|Pulsatility||%||maxA – minA/minA × 100||Relative change in lumen area during the cardiac cycle|
|Compliance||mm2/mm Hg||[(maxA – minA)/PP]||Absolute change in lumen area for a given change in pressure|
|Capacitance||mm3/mm Hg||SV/PP||Change in volume associated with a given change in pressure|
|Distensibility||%/mm Hg||[(maxA – minA)/PP × minA] × 100||Relative change in lumen area for a given change in pressure|
|Elastic modulus||mm Hg||PP × minA/(maxA – minA)||Pressure change driving a relative increase in lumen area|
|Stiffness index β||N/A||Ln(sPAP/dPAP)/[(maxA – minA)/minA]||Slope of the function between distending arterial pressure and arterial distension|
dPAP = diastolic pulmonary artery pressure; maxA = maximal area; minA = minimal area; N/A = not applicable; PA = pulmonary artery; PP = pulse pressure; sPAP = systolic pulmonary artery pressure.