Inhaled prostacyclin in the treatment of pulmonary hypertension

Pulmonary hypertension can occur primarily with an unknown aetiology or sec ondary in association with cardiac or pulmonary disorders such as congenita l diaphragmatic hernia, idiopathic respiratory distress syndrome, acute res piratory distress syndrome (ARDS), congenital heart disease with malformati on of the pulmonary blood vessels, chronic obstructive lung disease and fol lowing cardiac surgery. Prostacyclin (PGI(2)), an arachidonic acid metaboli te, has been evaluated for its efficacy in the treatment of pulmonary hyper tension and for its use in assessing the reversibility of the disorder prio r to surgical interventions. While the intravenous application of PGI(2) ca n cause a decrease not only of the pulmonary but also of the systemic vascu lar tone, aerosolised PGI(2) results in a selective pulmonary vasodilation without affecting the systemic blood pressure. Furthermore, aerosolised PGI (2) can improve gas exchange and pulmonary shunt in clinical settings of im paired ventilation/perfusion ratio such as ARDS, due to the redistribution of pulmonary blood flow from nonventilated to ventilated, aerosol-accessibl e lung regions. Conclusion Aerosolised prostacyclin can be a valuable tool in the treatment and diagnostic evaluation of elevated pulmonary vascular resistance and im paired pulmonary gas exchange. Reservations must be made for its long-term use, as its short half-life necessitates continuous inhalation.