[Plasma catecholamines in brain death]

The purpose of this study was to find out whether a severe fall in plasma catecholamines levels can be observed in brain dead patients, that might contribute to haemodynamic disturbances in these patients. Plasma catecholamines (epinephrine and norepinephrine) were measured by HPLC combined with electrochemical detection in 18 consecutive brain dead patients referred to the multiorgan donors unit at the Bordeaux University Hospital. Two samples were obtained: the first one at the time of donor referral (11.2 +/- 9 h after the clinical onset of brain death), and the second one just before organ procurement (19.8 +/- 1 h after the clinical onset of brain death). The results showed that plasma catecholamines levels were similar in both samples, with mean values within the normal range. There was no correlation between the plasma levels of each of the catecholamines and the mean arterial pressures at the time of sampling. Very high plasma catecholamines levels have been found by other authors after brain injuries. After the onset of brain death, they return to basal rest values and do not continue to fall as is the case in animal experiments. The haemodynamic disturbances observed in brain dead patients therefore cannot be due only to sympathoadrenal failure.