Normal values of non-invasive measurements of cerebral and muscle tissue oxygenation using near infrared spectroscopy in healthy near term and term newborn infants.

Monitoring of tissue oxygenation is considered as an essential component in the
monitoring and treatment of severely ill and hemodynamically unstable neonates
on a neonatal intensive care unit (NICU) and of neonates during anesthesia in a
surgical procedure.
Spatially resolved near infrared spectroscopy (NIRS) is a method for
non-invasive and continuous measurement of regional oxygen saturation (rsO2) in
tissue. Using this non invasive technique, the ratio of oxyhemoglobin and
deoxyhemoglobin in the tissue can be measured and expressed in rsO2 in percent.
Changing the rsO2 reflects a change in oxygen supply and oxygen demand in
tissue, indicating decrease of rsO2 tissue hypoxia. With this method it is
possible to measure the rsO2 in cerebral and muscle tissue.
Measurement of the cerebral rsO2 has been found to be useful in various
clinical conditions, especially during cardiac surgery as an indicator of
cerebral oxygenation and perfusion. There is a good relationship between venous
oxygen saturation in the jugular vein and rsO2. To date, no valid validation
studies have been published yet. The normal reference values **of rsO2 for term
and near term newborn in the literature are diverge and appear to be dependent
on the brand of the NIRS device. In previous CMO applications, we have
determined normal rsO2 values **in cerebral and muscle tissue in healthy near
term and term neonates with NIRS equipment of INVOS.
In the meanwhile, together with the Department of Anesthesiology, we have
purchased NIRS NIRO 200 NX (Hamamatsu) equipment for monitoring of cerebral
oxygenation in neonates during anesthesia in a surgical procedure. The values **
of rsO2 of NIRO 200 NX appear to differ from the values **of INVOS. The normal
reference values **of rsO2 for cerebral and muscle tissue are not known from
literature. It is therefore important to determine normal reference values **
for cerebral and muscular rsO2 in healthy near term and term neonates and also
to investigate the relationship between these variables. With the knowledge of
normal reference values, pathological conditions can be quickly recognized and
targeted therapies can be set to restore normal conditions.

To obtain reference values of rsO2 of cerebral and muscle tissue measured by
NIRO 200 NX for (relatively) healthy near term and term neonates.

On the first day after birth, a continuous measurement of the regional oxygen
saturation (rsO2) in the brain and in the quadriceps muscle will be performed
using NIRS (NIRO 200 NX) for 30 minutes. This is a non-invasive method, using a
local sensor that emits light locally, the change in regional oxygen saturation
can be measured directly in the mixed vascular bed directly below the sensor.
The sensors are attached to the skull and the upper leg with a double-sided
adhesive ring and with an elastic bandage.
The following physiological variables will also be recorded simultaneously,
continuously and non-invasively: heart rate and arterial O2 saturation (saO2,
puls oximetry)

NIRS is non-invasive and harmless to tissue. The burdening and risk for the
patient are almost nil