Pascual F E, Matthay M A, Bacchetti P, Wachter R M
Cardiovascular Research Institute, Department of Medicine, University of California, San Francisco, USA.
Chest. 2000 Feb;117(2):503-12. doi: 10.1378/chest.117.2.503.
Knowing that mortality is high in patients who require mechanical ventilation patients with community-acquired pneumonia (CAP), we hypothesized that the severity of acute lung injury could be used along with nonpulmonary factors to identify patients with the highest risk of death. We formulated a prediction model to quantitate the risk of hospital mortality in this population of patients.
Historical prospective study using data collected over the first 24 h of mechanical ventilation. We utilized a hypoxemia index-(1 - lowest [PaO(2)/PAO(2)]) x (minimum fraction of inspired oxygen to maintain PaO(2) at > 60 mm Hg) x 100], where PAO(2) is the alveolar partial pressure of oxygen-to grade the severity of acute lung injury on a scale from 0 to 100.
Tertiary care university hospital ICU.
One hundred forty-four adult patients mechanically ventilated for respiratory failure caused by CAP.
Hospital mortality was 46% (n = 66). Multivariate logistic regression analysis revealed five independent predictors of hospital mortality: (1) the extent of lung injury assessed by the hypoxemia index; (2) the number of nonpulmonary organs that failed; (3) immunosuppression; (4) age > 80 years; and (5) medical comorbidity with a prognosis for survival < 5 years. At a 50% mortality threshold, the prediction model correctly classified outcome in 88% of cases. All patients with > 95% predicted probability of death died in hospital.
Based on clinical parameters measured over the first 24 h of mechanical ventilation, this model accurately identified critically ill, mechanically ventilated patients with CAP for whom prolonged intensive care may not be of benefit.
鉴于社区获得性肺炎（CAP）机械通气患者死亡率较高，我们推测急性肺损伤的严重程度可与非肺部因素一起用于识别死亡风险最高的患者。我们构建了一个预测模型来量化该类患者的医院死亡风险。
采用机械通气最初24小时收集的数据进行历史性前瞻性研究。我们使用低氧血症指数 -（1 - 最低[动脉血氧分压（PaO₂）/肺泡氧分压（PAO₂）]）×（维持PaO₂>60 mmHg所需的最低吸入氧分数）×100]，其中PAO₂为肺泡氧分压，将急性肺损伤的严重程度按0至100分进行分级。
三级医疗大学医院重症监护病房。
144例因CAP导致呼吸衰竭而接受机械通气的成年患者。
医院死亡率为46%（n = 66）。多因素逻辑回归分析显示医院死亡的五个独立预测因素：（1）通过低氧血症指数评估的肺损伤程度；（2）发生功能衰竭的非肺部器官数量；（3）免疫抑制；（4）年龄>80岁；（5）生存预后<5年的内科合并症。在50%的死亡阈值下，预测模型在88%的病例中正确分类了结局。所有预测死亡概率>95%的患者均在医院死亡。
基于机械通气最初24小时测量的临床参数，该模型准确识别了患有CAP的重症机械通气患者，对于这些患者延长重症监护可能并无益处。
