Hemodynamic instability refers to global or regional perfusion that is inadequate to support normal organ function. Numerous hemodynamic parameters (heart rate, blood pressure, central venous pressure, pulmonary artery pressure, pulmonary artery occlusion pressure, and cardiac output) can be monitored and controlled, and abnormalities in any of them parameters may indicate hemodynamic instability.
This papers looks at the advantages and limitations of various methods for assessing hemodynamic instability, including invasive blood pressure monitoring, cardiac output monitoring, measurement of mixed-venous hemoglobin oxygen saturation, and echocardiography.
The author observes that when hemodynamic instability has been recognized as either hypotension or low cardiac output syndrome, treatment can be greatly facilitated by echocardiography. It provides a quick and accurate assessment of preload and contractility, along with cardiac dimensions and an estimate of ejection fraction.
In addition, it assesses valve function, regional wall motion abnormalities, sources of emboli, and pericardial constraints to normal hemodynamics, while allowing clinicians to distinguish right from left heart performance.
For these reasons, the author states that echocardiography is highly recommended whenever there is hemodynamic instability of unknown etiology or that is not readily corrected by standard therapy.
1James Bailey, MD, PhD, Associate Professor, Department of Anesthesiology, Cardiac Anesthesia and Critical Care Medicine Division, Emory University School of Medicine, Atlanta, Georgia, USA. Published by permission of GASNet Inc. © 2003.
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