Which of the following factors directly affects stroke volume?
Blood pressure
Preload
Afterload
Heart rate
The Correct Answer is B
Choice A Reason:
Blood pressure itself does not directly affect stroke volume. However, it can influence afterload, which in turn affects stroke volume. Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and while it is related to cardiac function, it is not a direct determinant of stroke volume.
Choice B Reason:
Preload directly affects stroke volume. Preload refers to the degree of stretch of the cardiac muscle fibers at the end of diastole, just before contraction. It is influenced by the volume of blood returning to the heart (venous return). According to the Frank-Starling law, an increase in preload leads to an increase in stroke volume due to the enhanced force of contraction.
Choice C Reason:
Afterload also directly affects stroke volume. Afterload is the resistance the ventricles must overcome to eject blood during systole. It is influenced by factors such as arterial blood pressure and vascular resistance. An increase in afterload can decrease stroke volume because the heart has to work harder to pump blood against the higher resistance.
Choice D Reason:
Heart rate does not directly affect stroke volume. Instead, heart rate and stroke volume together determine cardiac output (CO = HR × SV). While heart rate can influence the overall amount of blood pumped by the heart per minute, it does not directly change the volume of blood ejected with each beat.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A Reason:
Monitoring the client for an elevated temperature is crucial because it can indicate an infection at the pin sites or other complications. Infections are a common risk with halo fixation devices due to the invasive nature of the pins.
Choice B Reason:
Ensuring the halo jacket is snug against the client's skin is incorrect. The halo jacket should fit properly but not be too tight, as this can cause skin breakdown and discomfort. There should be enough space to insert a flat hand between the vest and the skin.
Choice C Reason:
Providing range of motion to the client's neck is not appropriate for a client with a halo fixation device. The purpose of the halo is to immobilize the neck to allow for proper healing of cervical injuries. Any movement could jeopardize the stability of the injury.
Choice D Reason:
Removing the vest daily to inspect the client's skin integrity is incorrect. The halo vest should not be removed frequently as it is meant to provide continuous immobilization. Skin integrity can be monitored by checking the areas around the vest without removing it.
Correct Answer is B
Explanation
Choice A Reason:
Core temperature is important to monitor in many clinical situations, but it is not the primary concern for a client with an abdominal aortic aneurysm. While fever can indicate infection, which is a potential complication, it is not directly related to the immediate risks associated with AAA.
Choice B Reason:
Blood pressure is the most critical vital sign to monitor in a client with an abdominal aortic aneurysm. Elevated blood pressure can increase the risk of aneurysm rupture, which is a life-threatening emergency. Maintaining blood pressure within a safe range is essential to prevent complications and ensure the stability of the aneurysm.
Choice C Reason:
Pulse rate is also important to monitor, but it is not as directly indicative of the risk of aneurysm rupture as blood pressure. While changes in pulse rate can signal cardiovascular stress or other issues, blood pressure provides more direct information about the forces acting on the aneurysm.
Choice D Reason:
Respiratory rate is a vital sign that can indicate respiratory distress or other systemic issues, but it is not the primary concern in the context of an abdominal aortic aneurysm. Blood pressure remains the most critical parameter to monitor to prevent rupture and manage the condition effectively.
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