Shi, Xiaofang; Guo, Jian; Gong, Sugang; Sapkota, Rikesh; Yang, Wenlan;
Liu, Hui; Xiang, Wenjing; Wang, Lan; Sun, Xingguo; Liu, Jinming.

Respirology, January 2016, Vol. 21 Issue: Number 1 p149-156, 8p;
Abstract: The responses of oxygen uptake efficiency (OUE) during
cardiopulmonary exercise training (CPET) have not been reported in
patients with pulmonary hypertension. We aimed to investigate the
differences in OUE between patients with idiopathic pulmonary arterial
hypertension (IPAH) and chronic thromboembolic pulmonary hypertension
(CTEPH). Forty‐four patients with IPAHand 29 patients with CTEPH were
retrospectively enrolled into our study. All patients underwent
right‐heart catheterization, pulmonary function test and performed the
6‐min walk test and CPET. We found that oxygen uptake efficiency
plateau (OUEP) and oxygen uptake efficiency at anaerobic threshold
(OUE@AT) was significantly higher in IPAH than that in CTEPH (both
P= 0.002). However, patients with CTEPH had lower mean pulmonary artery
pressure, pulmonary vascular resistance and transpulmonary gradient
(all P< 0.05). The correlation between OUEP and heart rate at anaerobic
threshold (HR_AT) was significant (r = 0.376, P< 0.05); however, no
statistically significant correlation was found with ventilation at
anaerobic threshold (VE_AT) (r = −0.074, P> 0.05) in patients with
IPAH. In patients with CTEPH, both anaerobic threshold (r = 0.307,
P> 0.05) and VE_AT (r = −0.709, P< 0.0001) were reduced. OUEP were
higher in WHO functional class I/IIpatients than in WHO functional class
III/IVpatients (all P< 0.05). OUEP and OUE@ATare higher in IPAHthan that
in CTEPH not in proportion to haemodynamics, probably due to differences
in cardiac function and pulmonary vascular occlusion. OUEP correlates
well with the exercise capacity and the severity of the disease.
Responses of oxygen uptake efficiency during cardiopulmonary exercise
testing in patients with pulmonary hypertension are reported. We
observed a higher oxygen uptake efficiency in patients with idiopathic
pulmonary arterial hypertension compared to patients with chronic
thromboembolic pulmonary hypertension. The oxygen uptake efficiency
plateau correlates with exercise capacity and disease severity.