Exercise capacity in idiopathic pulmonary fibrosis: The effect of pulmonary hypertension

Abstract

Background and objective: Increased pulmonary arterial pressure (PAP) usually coexists with impaired lung function in IPF. Data on the effect of pulmonary hypertension (PH) on cardiopulmonary responses during exercise in IPF patients is very limited. We sought to investigate the impact of PH on exercise capacity and the correlation between systolic PAP (sPAP) and pulmonary function testing, as well as cardiopulmonary exercise parameters, in patients with IPF and PH. Methods: Eighty-one consecutive patients with IPF, who were evaluated over a 6-year period, were retrospectively studied. Patients underwent pulmonary function testing, Doppler echocardiography and maximal cardiopulmonary exercise testing. PH was defined as sPAP > 35 mm Hg. Results: PH was diagnosed in 57% of the patients. Categorization of patients according to severity of PH indicated a significant reduction in maximum work rate, peak O2 uptake, anaerobic threshold and peak O2 pulse in those with sPAP > 50 mm Hg. In IPF patients with PH, estimated sPAP correlated with peak O2 uptake, anaerobic threshold, peak O2 pulse and endtidal CO2 at anaerobic threshold, while the strongest correlation was between sPAP and ventilatory equivalent for CO2 at anaerobic threshold (r = 0.611, P < 0.001). There were no differences in pulmonary function or exercise parameters indicative of lung volume reduction, across the patient categories, and none of these parameters correlated with sPAP. Conclusions: PH has a negative impact on exercise capacity in IPF patients. In IPF patients with PH, resting sPAP correlated with exercise parameters

Pulmonary vascular and cardiac impairment in interstitial lung disease

“…GLASER et al [59] reported a significant reduction in exercise capacity in IPF patients with systolic PAP >50 mmHg compared with those with moderate pulmonary hypertension, and a strong inverse correlation between systolic PAP at rest and maximal exercise performance. In the study by BOUTOU et al [60], maximum work rate, peak oxygen uptake, anaerobic threshold, peak oxygen pulse and ventilatory equivalent for carbon dioxide were significantly lower in IPF patients with severe pulmonary hypertension (systolic PAP >50 mmHg) compared with matched patients with mild pulmonary hypertension (systolic PAP 36-50 mmHg) or those without pulmonary hypertension. Also, systolic PAP at rest correlated with indices of gas exchange and circulatory status (peak oxygen uptake, anaerobic threshold, peak oxygen pulse and end-tidal oxygen at anaerobic threshold), but not with defective lung mechanics [60].…”

Physiology of the lung in idiopathic pulmonary fibrosis

“…When PH is present, it is associated with reduced oxygen pulse at exercise, consistent with haemodynamic limitation [123], with more severe arterial haemoglobin desaturation at exercise [87] and with increased VD/VT, as suggested by an increase in the ratio of minute ventilation (V′E) to carbon dioxide elimination (V′CO 2 ) at the ventilatory threshold [124]. Likewise, correlations exist between the 6-min walk distance and both mPAP and PVR [125].…”

Sildenafil Preserves Exercise Capacity in Patients With Idiopathic Pulmonary Fibrosis and Right-sided Ventricular Dysfunction

“…It has previously been demonstrated that PH results in exercise limitation in patients with IPF. 14 Prior work suggests that sildenafi l leads to preferential pulmonary artery vasodilation in well-ventilated lung tissue and may improve ventilation-perfusion matching and gas exchange in IPF. 4 Hence, STEP-IPF hypothesized that sildenafi l treatment would improve exercise capacity in advanced IPF.…”