The Comparison of Stroke Volume Variation and Arterial Pressure Based Cardiac Output with Standard Hemodynamic Measurements during Cardiac Surgery

BACKGROUND: Hemodynamic monitoring and fluid status assessment are essential for cardiovascular care in the surgical patient. Knowing when a patient’s hemodynamic instability comes from hypovolemia or other causes is imperative in providing safe patient care. Commonly used methods of determining fluid status such as central venous pressure (CVP) and pulmonary artery pressure (PAP) do not accurately reflect the left ventricular end diastolic area and volume values, even when trends are followed after the administration of a fluid challenge during hemodynamic instability. The purpose of this study was to compare the stroke volume variation (SVV) and arterial pressure based cardiac output (APCO) with the current accepted methods on cardiac output and preload status.METHODS: Prospective, observational study in 100 cardiac surgery patients. Continuous cardiac output (CCO), APCO, SVV, PCWP, CVP and ventricular end diastolic area and volume were measured. The APCO were compared with CCO, the cardiac output values of continuous thermodilutional method. The central APCO was compared with peripheral APCO. SVV values were compared with LVEDA, LVEDV, CVP, PAP, and other hemodynamic values.RESULTS: The correlations between SVV and LVEDA and LVEDV were R=0.7027 and R=0.7924 (p<.0001) respectively. The correlation between APCO and CCO was R=0.8309 (p<.0001). The correlation between central APCO and peripheral APCO was R=0.9155 (p<.0001).CONCLUSIONS: SVV is a good indicator of the cardiac preload. It is superior to static indicators of cardiac preload and has a higher correlation with LVEDA and LVEDV. It can therefore be used to guide intraoperaitve fluid therapy. APCO measured from peripheral artery has a high correlation with the central CO and conventional method for CO measurement, therefore, it can accurately reflect cardiac output. Sources: This work was supported by the Department of Anesthesiology and Pain Medicine, University of California Davis Health System. Part of the results were presented at the American Society of Anesthesiologists 2007 Annual Meeting, October 14-17, 2007 in San Francisco, California.