The Hemodynamic and Physiological Relevance （血流动力学及生理意义）.pdf

W The Hemodynamic and Physiological Relevance of Continuous H I T Central Venous Oxygenation Monitoring: It’s Not Just for Sepsis E P Eric Reyer, DNP, ACNP, CCNS, 2013 A P E R OVERVIEW SvO /ScvO (mixed or central venous oxygen saturation) is an important yet frequently misunderstood hemodynamic 2 2 parameter. Specifically, its use in patients other than those in cardiac surgery and with sepsis has not been widely understood as a useful tool in decision-making with critically ill patients. This paper covers tissue oxygenation and the role of continuous central venous oxygenation monitoring in the assessment of both potential oxygen delivery and consumption in the typical critical care patient. MEASURING POTENTIAL OXYGEN DELIVERY The normal oxygenation cycle begins with deoxygenated blood entering the right side of the heart. As hemoglobin molecules pass out of the right side of the heart and through the lungs/alveoli, four molecules of oxygen become attached to each individual hemoglobin molecule. This oxygenated blood then passes through the left side of the heart and out to the tissue. Upon reaching the capillary beds, an average patient extracts one molecule of oxygen from each hemoglobin molecule, leaving the red blood cells 75% saturated with oxygen as they return back to the right side of the heart.1 The amount of oxygen saturation in the arterial system as it passes into the capillary bed is referred to as potential oxygen delivery (DO ), as extraction has not yet occurred. In the early days of measuring DO , blood had to be sa