Optimal Positive End-Expiratory Pressure (PEEP) Level for Minimizing the Risk of Postoperative Atelectasis According to Lung Ultrasound Monitoring: A Retrospective Cohort Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 450
- 试验地点
- 1
- 主要终点
- Frequency of Postoperative Atelectasis
研究概览
简要总结
Background: After surgery with general anesthesia, it is common for parts of the lungs to collapse, a condition called atelectasis. This can lead to low blood oxygen levels and other lung complications. Doctors use a setting on the breathing machine called PEEP (Positive End-Expiratory Pressure) to help keep the lungs open, but the best level to use is still debated.
Purpose of the Study: The goal of this research is to find a PEEP level that minimizes the risk of lung collapse and low oxygen levels after surgery. The investigators will use lung ultrasound, a safe and non-invasive imaging method, to check the health of the lungs at the patient's bedside.
The investigators will not assign treatments; they will observe the outcomes based on the PEEP level chosen by the patient's anesthesiologist during routine care. A simplified ultrasound scan will be used to score the amount of lung collapse before and after surgery. The main outcomes will be the frequency of lung collapse and the frequency of low oxygen levels (defined as SpO₂ of 90% or less).
详细描述
Background and Rationale Postoperative pulmonary complications (PPCs) are a significant cause of morbidity and mortality, associated with a nearly 20% increase in lethality and prolonged hospital stays. The most common PPC is atelectasis, which can trigger more severe complications and develops in up to 90% of patients following the induction of general anesthesia. While computed tomography (CT) is the gold standard for diagnosing atelectasis, lung ultrasound (LUS) has emerged as a rapid, reliable, and validated bedside tool that is superior to standard chest radiography, with a high sensitivity (87.7%) and specificity (92.1%) compared to CT.
A key strategy for preventing atelectasis is the application of positive end-expiratory pressure (PEEP). While ventilation with zero PEEP is considered harmful, the optimal level remains controversial. Large randomized trials (e.g., PROVHILO, PROBESE) have not shown a benefit for universally high PEEP strategies (e.g., 12 cm H₂O) and have noted an increased risk of hemodynamic instability. This contrasts with other studies suggesting benefits from moderate or individualized PEEP levels. This study designed to address this gap by analyzing data to identify a PEEP threshold associated with minimal atelectasis and desaturation, using a simplified LUS monitoring protocol.
Study Objectives The primary objective of this study is to evaluate the effectiveness of a simplified LUS protocol for monitoring postoperative atelectasis and to determine a PEEP level associated with the minimum frequency and severity of atelectasis.
Specific study tasks include:
- To assess the frequency and severity of postoperative atelectasis in patients with different airway management strategies and PEEP levels.
- To determine an optimal PEEP threshold for minimizing the risk of atelectasis and desaturation using ROC analysis.
- To compare the rates of atelectasis and desaturation (SpO₂ ≤90%) between patient subgroups.
- To conduct a multifactorial analysis of risk factors for developing postoperative atelectasis and desaturation.
- To evaluate the prognostic value of the LUS score for predicting the risk of postoperative desaturation.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Retrospective
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
- •Patients undergoing surgical intervention under general anesthesia with mechanical ventilation.
- •Airway protection managed with either an endotracheal tube or a laryngeal mask.
- •A normal baseline ultrasound of the posterior-basal lung regions, corresponding to a score of 0 on the lung ultrasound scale.
排除标准
- •Patients undergoing cardiac or thoracic surgery.
- •Presence of a perioperatively identified pneumothorax.
- •Inability to obtain adequate ultrasound visualization of the target lung zones.
- •Presence of hydrothorax.
- •Confirmed perioperative pulmonary aspiration.
- •Presence of any pathological findings on the initial baseline ultrasound of the posterior-basal lung regions.
- •Requirement for massive blood transfusion during the operation.
- •Patients undergoing surgery on the diaphragm.
- •Prolonged residual sedation lasting more than 2 hours post-operation
研究组 & 干预措施
ETT with PEEP ≤7 cm H₂O
This cohort consists of patients who underwent surgery with general anesthesia managed with an endotracheal tube (ETT) and a positive end-expiratory pressure (PEEP) of 7 cm H₂O or less. This group will include 250 patients in the final analysis
ETT with PEEP ≥8 cm H₂O
This cohort consists of patients who underwent surgery with general anesthesia managed with an endotracheal tube (ETT) and a positive end-expiratory pressure (PEEP) of 8 cm H₂O or greater. This group will include 119 patients in the final analysis
Laryngeal Mask
This cohort consists of patients who underwent surgery with general anesthesia managed with a laryngeal mask (LM) for airway protection. This group will include 81 patients in the final analysis
结局指标
主要结局
Frequency of Postoperative Atelectasis
时间窗: The ultrasound measurement is performed within the first few hours after the completion of the surgical procedure
The measure assesses the presence of postoperative atelectasis, defined as a lung ultrasound (LUS) score greater than 0. The assessment is conducted using a simplified 2-zone LUS protocol, with aeration evaluated on a 4-point scale (from 0 for normal aeration to 3 for major consolidation). The outcome is the percentage of patients who develop any degree of atelectasis (LUS score \> 0) following surgery
次要结局
- Frequency of Postoperative Desaturation(Within the first few hours after completion of surgery)
- Severity of Postoperative Atelectasis Measured by Lung Ultrasound Score(The final LUS score is measured within the first few hours after completion of surgery)