Lung Ultrasound-guided Hemodynamic Optimization

The formalized expert recommendation of the French Society of Anesthesia and Intensive Care recommends guiding vascular filling by measuring the stroke volume (SV) in surgical patients considered at high risk. Vascular filling should be continued in the event of preload dependence and stopped in the event of the appearance of preload independence. The aim is to avoid vascular overload due to excessive vascular filling. The application of this recommendation has resulted in a reduction in postoperative morbidity, length of hospital stay and time to return to oral feeding. The superiority of this strategy is now being questioned and the predictive indices of response to vascular filling (static and dynamic) have many limitations. In addition, none of the cardiac output monitors are the gold standard for intraoperative use.

Through the study of artefacts, lung ultrasound has been gaining ground over the last twenty years, particularly in cardiology, nephrology and intensive care. By analogy with radiological B-lines, ultrasound B-lines result from the reverberation of ultrasound on the subpleural inter-lobular septa thickened by oedema. The Fluid Administration Limited by Lung Sonography (FALLS) protocol, described by Lichtenstein et al, is defined as the visualisation of new B lines during a vascular filling test. If a B-line appears in an area where it was not present during vascular filling, the most likely diagnosis is hydrostatic overload of the subpleural interstitial septum. This appearance of B-lines occurs at a sub-clinical stage.

The use of lung ultrasound could allow real-time assessment of vascular filling and its tolerance during the intraoperative period. The main objective of the study is to demonstrate a decrease in the incidence of postoperative complications (organ failure) (as defined by international guidelines) when using lung ultrasound-guided haemodynamic optimisation compared to standard optimisation.