Combined effect of aerosolized iloprost and oxygen on assessment of pulmonary vasoreactivity in children with pulmonary hypertension

Objective: The evaluation of pulmonary vascular reactivity plays a significant role in the management of patients with pulmonary hypertension. Inhaled nitric oxide in combination with oxygen (O2) has become widely used as an agent for pulmonary vasodilator testing. However, inhaled nitric oxide is not available in many developing countries. Recently, aerosolized iloprost was suggested as an alternative to nitric oxide for this purpose. In the present study, aerosolized iloprost was used together with O2 in the pulmonary vasoreactivity test of children with severe pulmonary hypertension. Thus, the synergistic effect of both vasodilators was utilized without extending the duration of cardiac catheterization. Methods: The prospective cohort study registered a total of 16 children with severe pulmonary hypertension whose median age was 4.5 years. Hemodynamic parameters were quantified before and after the vasoreactivity test. Increased left-to-right shunt, pulmonary vascular resistance of 6 Woods units (WU)/m^2 and a pulmonary-systemic resistance ratio of 0.3, as well as a decrease 10% in the pulmonary vascular resistance and pulmonary-systemic vascular resistance ratio after the vasoreactivity test were accepted as a positive response. The data were analyzed using Wilcoxon signed-rank and the Mann-Whitney U tests. Results: Eleven children gave a positive response to the vasoreactivity test, while 5 children did not respond. Pulmonary vascular resistance dropped from 9.98±1.39 WU/m^2 to 5.08±1.05 WU/m^2 (p=0.013) and the pulmonary-systemic vascular resistance ratio fell from 0.68±0.08 to 0.32±0.05 (p=0.003) in the children who were responsive. No side effects were observed related to iloprost administration. Conclusion: Administration of inhaled iloprost in combination with O2 for pulmonary vasoreactivity testing can be useful for correctly identifying pulmonary vasoreactivity without extending the duration of cardiac catheterization.