Physiopathologie de la défaillance cardio-circulatoire au cours de l’état de mort encéphalique

The studies presented in this report aimed to describe and to treat some of the physiopathological mechanisms at the origin of a cardiovascular dysfunction, which may appear during brain death. The combined measurement of cardiac biomarkers allows to dismiss the diagnosis of left ventricular systolic dysfunction (study 1). A glucose-insulin-potassium solution is as efficient as dobutamine in improving ventricular systolic function, without the adverse effects of dobutamine (study 2). Hypothalamo-pituitary-adrenal insufficiency is frequent; a systematic hydrocortisone supplementation enhances the hemodynamic stability (study 3). The biological method to diagnose the hypothalamo-pituitary-adrenal insufficiency by the total cortisol measurement is as accurate as the free cortisol measurement, even if albumin or corticosteroid-binding globulin concentrations are low (study 4). The adrenal gland volume measured by tomodensitometry is not accurate to diagnose hypothalamo-pituitary-adrenal insufficiency (study 5). In brain-dead patients, hypothalamo-pituitary-adrenal insufficiency is due to hypothamo-pituitary insufficiency, while in cardiac-dead patients, it is due to adrenal insufficiency (study 6). The calculation of the renal resistive index with renal Doppler assesses the effects of the hemodynamic instability treatment on the renal circulation. These results show that a better knowledge about physiopathological mechanisms of hemodynamic instability during brain death leads to improve hemodynamic care of brain-dead patients