BackgroundDecline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure. In this study we aimed to test the validity and usefulness of OUE in evaluating gas exchange abnormality of patients with idiopathic pulmonary arterial hypertension (IPAH).MethodsWe retrospectively investigated the cardiopulmonary exercise test (CPET) with gas exchange measurements in 32 patients with confirmed IPAH. All patients also had resting hemodynamic measurements and pulmonary function test (PFT). Sixteen healthy subjects, matched by age, sex, and body size were used as controls, also had CPET and PFT measurements.ResultsIn IPAH patients, the magnitude of absolute and percentage of predicted (%pred) oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP), as well as several other CPET parameters, were strikingly worse than healthy subjects (P<0.0001). Pattern of changes in OUE in patients is similar to that in controls, In IPAH patients, OUE values at rest, warming up, anaerobic threshold and peak exercise were all significantly lower than in normal (P<0.0001). OUEP%pred, better than OUES%pred, correlated significantly with New York Heart Association (NYHA) functional Class (r = −0.724, P<0.005), Total Pulmonary Vascular Resistance (TPVR) (r = −0.694, P<0.005), diffusing capacity for carbon monoxide (DLCO) (r = 0.577, P<0.05), and the lowest ventilation versus CO2 output ratio during exercise (LowestV˙E/V˙CO2) (r = −0.902, P<0.0001). In addition, the coefficient of variation (COV) of OUEP was lower (20.9%) markedly than OUES (34.3%) (P<0.0001).ConclusionsIn patients with IPAH, OUES and OUEP are both significantly lower than the healthy subjects. OUEP is a better physiological parameter than OUES in evaluating the gas exchange abnormality of patients with IPAH.
Background: Previous studies demonstrated a relationship between pulmonary hemodynamics and shape of pulmonary artery (PA) Doppler-flow profiles in a mixed pulmonary hypertension (PH) cohort. Hypothesis: Shape of PA Doppler-flow profiles could illustrate the hemodynamic characteristics of pulmonary venous hypertension (PVH), especially identifying it with or without pulmonary vascular disease (PVD). Methods: We retrospectively analyzed hemodynamic, echocardiographic, and clinical data from 47 patients referred for PH caused by left-sided heart disease (PH-LHD). All patients underwent right-sided heart catheterization within 1 week of echocardiography. We concluded a simple echocardiographic prediction rule to give hemodynamic differentiation of PVH with PVD, defined as capillary wedge pressure >15 mm Hg and pulmonary vascular resistance (PVR) >3 Wood units (WU). The PA Doppler-flow profiles were categorized into 2 groups, no notch (NN) and MSN/LSN. Results: The PVR was higher in the MSN/LSN group at 4.04 WU (interquartile range, 3.1-5.3) vs the NN group at 1.91 WU (interquartile range, 1.8-3.0; P < 0.001). Pulmonary artery Doppler-flow notching (MSN and LSN) was highly associated with PVR >3 WU, whereas the NN pattern predicted a PVR ≤3 WU (odds ratio: 19.8, 95% confidence interval: 4.3-91.3) and normal transpulmonary pressure gradient ≤12 mm Hg (odds ratio: 4.7, 95% confidence interval: 1.3-16.2). The NN pattern had 74% specificity and 88% sensitivity for PVR ≤3 WU. Conclusions: Absence of PA Doppler-flow notching was highly associated with PVH, and a notching pattern indicated PVH with PVD in the PH-LHD cohort.
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