Hemodynamics and Cardiac Output

These flashcards cover essential concepts of hemodynamics, cardiac output, and related physiological principles.

What is cardiac output (CO)?

The volume of blood pumped by the left ventricle in one minute.

What are the normal values for cardiac output?

About four to seven liters per minute.

What is stroke volume (SV)?

The volume of blood pumped by the left ventricle with each contraction or beat.

What is the normal stroke volume?

70 mL.

What is heart rate (HR)?

The number of times the left ventricle contracts in one minute.

What is the normal heart rate range?

60 to 100 beats per minute.

What three variables impact stroke volume?

Preload, afterload, and contractility.

Define preload.

The amount of blood in the ventricles at the end of diastole and the amount of stretch in the muscle tissue when the ventricle is completely full.

What does afterload refer to?

The resistance the ventricle must overcome to eject blood through the aortic valves.

How does increased afterload affect cardiac output?

It leads to an increase in cardiac workload.

What influences contractility?

It can be increased by sympathetic stimulation or decreased by hypoxia or acidosis.

Explain Starling's law in relation to cardiac output.

The greater the stretch on the myocardium before systole (preload), the stronger the ventricle contraction, up to a certain point.

What happens if the heart rate is too low?

Cardiac output will be low since both heart rate and stroke volume contribute to cardiac output.

What happens to cardiac output if heart rate is too high?

If heart rate is fast for an extended period, cardiac output can be low due to insufficient time for the ventricles to fill.

What are some conditions that can decrease cardiac output?

Hypovolemia, myocardial infarction (MI), sepsis, anaphylaxis, and cardiogenic shock.

What symptoms might you observe in a patient with low cardiac output?

Pale, cool, clammy skin; nausea; dizziness; weakness; hypotension; confusion; cyanosis; decreased urine output.

What are ionotropic agents and their effect on cardiac output?

They increase contractility, stroke volume, and cardiac output but also increase the heart's oxygen demand.

Name an example of a vasodilator and its effect.

Nitroglycerin reduces preload, afterload, and oxygen demand but can cause hypotension.

What do vasopressor agents do?

They increase blood pressure by vasoconstriction but can increase cardiac workload and may decrease perfusion to organs.