Serial pulmonary angiography in rats with pulmonary damage due to intravascular coagulation

Serial pulmonary angiography was performed in 30 rats with pulmonary damage caused by injection of a fibrinolysis inhibitor, tranexamic acid (200 mg/kg body weight injected intraperitoneally) and bovine thrombin (500 NIH/kg body weight injected into the right atrium or ventricle). The degree of inhomogeneity of the capillary phase was graded and compared with that in a group of normal rats. Changes in the capillary phase were well correlated to other signs of lung trauma, namely increase in lung weight and microscopic occurrence of interstitial and alveolar oedema and of intravascular fibrin deposits. Increased lung weight similarly was found to be well correlated to increased interstitial oedema. It had also a distinct relationship to increased inhomogeneity of the capillary phase. The disturbance of the capillary phase may have been caused by mechanical blockage due to intravascular coagulation with microembolism, and interstitial oedema, vasospasm of precapillary arteries, or by arteriovenous shunting. Inhomogeneity of the capillary phase is consistent with a gross change in the ventilation/perfusion ratio, which could explain arterial hypoxaemia observed in other investigations.