Fibrinolytic therapy of pulmonary embolism

Fibrinolytic therapy of pulmonary emboli is indicated in persistent pulmonary hypertension or acute shock. If possible, diagnosis should be confirmed by pulmonary angiography - in our hands digital subtraction angiography has proved of value. Emboli of such size that spontaneous lysis is unlikely can be actively removed by lysis therapy so as to minimize late damage. Small or insignificant emboli do not require such therapy. As lysis therapy does not reduce early mortality it follows that mortality is not a suitable parameter for evaluating the results of treatment. Rapid clinical improvement and fall in pulmonary arterial pressure and oxygen tension some 24 to 48 hours later should not lead to erroneous conclusion that the thrombus mass has been lysed. Pulmonary angiography demonstrates that lysis takes 48 hours to 13 days. Large thrombi require a mean duration of treatment of 6 days. Only complete elimination of the vascular occlusion leads to permanent improvement. Obviously, the duration of therapy in cases of demonstrable phlebothrombosis will also depend upon the results of phlebography. In the case of contraindications lytic therapy should only be initiated where the risk from the emboli is greater than the possible haemorrhagic risk from the contraindication. Under such circumstances urokinase therapy with 40,000 to maximal 60,000 units/hour is preferable.