1. Adequate cardiac output is necessary in order to supply oxygen and other nutrients to all body tissues. Cardiac output is influenced by stroke volume and heart rate. Factors affecting the stroke volume include PRELOAD, CONTRACTILITY and AFTERLOAD.
In the following conditions, indicate what factor/s influence the cardiac output: PRELOAD, CONTRACTILITY, AFTERLOAD, HEART RATE. Explain why the factor/s affects cardiac output in 1 to 2 sentences.
a. High blood pressure
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High blood pressure increases the workload on your heart usually because of narrowed, less elastic arteries that make it more difficult for blood to circulate throughout your body. With this, the afterload of cardiac output is compromised (Oh, 2020).
b. Massive bleeding
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Massive bleeding reduces blood volume, which lowers central venous pressure and decreases heart filling. As a result, cardiac output is affected as the body compensates for the reduced blood volume by increasing the heart rate and contractility while the preload decreases along with blood volume (Klabunde, 2021).
c. the drug dopamine
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Dopamine affects the cardiac output as it increases myocardial contractility and heart rate. Dopamine increases heart rate and cardiac contractility through having good chronotropic and inotropic effects on the myocardium (Dopamine: Uses, Interactions, Mechanism of Action | DrugBank Online, n.d.).
d. Running a sprint
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When running a sprint, your muscles require more oxygen when you exert yourself. Thus, your body may require more than your typical cardiac output, resulting in a faster heart rate so that more blood can leave your body (Healthwise Staff, 2022).
e. Hyperthyroidism with increased secretion of thyroid hormones
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Hyperthyroidism is a condition that occurs when the thyroid gland secretes excessive thyroid hormones. Thus, it is accompanied by a state of high cardiac output with a significant rise in heart rate and cardiac preload (Vargas-Uricoechea, 2014).
f. Massive myocardial infarction (cardiac tissue death)
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Massive myocardial infarction is the permanent necrosis of cardiac muscle brought on by prolonged ischemia. It compromises cardiac output as it is accompanied by increased contractility and to compensate for the decreased number of functional myocardial cells and decreased heart rate (Zafari, 2022).
g. Hypothermia
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Hypothermia is a condition in which the body enters an abnormal blood temperature. This affects the cardiac output as the contractility and heart rate are significantly reduced (Kelly & Nolan, 2010).
h. Emotional distress
When one is under emotional distress, stress hormones are released, blood pressure rises, and heart beats quicker than before. Thus, cardiac output is affected as the heart rate is increased, especially when the body experiences emotional distress that causes the body to consume more oxygen (Content - Health Encyclopedia - University of Rochester Medical Center, n.d.).