Which of the following is a compensatory response to decreased cardiac output?
A. Decreased BP.
B. Alteration in LOC.
C. Decreased BP and diuresis.
D. Increased BP and fluid retention.
Correct Answer: D. Increased BP and fluid retention
The body compensates for a decrease in cardiac output with a rise in BP, due to the stimulation of the sympathetic NS and an increase in blood volume as the kidneys retain sodium and water. Compensation may help the body adjust to the effects of heart failure in the short term. But over time it can make heart failure worse by further enlarging the heart and reducing the pumping ability of the heart.
Option A: Blood pressure doesn’t initially drop in response to the compensatory mechanism of the body. The body’s hormone and nervous systems try to make up for this by increasing blood pressure, holding on to salt (sodium) and water in the body, and increasing heart rate. These responses are the body’s attempt to compensate for the poor blood circulation and backup of blood.
Option B: Alteration in LOC will occur only if the decreased cardiac output persists. If the body senses that the brain and vital organs aren’t receiving enough blood, the sympathetic nervous system starts working to get more blood to the brain and organs. This system releases substances called catecholamines into the bloodstream. These substances cause the blood vessels to constrict and speed up the heart rate. At the same time, the arteries supplying the brain and vital organs widen to carry the increased blood flow.
Option C: When the body thinks it needs more fluid in its blood vessels, it releases specific chemicals (renin, angiotensin, and aldosterone) that cause the blood vessels to constrict. In addition, these hormones cause the body to retain more sodium and water. This adds fluid to the circulatory system. This fluid becomes part of the blood circulating throughout the system.
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