Figure 1.

Pulmonary arterial pressure (PAP)-flow relationships based on serial measurements of mean PAP and cardiac output during incremental exercise. Normal subjects (□), patients with scleroderma with PAP in the lower normal range (◊) and upper normal range (♦), and patients with resting PAH (•) demonstrate approximately linear pressure-flow responses during exercise with progressively higher ΔPAP/ΔCO that may be indicative of early pulmonary vasculopathy in the scleroderma groups. Adapted with permission from (□) Reeves,³⁵ Kovacs (◊,♦),⁵⁴ and (•)Janicki.¹³