The correct answers are A. Lowers cardiac output and C. Reduces cerebral perfusion.

After Return of Spontaneous Circulation (ROSC), excessive ventilation (hyperventilation) is dangerous due to its effects on intrathoracic pressure and carbon dioxide levels.

1. Lowers Cardiac Output (A):

Excessive ventilations increase intrathoracic pressure, which decreases venous return to the heart. This leads to:

Reduced preload

Decreased cardiac output

NREMT/AHA-aligned guidance states:

“Excessive ventilation increases intrathoracic pressure, decreasing venous return and cardiac output.”

2. Reduces Cerebral Perfusion (C):

Hyperventilation lowers CO₂ levels (hypocapnia), which causes cerebral vasoconstriction. This results in:

Reduced blood flow to the brain

Decreased cerebral perfusion

NREMT-aligned material states:

“Hyperventilation decreases PaCO₂, leading to cerebral vasoconstriction and reduced cerebral blood flow.”

Why the other options are incorrect:

B. Depletes oxygen stores: Incorrect—ventilation increases oxygen delivery, not depletion.

D. Increases pulmonary edema: Not a primary or direct effect of excessive ventilation in this context.

E. Increases intracranial hemorrhage: Not a recognized direct consequence of hyperventilation in ROSC patients.

Exact Extracts (NREMT/AHA-aligned references):

“Avoid excessive ventilation… it increases intrathoracic pressure and decreases cardiac output.”

“Hyperventilation reduces carbon dioxide levels, causing cerebral vasoconstriction.”

“This results in decreased cerebral perfusion.”

Clinical Priority Summary:

After ROSC, ventilations should be controlled and appropriate, because excessive ventilation can decrease both cardiac output and brain perfusion, making A and C correct.