Fluid administration limited by lung sonography: the place of lung ultrasound in assessment of acute circulatory failure (the FALLS-protocol).

The FALLS-protocol is included in a limited investigation to diagnose the cause of shock. After simple echocardiography has ruled out obstructive shock (tamponade, pulmonary embolism), the lung is investigated. Absence of disseminated lung rockets rules out cardiogenic shock. At this point, hypovolemic and septic shock are differential diagnoses (rarities apart), and the FALLS-protocol provides fluid therapy with constant monitoring of lung artifacts. Hypovolemic shock will eventually improve - septic shock will not, and the slight excess fluid creates an early, silent stage of interstitial edema, demonstrated by B-lines, demanding interruption of fluid therapy. This sequential approach, combined with the usual, clinical, biochemical and echocardiographic parameters, must be evaluated in multicenter studies.