Figure 1.

Definitions of iNO and oxygen responders. Mean pulmonary arterial pressure (mPAP) was measured at baseline (ambient room air or patient's chronic home oxygen requirement, if applicable), after 2 min at 100% fractional inspired oxygen (“oxygen phase”), and after 5 min at 100% FiO₂ + 40 ppm inhaled nitric oxide (“vasodilator phase”). Both iNO and oxygen responders had a reduction of ≥10 mmHg from baseline to vasodilator phase with a final mPAP ≤ 40 mmHg. “iNO Responders” had a ≥10 mmHg reduction in mPAP from Oxygen Phase to Vasodilator Phase. “Oxygen responders” had a <10 mmHg reduction in mPAP from oxygen phase to vasodilator phase.