When should a brain scan with HMPAO be performed to diagnose brain death?

Current Spanish law defines the criteria to be met in the case of brain death (BD) and the complementary tests to confirm it, although they do not always need to be carried out. In Spain one of the most frequently used methods is the electroencephalogram (EEG), which has its shortcomings in patients who are under sedation with barbiturates. Transcranial Doppler (TCD) offers a number of advantages in the diagnosis of BD, but it also has certain limitations. In these cases, a cerebral perfusion scan (CPS) with HMPAO can be very useful. We describe the case of two patients who were admitted to the Intensive Care Unit with serious traumatic brain injuries. Progress was unfavourable and the findings of the clinical exploration were compatible with BD. Since we were dealing with patients under barbiturate therapy, the EEGs were complex and difficult to interpret. TCD was difficult to perform in both cases because of loss of brain matter and displacement of intracranial structures, respectively. CPS, however, allowed us to confirm the diagnosis of BD. Although it has obvious advantages, TCD cannot always be performed to confirm BD diagnosis. In these cases, CPS can be an extremely valuable tool