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Usefulness of decrease in oxygen uptake efficiency to identify gas exchange abnormality in patients with idiopathic pulmonary arterial hypertension.

Tan X, Yang W, Guo J, Zhang Y, Wu C, Sapkota R, Kushwaha SP, Gong S, Sun X, Liu J - PLoS ONE (2014)

Bottom Line: Decline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure.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).

View Article: PubMed Central - PubMed

Affiliation: Department of Pulmonary Function Test, Shanghai Pulmonary Hospital Affiliated to Tongji University, Shanghai, China; State Key Laboratory of Cardiovascular Disease, Heart-Lung Function Testing Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

ABSTRACT

Background: Decline 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).

Methods: We 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.

Results: In 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).

Conclusions: In 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.

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Related in: MedlinePlus

Difference of OUEP and OUE between a typical IPAH patient and a control subject.The kinetics of changes in oxygen uptake efficiency (OUE) for the same tests and subjects as depicted in Figure 1. OUE typically increase during exercise from rest to plateau in normal subjects and then decrease gradually until exercise end. It then decreases further in the immediate recovery period and begin stabilizing after about 2 minutes. In IPAH patients, OUE changes in a similar way as the controls, but is always lower than the controls in the transition from rest to exercise end.
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pone-0098889-g002: Difference of OUEP and OUE between a typical IPAH patient and a control subject.The kinetics of changes in oxygen uptake efficiency (OUE) for the same tests and subjects as depicted in Figure 1. OUE typically increase during exercise from rest to plateau in normal subjects and then decrease gradually until exercise end. It then decreases further in the immediate recovery period and begin stabilizing after about 2 minutes. In IPAH patients, OUE changes in a similar way as the controls, but is always lower than the controls in the transition from rest to exercise end.

Mentions: The OUES was defined as the regression slope “a” in V˙O2 = a×log10V˙E+b. A steeper slope or higher OUES represents a more efficient oxygen uptake per volume of ventilation (Figure 1). The OUEP was defined as the 90 sec average of the highest consecutive measurements of V˙O2/V˙E near the AT (Figure 2) [14].


Usefulness of decrease in oxygen uptake efficiency to identify gas exchange abnormality in patients with idiopathic pulmonary arterial hypertension.

Tan X, Yang W, Guo J, Zhang Y, Wu C, Sapkota R, Kushwaha SP, Gong S, Sun X, Liu J - PLoS ONE (2014)

Difference of OUEP and OUE between a typical IPAH patient and a control subject.The kinetics of changes in oxygen uptake efficiency (OUE) for the same tests and subjects as depicted in Figure 1. OUE typically increase during exercise from rest to plateau in normal subjects and then decrease gradually until exercise end. It then decreases further in the immediate recovery period and begin stabilizing after about 2 minutes. In IPAH patients, OUE changes in a similar way as the controls, but is always lower than the controls in the transition from rest to exercise end.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048265&req=5

pone-0098889-g002: Difference of OUEP and OUE between a typical IPAH patient and a control subject.The kinetics of changes in oxygen uptake efficiency (OUE) for the same tests and subjects as depicted in Figure 1. OUE typically increase during exercise from rest to plateau in normal subjects and then decrease gradually until exercise end. It then decreases further in the immediate recovery period and begin stabilizing after about 2 minutes. In IPAH patients, OUE changes in a similar way as the controls, but is always lower than the controls in the transition from rest to exercise end.
Mentions: The OUES was defined as the regression slope “a” in V˙O2 = a×log10V˙E+b. A steeper slope or higher OUES represents a more efficient oxygen uptake per volume of ventilation (Figure 1). The OUEP was defined as the 90 sec average of the highest consecutive measurements of V˙O2/V˙E near the AT (Figure 2) [14].

Bottom Line: Decline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure.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).

View Article: PubMed Central - PubMed

Affiliation: Department of Pulmonary Function Test, Shanghai Pulmonary Hospital Affiliated to Tongji University, Shanghai, China; State Key Laboratory of Cardiovascular Disease, Heart-Lung Function Testing Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

ABSTRACT

Background: Decline 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).

Methods: We 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.

Results: In 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).

Conclusions: In 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.

Show MeSH
Related in: MedlinePlus