Cardiac Output Measurement

These flashcards cover key terms and concepts related to cardiac output measurement, including definitions and functions.

Cardiac Output (CO)

The amount of blood the heart pumps in 1 minute, a product of stroke volume and heart rate.

Stroke Volume

The amount of blood ejected from the left ventricle with each contraction, normally from 60 to 130 mL.

Venous Return

Amount of blood returning to the right atria each minute, usually equal to cardiac output.

Cardiac Index (CI)

Describes flow output by dividing cardiac output (CO) by body surface area (BSA); normal CI is 2.5 to 4.0 L/min/m2.

Preload

The initial stretching of the cardiac muscle prior to contraction, related to end-diastolic volume.

Afterload

The pressure the heart must work against to eject blood; determined by ventricular wall stress and peripheral vascular resistance.

Contractility

A measure of the strength of myocardial contraction, influenced by preload and inotropic state.

Ejection Fraction (EF)

The fraction of end-diastolic volume ejected with each systole; normally 65% to 70%.

Fick Method

A method for measuring cardiac output based on the relationship between oxygen consumption and arterial and venous oxygen content.

Pulmonary Artery Thermodilution

A common technique for measuring cardiac output that involves injecting a cold solution and recording temperature changes.

Cardiac Reserve

The difference between resting and maximal cardiac output; it indicates the capacity of the heart to respond to increased workload.

Ventricular Hypertrophy

The thickening of the heart's ventricular walls, often resulting from increased workload and afterload.

Heart Rate Variability (HRV)

The measure of variations in time between heartbeats, reflecting autonomic nervous system activity and cardiovascular fitness.

Shock

A clinical syndrome characterized by inadequate tissue perfusion and oxygenation, potentially leading to organ dysfunction.

Congestive Heart Failure (CHF)

A condition in which the heart is unable to pump effectively, leading to fluid buildup in lungs and other body tissues.