Pulmonary hemodynamic profile in chronic obstructive pulmonary disease

Abstract

Introduction: Few data are available in regards to the prevalence of pulmonary hypertension (PH) in the broad spectrum of COPD. This study was aimed at assessing the prevalence of PH in a cohort of COPD patients across the severity of airflow limitation, and reporting the hemodynamic characteristics at rest and during exercise.

Methods: We performed a retrospective analysis on COPD patients who underwent right-heart catheterization in our center with measurements obtained at rest (n=139) and during exercise (n=85). PH was defined as mean pulmonary artery pressure (mPAP) ≥25 mmHg and pulmonary capillary wedge pressure <15 mmHg. Exercise-induced PH (EIPH) was defined by a ratio of ΔmPAP/Δcardiac output >3.

Results: PH was present in 25 patients (18%). According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, PH prevalence in GOLD 2 was 7% (3 patients); 25% (14 patients) in GOLD 3; and 22% (8 patients) in GOLD 4. Severe PH (mPAP ≥35 mmHg) was identified in four patients (2.8%). Arterial partial oxygen pressure was the outcome most strongly associated with PH (r=-0.29, P<0.001). EIPH was observed in 60 patients (71%) and had a similar prevalence in both GOLD 2 and 3, and was present in all GOLD 4 patients. Patients with PH had lower cardiac index during exercise than patients without PH (5.0±1.2 versus 6.7±1.4 L/min/m(2), respectively; P=0.001).

Conclusion: PH has a similar prevalence in COPD patients with severe and very-severe airflow limitation, being associated with the presence of arterial hypoxemia. In contrast, EIPH is highly prevalent, even in moderate COPD, and might contribute to limiting exercise tolerance.

Keywords: GOLD; cardiac index; pulmonary hypertension; right heart catheterization.

Figure 1

Changes from rest to peak exercise in the hemodynamic variables in 85 patients who underwent exercise testing, grouped according GOLD stage. Note: P-value differences from rest to exercise (paired t-tests). Abbreviations: CI, cardiac index; GOLD, Global Initiative for Chronic Obstructive Pulmonary Disease; mPAP, mean pulmonary artery pressure; PCWP, pulmonary capillary wedge pressure; PVR, pulmonary vascular resistance; NS, not significant.

Figure 2

Cardiac index during exercise in patients with and without pulmonary hypertension (n=85). Note: P-value indicates comparison between PH and non-PH (Mann–Whitney U-test). Abbreviations: CI, cardiac index; PH, pulmonary hypertension.