P719Different hemodynamic profiles to exercise in COPD and IPF candidates to lung transplantation: role of the pulmonary arterial stiffness

Abstract

Purpose: Exercise intolerance in chronic obstructive disease (COPD) and idiopathic pulmonary fibrosis (IPF) is multifactorial. We analyzed the hemodynamic profiles to exercise in COPD and IPF candidates to lung transplantation (LTx) and correlated them to pulmonary arterial stiffness (PAS). Method(s): We studied 45 patients (p) awaiting LTx, 25 COPD (57+/-4 y, 3 F) and 20 IPF (58+/-8 y, 8 F). All p were submitted to right heart catheterization and intravascular ultrasound in medium sized PAs. We assessed the mean pulmonary arterial pressure (mPAP), right atrial and PA wedge pressure (PAWP), aortic pressure, cardiac output and index (CO, CI), total (TPR) and peripheral pulmonary vascular resistance, pulmonary arterial capacitance (PAC), and local PAS (elastic modulus -EM-: diastolic lumen areaxpulse PAP/(systolic-diastolic lumen area)) at rest and during a dynamic supine leg exercise (stepwise increment of 10W for 3 min) until exhaustion. We divided the p of each group based on the median mixed venous oxygen saturation (SvO2) at peak effort. The lower SvO2, the higher circulation exercise limitation. Result(s): 24% of p had PAWP >=15 mmHg and were not analyzed. 7/16 of COPD and 7/18 of IPF p had pulmonary hypertension. COPD showed a significant lower of 6MWD (307+/-104 vs 364+/-83m) and maximal work (23+/-8 vs 32+/-10W) than IPF p with a similar peak single-point mPAP-CO ratio (8.2+/-3.6 and 7.2+/-3 mmHg/L/min) and heart rate (50+/-7 and 54+/-11% of the predicted maximum), -TPR, -PAC and -EM. However, PAS was lower in COPD vs IPF p (62+/-33 vs 94+/-46 mmHg, p<0.05) and showed different hemodynamic profiles (Table). Those COPD p with lower peak SvO2 ( 47%. By contrast, PAS and -SVI was similar beyond peak SvO2 in IPF p. (Figure Presented) Conclusion(s): Both groups had a significantly impaired exercise capacity with a circulatory exercise limitation. PAS of COPD p and RV impairment of IPF p would be associated with the circulatory reserve, respectively. Factors other the impairment of the RV-vascular unit would explain the differences in exercise capacity between COPD and IPF candidates to LTx.