Key Concepts
Introduction
Hemodynamic monitoring provides objective, continuous measurement of cardiovascular function to guide critical care management. The fundamental concepts are: Preload (the volume of blood stretching the ventricle at end-diastole, measured by CVP for the right heart and PAWP/PCWP for the left heart), Afterload (the resistance the ventricle must overcome to eject blood, measured by SVR for the left ventricle and PVR for the right ventricle), and Contractility (the intrinsic force of myocardial contraction, inferred from cardiac output/cardiac index in relation to preload). Cardiac Output (CO = Heart Rate x Stroke Volume) is the total volume of blood pumped per minute (normal 4-8 L/min); Cardiac Index (CI = CO/BSA) adjusts for body size (normal 2.5-4.0 L/min/m2). Mean Arterial Pressure (MAP = [(2 x Diastolic) + Systolic] / 3) represents the average pressure driving organ perfusion (target >65 mmHg). An arterial line provides continuous, beat-to-beat blood pressure monitoring and allows arterial blood sampling. Central venous pressure (CVP) is measured via a central venous catheter (internal jugular, subclavian, or femoral vein) and reflects right heart preload (normal 2-8 mmHg). A pulmonary artery (Swan-Ganz) catheter...