AIM: The authors propose the use of ABR as an instrument for the detection of brainstem dysfunction in the trans- and post-operatory period of surgeries with total circulatory arrest (TCA) and deep hypothermia for correction of aneurysms of the thoracic aorta. STUDY DESIGN: Longitudinal Cohort. MATERIAL AND METHOD: Eight adult patients that underwent surgery for correction of aneurisms of thoracic aorta had their brainstem monitored through ABR. The patients had their body temperature lowered to 18ºC. At this moment, TCA was performed for a period of up to 60 minutes. The recordings were done at the following: before lowering the body temperature, during the cooling process, at the time of TCA (18ºC), and during the re-warming process. RESULTS: The initial tracings (35ºC) were normal. At 26ºC, ABR waves disappeared. At 18ºC and TCA, ABR showed isoelectric tracings. Waves I, III and V reappeared at 27ºC, although with prolonged latencies. When temperature reached 35ºC, latencies were back to normal. CONCLUSIONS: The ABR seems to be a useful monitor for evaluating brainstem function during surgeries with TCA and deep hypothermia. Our experience showed the extreme usefulness of the evoked auditory potentials in such procedures as a noninvasive, reliable and objective method for the monitoring of variations in the neurophysiological pattern of the brainstem. This can be of great value in presuming the patient's neurological outcome in a moment when the neurological status cannot be clinically accessed due to the several drugs used during surgery.
brainstem auditory evoked potentials; ABR; heart surgery; total circulatory arrest; deep hypothermia; brainstem monitoring
