title: Exhaled nitric oxide in pulmonary arterial hypertension associated with systemic sclerosis.
abstract: The fractional exhaled concentration of nitric oxide (FENO) has been shown to be reduced in idiopathic pulmonary arterial hypertension (PAH) but has not been adequately studied in PAH associated with systemic sclerosis (SSc). We measured FENOat an expiratory flow rate of 50 mL/s in 21 treatment-naive patients with SSc-associated PAH (SSc-PAH), 94 subjects with SSc without pulmonary involvement, and 84 healthy volunteers. Measurements of FENOat additional flow rates of 100, 150, and 250 mL/s were obtained to derive the flow-independent nitric oxide exchange parameters of maximal airway flux (J'awNO) and steady-state alveolar concentration (CANO). FENOat 50 mL/s was similar (P= 0.22) in the SSc-PAH group (19 ± 12 parts per billion [ppb]) compared with the SSc group (17 ± 12 ppb) and healthy control group (21 ± 11 ppb). No change was observed after 4 months of targeted PAH therapy in 14 SSc-PAH group patients (P= 0.9). J'awNOwas modestly reduced in SSc group subjects without lung disease (1.2 ± 0.5 nl/s) compared with healthy controls (1.64 ± 0.9;P< 0.05) but was similar to that in the SSc-PAH group. CANOwas elevated in individuals with SSc-PAH (4.8 ± 2.6 ppb) compared with controls with SSc (3.3 ± 1.4 ppb) and healthy subjects (2.6 ± 1.5 ppb;P< 0.001 for both). However, after adjustment for the diffusing capacity of CO, there was no significant difference in CANObetween individuals with SSc-PAH and controls with SSc. We conclude that FENOis not useful for the diagnosis of PAH in SSc. Increased alveolar nitric oxide in SSc-PAH likely represents impaired diffusion into pulmonary capillary blood.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Zeling
authors.initials: Z
authors.lastname: Cao
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Mathai
authors.affiliation: Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Laura K
authors.initials: LK
authors.lastname: Hummers
authors.affiliation: Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Ami A
authors.initials: AA
authors.lastname: Shah
authors.affiliation: Division of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Fredrick M
authors.initials: FM
authors.lastname: Wigley
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Noah
authors.initials: N
authors.lastname: Lechtzin
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Hassoun
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Spectrum Health and Michigan State University College of Human Medicine, Grand Rapids, Michigan, USA.
authors.forename: Reda E
authors.initials: RE
authors.lastname: Girgis
keywords: exhaled nitric oxide; pulmonary arterial hypertension; scleroderma; systemic sclerosis