Vaso reactivity test using inhaled nitric oxide for pulmonary arterial hypertension accompanied by severe interstitial lung disease attributed to systemic sclerosis: A case report

A 70-year-old man with severe interstitial pneumonia attributed to limited cutaneous systemic sclerosis was referred to our institution because of worsening dyspnea. High-resolution computed tomography did not show considerable progression compared with previous images, whereas transthoracic echocardiography showed severe right ventricular dysfunction. Oxygen saturation was decreased to 84% at room air. A blood test showed an increase in the plasma brain natriuretic peptide level (289.4 pg/mL). Right heart catheterization (RHC) showed a remarkably high mean pulmonary arterial pressure (mPAP) of 48 mmHg at room air. A vaso reactivity test using inhaled nitric oxide showed improvement of mPAP, pulmonary vascular resistance (PVR), and partial pressure of arterial oxygen. These findings suggested that the patient responded to pulmonary hypertension (PH)-targeted drugs. We then prescribed tadalafil 10 mg and inhaled iloprost 5 µg six times daily. Three weeks after initiating PH-targeted drugs, RHC indicated hemodynamic improvement similar to hemodynamic changes in the vaso reactivity test (mPAP: 28 mmHg; PVR: 4.2 W.U.). He was discharged with improved symptoms. Inhaled nitric oxide during RHC might be helpful to consider the treatment strategy when patients have PH comorbid systemic sclerosis and severe interstitial lung disease.