Effectiveness and safety of a new protocol of intrapulmonary administration of urokinase in massive pulmonary embolism

Abstract

Purpose: Previous clinical studies have shown the efficacy of thrombolysis in patients affected by pulmonary embolism. However, there is no standardized technique or dose regimen for pulmonary thrombolysis, and direct comparison between the various reported data is difficult. We have developed a new method of thrombolysis based on local infusion of urokinase by which catheter position and infusion duration can be precisely adjusted to the individual patient's condition. The aim of this study was to evaluate the effectiveness and safety of our procedure. Materials and methods: Fourteen consecutive patients entered the study over a 2-year period. The diagnosis of pulmonary embolism was confirmed by means of pulmonary angiography and the severity of embolism was assessed by the Miller method. All patients underwent intrapulmonary thrombolysis with urokinase: an initial bolus of 3,300 IU/kg in 10 min was followed by infusion of 1,000–1,500 IU/kg per hour for 24 h. Blood samples for study of the coagulation and fibrinolytic systems were taken every 8 h. Pulmonary angiography was repeated after 24 h to evaluate treatment results. Variation of catheter tip position and the continuation of thrombolysis for a new cycle of 24 h were decided on by a medical team individually for each patient. All adverse events were recorded; if a major complication (severe bleeding) occurred, thrombolytic administration was interrupted. Results: In one patient thrombolysis was interrupted after 24 h because of the onset of hematemesis. Mean Miller index fell from 19.42 ± 4.76 to 12.85 ± 5.26 in 14 patients (P < 0.01). A systemic effect of the urokinase was not suspected as both coagulation tests and the platelet counts were unchanged. Conclusion: Our results suggest that our procedure of local administration of urokinase could provide a suitable approach to thrombolytic therapy in patients with massive pulmonary embolism. However, further research with a larger number of patients is needed to confirm our preliminary data.