U01.21.036 Pulmonary Vascular Resistance (PVR)

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Learning Objective:
Understand and calculate pulmonary vascular resistance (PVR), which measures the resistance blood encounters in the pulmonary circulation.

Formula:

PVR = \frac{P_{pulm \ artery} - P_{L \ atrium}}{CO}

Explanation:

  • P_{pulm \ artery} = Pulmonary artery pressure (mm Hg)
  • P_{L \ atrium} = Left atrial pressure (mm Hg)
  • CO = Cardiac Output (L/min)

PVR quantifies the pressure difference driving blood through the pulmonary circulation relative to flow.

Concept Summary:

  • Normal PVR ≈ 100–200 dyn·s·cm⁻⁵
  • ↑ PVR → pulmonary hypertension
  • ↓ PVR → conditions like sepsis or exercise may temporarily reduce PVR

Example:

Given:
P_{pulm \ artery} = 25 \text{ mm Hg}
P_{L \ atrium} = 5 \text{ mm Hg}
CO = 5 \text{ L/min}

PVR = \frac{25 - 5}{5} = \frac{20}{5} = 4 \text{ mm Hg·min/L}

✅ Answer: PVR = 4 mm Hg·min/L

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