Stein P D, Goldhaber S Z, Henry J W
Henry Ford Heart and Vascular Institute, Detroit, Mich 48202-2691.
Chest. 1995 Jan;107(1):139-43. doi: 10.1378/chest.107.1.139.
The purpose of this investigation is to evaluate the utility of the alveolar-arterial (A-a) oxygen gradient in the diagnosis of acute pulmonary embolism (PE) among patients who participated in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIO-PED).
Pulmonary embolism was diagnosed (n = 280) or excluded (n = 499) by angiography in all patients. Patients were then categorized as (1) the entire cohort, (2) no prior cardiopulmonary disease and no prior PE, and (3) no prior PE or deep venous thrombosis. Normal values of the A-a gradient were defined in three ways: (1) values < or = 20 mm Hg; (2) values < or = age/4 + 4; and (3) values based on age from the literature.
When a normal A-a gradient was defined as < or = 20 mmHg, 11 to 14% of patients with PE in the three categories of patients had a normal A-a gradient. When the equation age/4 + 4 was used, 8% to 10% of patients with PE in the three categories of patients had a normal A-a gradient. With age-related values from the literature, 20 to 23% of patients with PE in the three categories of patients had a normal A-a gradient. The A-a gradient was normal in comparable percentages of patients who did not have PE.
Normal values of the A-a gradient did not exclude the diagnosis of acute PE.
本研究旨在评估肺泡-动脉（A-a）氧梯度在参与肺栓塞诊断前瞻性研究（PIO-PED）的患者中诊断急性肺栓塞（PE）的效用。
所有患者均通过血管造影确诊（n = 280）或排除（n = 499）肺栓塞。然后将患者分为以下几类：（1）整个队列；（2）无既往心肺疾病且无既往PE；（3）无既往PE或深静脉血栓形成。A-a梯度的正常数值通过三种方式定义：（1）数值≤20 mmHg；（2）数值≤年龄/4 + 4；（3）基于文献中年龄的数值。
当将正常A-a梯度定义为≤20 mmHg时，三类患者中11%至14%的PE患者A-a梯度正常。当使用年龄/4 + 4的公式时，三类患者中8%至10%的PE患者A-a梯度正常。根据文献中的年龄相关数值，三类患者中20%至23%的PE患者A-a梯度正常。在无PE的患者中，A-a梯度正常的比例相当。
A-a梯度的正常数值不能排除急性PE的诊断。
