الفهرس 
THE CARDIAC CYCLEOnly 14 pages are availabe for public view
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Abstract
There are an increasing number of different technological advances available that allow monitoring and assessment of wide range physiologic variables; however, most intensive care (ICU) monitors display only blood pressure (BP), heart rate (HR), and oxygen saturation by pulse oximetry (SpO2). These monitors serve to alert the patient’s caregivers to vital signs that require further attention but are not sufficiently sensitive to drive treatment protocols.
Static hemodynamic parameters including CVP and PAOP have been used to estimate preload, although their predictive value on fluid responsiveness is quite limited since the responders and non-responders overlap. To overcome the limitations of these “static” indices, “dynamic” circulatory indices have been recently introduced and validated.
Although trends in specific variables over time are useful in defining hemodynamic stability, their rapid change in response to application of a therapy has greater clinical utility. The most common example of functional monitoring is in a therapeutic trial. These are some of the various types of functional monitoring presently validated, volume challenge, passive leg raising, changes in central veno us pressure during spontaneous breathing, changes in left ventricular output during positive pressure ventilation, identification of cardiovascular insufficiency using vascular occlusion test, imaging of vena caval collapse during positive pressure ventilation using transthoracic or transesophageal echocardiography.
In order to achieve a good understanding of functional hemodynamic monitoring a detailed and close understanding of the cardiac cycle must be linked to the topic, as well as the relation of the cardiac cycle and cardiac output, central venous pressures, end diastolic volume, heart-lung interactions and arterial wave pulse pressure.
A fundamental concept often ignored by proponents of functional hemodynamic monitoring approaches is the integration of other clinical variables, such as the clinical condition, serum lactate levels, etc., a priori into the decision analysis of cardiovascular instability and its response to therapy. In essence, functional hemodynamic monitoring, though profoundly insightful in its values, is only another parameter that needs to be integrated into the greater view of patient care if its use is to realize its full potential.