Cerebral Monitoring Using Pulsatile Near Infrared Spectroscopy in Neonates

The transition from fetus to newborn is a complex physiological process. Monitoring this process to detect potential disruptions is critical but remains a challenge. Initial evaluation of neonates is usually based on visual inspection, palpation and/or auscultation, and response to stimuli. To objectify the condition of the newborn during this vulnerable transitional period, Virginia Apgar developed a clinical assessment-based scoring system called the Apgar Score, which is widely used around the world. However, there is significant inter-observer and intra-observer variability in clinical assessments using the Apgar score. To objectively assess the condition of the newborn, the latest guidelines for postnatal adaptation and resuscitation recommend the use of electrocardiography (ECG) and pulse oximetry in the delivery room in addition to clinical evaluation. These monitoring methods allow non-invasive continuous monitoring of SpO2 (Oxygen saturation) as well as heart rate (HR), but do not provide information about potentially compromised cardiovascular status, resulting in severely restricted oxygen transport to tissues.

Cerebral Oxygenation:

The brain is one of the most vulnerable organs to hypoxia during the postnatal adaptation period. The recommended routine monitoring during the neonatal transition is SpO2 and heart rate. Unfortunately, these parameters do not provide any information about cerebral blood flow or oxygen supply or brain activity. About 30% of premature babies develop cerebral hemorrhage in the first 3 days after birth. This can lead to the development of hydrocephalus, poor neurological outcome and even death. For the above reasons, there is increasing interest in additional brain monitoring. Our research group has already shown in various studies that additional cerebral monitoring using near-infrared spectroscopy (NIRS) is possible in newborns immediately after birth and may be beneficial during this vulnerable phase of life. Furthermore, this add-on monitoring could inform interventions to optimize brain oxygenation, potentially affecting survival with improved short- and long-term neurological outcomes.

Background:

The transition from fetus to newborn is a complex physiological process. Monitoring this process to detect potential disruptions is critical but remains a challenge. Initial evaluation of neonates is usually based on visual inspection, palpation and/or auscultation, and response to stimuli. To objectify the condition of the newborn during this vulnerable transitional period, Virginia Apgar developed a clinical assessment-based scoring system called the Apgar Score, which is widely used around the world. However, there is significant inter-observer and intra-observer variability in clinical assessments using the Apgar score. To objectively assess the condition of the newborn, the latest guidelines for postnatal adaptation and resuscitation recommend the use of electrocardiography (ECG) and pulse oximetry in the delivery room in addition to clinical evaluation. These monitoring methods allow non-invasive continuous monitoring of SpO2 as well as HR, but do not provide information about potentially compromised cardiovascular status, resulting in severely restricted oxygen transport to tissues.

Pulsatile mode of NIRS Recently, Hamamatsu developed new software and implemented it as a pulsatile mode in one of their near-infrared spectroscopy (NIRS) instruments, the NIRO 200 NX. In contrast to the conventional NIRS technique, which measures tissue saturation closer to venous oxygen saturation than arterial oxygen saturation, the pulsatile NIRS technique uses a higher measurement rate of 20 Hertz and can therefore measure cerebral pulse rate (cPR) and cerebral arterial oxygen saturation (SnO2) in small vessels.

Using the non-invasive pulsatile NIRS technique could be a viable new method to continuously monitor blood flow to the brain during resuscitation. This can be particularly beneficial for critically ill newborns and premature babies.

To date, no data have been published in neonates using the pulsatile NIRS technique.