Q81 / 110
Which mechanism is most strongly implicated in vasoplegia during cardiopulmonary bypass?
Correct answer: B — Nitric oxide overproduction and related vasodilatory signaling
The pathophysiology of vasoplegia is complex, but nitric oxide dysregulation is a major contributor to profound vasodilation. Other implicated mechanisms include vasopressin depletion and inflammatory mediator release. This is why agents targeting non-catecholamine vasodilatory pathways are often used when standard vasopressors are insufficient. Understanding the mechanism helps explain rescue drug choice.
Board pearl: Nitric oxide pathway dysregulation is central to vasoplegia during CPB.
The pathophysiology of vasoplegia is complex, but nitric oxide dysregulation is a major contributor to profound vasodilation. Other implicated mechanisms include vasopressin depletion and inflammatory mediator release. This is why agents targeting non-catecholamine vasodilatory pathways are often used when standard vasopressors are insufficient. Understanding the mechanism helps explain rescue drug choice.
Board pearl: Nitric oxide pathway dysregulation is central to vasoplegia during CPB.
Q82 / 110
Which of the following is a standard first-line treatment for vasoplegia during cardiopulmonary bypass?
Correct answer: C — Norepinephrine
Initial treatment of vasoplegia usually begins with standard vasopressors such as norepinephrine, epinephrine, or phenylephrine. Rescue agents are considered when hypotension remains refractory despite adequate doses of these conventional agents. This stepwise approach helps rule out transient or correctable causes before escalating to more specialized therapies. Norepinephrine therefore remains first-line.
Board pearl: Catecholamine vasopressors remain first-line therapy for vasoplegia.
Initial treatment of vasoplegia usually begins with standard vasopressors such as norepinephrine, epinephrine, or phenylephrine. Rescue agents are considered when hypotension remains refractory despite adequate doses of these conventional agents. This stepwise approach helps rule out transient or correctable causes before escalating to more specialized therapies. Norepinephrine therefore remains first-line.
Board pearl: Catecholamine vasopressors remain first-line therapy for vasoplegia.
Q83 / 110
A patient remains profoundly hypotensive on cardiopulmonary bypass despite adequate flow and escalating catecholamines. Which rescue therapy most directly counteracts nitric oxide-mediated vasodilation?
Correct answer: B — Methylene blue
Methylene blue inhibits the nitric oxideÐguanylate cyclase pathway and is therefore a classic rescue therapy for refractory vasoplegia. Vasopressin is also commonly used in this setting, but methylene blue more directly targets nitric oxide-mediated vasodilation. This question assumes adequate bypass flow and exclusion of other causes of hypotension. Rescue therapy should be paired with correction of physiologic contributors and reassessment for other pathology.
Board pearl: Methylene blue counteracts nitric oxide-mediated vasodilation in refractory vasoplegia.
Methylene blue inhibits the nitric oxideÐguanylate cyclase pathway and is therefore a classic rescue therapy for refractory vasoplegia. Vasopressin is also commonly used in this setting, but methylene blue more directly targets nitric oxide-mediated vasodilation. This question assumes adequate bypass flow and exclusion of other causes of hypotension. Rescue therapy should be paired with correction of physiologic contributors and reassessment for other pathology.
Board pearl: Methylene blue counteracts nitric oxide-mediated vasodilation in refractory vasoplegia.
Q84 / 110
Why is anticoagulation required during ECMO support?
Correct answer: B — To prevent thrombosis of the cannulas, oxygenator, and circuit
Blood exposure to the non-endothelial ECMO circuit activates hemostatic pathways and promotes thrombosis. Without anticoagulation, clot can form in the cannulas, tubing, or oxygenator and compromise support. This prothrombotic surface is one reason ECMO care is so complex. Anticoagulation is therefore fundamental even when bleeding risk is high.
Board pearl: The ECMO circuit activates coagulation, so anticoagulation is needed to prevent circuit thrombosis.
Blood exposure to the non-endothelial ECMO circuit activates hemostatic pathways and promotes thrombosis. Without anticoagulation, clot can form in the cannulas, tubing, or oxygenator and compromise support. This prothrombotic surface is one reason ECMO care is so complex. Anticoagulation is therefore fundamental even when bleeding risk is high.
Board pearl: The ECMO circuit activates coagulation, so anticoagulation is needed to prevent circuit thrombosis.
Q85 / 110
What is a major challenge in anticoagulation management during ECMO?
Correct answer: C — Clinicians must balance competing bleeding and thrombosis risks
ECMO creates a strongly prothrombotic circuit while patients often have surgical bleeding, coagulopathy, or platelet dysfunction. The result is a constant need to balance under-anticoagulation against over-anticoagulation. This is one reason protocols vary widely among institutions. The management challenge is therefore not choosing one risk but balancing two competing ones.
Board pearl: ECMO anticoagulation is difficult because patients are simultaneously at risk for bleeding and thrombosis.
ECMO creates a strongly prothrombotic circuit while patients often have surgical bleeding, coagulopathy, or platelet dysfunction. The result is a constant need to balance under-anticoagulation against over-anticoagulation. This is one reason protocols vary widely among institutions. The management challenge is therefore not choosing one risk but balancing two competing ones.
Board pearl: ECMO anticoagulation is difficult because patients are simultaneously at risk for bleeding and thrombosis.