Clinical characteristics and prediction of pulmonary hypertension in severe emphysema

Abstract

Background: We explored the prevalence, clinical and physiologic correlates of pulmonary hypertension (PH), and screening strategies in patients with severe emphysema evaluated for the National Emphysema Treatment Trial (NETT).

Methods: Patients undergoing Doppler echocardiography (DE) and right heart catheterization were included. Patients with mean pulmonary arterial pressure ≥ 25 mmHg (PH Group) were compared to the remainder (non-PH Group).

Results: Of 797 patients, 302 (38%) had PH and 18 (2.2%) had severe PH. Compared to the non-PH Group, patients with PH had lower % predicted FEV1 (p < 0.001), % predicted diffusion capacity for carbon monoxide (p = 0.006), and resting room air PaO2 (p < 0.001). By multivariate analysis, elevated right ventricular systolic pressure, reduced resting room air PaO2, reduced post-bronchodilator % predicted FEV1, and enlarged pulmonary arteries on computed tomographic scan were the best predictors of PH. A strategy using % predicted FEV1, % predicted DLCO, PaO2, and RVSP was predictive of the presence of pre-capillary PH and was highly predictive of its absence.

Conclusions: Mildly elevated pulmonary artery pressures are found in a significant proportion of patients with severe emphysema. However, severe PH is uncommon in the absence of co-morbidities. Simple non-invasive tests may be helpful in screening patients for pre-capillary PH in severe emphysema but none is reliably predictive of its presence.

Keywords: Chronic obstructive pulmonary disease; Emphysema; Hypoxemia; Lung disease; Pulmonary hypertension.