Abstract
Low cardiac output syndrome (LOS), one of the most serious complications of cardiovascular surgery, is defined as an imbalance of oxygen demand and supply due to a deterioration of cardiac function. Critical oxygen delivery marks the turning point from the dependent to the independent phase in the relationship between oxygen delivery and consumption. It is crucial to maintain oxygen delivery beyond the point of critical oxygen delivery (the independent phase) after cardiovascular surgery or in critically ill patients. Critical oxygen delivery is approximately 400ml·min-1·m-2 immediately after cardiovascular surgery under controlled ventilation. To maintain critical oxygen delivery, hemodynamic management requires a CI (l·min-1·m-2)>40/CaO2(vol%). A CaO2(vol%) of 40/CI(l·min-1·m-2) is the critical level when anemia is present. Alternative strategies to control LOS by improving the imbalance of oxygen demand and supply include the inhalation of nitric oxide, which increases oxygen delivery, and the presence of mild hypothermia (a core temperature of approximately 35°C), which reduces critical oxygen delivery.
