Fractional exhaled nitric oxide in pulmonary hypertension
Paz, Miguel Ángel
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BACKGROUND: Pulmonary Hypertension (PH) is a common form of high blood pressure in the lungs. It affects the pulmonary arteries, which normally allow blood to flow from the right heart to the lungs. Nitric Oxide (NO) is a potential mediator for establishing PH and decreasing its availability is implicated in the pathogenesis of PH. HYPOTHESIS: We tested the hypothesis that Fractional Exhaled Nitric Oxide (FeNO) is a good indicator to assess disease severity that may add to understanding the disease. METHODS: The aim of the study was to measure FeNO levels in consecutive PH patients and seek correlations with the 6 Minute walk distance (6MWD) within different World Health Organization (WHO) groups and New York Health Association Function Class (NYHA FC). Assignment to groups I or IV was done respecting the current guidelines. All values were taken at Tufts Medical Center PAH clinic visits. FeNO levels were measured utilizing the NIOX device. RESULTS: FeNO levels were highest in WHO Group 1 and lowest in WHO Group 5 patients. There was a strong inverse correlation between FeNO and 6MWD for each NYHA FC. (Pearson correlation of -0.986, p = 0.014). Within WHO Groups, we found significantly inverse correlations between FeNO and 6MWD in PH Group 4 (p= 0.012) and PH Group 5 (p=0.001). NYHA FC correlated with 6MWD across all WHO Groups (P=0.001). CONCLUSION: We report for the first time FeNO levels in all WHO Groups of PH. FeNO levels are low in early disease. FeNO levels correlate inversely with the severity of PH in WHO Group 4 and 5 patients. The increase in FeNO in more severe patients may reflect the degree of oxidative stress and inflammation in severe PH. Further studies to determine whether FeNO may be a biomarker in early disease, especially in PH Group 4 and 5 warrants further investigation.
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