Last Attempt EMT Questions

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.

Pulmonary edema is caused by fluid accumulation in the alveoli, impairing gas exchange. It is typically due to:

Left-sided heart failure: Blood backs up into the pulmonary circulation

Hypertensive crisis: Increases hydrostatic pressure in the lungs

Anaphylaxis causes vasodilation and bronchospasm, not fluid overload. Increased oncotic pressure would retain fluid in capillaries — the opposite of edema.

This patient presents with severe head trauma, unresponsiveness, hypotension, tachycardia, and apnea (R = 0). NREMT education stresses that apnea following head injury is a critical red flag for increased intracranial pressure (ICP) and potential brain herniation.

Option B is correct because brain herniation occurs when swelling or bleeding within the skull forces brain tissue downward, compressing the brainstem. Compression of the brainstem can result in loss of respiratory drive, explaining the absence of respirations. Elderly patients are at increased risk due to cerebral atrophy and fragile bridging veins.

Option A is possible but does not directly explain apnea.

Option C is associated with sudden cardiac arrest after chest impact, not head trauma.

Option D would present with respiratory compromise but not directly from a forehead injury.

NREMT emphasizes rapid airway management, ventilation, spinal precautions, and immediate transport for suspected brain herniation.

The correct answer is D. Peripheral vasodilation.

Why D is correct (Peripheral vasodilation):

Neurogenic shock occurs due to loss of sympathetic nervous system tone, usually from a spinal cord injury. This leads to:

Widespread peripheral vasodilation

Pooling of blood in the extremities

Decreased venous return

Hypotension

Additionally, patients often present with:

Warm, dry skin (unlike other shock types)

Bradycardia (due to unopposed parasympathetic tone)

NREMT-aligned guidance states:

“Neurogenic shock results from loss of sympathetic tone leading to vasodilation.”

“Peripheral vasodilation causes hypotension and inadequate perfusion.”

Why the other options are incorrect:

A. Central vasodilation: Not a recognized defining feature; neurogenic shock primarily affects peripheral vessels.

B. Peripheral vasoconstriction: Seen in hypovolemic shock, not neurogenic shock.

C. Central vasoconstriction: Not associated with neurogenic shock.

Exact Extracts:

“Neurogenic shock is caused by loss of sympathetic tone.”

“This results in widespread peripheral vasodilation.”

“Patients may present with hypotension and bradycardia.”