Non invasive transcutaneous hyperbilirubinemia analyzer.
RECOMMENDATIONS FOR CLINICAL USE
The intended use of the BILITEST Hyperbiliruinemia Analyzer
is to screen newborn infants for hyperbilirubinemia, including:
2. MESUREMENT PRINCIPLE
High correlation between noninvasive measurement results
of bilirubin concentration in derma and bilirubin concentration
in blood has provided the basis for promoting Method of
Transcutaneous Bilirubinometry into medical practice. This
concept has been embodied in the BILITEST Hyperbilirubinemia
The correlation is caused by existing dynamical balance
between bilirubin concentration in blood and subcutaneous
tissues due to reversible diffusion of a bilirubin between
blood and tissues.
High level of bilirubin concentration in blood leads to
a high bilirubin concentration in derma and vice versa -
low level of bilirubin concentration in blood (for example,
during exchange transfusion) results in bilirubin counterblow
from tissues to blood until the balance between these to
bilirubin reserving systems is reached.
It is important that after such therapeutic measures as
phototherapy and exchange transfusion a balance between
these two bilirubin reserving systems is reached as a rule
within 5 - 6 hours.
3. BILITEST FEATURES
The BILITEST is a portable fully automated photometer.
Its operation is based on the principle of two-wave skin
reflectance measurements. It analyses spectrum of optical
signal reflected from infants subcutaneous tissues.
The BILITEST makes it almost unfeasible for light detectors
to record the skin colour influence upon the results.
In essence the BILITEST determines bilirubin concentration
in derma through the use of subcutaneous tissues photometry.
Because there are no reference materials for bilirubin
concentration in derma, the device is calibrated by convention
in units of Transcutaneous Bilirubin Index (TBI) following
the international practice.
4. OPERATING PROCEDURE
Transcutaneous Bilirubinometry Operating Procedure is
rather simple with the use of the BILITEST hyperbilirubinemia
analyzer. The BILITEST optic head is gently pressed against
infants skin (usually forehead or upper part of
sternum). The measuring procedure of the BILITEST lasts
for 2 - 3 seconds and is accompanied by a soft sound.
When the sound has finished, the procedure is over. The
BILITEST digit display reads the result. The device is
now ready for anther measurement. Display keeps the result
of single measurement for about 60 seconds then automatically
erases it and the device is switched to the standby mode.
The device is in the standby mode until following measurement.
The verification of devices performance should be
made before and after run measurements, using two Control
In case the readings are supposed
to be incorrect it is recommended to perform three additional
measurements at a time. If three obtained readings differ,
the average value should be chosen, the least and the
greatest exempted. To avoid Hyperaemia anther part of
infants skin should be chosen for repeat measurement.
Hyperaemia may influence the result.
Avoid measurements against Bruising, Birthmarks and subcutaneous
5. ESTIMATION OF SERUM BILIRUBIN CONCENTRATION USING
THE BILITEST READINGS
The BILITEST is calibrated so that the value of TBI multiplied
by 10 approximates the value of serum bilirubin concentration,
if TBI measuring is made against infants forehead.
Normally the real serum bilirubin concentration doesnt
differ from corresponding estimation more than 35 m mol/l.
One should remember that in a number
of clinical cases, described in subsection 6, the balance
between bilirubin concentration in blood and in subcutaneous
tissues is disrupted. In these cases, serum bilirubin
testing is needed and the use of the BILITEST for estimation
of the serum bilirubin concentration is not recommended.
The BILITEST has been calibrated for the
newborn infants without intensive skin pigmentation (for
In other cases correspondence between TBI and serum bilirubin
concentration values should be refined. The User refine
it himself, comparing the readings of the BILITEST with
the corresponding laboratory data of serum bilirubin testing.
To obtain calibration coefficients for
the BILITEST the bilirubin concentration in blood was
measured with the help of two-wave photometrical method.
The newborn capillary blood plasma was put through a direct
photometrical process. Near 300 newborn infants, gestational
age of 30 - 40 weeks and weight of 1400 - 3500 g, were
examined. In parallel with determination of bilirubin
concentration in blood, all the infants were examined
for TBI on forehead, on upper part of sternum and inner
surface of leg. Correlation coefficients between bilirubin
concentration in blood and corresponding TBI values were
equal to: r = 0.92 for forehead; r = 0.86 for sternum;
r = 0.54 for leg inner surface.
Because the best correlation between TBI and bilirubin
concentration in blood was shown on forehead, the corresponding
data had been chosen for the BILITEST calibration. Measuring
TBI on forehead also allows infants examinations
to be performed without additional manipulations with
the newborns (e.g. taking clothes off).
- To estimate the reproducibility of the BILITESTs
readings 76 infants were examined. During examination, every
infant was subjected to measurement 5 times and CV% for
each of it was calculated.
The results of examination were the following:
The good reproducibility of the BILITEST
allows carrying out TBI measurements only once for every
infant in clinical use.
The examinations have shown that medical staff (even with
a little experience) can use the BILITEST.
6. TRANSCUTANEOUS BILIRUBINOMETRY FEATURES
One should bear in mind that the result may be incorrect
if measurements are carried out against bruising or subcutaneous
hematomas (for example, after infusion therapy). In this
case, the TBI measurement is preferable to be made on
the upper part of sternum.
While measuring TBI of the low weight newborns who suffer
from hemodynamics disorder and are in severe somatic state,
the Hyperaemia spot appears in the area where the device's
optic head is pressed against the skin. Repeat measurements
against this area show overestimated results due to emerged
local stasis of the blood. Although such spot vanishes
quickly, repeat measurements are recommended to be made
on near-by locations.
When phototherapy is used, photooxidation of bilirubin
takes place and it is converted into water-soluble non-toxic
lumirubin form. In this case, direct correlation between
bilirubin concentration in subcutaneous tissues and in
blood is not quoted. Thus, TBI determination during phototherapy
does not permit to assess the bilirubin concentration
level in blood. However, the estimation of newborn phototherapy
efficiency can be made based on the dynamics of the BILITEST's
readings during the whole treatment period.
In case of haemolytic disease of newborn infants the BILITEST
should not be used to assess bilirubin concentration in
blood because the rate of bilirubin penetration growth
due to intensive intervascular hemolysis. In this case,
even relatively small TBI values need bilirubin level
control in the blood to be carried out.
7. JAUNDICE TREATMENT USING THE TBI MEASUREMENT RESULTS
In Case Of Jaundice, it is recommended to carry out TBI
measurements not less than 4 times a day to control the
disease dynamics and therapy efficiency.
Premature infants (having weight less than 1500 g) are
recommended to receive phototherapy if TBI value equals
12-15, as they are highly sensitive to bilirubin and lower
bilirubin concentration may cause Encephalopathy. As a
rule, if on the second-fourth day of an infant's life
TBI value exceeds 15, this point out to serious illness
and demands combined conservative treatment.
If TBI value is more than 20, one should control bilirubin
concentration growth in blood and make measurements every
hour. The same recommendations can be used if TBI value
exceeds 20 and 25 on the 4th-7th day correspondingly.
In case TBI value is more than 27-30, an urgent serum
bilirubin testing is needed (with fractions of bilirubin).
If there is no Jaundice, it is
impossible to assess bilirubin concentration in blood
using TBI values. It is necessary to determine bilirubin
concentration in venous and umbilical blood of the newborn,
who run the danger of haemolytic disease, in order to
make decision on exchange transfusion during the first
REMEMBER that estimation of bilirubin levels in blood
using the TBI readings is approximate. If exchange transfusion
is thought to be made, serum bilirubin concentration measurement