Mean pulmonary artery pressure is calculated as which expression?

Mean pulmonary artery pressure is calculated as which expression?

• A. (PAS + PAD) / 2
• B. PAS
• C. (PAS + 2 × PAD) / 3
• D. (MAP + PAD) / 2

Answer: (C)

The mean pulmonary artery pressure is estimated by weighting diastole more than systole, because the heart spends more time in diastole than systole. This leads to an approximation where the mean is calculated as PAS plus twice PAD, all divided by three. In other words, MPAP ≈ (PAS + 2 × PAD) / 3. This mirrors the idea used for systemic mean arterial pressure, but applied to the pulmonary circulation. Why the other forms aren’t as accurate: averaging PAS and PAD equally ignores that diastole lasts longer in the cardiac cycle, so the diastolic pressure should count more toward the mean. Using only PAS would give a value that reflects systole only, not the steady-state pressure over time. Mixing MAP into the calculation or any other odd combination does not reflect the time-weighted nature of the pressure waveform.

The mean pulmonary artery pressure is estimated by weighting diastole more than systole, because the heart spends more time in diastole than systole. This leads to an approximation where the mean is calculated as PAS plus twice PAD, all divided by three. In other words, MPAP ≈ (PAS + 2 × PAD) / 3. This mirrors the idea used for systemic mean arterial pressure, but applied to the pulmonary circulation.

Why the other forms aren’t as accurate: averaging PAS and PAD equally ignores that diastole lasts longer in the cardiac cycle, so the diastolic pressure should count more toward the mean. Using only PAS would give a value that reflects systole only, not the steady-state pressure over time. Mixing MAP into the calculation or any other odd combination does not reflect the time-weighted nature of the pressure waveform.