Invasive Hemodynamic Monitoring in the Intensive Care Unit

Optimal support of critically ill surgical patients with cardiovascular dysfunction requires that the bedside clinician have both a clear understanding of basic cardiovascular physiology and thorough knowledge of the information available from invasive hemodynamic monitors, including the advantages and pitfalls of each system. Assessment of hemodynamic function in underperfused patients should start with a quantitative assessment of global cardiovascular function. Global variables can be flow derived (e.g., cardiac output), pressure derived (e.g., systolic blood pressure), or both (e.g., ventricular stroke work and power). Any assessment consistent with inadequate global hemodynamic performance should be followed by analysis of the independent determinants of cardiovascular function. These independent determinants include heart rate, preload, afterload, and myocardial contractility. Invasive hemodynamic monitors allow the bedside clinician to measure and quantitate various combinations of global performance and the determinants of cardiac function depending on the monitoring system employed. Central venous lines enable measurement of central venous pressure but limited measure of r