Pulmonary embolism in chronic hypoxemic patients with and without secondary polycythemia--analysis of risk factors in prospective clinical study.

Aim Prospectively evaluate the incidence of pulmonary embolism and risk factors for this life-threatening disease on chronic hypoxemic patients treated in intensive respiratory care unit. Methods The study enrolled 842 consecutive patients with severe exacerbation of chronic obstructive pulmonary disease or respiratory failure. The initial assessment included clinical history collection, physical examination, hematological and biochemical analysis, gas analysis, chest X ray, 12 lead electrocardiography and determination of value of D-dimer. Of all enrolled patients, 211 met the exclusion criteria. Of 631 included patients, 269 (42.6%) had normal D-dimer. D-dimer level ≥500 μg/L was found in 362 (57.5%) patients who were referred to Doppler echocardiography, lower limb color Doppler ultrasonography and thoracic multidetector helical computed tomography. According the value of hematocrit, all patients were divided in two groups: group I (100 patients) with polycythema and group II (262 patients) without polycythemia. Results The first outcome of the study was the significantly higher incidence of pulmonary embolism in group I of patients than in group II, 39 (39%) and 29 (11.06%), respectively. Patients in group I had significantly worse disturbance of pulmonary function and higher degree of pulmonary hypertension (58.4±3.66 vs. 30.3±9.41). Apart from polycythemia in group I, the most common risk factors were arrhythmia, absolute and varicose veins. Conclusion Polycythemia is a single most significant risk factor for pulmonary embolism in chronic hypoxemic patients. Value of D-dimer ≥500 μg /L, as well as presence of comorbidity, particularly vein varicose, in these patients should raise clinical suspicion of PE.