If a clinician wants to raise local gut perfusion with minimal risk to the heart, which mechanism would likely be employed?

If a clinician wants to raise local gut perfusion with minimal risk to the heart, which mechanism would likely be employed?

• A. Increase heart rate.
• B. Increase vascular resistance in non-target tissues.
• C. Increase diameter of local arteries in gut.
• D. Decrease blood pressure systemically.

Answer: (C)

The concept being tested is boosting blood flow to a specific tissue by lowering the local resistance in that tissue’s vessels, rather than pushing the heart harder or altering systemic pressures. If the gut arteries are dilated, their resistance drops, so the flow to the gut increases for a given driving pressure. Because flow is highly sensitive to the vessel radius (radius to the fourth power), even a modest widening of local gut arterioles can substantially raise gut perfusion. This targeted approach raises blood supply to the gut while minimizing stress on the heart, since it doesn’t require increasing heart rate or systemic vasoconstriction. In contrast, increasing heart rate raises cardiac work and oxygen demand; increasing vascular resistance elsewhere diverts blood away from the gut; and lowering systemic blood pressure would reduce gut perfusion and could provoke compensatory mechanisms that stress the heart.

The concept being tested is boosting blood flow to a specific tissue by lowering the local resistance in that tissue’s vessels, rather than pushing the heart harder or altering systemic pressures. If the gut arteries are dilated, their resistance drops, so the flow to the gut increases for a given driving pressure. Because flow is highly sensitive to the vessel radius (radius to the fourth power), even a modest widening of local gut arterioles can substantially raise gut perfusion. This targeted approach raises blood supply to the gut while minimizing stress on the heart, since it doesn’t require increasing heart rate or systemic vasoconstriction. In contrast, increasing heart rate raises cardiac work and oxygen demand; increasing vascular resistance elsewhere diverts blood away from the gut; and lowering systemic blood pressure would reduce gut perfusion and could provoke compensatory mechanisms that stress the heart.