While assessing a critically ill patient in the emergency department, the nurse notes on the cardiac monitor an R-on-T premature ventricular beat that develops into ventricular tachycardia (VT)
Immediately, the patient became unresponsive. The nurse knows that based on pathophysiologic principles, the most likely cause of the unresponsiveness is
A)
metabolic acidosis that occurs spontaneously following any dysrhythmias.
B)
interruption of the blood/oxygen supply to the brain.
C)
massive cerebrovascular accident (CVA) resulting from increased perfusion.
D)
a blood clot coming from the heart and occluding the carotid arteries.
Ans:
B
Feedback:
The brain receives 15% to 20% of the total resting cardiac output and consumes 20% of its oxygen. The brain cannot store oxygen or engage in anaerobic metabolism. An interruption of blood or oxygen supply to the brain rapidly leads to clinically observable signs and symptoms. Unconsciousness occurs almost simultaneously with cardiac arrest. Metabolic acidosis will occur later in the cardiac arrest but not immediately and is not responsible for the patient's unresponsiveness. CVAs can be caused by thrombosis formation or plaque occlusions, but it is not the primary reason for unconsciousness in VT.
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