Effects of Induced Moderate Hypothermia on ARDS Patients Under Venovenous ExtraCorporeal Membrane Oxygenation

Acute respiratory distress syndrome (ARDS) is a lesional pulmonary edema that occurs as a result of direct or indirect lung injury. This condition accounts for 10-15% of ICU admissions and 20-25% of patients admitted require invasive ventilation. Its incidence has increased markedly with the Covid-19 epidemic. ARDS is defined as hypoxemia (Pa02/Fi02 \< 300 mmHg) in ventilated patients without heart failure. Currently, the recommendations of the resuscitation societies advocate a management combining invasive ventilation, short duration curarization and prone sessions. In case of failure of these therapies, venovenous ExtraCorporeal Membrane Oxygenation (VV ECMO) is recommended in case of Pa02/Fi02 \< 80 mmHg. Nevertheless, approximately 40% of patients have refractory and persistent hypoxemia despite optimization of ECMO parameters and invasive ventilation. The refractory hypoxemia is defined as Pa02 \< 55 mmHg and/or Sa02 \< 90% and may be due to a recirculation phenomenon or a significant intra-pulmonary shunt. Currently, there is no official recommendation for the management of these patients, leading to the use of various unvalidated field practices. In addition, hospital mortality of the order of 60% is observed in these patients with high management costs. Some data in the literature suggest that induced therapeutic hypothermia (HT) at 34°C for 48 hours could improve the prognosis of these patients by improving oxygenation. Nevertheless, the level of evidence of published studies remains low because they are either case reviews or studies whose methodology does not guarantee the absence of potential bias. The research hypothesis is that HT at 34°C or 33°C for 48 hours is effective on refractory hypoxemia.

The investigators propose a pilot study, monocentric, prospective, controlled, randomized, to apprehend in an objective and reliable way the effects of induced moderate hypothermia at 34°C, or at 33°C in case of persistence of a Sa02 lower than 90%, during 48 hours in patients under ECMO VV for ARDS. The objective of this study is to show the beneficial effect of the treatment on the patient's oxygenation and to understand the physiopathological mechanism of action at work through different parameters at different times. In parallel, the undesirable effects will be recorded and weighed against the positive effects of the treatment in order to understand the benefit/risk ratio of light HT. The effect on survival will also be evaluated as a secondary objective, not to demonstrate efficacy in this small pilot trial, but to determine the size of the effect that can be expected.