Final answer:
The most direct non-invasive method for quickly assessing Cardiac Output (CO) is echocardiography (C), which uses ultrasound to measure heart rate and stroke volume, thereby calculating CO. Option C.
Step-by-step explanation:
To quickly assess Cardiac Output (CO), the most direct non-invasive method would be echocardiography (C). Echocardiography uses ultrasound technology to visualize the heart and can allow for measurement of stroke volume and heart rate, ultimately providing a calculation of CO.
While measuring blood pressure (A) and heart rate (B) can provide indirect information about cardiac function, they do not measure CO directly. Auscultation of lung sounds (D) is useful in identifying pulmonary abnormalities but is not a method to assess CO.
Cardiac Output is defined as the amount of blood pumped by each ventricle in one minute, and it can be represented by the equation CO = HR × SV. An increase in CO will usually lead to an increase in blood pressure and vice versa. Both heart rate and stroke volume are influenced by various neural, endocrine, and environmental factors.
Therefore, echocardiography, which can measure these variables, is the most reliable way to quickly determine CO.
Pulse measurements can also provide some insight into heart rate and thus cardiac output, though these are more of an indirect indicator and not a direct measurement of CO. Option C.