RESUMEN
This study included 47 pulmonary hypertensive patients secondary to chronic hypoxia due to chronic obstructive pulmonary diseases [COPD] and interstitial pulmonary fibrosis [IPF]. They were sampled in the morning after an overnight fast, before medication and after termination of treatment. Endothelin-1 level was 1.45 +/- 0.32 pg/ml which was increased compared with the normal controls [0.5 +/- 0.02]; the difference was statistically significant. Endothelin-1 was significantly correlated with pulmonary pressure and its degree of severity, especially among chronic obstructive pulmonary disease patients. There was a significant reduction in the level of endothelin-1 after long-term oxygen therapy; whereas, it did not correlate with the level of PaO2 either before or after oxygen therapy. Plasma thrombomodulin level was measured to study its pathophysiological significance in pulmonary hypertension secondary to hypoxia. Patients with pulmonary hypertension had higher concentrations of thrombomodulin [15.25 +/- 1.5] than the age matched normal controls [4.8 +/- 0.5 ng/ml]. There was a significant reduction in thrombomodulin after oxygen therapy. Plasma concentrations of thrombomodulin were significantly correlated with time to peak velocity [TPV] as a strong echo parameter of pulmonary hypertension and its severity in mild PH thrombomodulin level was 10.46 +/- 0.56 ng/ml versus 15.82 +/- 3.08 ng/ml among patients with severe pulmonary hypertension. Moreover, thrombomodulin correlated with PaO2 after oxygen therapy especially with patients of IPF