NeoGuard is a bed-side device for continuous EEG monitoring of the brain function in very ill newborn babies admitted to the Neonatal Intensive Care Unit (NICU).
It is a product of the neonatal brain monitoring group, that is a research collaboration between groups from Leuven, Rotterdam, Antwerpen and Ghent.
Why monitor brain function in the newborn baby?
The neonatal brain is vulnerable to various insults occurring in the perinatal (before, during and immediately after birth) period. These include a temporary lack of oxygen and blood supply (asphyxia), metabolic disturbances (disturbances in blood glucose, calcium, sodium etc.), infections, stroke and trauma. Often the neonatal brain reacts to these injuries by suppression of the electrical activity of the brain cells (neurons) and by expressing seizures. Monitoring neonatal brain activity helps in detecting these harmful conditions in an early and potentially reversible stage, allowing timely treatment. This will help to prevent serious damage to the brain.
How is brain monitoring done in the neonate?
The electrical activity of the brain cells, the electroencephalogram (EEG) can be recorded non-invasively using small cup electrodes pasted on the scalp. Continuous recording of the EEG allows the detection of dynamic changes in brain activity (as reflected by deterioration or improvement of the background EEG activity) as well as the occurrence of seizures, which can be likened to abnormal ‘storms of electrical activity’. These electrical signals are amplified, filtered and displayed on a computer screen. Physicians with specialized training interpret these signals.
Why is neonatal brain monitoring not widely done in NICUs?
Recording and interpreting the neonatal EEG, recorded from multiple scalp electrodes is technically demanding. These skills are not available around-the clock in most NICUs. Even when it is available, continuous EEG monitoring (cEEG) accumulates large amounts of data, making it very labour-intensive to interpret it.
Are there simpler methods of neonatal brain monitoring?
Many NICUs use amplitude integrated EEG (aEEG), a simple compressed EEG trend recorded from two electrodes. This user-friendly bed-side method can detect changes in EEG background activity over time and also detect some of the seizures. However, due to limited coverage of the head, localised abnormalities are missed and also information about features like frequency, amplitude, morphology and spread of seizures are missed by aEEG.
Automated methods of neonatal brain monitoring
There is an unmet need for reliable methods for automated EEG analysis. Various research groups have published neonatal seizure detection methods in the last few years. However, there is no validated system that is reliable and ready for use at the bed-side. Our research group has developed a reliable automated seizure detection system, which mimics a clinical neurophysiologist reading the EEG. This works by identifying two major properties of neonatal seizures as seen on EEG signals, i.e., a change in EEG activity relative to the ongoing background activity and increase in repetitiveness. We classified seizures into two major types, according to their morphology (pattern expressed), i.e the spike-trains and oscillations, or combinations thereof and developed algorithms to detect them. This system, named NeoGuard, detects seizures with a sensitivity of 86.9% with a false positive rate of less than 1 per 3 hours and is suited for clinical use. We have further refined this system, mainly in automated artifact reduction. We are now busy developing automated EEG background analysis, mainly with the goal of classifying the severity of encephalopathy in neonates and to detect dynamic changes ( improvement or deterioration in the background activity). EEG background has been shown by previous studies to be the most sensitive parameter for outcome prediction in asphyxiated neonates. We hope that the automated background classification will also help in future to refine selection of neonates with moderate to severe postasphyxial brain dysfunction (hypoxic ischemic encephalopathy) for therapeutic hypothermia.