Table 3.
Formula and equations commonly used to calculate PVR and PAP
| Equations | Definition | Reference(s) |
|---|---|---|
| PAP = PVR × CO | Where PVR is the vascular resistance of the whole lung including the pulmonary arteries (PVRA), capillaries (PVRC), and veins (PVRV) and CO is cardiac output | (33–35) |
| PVR = PVRA + PVRC + PVRV | ||
| PAP = CO × (PVRA + PVRC + PVRV) | ||
| Hagen–Poiseuille equation (or the Poiseuille law) | ||
| Q = ΔP × [(πr4) ÷ (8ηL)] | Where Q is flow; π is the constant of 3.14; ΔP is the pressure difference, r is the inner radius of the cylindrical tube (e.g., blood vessel), η is the viscosity of the fluid (e.g., blood), and L is the length of the tube (e.g., the total the blood vessel tree) | (33–35) |
| PVR = ΔP ÷ Q (in mmHg·min/L) | Where ΔP is the difference between pulmonary arterial pressure (PAP) and left atrial pressure or pulmonary arterial wedge pressure (PAWP), and Q is cardiac output (CO). | (35) |
| PVR = (PAP – PAWP) ÷ CO | ||
| PVR = (8Lη) ÷ (πr4) (in dyn/cm5) | Where L is the total length of the pulmonary vasculature, η is the viscosity of the venous blood through the lung circulation, π is the constant (3.14), and r is the radius of the lumen of pulmonary vessels | (35) |