In circulatory failure, fluid administration limited by lung sonography protocol uses lung ultrasound artifacts and makes sequential diagnosis of obstructive, cardiogenic, hypovolemic, and septic shock. Lung ultrasound is used along with simple cardiac and vena cava analysis. Whenever echocardiography cannot be performed, fluid administration limited by lung sonography protocol is favored because of its simplicity and could prove contributive. It is based on the presence (B profile) or the absence (A profile) of interstitial pulmonary edema. However, the latter does not represent actual alveolar edema, and transthoracic echocardiography is still used by intensivists as a pivotal hemodynamic measure. Tissue Doppler imaging facilitates the estimation of left ventricular filling pressures, whereas assessing right ventricular function is of prognostic value in states of shock due to massive pulmonary embolism and acute respiratory distress syndrome. In mechanically ventilated patients, poor acoustic windows are evident and performing transesophageal echocardiography may be necessary. Whenever noninvasive hemodynamic measures are inconclusive, in a deteriorating patient, a pulmonary artery catheter may be placed. Ultrasound is not a therapy but a guide for treatment, and physicians should aim to treat underlying pathologies. Despite its limitations, general chest ultrasound (lung and cardiac ultrasound) is a powerful diagnostic and monitoring tool reflecting an era of genuine "visual" medicine.
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