Chapter 12 ■ Transcutaneous Bilirubin Monitoring 81

b. The use of a photo-opaque patch on the forehead to

shield the skin may allow for continued measurement TCB levels in term infants undergoing

phototherapy. Good agreement has been shown

between serum bilirubin levels and TCB measured

from the patched area, and is most effective in following trends in bilirubin values in infants undergoing phototherapy (12).

5. Measurements should not be made on skin that is

bruised, covered with hair, or has a birthmark.

Localized edema and poor tissue perfusion may also

alter TCB readings (15).

6. TCB measurements may decrease the need for multiple TSB measurements in late preterm infants; little

information is available in very preterm infants, in

whom measurements may be less reliable (12,14,15).

D. Equipment

TCB monitors currently in use in the United States include:

1. Konica Minolta/Air-Shields JM-103 Jaundice Meter

(Dräger Medical, Telford, Pennsylvania) (Figs. 12.1

and 12.5)

a. Determines the yellowness of subcutaneous tissue

by measuring the difference between optical densities for light in the blue and green wavelengths

b. Measurement probe has two optical paths

c. By calculating the difference between the optical

densities, the parts common to the epidermis and

dermis are deducted. As a result, the difference can

be obtained for subcutaneous tissue only.

d. Theoretically allows for measurement of degree of

yellowness of skin and subcutaneous tissue with minimal influence of melanin pigment and skin maturity

e. Linear correlation of this measurement with TSB

allows for conversion to TSB by the meter, which is

indicated digitally.

2. BiliChek Noninvasive Bilirubin Analyzer (Children’s

Medical Ventures/Respironics, Norwell, Massachusetts)

(Figs. 12.2 and 12.6)

a. Noninvasive device consisting of light source,

microspectrophotometer, fiberoptic probe, and

microprocessor control circuit

b. Uses entire spectrum of visible light reflected by the

skin

c. White light is transmitted into the skin and the

reflected light is collected for analysis.

d. Algorithms take into account the effect of hemoglobin, melanin, and dermal thickness.

e. Absorption of light due to bilirubin in the capillary

bed and subcutaneous tissue is isolated by spectral

subtraction.

E. Special Circumstances/Considerations

1. Hospital protocols should include the conditions under

which TCB and TSB levels are to be obtained (1).

Protocols for training and recertification of TCB users

should be in place.

Fig. 12.4. Nomogram showing smoothed curves for the 5th, 25th, 50th, 75th and 95th percentiles for TCB measurements among healthy newborns (gestational age ≥35 weeks). A total of 9,397

TCB measurements were obtained for 3,894 newborns. The number of infants studied at each

interval is shown in parentheses. (Reproduced with permission from Pediatrics, Vol. 117(4), Pages

1169–1173, Copyright © 2006 by the AAP.)