Effects on Biotrauma of NMBAs and PP Association During ARDS

The improved survival of patients with acute respiratory distress syndrome (ARDS) over the last decades is related to the use of so-called "protective" mechanical ventilation. Two therapies have been shown to increase survival among the most hypoxemic patients (PaO2/FiO2 \< 150 mmHg): a continuous use of neuromuscular blocking agents (NMBAs) for 48 hours in the acute phase of ARDS and prone positioning (PP). NMBAs and PP are part of the latest guidelines from French ICU Society. However, North American guidelines recommend PP for patients with severe ARDS only but not NMBAs, given the results of the ROSE study which did not confirm the benefit on mortality demonstrated in the ACURASYS study. However, in the ROSE study, ventilatory strategy, use of NMBAs and PP were different from the ACURASYS study. Yet, NMBAs and PP are frequently associated in clinical practice, particularly with the COVID-19 pandemic, but also in randomized trials. In the PROSEVA study, almost all the patients (91%) received a continuous infusion of NMBAs during PP. Indeed, there is a common physiopathological rationale in both techniques: they favor the homogenization of transpulmonary pressures (TPP), reduce lung overdistension, Pendelluft effect and thus ventilator induced lung injury (VILI), in particular barotrauma and biotrauma. This reduction of biotrauma has been demonstrated for PP and NMBAs separately, but never by comparing the combined effect of the 2 techniques to each of them separately. This comparison requires reliable tools. In recent years, the "soluble form of the receptor for advanced glycation end products" (sRAGE), a new biomarker specific of pulmonary epithelial aggression and therefore of biotrauma, has been described and evaluated during ARDS and appears to be associated with the severity of pulmonary damage and prognosis. Overall, despite an interesting physiopathological rationale and a clinically widespread practice, there is currently no study evaluating the synergistic effect of PP and NMBAs in the treatment of ARDS, in particular on the prevention of VILI, and more precisely of biotrauma. This question seems crucial to better specify the respective place of each of these treatments in the management strategy of ARDS patients whose prevalence and mortality remain high. The objective of this study is therefore to evaluate, using a recent and reliable biomarker, the synergistic effect of a short-term NMBAs infusion using cisatracurium and PP on the reduction of biotrauma during moderate to severe ARDS. The investigators will compare this "synergistic" treatment to the use of PP alone. They will also evaluate, in secondary objectives, the effects of PP and NMBAs combination on clinical outcomes and on the patients' prognosis.