Clinical meaning
Cardiac output (CO = HR x SV) is determined by four factors: heart rate, preload (Frank-Starling mechanism), afterload (systemic vascular resistance), and contractility (inotropic state). Optimizing each determinant independently allows targeted therapy: volume for preload, vasopressors/vasodilators for afterload, and inotropes for contractility.
Diagnosis & workup
Diagnostics & workup: - Order thermodilution cardiac output via PA catheter - Order non-invasive cardiac output monitoring (pulse contour analysis) - Order echocardiographic cardiac output estimation - Order arterial line for continuous hemodynamic monitoring - Order SvO2 or ScvO2 for oxygen delivery assessment - Order lactate clearance as perfusion marker
Risk factors: - Low cardiac output states: cardiogenic shock, decompensated heart failure, post-cardiotomy - High cardiac output states: sepsis (hyperdynamic phase), thyrotoxicosis, AV fistula, severe anemia, pregnancy - Mixed shock requiring optimization of each CO determinant independently - Post-cardiac surgery requiring precise hemodynamic management