Influence of inhaled nitric oxide on plasma nitrate concentrations in patients with adult respiratory distress syndrome and sepsis: results of a pilot study.

STUDY OBJECTIVE: To measure plasma nitrate concentrations after inhalation of nitric oxide for treatment of adult respiratory distress syndrome (ARDS) and sepsis. DESIGN: Prospective pilot study. SETTING: Intensive care unit at a university-affiliated hospital. PATIENTS: Nine consecutive medical intensive care unit patients with ARDS and sepsis. INTERVENTIONS: After diagnosis of ARDS, all patients received a balloon-tipped triple-lumen thermodilution pulmonary artery catheter (Baxter Healthcare Corp, Irvine, CA). Inhaled nitric oxide was initiated starting at a dose of one part per million and titrated according to the maximal achievable increase in arterial oxygenation. Hemodynamic measurements including intrapulmonary shunt fraction and blood as analyses were performed before nitric oxide application, as well as 1 and 24 hours after starting nitric oxide, respectively. Plasma samples for determination of nitrate were taken from the arterial line and from the pulmonary thermodilution catheter and analyzed using high-performance liquid chromatography. MEASUREMENTS AND MAIN RESULTS: Eight of 9 patients were nitric oxide responders (intrapulmonary shunt decrease >5%). There was no statistically significant increase in nitrate plasma concentration measured both in peripheral arterial and in mixed venous blood with inhaled nitric oxide up to a concentration of 40 parts per million. CONCLUSION: Inhalation of nitric oxide in patients with ARDS and sepsis does not result in increased plasma nitrate concentrations.