What causes bradycardia in a person with increased intracranial pressure?
Vasoconstriction from cerebral ischemia
Compensation for elevated blood pressure
Excess swelling of the person's optic disc
Stretching of the dura mater and blood vessels
The Correct Answer is B
A. Vasoconstriction from cerebral ischemia: Cerebral ischemia from vasoconstriction primarily leads to hypoxia and tissue injury. While it can influence systemic responses, it does not directly cause bradycardia associated with increased intracranial pressure.
B. Compensation for elevated blood pressure: Increased intracranial pressure triggers a Cushing reflex, a physiological response to maintain cerebral perfusion. As systemic blood pressure rises to overcome the pressure in the cranium, the baroreceptors detect the elevated pressure and induce reflex bradycardia to prevent excessive cardiac workload.
C. Excess swelling of the person's optic disc: Papilledema, or optic disc swelling, is a sign of increased intracranial pressure but is a consequence rather than a direct cause of bradycardia. It reflects chronic ICP elevation but does not initiate the cardiac reflex.
D. Stretching of the dura mater and blood vessels: While stretching of intracranial structures can contribute to headache and pain, it is not the primary mechanism for bradycardia. The heart rate change is mainly a baroreceptor-mediated response to hypertension caused by increased intracranial pressure.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Blood urea nitrogen is decreased:In kidney failure, blood urea nitrogen (BUN) typically increases because the kidneys are unable to excrete nitrogenous waste effectively. A decreased BUN is not expected and may indicate malnutrition or liver disease rather than renal impairment.
B. Serum potassium levels are decreased:Kidney failure impairs potassium excretion, leading to hyperkalemia rather than hypokalemia. Elevated serum potassium is a common and potentially dangerous complication of renal dysfunction.
C. Creatinine level is decreased:Serum creatinine usually rises in kidney failure due to reduced filtration by the glomeruli. A decreased creatinine level is not associated with impaired kidney function and would be unexpected in this context.
D. Glomerular filtration rate is decreased:Glomerular filtration rate (GFR) measures how effectively the kidneys filter blood. In kidney failure, GFR declines because nephron function is compromised, making a decreased GFR a primary laboratory indicator of impaired renal function.
Correct Answer is A
Explanation
A. Troponin:Troponin is a cardiac-specific protein released into the bloodstream when myocardial cells are damaged. During a myocardial infarction (MI), necrosis of heart muscle elevates troponin levels within a few hours, making it the most sensitive and specific marker for acute myocardial injury. Serial measurements help confirm diagnosis and assess infarct size.
B. Potassium:Potassium levels may fluctuate during an MI due to cellular injury or reperfusion, but potassium is not a primary marker of myocardial infarction. Hyperkalemia or hypokalemia may occur secondary to complications but does not reliably indicate MI.
C. Hemoglobin:Hemoglobin reflects red blood cell concentration and is unaffected by myocardial ischemia or infarction. It may be influenced by blood loss or hydration status but is not elevated as a result of myocardial injury.
D. Creatinine:Creatinine reflects renal function and can rise in cases of acute kidney injury or chronic kidney disease. It is not directly elevated due to myocardial infarction unless secondary renal impairment occurs.
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