Abstract:OBJECTIVE: This study examined the effect of mild hypothermia on amplitude integrated electroencephalogram (aEEG) recordings in neonatal pigs with hypoxic-ischemic brain damage (HIBD) and investigated the role of aEEG in the assessment of the effect of mild hypothermia on HIBD. METHODS: Thirty-four 5-day-old piglets were randomly divided into four groups: a Normal control group (normal temperature, n = 7), a Hypothermic-control group (n = 9), a Normothermic hypoxic-ischemic (HI) group (n = 9) and a Hypothermia-treated HI group (n = 9). HIBD was induced by a temporary occlusion of both carotid arteries, followed by mechanical ventilation with low concentration of oxygen (FiO_2 = 0.06) for 30 minutes. The nasopharyngeal and rectal temperature maintained at 35℃±2℃ and 36.0℃±2℃ respectively by head cooling in the two hypothermia-treated groups. The aEEG was recorded before HI and 15 mins, 2 hrs, 12 hrs, 24 hrs, 48 hrs, 72 hrs and 6 days after HI. RESULTS: The normal piglets presented with continuous normal voltage (CNV). The incidence of abnormal waves reflecting the severity of brain damage, continuous low voltage (CLV), burst-suppression (BS) and flat tracing (FT), significantly increased 24 hrs after HI. The incidence of three abnormal waves in the Hypothermia-treated HI group was significantly lower than that in the normothermic HI group. A significant difference was also observed in the incidence of CNV between the two groups 6 days after HI. CONCLUSIONS: The incidence of CLV, BS and FT recorded by aEEG decreased significantly after mild hypothermia treatment, suggesting that mild hypothermia has a neuroprotecive effect against HIBD.
