Pulmonary vascular limitation to exercise and survival in idiopathic pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: Pulmonary hypertension is frequently observed in advanced idiopathic pulmonary fibrosis (IPF) and is associated with poor prognosis. Cardiopulmonary exercise testing (CPET) can be used to detect less advanced pulmonary vascular impairment, and therefore may be of prognostic use. We studied the predictive value of non-invasive exercise parameters that were associated with elevated systolic pulmonary artery pressure (sPAP) for survival in IPF patients. METHODS: From our interstitial lung disease database, we reviewed records of consecutive patients with IPF in whom CPET and echocardiography were performed within 2 weeks (n = 38). RESULTS: Eleven patients (29%) had increased sPAP (≥40 mm Hg). From all non-invasive CPET parameters, only the ventilatory equivalent for CO2 (V'E /V'CO2 ) at anaerobic threshold differed significantly between patients with and without sPAP ≥ 40 mm Hg. The receiver-operator characteristic curve for V'E /V'CO2 resulted in areas under the curve of 0.77 (95% CI: 0.569-0.970; P = 0.026), with a cut-off value for predicting sPAP ≥ 40 mm Hg of >45.0. Patients with V'E /V'CO2 > 45.0 had significantly worse survival compared with patients with V'E /V'CO2 ≤ 45.0 (P = 0.001). In contrast, sPAP did not predict survival. CONCLUSIONS: V'E /V'CO2 , the only CPET parameter associated with elevated sPAP, appears a potentially useful non-invasive marker for early detection of pulmonary vascular impairment, and therefore may be of use for a more accurate prognostic assessment in IPF patients.

Fibrotic idiopathic interstitial pneumonias: mortality is linked to a decline in gas transfer.

BACKGROUND AND OBJECTIVE: Baseline clinical and physiological features and changes in these parameters over time are known predictors of survival in patients with fibrotic idiopathic interstitial pneumonia (IIP). Pulmonary hypertension is common in advanced fibrotic IIP, and has a negative impact on survival. Serial pulmonary function profiles, indicative of increasing vascular impairment in patients with IIP, and in particular, selective reductions in gas transfer, have not been studied previously. METHODS: Predictors of event-free survival time were investigated in a cohort of Dutch patients with IPF and fibrotic non-specific interstitial pneumonia (n = 117). Pulmonary function test data were prospectively collected from November 1993 to December 2005. Multivariate Cox regression models were developed to identify the prognostic relevance to survival of variables related to baseline demographics, histopathology, pulmonary function and the 6- and 12-month changes in pulmonary function parameters. RESULTS: Different survival patterns were observed for patients with different histopathological diagnoses. At baseline, FVC was the most important prognostic factor. At the 6-month follow up, change in transfer coefficient (K(CO), DL(CO)/V(A)), and at the 12-month follow up, age, baseline K(CO) and 12-month change in FVC and K(CO), were independent predictors of event-free survival. CONCLUSIONS: Apart from histopathology, change in K(CO) over time appeared to be the most consistent and powerful predictor of survival in these patients. The decline in K(CO) may be indicative of increasing vascular impairment, which may have a major impact on survival, in patients with fibrotic IIP.