Ventilation-perfusion relationships in pulmonary arterial hypertension : Effect of intravenous and inhaled prostacyclin treatment

• In seven patients with idiopathic or secondary pulmonary arterial hypertension (PAH), ventilation-perfusion (V-A/Q) relationships were measured during a right heart catheterization using the multiple inert-gas elimination technique before and during intravenous infusion with epoprostenol (EPO), and following 5 months of 20 mu g inhaled iloprost taken three times daily (ILO). Pre-treatment pulmonary vascular resistance (PVR) was 9.3 +/- 5.0 mmHg/l/min and the dispersion of perfusion and ventilation for V-A/Q-ratios was increased. EPO reduced PVR by 20%, and increased cardiac output, shunt, and mixed venous oxygenation (Sv(O2)) The arterial oxygen tension (Pa-O2) remained unchanged. Basal central haemodynamics did not change after 5 months of ILO. Fifteen minutes after ILO, PVR decreased by 20%, and the shunt, Sv(O2), and Pa-O2 remained unaltered. Conclusions: In secondary PAH with normal lung volumes, significant V-A/Q mismatching occurred. The PVR was reduced to a similar degree during EPO and after ILO, but only EPO increased the shunt and Sv(O2). EPO and ILO did not significantly affect the Pa-O2.

Nyckelord

V-A/Q ratios

multiple inert-gas elimination technique

shunt

mixed venous oxygenation

pulmonary arterial hypertension

epoprostenol

inhaled iloprost

hypoxaemia

gas-exchange

nitric-oxide

continuous distributions

cardiac-output

disease

exercise

iloprost

therapy

inequality

mechanisms

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art (ämneskategori)