Pulmonary arterial hypertension Pulmonary arterial hypertension with positive acute response to NO challenge 2021-01-09T17:33:05Z A form of pulmonary arterial hypertension in which there is a reduction of mean pulmonary artery pressure (mPAP) at least 10 mmHg to reach an absolute value of mPAP not more than 40 mmHg with an increased or unchanged cardiac output (CO) in response to inhaled nitric oxide at 10-20 ppm.