Cardiac output (CO) equals:
Stroke volume x heart rate.
Afterload x preload.
Ejection fraction x blood pressure.
Systolic x diastolic BP.
The Correct Answer is A
Choice A reason: Stroke volume x heart rate. Cardiac output is the volume of blood the heart pumps per minute, calculated by multiplying the stroke volume (the amount of blood ejected with each heartbeat) by the heart rate (the number of beats per minute).
Choice B reason: Afterload x preload. Afterload and preload are important factors influencing cardiac function but do not directly calculate cardiac output. Afterload refers to the resistance the heart must overcome to eject blood, and preload refers to the initial stretching of the heart muscle prior to contraction.
Choice C reason: Ejection fraction x blood pressure. Ejection fraction is a measure of the percentage of blood ejected from the heart with each beat, and blood pressure is the force exerted by circulating blood on the walls of blood vessels. These factors influence cardiac function but do not directly calculate cardiac output.
Choice D reason: Systolic x diastolic BP. Systolic and diastolic blood pressure are measurements of pressure during heartbeats and between beats, respectively. They are not used to calculate cardiac output.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A reason: Oliguria. Oliguria, or reduced urine output, is a manifestation that occurs later as shock progresses and renal perfusion decreases. It is not typically seen in the initial stage of shock.
Choice B reason: Hypotension. Hypotension generally appears in the compensatory and progressive stages of shock as the body's compensatory mechanisms begin to fail. In the initial stage, blood pressure may still be maintained by compensatory mechanisms.
Choice C reason: Respiratory alkalosis. Respiratory alkalosis is more likely to occur during the compensatory stage of shock due to hyperventilation as the body attempts to compensate for hypoxia. It is not anticipated in the initial stage of shock.
Choice D reason: Hypoxia. During the initial stage of shock, the body's cells and tissues begin to experience hypoxia due to reduced oxygen delivery. This is an early manifestation that the nurse should monitor for.
Correct Answer is B
Explanation
Choice A reason: Decreased systemic vascular resistance, decreased CVP. In hypovolemic shock, the body compensates by increasing systemic vascular resistance to maintain blood pressure. Therefore, decreased systemic vascular resistance is not consistent with hypovolemic shock. Central venous pressure (CVP) would be low due to reduced blood volume.
Choice B reason: Increased systemic vascular resistance, decreased CVP. Hypovolemic shock is characterized by low blood volume, leading to decreased cardiac output and low CVP. The body compensates by increasing systemic vascular resistance to maintain blood pressure, making this the correct answer.
Choice C reason: Increased systemic vascular resistance, increased CVP. While systemic vascular resistance increases, CVP is typically decreased in hypovolemic shock due to the lack of circulating blood volume.
Choice D reason: Decreased systemic vascular resistance, increased CVP. Decreased systemic vascular resistance and increased CVP are not consistent with hypovolemic shock. These parameters might be seen in conditions with different hemodynamic profiles.
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