Cardiac alterations may be defined as changes that lead to abnormal cardiac function. They include decrease in preload, increase in afterload, and depressed cardiac contractility. Cardiac dysfunction differs from cardiac failure: cardiac performance is altered, but this does not necessarily mean that the cardiovascular system is failing. Several tools are available to detect cardiac alterations. Some may continuously assess cardiac performance by mainly or exclusively measuring cardiac output, but no information is given about the mechanisms underlying the cardiac output decrease. Doppler echocardiography allows noncontinuous cardiac monitoring, but it is perfectly adapted to evaluation of cardiac performance. It directly visualizes cardiac contractility and assesses cardiac preload. Only when there is an imbalance between oxygen demand and oxygen transport is correction of cardiac alterations required. But the truth is that no study supports the use of one treatment rather than another. Changes in respiratory settings or in respiratory mechanics induce changes in cardiac function and must then be considered in the strategy.
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