RESUMO
The purpose of this study was to evaluate the hemodynamic effects of inhaled nitric oxide in oxygen (NO + O2) in patients with pulmonary hypertension. Eighteen patients (median age 31.5 months) with pulmonary hypertension inhaled through a mask 100% O2 and 20 parts per million NO + inspired O2 fraction (FiO2) at 0.4. Hemodynamic measurements were made at baseline and after O2 and NO + O2 administration. The pulmonary vascular resistance index decreased after inhalation of O2 and NO + O2 (p = 0.0018 and p = 0.0003, respectively), the decrease being significantly greater after NO + O2 (p = 0.0311). Concerning the transpulmonary pressure gradient, a reduction occurred in values after O2 and NO + O2 inhalation when compared with baseline values (p = 0.0014 and p = 0.0008). In patients with congenital heart disease, an increase occurred in pulmonary blood flow after O2 (p = 0.0089) and NO + O2 (p = 0.0019) compared with baseline values, and an increase also occurred in the pulmonary/systemic blood flow ratio after NO + O2 (p = 0.0017). The main side effect related to NO + O2 was pulmonary congestion in 3 patients. Low doses of NO combined with O2 demonstrated a selective pulmonary vasodilator response in patients with pulmonary hypertension. Despite its use for testing pulmonary reactivity, inhalation of NO + O2 should be carefully administered because of the potential risk of pulmonary congestion.
