Dobutamine's effect on pulmonary vascular resistance (PVR) is which of the following?

Dobutamine's effect on pulmonary vascular resistance (PVR) is which of the following?

• A. Increases PVR
• B. Decreases PVR
• C. No change
• D. PVR fluctuates with dose

Answer: (B)

Dobutamine increases cardiac output by boosting myocardial contractility (beta-1 agonism) and also has mild beta-2–mediated vasodilation. In the pulmonary circulation, this combination tends to dilate the pulmonary vessels and improve forward flow without a proportional rise in left-sided filling pressures. Because PVR is roughly the pressure difference across the pulmonary circulation divided by flow (PVR ≈ (mean PAP − PCWP) / CO), increasing CO while left-sided pressures don’t rise as much leads to a lower PVR. In practical terms, dobutamine often lowers the resistance the right ventricle has to pump against, aiding those with right-sided or pulmonary vascular stress.

Dobutamine increases cardiac output by boosting myocardial contractility (beta-1 agonism) and also has mild beta-2–mediated vasodilation. In the pulmonary circulation, this combination tends to dilate the pulmonary vessels and improve forward flow without a proportional rise in left-sided filling pressures. Because PVR is roughly the pressure difference across the pulmonary circulation divided by flow (PVR ≈ (mean PAP − PCWP) / CO), increasing CO while left-sided pressures don’t rise as much leads to a lower PVR. In practical terms, dobutamine often lowers the resistance the right ventricle has to pump against, aiding those with right-sided or pulmonary vascular stress.