Pulmonary vascular resistance is calculated as which formula?

Pulmonary vascular resistance is calculated as which formula?

• A. (PAP - PAOP) / CO x 80
• B. (PAP - PAOP) / CO
• C. (PAP - PAOP) / CO x 60
• D. (PAP - PAOP) / CI x 80

Answer: (A)

Pulmonary vascular resistance measures the pressure the right ventricle must generate to push blood through the lungs for a given flow. It uses the pressure drop across the pulmonary vasculature (mean pulmonary arterial pressure minus the left atrial/PAOP pressure) divided by the cardiac output. To get the standard clinical unit, dynes·second·centimeter⁻⁵, you multiply by 80. So the formula is (mean PAP − PAOP) / CO × 80. The pressure gradient provides the driving force and CO represents the flow, so dividing the gradient by flow follows the same Ohm’s law relationship as other vascular beds. Using just the gradient divided by CO without the 80 would yield Wood units, not dynes·s·cm⁻⁵, and using CI or other factors would not reflect the conventional calculation.

Pulmonary vascular resistance measures the pressure the right ventricle must generate to push blood through the lungs for a given flow. It uses the pressure drop across the pulmonary vasculature (mean pulmonary arterial pressure minus the left atrial/PAOP pressure) divided by the cardiac output. To get the standard clinical unit, dynes·second·centimeter⁻⁵, you multiply by 80. So the formula is (mean PAP − PAOP) / CO × 80. The pressure gradient provides the driving force and CO represents the flow, so dividing the gradient by flow follows the same Ohm’s law relationship as other vascular beds. Using just the gradient divided by CO without the 80 would yield Wood units, not dynes·s·cm⁻⁵, and using CI or other factors would not reflect the conventional calculation.