Hsu Jen Te, Chu Chi Ming, Chang Shih Tai, Cheng Hui Wen, Lin Pi Chi, Hsu Tsu Shiu, Hsiao Ju Feng, Ho Wan Ching, Chung Chang Min
Division of Cardiology, Chiayi Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan.
Circ J. 2007 Oct;71(10):1560-6. doi: 10.1253/circj.71.1560.
Because the arterial/alveolar oxygen tension ratio (a/APO2) is relatively constant throughout the entire range of fractional inspired oxygen concentration (FiO2), its use in determining the prognosis of acute pulmonary embolism (APE) was investigated.
This study retrospectively assessed 202 consecutive patients with APE confirmed by computed tomography or high probability lung scintigraphy. All patients underwent initial arterial blood gas analysis during the first 24 h of admission. Receiver-operating characteristic analyses were performed to determine the a/APO2 cut-off value for predicting 30-day death or 30-day composite events. Cut-off values for a/APO2 were used to determine stability in all patients and 2 subgroups (0.49 for all patients; 0.49 for FiO2 =0.21; 0.46 for FiO2 >0.21). Using the cut-off value of a/APO2 <0.49 for predicting 30-day death, the negative predictive value (NPV) was 90%, and the positive predictive value (PPV) was 30.3%. For the 30-day composite end point, the NPV was 81.3%, and the PPV was 40.9%. Excluding massive APE, the a/APO2 also had high NPV and moderate PPV in predicting short-term prognosis. This study additionally demonstrated a linear relationship between platelet count and a/APO2.
The cut-off value of a/APO2 <0.49 exhibits stability at variable FiO2 values and is a useful prognostic predictor in APE.
由于动脉血氧分压与肺泡氧分压之比（a/APO2）在整个吸入氧分数（FiO2）范围内相对恒定，因此对其在急性肺栓塞（APE）预后评估中的应用进行了研究。
本研究回顾性分析了202例经计算机断层扫描或高概率肺通气灌注显像确诊的APE患者。所有患者在入院后24小时内均接受了首次动脉血气分析。通过受试者工作特征分析确定预测30天死亡或30天复合事件的a/APO2临界值。使用a/APO2临界值来确定所有患者及2个亚组的稳定性（所有患者为0.49；FiO2 = 0.21时为0.49；FiO2 > 0.21时为0.46）。使用a/APO2 < 0.49预测30天死亡时，阴性预测值（NPV）为90%，阳性预测值（PPV）为30.3%。对于30天复合终点，NPV为81.3%，PPV为40.9%。排除大面积APE后，a/APO2在预测短期预后方面也具有较高的NPV和中等的PPV。本研究还证实血小板计数与a/APO2之间存在线性关系。
a/APO2 < 0.49的临界值在不同FiO2值时具有稳定性，是APE中一个有用的预后预测指标。
