evaluate the effect of different positive end-expiratory pressure (PEEP) levels on postoperative oxygenation and lung aeration in adult patients undergoing elective non-cardiac and non-thoracic surgery under general anesthesia. Moving away from traditional binary outcomes, this study utilizes a continuous functional metric, the non-invasive oxygenation index SpO2/FiO2 (S/F ratio), as the primary endpoint to precisely capture the degree of respiratory function preservation.
Patients will be stratified into four distinct surgical cohorts based on the type and aggressiveness of the procedure: non-abdominal surgery, major open abdominal surgery, major laparoscopic abdominal surgery, and low-trauma laparoscopic surgery. This adaptive design aims to investigate how protective PEEP strategies interact with varying degrees of surgical trauma and intraoperative pneumoperitoneum, allowing the optimization of mechanical ventilation parameters for routine clinical practice.
详细描述
Postoperative pulmonary complications remain a significant cause of morbidity and prolonged hospital stay after major surgical interventions under general anesthesia. While positive end-expiratory pressure (PEEP) is widely used to prevent alveolar collapse, the optimal target levels across different surgical sub-types remain controversial in modern anesthesiology. This trial aims to establish robust clinical evidence regarding perioperative lung protection using a comprehensive functional-anatomical approach.
Primary Endpoint and Measurement Standardization:
The primary outcome of the trial is the non-invasive oxygenation index, the S/F ratio (SpO2/Fraction of inspired oxygen), assessed exactly 2 hours post-extubation in the Post-Anesthesia Care Unit (PACU) and tracked dynamically over the first 24 hours of the postoperative period. To eliminate confounding variables and ensure absolute reproducibility across participating centers, the primary endpoint measurement is strictly standardized according to the following criteria:
- Room Air Breathing (FiO2 0.21): The evaluation is performed while the patient breathes atmospheric air without supplemental oxygen. This eliminates the masking of intrapulmonary shunts and prevents hyperoxia-induced absorption atelectasis.
- Patient Position: The patient must be placed in a strict supine position. This positioning represents the most physiologically challenging state for the respiratory system, inducing cranial displacement of the diaphragm and maximizing gravity-dependent alveolar collapse.
- Full Wakefulness Criteria: The measurement is executed only when the patient reaches a full awake status, defined as a modified Post Anesthesia Recovery Score (PARS) greater than 8, with the specific ventilation sub-score being equal to 2 (ability to deep breathe and cough freely). This cognitive and motor filter guarantees that any recorded functional impairment is caused by true parenchymal collapse rather than residual neuromuscular blockade or opioid-induced respiratory depression.
Differentiated Lung Ultrasound (LUS) Track:
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Prevention
- 盲法
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
盲法说明
The automated intraoperative positive end-expiratory pressure (PEEP) settings are completely hidden from the post-anesthesia care unit (PACU) nursing staff, ward physicians, and investigators. All parameters are documented in a separate file inaccessible during the evaluation period. The clinical operators performing both the preoperative and postoperative lung ultrasound (LUS) examinations, as well as the personnel calculating the primary functional outcome (SpO2/FiO2 ratio), are strictly blinded to the assigned PEEP strategy and the patient's intraoperative ventilator settings.
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age greater than or equal to 18 years.
- •Planned elective non-cardiac and non-thoracic surgical intervention requiring general anesthesia with mechanical ventilation.
- •Airway protection utilizing an endotracheal tube.
- •Assignment to one of the four specific surgical strata: non-abdominal, major open abdominal, major laparoscopic abdominal, or low-trauma laparoscopic surgery.
- •Baseline lung ultrasound showing no pathological findings, corresponding to a total preoperative LUS score of
- •Technical feasibility of performing a postoperative lung ultrasound within the first 2 hours after the completion of surgery.
- •Signed written informed consent to participate in the clinical trial.
排除标准
- •Planned cardiac or thoracic surgery (e.g., coronary artery bypass grafting, valve replacement, heart transplantation, lung resection, esophageal surgery).
- •Pneumothorax diagnosed before or during the surgical procedure.
- •Inability to adequately visualize the target dorsal-basal lung zones by ultrasound due to physical limitations (e.g., morbid obesity, massive surgical dressings, anatomical anomalies, or dermatological lesions in the scanning area).
- •Presence of hydrothorax detected on the baseline preoperative ultrasound.
- •Confirmed perioperative aspiration of gastric contents or other foreign material.
- •Any pathological changes identified during the baseline ultrasound of the dorsal-basal lung regions (a total preoperative LUS score greater than 0).
- •Requirement for massive blood transfusion during the surgery, defined according to local institutional criteria.
- •Surgical interventions directly involving or violating the diaphragm.
- •Expected inability to conduct reliable postoperative clinical and ultrasound assessments (e.g., need for deep sedation preventing wakefulness and contact, or planned transfer to another facility).