Posttraumatic pulmonary microembolism. Pathophysiology and treatment.

The aetiology of respiratory insufficiency in man following massive trauma, major surgery or serious illness may vary. There is, however, one special type, the pathogenesis of which remains controversial despite several clinical, autopsy and experimental investigations. Our concept of this syndrome, which is summarized in this review has been arrived at from clinical, pathologico-anatomical and experimental studies. In its pure form the syndrome is most appropriately called "posttraumatic pulmonary microembolism", because the major underlying mechanism is probably a release of thromboplastic products from injured tissues, which generate platelet and fibrin microemboli which are trapped in the lungs during a phase of fibrinolysis inhibition. Preventive measures against pulmonary microembolism include immediate restoration of the haemodynamic state to ensure good tissue perfusion, and prompt reduction and immobilization of internal fixation of long bone fractures. The cardinal feature in the treatment of impending respiratory dysfunction is early institution of volume-controlled ventilation, using positive end-expiratory pressures of between 8 and 15 cm H2O synchronously with low dose heparin treatment and administration of one or two high doses of corticosteroids.