Pulsed Doppler echocardiographic assessment of changes in pulmonary artery pressure during oxygen breathing

To validate the use of pulsed Doppler echocardiography in detecting changes in pulmonary artery pressure (PAP), several parameters of flow velocity profiles of the right ventricular outflow tract were compared with changes in PAP and pulmonary vascular resistance measured directly by cardiac catheterization. The study was performed in 33 patients with chronic pulmonary disease (chronic obstructive pulmonary disease or pulmonary fibrosis) or pulmonary thromboembolism, during room air and 100% oxygen breathing. Inhalation of 100% oxygen for 15 min significantly reduced PAP in patients with mild pulmonary hypertension (20 < or = mean PAP < or = 24 mm Hg; control: 21.3 +/- 1.3, O2: 17.9 +/- 2.2 mm Hg, p < 0.05) and those with severe pulmonary hypertension (mean PAP > or = 25 mm Hg; control 44.9 +/- 16.8, O2: 35.4 +/- 13.5 mm Hg, p < 0.05). It also significantly reduced the pulmonary vascular resistance and cardiac output in both groups. The ratio of acceleration time to right ventricular ejection time (AT/RVET), a parameter measured by Doppler echocardiography, correlated significantly with mean PAP during room air (r = 0.73, p < 0.0001) and oxygen breathing (r = 0.64, p < 0.0001). Furthermore, AT/RVET increased significantly in patients with mild pulmonary hypertension and those with severe pulmonary hypertension. Our results suggest that the Doppler technique provides a clinically useful, noninvasive index for assessing changes in PAP during oxygen breathing in patients with pulmonary hypertension complicating chronic pulmonary disease or pulmonary thromboembolism.