[Non-thrombotic pulmonary embolisms]

In the absence of intracardiac or intrapulmonary shunts, the pulmonary microvasculature traps all embolized particles greater than 10 microns. In the vast majority of cases these emboli are venous thrombi which lodge in larger pulmonary arteries, resulting in obstructive phenomena rather than primarily being injurious to lung parenchyma. This review deals exclusively with nonthrombotic pulmonary embolism which involves substances that lodge predominantly in the pulmonary microvessels and cause a true endothelial and parenchymal injury, as well as obstructive phenomena. The article focuses on fat embolism, amniotic fluid embolism, gas embolism, septic emboli, and tumour pulmonary embolism.