Cardiac Output

Definition

Cardiac output (CO) is the total volume of blood pumped by the left ventricle per minute, calculated as stroke volume (SV) multiplied by heart rate (HR). Normal adult CO is 4 to 8 L/min.

Determinants of Stroke Volume

• Preload: Ventricular filling volume (affected by venous return, volume status).
• Afterload: Resistance the ventricle must overcome (related to BP, vascular tone).
• Contractility: Strength of cardiac muscle contraction.

Clinical Correlates

Decreased CO occurs in heart failure, myocardial infarction, hypovolemic shock, cardiac tamponade, and severe bradycardia, such as signs include hypotension, tachycardia, weak pulses, cool clammy skin, decreased urine output, and altered mental status.

Nursing Interventions

Optimize preload (fluids or diuretics as appropriate), afterload (vasodilators or vasopressors), contractility (inotropes), and rate (anti-arrhythmics, pacing). Monitor hemodynamics, I&O, and end-organ perfusion.

NCLEX Relevance

Foundational concept in heart failure, shock, and critical care content. Expect questions linking interventions to CO determinants.