Fig. 6
\({\dot{\rm V}}/{\dot{\rm Q}}\) distributions in PAH subjects and controls. The distributions of \({\dot{\rm V}}/{\dot{\rm Q}}\) ratios at baseline in PAH subjects were overall broader than in controls at baseline, approaching statistical significance, consistent with moderate degrees of vascular disease, causing a mismatch. There was no difference in the \({\dot{\rm V}}/{\dot{\rm Q}}\) distribution among groups while breathing O2 + iNO, in large part due to the widening of the \({\dot{\rm V}}/{\dot{\rm Q}}\) distribution in controls. \({\dot{\rm V}}/{\dot{\rm Q}}\) distributions while breathing O2 + iNO were unimodal in all subjects, including those with a bimodal distribution prior to the intervention