The increase of yellow skin colour beyond that of serum bilirubin: a proposed indicator of risk for bilirubin encephalopathy in the newborn

Thumb Imprint Based Detection of Hyperbilirubinemia Using Luminescent Gold Nanoclusters

Early and easy detection of diseases, using point-of-care and inexpensive devices, not only provides option for early treatment but also reduces the risk of propagation. Herein we report the fabrication of a robust film based luminescence indicator of bilirubin, which can indicate hyperbilirubinemia through the thumb imprint of the patient. The UV-light induced luminescence intensity of the film, made out of chitosan stabilised gold (Au) nanoclusters, which was effectively quenched in the presence of Cu²⁺ ions, recovered in the presence of bilirubin from skin or blood serum. Moreover, the sensitivity of detection of bilirubin was tuneable with the amount of Cu²⁺ added, thereby facilitating the detection of the desired concentration range of bilirubin.

Limitations and opportunities of transcutaneous bilirubin measurements

OBJECTIVE

Although transcutaneous bilirubinometers have existed for over 30 years, the clinical utility of the technique is limited to a screening method for hyperbilirubinemia, rather than a replacement for invasive blood sampling. In this study, we investigate the reason for this limited clinical value and address possibilities for improvement.

METHODS

To obtain better insight into the physiology of bilirubin measurements, we evaluated a transcutaneous bilirubinometer that determines not only the cutaneous bilirubin concentration (TcB) but also the blood volume fraction (BVF) in the investigated skin volume. For 49 neonates (gestational age 30 ± 3.1 weeks, postnatal age 6 [4-10] days) at our NICU, we performed 124 TcB and 55 BVF measurements.

RESULTS

The TcB correlated well with the total serum bilirubin concentration (TSB) (r = 0.88) with an uncertainty of 55 µmol/L. The BVF in the measured skin volume ranged between 0.1% and 0.75%.

CONCLUSIONS

The performance of our bilirubinometer is comparable to existing transcutaneous devices. The limited clinical value of current bilirubinometers can be explained by the low BVF in the skin volume that is probed by these devices. Because the TcB depends for over 99% on the contribution of extravascular bilirubin, it is a physiologically different parameter from the TSB. Hence, the standard method of evaluation that compares the TcB to the TSB is insufficient to fully investigate the clinical value of transcutaneous bilirubinometers, ie, their predictive value for kernicterus. We suggest that the clinical value may be improved considerably by changing either the method of evaluation or the technological design of transcutaneous bilirubinometers.

Point of care testing: transcutaneous bilirubinometry in neonates

Physicians taking care of infants in the first days of life are often faced with neonatal jaundice, especially in an era where post-partum discharge occurs earlier and assessment of newborn bilirubinemia status is required prior to discharge. The Canadian Pediatric Society and the American Academy of Pediatrics have developed and published guidelines for the diagnosis and management of hyperbilirubinemia in newborns. Point of care testing refers to any test performed outside of laboratory by clinical personnel and close to the site of patient care. Based on a summary of multiple reports during the last twenty years, we realize that devices which provide a non-invasive transcutaneous bilirubin (TcB) measurement have proven to be very useful as screening tools and provide a valid estimate of the total serum bilirubin level (TSB). Published data suggest that these devices provide measurements within 30-50 micromol/L of the TSB levels and can replace laboratory measurement particularly when TSB levels are less than 260 micromol/L. At the present time, in the literature, evidence is insufficient to abandon neonatal serum bilirubin testing and replace it with TcB. Any measurement, TSB or TcB, has potential for error. However, we have evidence that TcB, can help avoiding potential errors associated with even visual assessment of jaundice and may be useful as screening device to detect significant jaundice and decrease a large number of unnecessary skin punctures. The current manuscript is based on a careful comprehensive literature review concerning neonatal hyperbilirubinemia. We consider that this manuscript will help clinicians and laboratory professionals in the management of neonatal jaundice.

A comparison of transcutaneous bilirubinometers: SpectRx BiliCheck versus Minolta AirShields

BACKGROUND

Two devices are available for making transcutaneous estimates of serum bilirubin (SBR): the Minolta AirShields JM102 and the new SpectRx BiliCheck.

OBJECTIVES

(a) To measure how well the readings produced by these devices agree with SBR measured in the laboratory; (b) to estimate for each device, the proportion of infants with clinical jaundice who would require blood sampling if the device was used as a screening tool to detect infants with SBR > or = 250 micromol/l.

DESIGN

Prospective cohort study of jaundiced infants who required SBR at < or = 20 days of postnatal age. Those who had received phototherapy or exchange transfusion were excluded.

SETTING

Tertiary neonatal service in South-East Scotland.

INTERVENTIONS

Within 30 minutes of SBR sampling, transcutaneous bilirubinometry was performed using one Minolta and two SpectRx devices (designated A and B).

RESULTS

Sixty-four neonates were enrolled, 19 of which were preterm (31-35 weeks). The 95% confidence intervals of a device reading corresponding to SBR were +/- 66.7, +/- 67.9, and +/- 66.4 micromol/l respectively. Using the devices to identify all SBR > or = 250 micromol/l would reduce SBR sampling by 23%, 16%, and 20% respectively.

CONCLUSIONS

Given that SBR levels range from 50 to 400 micromol/l in jaundiced infants, the 95% confidence intervals of the devices are wide at +/- 67 micromol/l. The SpectRx can be used as a screening tool for hyperbilirubinaemia but there is no advantage in using it over the Minolta.

Transcutaneous bilirubinometry: its role in the assessment of neonatal jaundice

OBJECTIVE

To review the literature on transcutaneous bilirubinometry so that its exact role in the prevention of kernicterus or bilirubin encephalopathy could be determined.

DESIGN AND METHODS

Literature searches were done in Medline and Current Contents.

RESULTS

It is estimated that about 50% of newborns have an episode of jaundice in the first few days of life. Six percent of newborns may develop hyperbilirubinemia (> 220 mumol/L), which can potentially cause bilirubin encephalopathy or kernicterus, a severe neonatal disease. In the past, serum bilirubin (SB) has been the preferred method of detecting hyperbilirubinemia in newborns. The ordering of SB in neonates is based on visual evaluation by either physicians or nursing staff. Skin puncture collection of blood exposes the neonate to trauma and risk of infection. A noninvasive device for predicting serum bilirubin levels in newborns diminishes the need to do skin punctures. One such device that has been very extensively studied is the Minolta AirShields Jaundice Meter. It is a portable light-weight instrument that uses reflectance measurements on the skin to determine the amount of yellow color present in the skin, namely transcutaneous bilirubin (TcB). Although the TcB measurements correlate well with serum bilirubin (SB) levels, they cannot accurately predict serum bilirubin because of error related to a variety of factors.

CONCLUSIONS

TcB cannot be used directly to make decisions about transfusions or phototherapy in neonates. It is a good tool for screening neonates to determine when a laboratory measurement of serum bilirubin is needed. Such a practice requires careful selection of the decision level so that false-negative TcB values do not prevent appropriate serum bilirubin tests from being done.

Transcutaneous bilirubinometry in neonatal intensive care units

AIMS

To study the influence of several clinical and paraclinical factors on the association between jaundice meter readings and plasma bilirubin concentration; and to comment on the usefulness of the jaundice meter as a screening device for hyperbilirubinaemia in neonatal intensive care units.

METHODS

Three hundred and seventy seven newborn babies admitted to the neonatal intensive care unit for various causes were included in the study. When the plasma bilirubin concentration needed to be determined for clinical reasons, the extent of the yellow skin colour was measured transcutaneously, using a jaundice meter. The haemoglobin concentration was also determined. This had no independent influence on the jaundice meter readings. The yellow skin colour was significantly and positively correlated with the bilirubin concentration and the presence of respiratory distress syndrome (RDS), and negatively with gestational age and postnatal ages.

CONCLUSIONS

These findings were interpreted as being due to variations in the ability of albumin to bind bilirubin, and in the basal yellow skin colour. It was impossible to derive simple criteria for detection of hyperbilirubinemia by jaundice meter readings in this study group.

Prediction and non-invasive assessment of neonatal jaundice in the term healthy newborn infant

The maternal and umbilical cord bilirubin concentration at delivery, a yellow skin colour on the first postnatal day, an increase in the yellow skin colour during the first 24 h or postnatal life, and carbon monoxide excretion are all associated with the later development of neonatal jaundice in the healthy, mature newborn infant. Based on the results from these methods, and especially when the results from two or more of the methods are combined, it is possible to define low- and high-risk groups as far as subsequent jaundice is concerned. If jaundice develops, yellow skin colour measurements can often replace plasma bilirubin determinations. Dependent upon the local current consensus for bilirubin determinations, around 50% of plasma bilirubin determinations can be avoided. Recent research suggests that yellow skin colour measurements may provide information concerning the risk of bilirubin encephalopathy, in addition to their relation to the plasma bilirubin concentration.