Cerebral Function Monitoring In Neonates With Brain Injury

Mild hypothermia is regarded as one of the most potential methods for hypoxic-ischemic encephalopathy (HIE), especially moderate or severe HIE. However, it should be applied within a "therapeutic window"(six hours after insult). Therefore it's imperative to find out sensitive markers for early diagnosis of HIE. Amplitude electroencephalography (aEEG) is a recently developed technique, which is suitable for the monitoring of neonatal cerebral function. It could predict the severity and neurological outcome of HIE. There is no related study available in China up to now.Intraventricular hemorrhage (IVH) and periventricular leucomalacia (PVL) are the main brain injury in the preterm infants. The impaired cerebral autoregulation and hemodynamics are the primary pathophysiologic mechanisms of brain injury in preterm. Currently head ultrasound is used clinically to diagnosis the brain injury in preterm infants. However, it is impossible to predict brain injury in preterm infants. Therefore early cerebral function monitoring and early detection of the impaired cerebral hemodynamics, which in turn lead to immediate treatment, are very important for the high risk preterm with regard to prevention of brain injury and subsequent handicaps. Near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD) have been recently used in NICU to monitor cerebral hemodynamics and cerebral oxygenation. There were few studies about the combined application of these techniques in preterm infants.The study is designed (1) to investigate the value of aEEG in the early diagnosis of HIE and prediction of neurological outcome in term infants; (2) to assess the effect of NIRS, TCD and aEEG on early diagnosis of brain injury and prediction of long term outcome in the preterm infants. The objective is to seek the most valuable method for the cerebral function monitor in neonates with brain injury.Part One Clinical Application of aEEG and Assessment of aEEG in TermInfants with HIEObjective: To study the changes of the aEEG tracings within 6 hours after insult in term infants with HIE and explore the effect of aEEG in early diagnosis and prediction of neurological outcome in term infants.Methods: Ten healthy term infants and 33 term infants with HIE were studied byamplitude-integrated electroencephalography within 6 hours after insult from May 2003 to February 2005. The aEEG tracings were categorized into three groups (normal, mildly abnormal and severely abnormal aEEG) by two methods of classification. HIE was clinically classified into three grade (mild, moderate and severe). The correlation between the results of aEEG and HIE severity, neurological outcome were analyzed, respectively.Results: There were 17 infants with mild HIE, 19 moderate and 7 severe HIE, respectively. All the 10 healthy term infants showed normal aEEG. Among 33 term infants with HIE, according to the first methods of classification, there were 20 infants with normal aEEG 5 with mildly abnormal aEEG and 8 with severely abnormal aEEG respectively. With the second methods of aEEG classification, there were 4 infants with normal aEEQ 16 with mildly abnormal and 13 with severely abnormal aEEG There was a correlation between two methods of aEEG classification and clinically classification. However, the sensitivity and negative predictive value of the first method of aEEG classification was much higher than those of the second method of aEEG classification with regard to prediction of severity and neurological outcome in infants with HIE. The specificity of the first method of aEEG classification was slightly lower than that of the second method. The positive predictive value of both methods was similar.Part Two Cerebral Function Monitoring of Brain injury in Preterm InfantsObjective: To assess brain injury and its prognosis by combined application of NIRS, TCD and aEEG in the preterm infants.Methods: One hundred thirty preterm infants were monitored by NIRS, TCD and aEEG early after birth (12-36 hours after birth) They were investigated for brain injury by cranial ultrasonography and assessed for the neurological development by follow-up. The results of NIRS, TCD and aEEG were compared with those of cranial ultrasonography and follow- up.Results: 1. The incidence of brain injury of the high-risk preterm infants in NICU was 66.7%, and 67% of these infants with severe brain injury. Small gestational age, low birth weight, resuscitation, hypoxia and nCPAP or mechanical ventilation after birth were the main high risk factors of brain injury in preterm infants.2. The results of NIRS indicated that 47.5% of the preterm infants showed impaired cerebral autoregulation and they all developed severe brain injury, in whom 41.7% showed poor neurological prognosis. The saturation of cerebral oxygen (SCO2)...