Mean, SD, range and COV of OUE measurements during Cardiopulmonary Exercise Testing in IPAH patients (N = 32).

<p>***P<0.0001 by paired t test, versus OUES.</p><p>COV  =  coefficient of variation (SD/mean); all other abbreviation definitions are same as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098889#pone-0098889-t001" target="_blank">Table 1</a>.</p

Demographics, hemodynamics, Pulmonary Function Testing and Cardiopulmonary Exercise Testing parameters in IPAH patients and Control subjects.

<p>Values are expressed as mean ± SD and percentage of measured to predicted values (%pred).</p><p>*<i>p</i><0.05, †<i>p</i><0.005, ‡<i>p</i><0.0001, vs. controls using unpaired <i>t</i> test. NA = not applicable.</p><p>NYHA  =  New York Heart Association functional classification; mPAP  =  mean pulmonary artery pressure; mRAP = mean right atrial pressure; mPWP = mean pulmonary artery wedge pressure; TPVR  =  total pulmonary vascular resistance; FVC  =  forced vital capacity; FEV₁  =  forced expiratory volume in 1 second; MVV  =  maximum voluntary ventilation; DL_CO  =  gas transfer index or diffusing capacity for carbon monoxide; TLC  =  total lung capacity; AT  =  anaerobic threshold; %MVV  =  percentage of maximum voluntary ventilation; P_ETCO₂  =  partial pressure of end-tidal carbon dioxide; OUES  =  oxygen uptake efficiency slope; OUEP  =  oxygen uptake efficiency plateau; IPAH  =  idiopathic pulmonary arterial hypertension; %pred  =  percent of predicted; V˙O₂  =  peak oxygen uptake, STPD  =  standard temperature pressure dry; V˙E  =  minute ventilation, BTPS  =  body temperature pressure saturated; V˙CO₂  =  carbon dioxide output, STPD.</p

Difference of OUEP and OUE between a typical IPAH patient and a control subject.

<p>The kinetics of changes in oxygen uptake efficiency (OUE) for the same tests and subjects as depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098889#pone-0098889-g001" target="_blank">Figure 1</a>. 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.</p

Difference of CPET parameters between IPAH and control groups at different stages of exercise.

<p>The group mean±SD Values of IPAH) and control (NORMAL) groups are shown at stages of rest, unloaded cycling, AT, and peak exercise during incremental cycle ergometry tests. Values are. On the left side from top to bottom, they are OUE, V˙E/V˙CO₂ and P_ETCO₂.; on the right side from top to bottom they are V˙O₂, V˙CO₂ and V˙E. Statistically significant differences between groups at the same stage are shown as NS for no significance, * for P<0.05, ** for <i>P</i><0.005, below value symbol.</p