PT  - JOURNAL ARTICLE
AU  - Bryan Taylor
AU  - Barry Borlaug
AU  - Thomas Olson
AU  - Andrew Miller
AU  - Manda Keller
AU  - Bruce Johnson
TI  - Pulmonary gas exchange differentiates pulmonary arterial from venous hypertension
DP  - 2013 Sep 01
TA  - European Respiratory Journal
PG  - 4832
VI  - 42
IP  - Suppl 57
4099  - http://erj.ersjournals.com/content/42/Suppl_57/4832.short
4100  - http://erj.ersjournals.com/content/42/Suppl_57/4832.full
SO  - Eur Respir J2013 Sep 01; 42
AB  - Impaired gas exchange (PGX) is common in both pulmonary arterial (PAH) and venous (PVH) hypertension. We aimed to determine whether PGX measures during rest and moderate exercise (RPE ∼15) differentiate these patient groups. Pulmonary arterial pressure (PAP), wedge pressure (PWP), transpulmonary gradient (TPG) and PGX indices (end-tidal CO2, PETCO2; ventilatory efficiency, VE/VCO2; dead space/tidal volume; VD/VT) were assessed simultaneously at rest and during exercise in 10 PAH and 7 PVH patients (i.e. left heart disease). Arterial blood was drawn for measurement of PaO2, PaCO2 and SaO2. Mean PAP increased during exercise in PAH and PVH patients and was not different at end exercise (65±24 vs. 54±5 mmHg, P=0.26). Conversely, mean PWP increased during exercise in PVH but not PAH. Thus, TPG (mPAP-mPWP) was greater at end exercise in PAH vs. PVH (48±29 vs. 17±8 mmHg, P=0.02). At rest, all key PGX indices were similar between groups (Fig. 1). At end exercise, however, VD/VT, PaCO2-PETCO2 difference and VE/VCO2 ratio were higher whereas PETCO2 and SaO2 were lower in PAH vs. PAH (Fig. 1). Thus, gas exchange indices during exercise, but not rest, differentiate PAH from PVH patients, despite similar levels of exercise induced PH. These differences are consistent with greater ventilation/perfusion inhomogeneities and/or right to left shunt in PAH patients. Supported by Gilead Sciences.Fig. 1. *P<0.05, value significantly different vs. PAH.