Sassoon C S, Mahutte C K
Department of Medicine, Veterans Affairs Medical Center, Long Beach, California 90822.
Am Rev Respir Dis. 1993 Oct;148(4 Pt 1):860-6. doi: 10.1164/ajrccm/148.4_Pt_1.860.
Airway occlusion pressure (P0.1) and the ratio of breathing frequency (f) to tidal volume (VT) (f/Vt) are good predictors of weaning outcome. However, the specificity of f/VT in predicting weaning success is relatively low. We postulated that the product of P0.1 and f/VT (P0.1f/VT) would better predict weaning outcome than either variable alone. In 45 male patients, we prospectively evaluated P0.1f/VT, P0.1, and f/VT in predicting weaning outcome. The threshold values of each variable were determined from published data. The sensitivity, specificity, and positive and negative predictive values in detecting weaning success, and the area under the receiver operating characteristic (ROC) curves were calculated. Ten (22%) of the 45 patients failed weaning. P0.1f/VT yielded the highest specificity and positive and negative predictive values. P0.1f/VT, P0.1, and f/VT were all highly sensitive (0.97); but they were less specific, 0.60 for P0.1f/Vt and 0.40 for P0.1 and f/VT. The areas under the ROC curves for P0.1f/VT, P0.1, and f/VT were not significantly different. We conclude that P0.1*f/VT has equivalent sensitivity as P0.1 and f/VT. P0.1 slightly improves the specificity of f/VT in predicting weaning success.
气道闭塞压（P0.1）以及呼吸频率（f）与潮气量（VT）的比值（f/Vt）是撤机结果的良好预测指标。然而，f/VT预测撤机成功的特异性相对较低。我们推测P0.1与f/VT的乘积（P0.1f/VT）比单独的任何一个变量都能更好地预测撤机结果。在45例男性患者中，我们前瞻性地评估了P0.1f/VT、P0.1和f/VT对撤机结果的预测情况。每个变量的阈值根据已发表的数据确定。计算了检测撤机成功的敏感性、特异性、阳性和阴性预测值，以及受试者工作特征（ROC）曲线下的面积。45例患者中有10例（22%）撤机失败。P0.1f/VT的特异性、阳性和阴性预测值最高。P0.1f/VT、P0.1和f/VT的敏感性均很高（0.97）；但它们的特异性较低，P0.1f/Vt为0.60，P0.1和f/VT为0.40。P0.1f/VT、P0.1和f/VT的ROC曲线下面积无显著差异。我们得出结论，P0.1*f/VT与P0.1和f/VT具有同等的敏感性。P0.1在预测撤机成功方面可略微提高f/VT的特异性。
