Transcutaneous bilimeter

A transcutaneous bilimeter is a non-invasive device used to estimate bilirubin levels in newborns by measuring the spectral reflectance of light through the skin. It helps screen for neonatal jaundice without the need for a blood draw, making it especially useful in early discharge settings or community care.

Unit of Measurement

The bilirubin level will be measured using this device by mg/dL or mol/L.

Purpose

To assess the risk of hyperbilirubinemia among newborns

Mode of Operation of transcutaneous Bilimeter

Bilimeter works by directing white light into the skin of the neonate and measuring the intensity of the specific wavelengths that are returned.

How It Works

• The device emits multi-wavelength white light into the skin (usually forehead or sternum).
• It measures the intensity of reflected light absorbed by bilirubin in subcutaneous tissues.
• Algorithms convert this data into an estimated total serum bilirubin (TSB) level.

Interpretation Tips

• TcB is a screening tool, not a replacement for serum bilirubin in critical decisions.
• Always correlate with clinical signs (e.g., jaundice progression, feeding, activity).
• Use bilirubin nomograms (e.g., Bhutani chart) to assess risk zones.

Accuracy Insights

• Before phototherapy: TcB closely correlates with TSB (mean difference ~2.5 μmol/L).
• During phototherapy:
  • Covered skin (e.g., under eye patches): TcB remains fairly reliable (mean difference ~−0.3 μmol/L).
  • Uncovered skin: TcB significantly underestimates TSB (mean difference ~−28.6 μmol/L).
• After phototherapy: Accuracy decreases, especially on uncovered skin.
• Best site: Forehead shows the most consistent agreement with serum levels.

Advantages

• It is a noninvasive technique that uses light instead of needle to assess serum bilirubin; hence, there is no pain for newborns.
• The measurement of bilirubin by this device is within a clinically beneficial range that has been correlated with total serum bilirubin concentration measured by high-pressure liquid chromatography.
• This device can be used by healthcare professionals at all levels of healthcare system: physician clinics, hospitals, as well as community health centers.
• No need to wait for the results.
• Easy to operate and carry from place to place.

Disadvantages

• Use of bilimeter is limited to the routine screening of all newborns for hyperbilirubinemia.
• The measurement of bilirubin mainly depends on the extravascular level of bilirubin present in the body.
• There is less evidence for its effectiveness in assessing bilirubin level in preterm neonates and dark-skinned babies.

Sites

• Forehead
• Sternum (most preferable site)

Procedure

1. Wash hands.
2. Wear disposable gloves.
3. Calibrate the device by pushing the button.
4. Place the bilimeter on forehead or sternum.
5. Press the measurement button (the number of time of pressing will vary depending on the manufacturer) and the result will appear on the screen immediately.
6. Dispose the calibration tip.

Guidelines

• The healthcare personnel must undergo training for the technique of using this device.
• Cleaning of the device is based on the manufacturer guidelines.
• This device should be charged using batteries.

Best Practices

• Calibrate the device per manufacturer instructions.
• Take 3 consecutive readings and use the average.
• Avoid bruised, discolored, or edematous skin.
• Clean the probe tip between uses to prevent cross-contamination

REFERENCES

1. Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
2. Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
3. Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwer’s, ISBN-13:978-9388313285
4. Marcia London, Ruth Bindler, Principles of Paediatric Nursing: Caring for Children, 8th Edition, 2023, Pearson Publications, ISBN-13: 9780136859840
5. Naveen Bajaj, Rajesh Kumar, Manual of Newborn Nursing, 2nd Edition, 2023, Jaypee Publishers, ISBN:978-9354659294
6. Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/

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