Impact of pulmonary hypertension on exercise performance in patients with interstitial lung disease undergoing evaluation for lung transplantation

Abstract

Background and objective Pulmonary hypertension (PH) is a known complication in patients with interstitial lung disease (ILD). Cardiopulmonary exercise testing (CPET) is an essential tool for the assessment of patients with cardiac and pulmonary diseases due to its prognostic and therapeutic implications. Few studies have evaluated the relationship between CPET response and mean pulmonary artery pressures (mPAP) in ILD. The purpose of the present study was to determine and compare the potential correlations between CPET, 6-min walk test (6MWT), pulmonary function testing (PFT) and PH in patients with ILD being evaluated for lung transplantation. Methods The present study reviewed patients with ILD who received lung transplantations and had CPETs within 2 years before transplantation, right heart catheterizations, PFTs and 6MWTs within 4 months of CPET. Results A total of 72 patients with ILD were analysed; 36% had PH. There were significant correlations between mPAP and CPET parameters in patients with PH; but mPAP had no impact on percent of predicted diffusion capacity of the lung for carbon monoxide or 6-min walk distance (6MWD). CPET parameters were able to detect differences between levels of severity of PH through the use of the ratio of minute ventilation to rate of carbon dioxide production (V̇E/V̇CO2) and the partial pressure of end-tidal carbon dioxide. Conclusions This is the first study that analyses 6MWD, PFT and CPET in patients with ILD awaiting lung transplantation with and without PH. The present study demonstrates the significant impact of PH on exercise capacity and performance in patients with ILD awaiting lung transplantation. A direct comparison of the 6-min walk test, CPET and pulmonary function tests for correlation with mean pulmonary arterial pressure is unknown in interstitial lung disease patients with pulmonary hypertension. CPET variables are strongly associated with presence or absence of pulmonary hypertension, independent of resting lung volumes. © 2014 Asian Pacific Society of Respirology.