Fractional exhaled nitric oxide in pulmonary hypertension

Abstract

Introduction: Decreased nitric oxide (NO) availability is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Prior studies found low fractional exhaled NO (FeNO) in idiopathic PAH (IPAH) and scleroderma-related PAH (SSc-PAH) patients. Comparison among different forms of PH has not been reported. Aims: Compare FeNO levels among different PH groups using NIOX® (Aerocrine) and assess correlations with disease activity. Methods: Consecutive patients with PAH WHO groups 1 and 4 (chronic thromboembolic PH, CTEPH) seen at Tufts PH clinic underwent FeNO measurements. All measurements were performed at the same visit. T tests and regression analyses were performed as appropriate. Results: Patients were middle aged, with mild to moderate functional impairment All were on PAH medications. FeNO levels were significantly lower in SSc-PAH vs. IPAH and CTEPH patients FeNO correlated inversely with the distance walked in 6 min in the CTEPH group (r=0.8) Conclusions: FeNO levels vary between different types of PH and are particularly low in SSc-PAH. In CTEPH, FeNO levels correlate with functional capacity. FeNO may be a useful diagnostic or disease monitoring tool.