Treatment of acute pulmonary embolism with a low molecular weight heparin by the intravenous route. Study of the optimal dosage

: Experimental studies on rabbits have shown that CY 222, a low molecular weight heparin (mean: 2.500 daltons), has the anti-thrombosis properties of heparin but reduces the risk of haemorrhage in optimal doses of 1.000 AXa IC (Institut Choay) units/kg/day. The safety and effectiveness of CY 222 were tested in 47 patients presenting with a less than 5 days' old pulmonary embolism. The patients were divided into three groups according to dosage: group I (n = 16) received 500 AXa ICu/kg/day; group II (n = 17), 750 AX ICu/kg/day, and group III (n = 14), 1.000 AXa ICu/kg/day. The drug was administered by continuous intravenous infusion during 10 days. Its effectiveness was assessed from the Miller index calculated on conventional pulmonary angiograms on days 0, 5 and 10. On the 10th day of treatment, the percentage of revascularization was similar in all three groups (group I 65.9 +/- 9.9 p. 100; group II 71 +/- 6.8 p. 100; group III 68 +/- 8.5 p. 100), but the improvement was significantly more rapid in group III patients. Embolism recurred in 5 cases (2 in group I, 1 in group II, 2 in group III) and was fatal in 1 case (group I). Haemorrhagic complications were noted in 3 cases (group III patients). Except for thromboelastography, all coagulation tests were unmodified by CY 222. The anti Xa and the (very low) anti IIa activities of the drug were directly related to the doses administered.(ABSTRACT TRUNCATED AT 250 WORDS)