目的：探讨急性肺栓塞通气灌注比例（Ｖ／Ｑ）失调、肺内分流、弥散损伤及右向左心内分流在低氧血症中各自所起的作用。方法：８例确诊为急性肺栓塞的患者，卧位休息１０分钟，行血流动力学检查，同时取动脉及混合静脉血，作血气分析；计算肺内分流及Ｖ／Ｑ。结果：患者出现症状３天内Ｘ线胸片无异常，３天后患者有局限性肺不张或小灶性浸润。血流动力学显示肺动脉平均压中、重度升高［平均５．１±１．１ｋＰａ（３８±８ｍｍＨｇ）］，肺血管阻力上升（平均７８．６±３２．８ｋＰａｓ／Ｌ），心脏指数降低［平均２．６±０．５Ｌ／（ｍｉｎｍ２）］。所有患者都有低氧血症［平均动脉氧分压７．１±０．９ｋＰａ（５３±７ｍｍＨｇ）］和低碳酸血症。肺泡动脉氧差增宽，分流量增加，死腔量升高。结论：急性肺栓塞的低氧血症主要原因为Ｖ／Ｑ失调，同时发生的心功能抑制也进一步促进了低氧血症，而肺内分流只在有肺膨胀不全或肺容积丧失时才起作用。 Objective: To investigate the role of V / Q imbalance, intrapulmonary shunt, diffuse injury and right-to-left cardiac shunt in hypoxemia in patients with acute pulmonary embolism. Methods: Eight patients with acute pulmonary embolism were diagnosed as having acute pulmonary embolism. The patients were rest for 10 minutes in the supine position. The patients underwent hemodynamic examination. Blood samples were taken from the arterial blood and mixed venous blood samples. The intrapulmonary shunt and V / Q were calculated. Results: The patients showed no abnormalities in X-ray in 3 days and patients had limited atelectasis or focal infiltration after 3 days. Hemodynamics showed moderate and severe increases in mean pulmonary artery pressure [mean 5.1 ± 1.1 kPa (38 ± 8 mmHg)], increased pulmonary vascular resistance (mean, 78.6 ± 32.8 kPas / L) and decreased cardiac index Average 2.6 ± 0.5L / (minm2)]. All patients had hypoxemia [mean arterial partial pressure 7.1 ± 0.9 kPa (53 ± 7 mmHg]] and hypocapnia. Alveolar artery oxygen difference broadened, increased shunt, dead space increased. Conclusions: The main cause of hypoxemia in patients with acute pulmonary embolism is V / Q imbalance, and concomitant cardiac arrest further contributes to hypoxemia, whereas intrapulmonary shunts develop only when there is antecedent lung insufficiency or loss of lung volume effect.