Hemodynamic Monitoring: Invasive

Hemodynamic monitoring measures cardiovascular performance through the determinants of cardiac output: preload (end-diastolic volume/pressure reflecting venous return and volume status), afterload (systemic vascular resistance that the ventricle must overcome to eject blood), contractility (intrinsic myocardial force generation independent of loading conditions), and heart rate. Central venous pressure (CVP) measured through a central line reflects right atrial pressure and right ventricular preload (normal 2-8 mmHg). Pulmonary artery catheter (Swan-Ganz) measures right heart pressures, pulmonary artery pressure, pulmonary artery wedge pressure (PAWP, reflecting left atrial pressure and left ventricular preload, normal 8-12 mmHg), and cardiac output via thermodilution. Derived parameters include cardiac index (CI = CO/BSA, normal 2.5-4.0 L/min/m2), systemic vascular resistance (SVR, normal 800-1200 dynes/sec/cm5), and mixed venous oxygen saturation (SvO2, normal 60-80%, reflecting the balance between oxygen delivery and consumption). Non-invasive alternatives include pulse contour analysis, transthoracic echocardiography, and passive leg raise test for fluid responsiveness.