The phototherapy light shines light onto the baby’s skin. The light must be the correct wavelength (colour) and the correct intensity (brightness). It is used for treating a condition called Jaundice or Hyperbilirubinemia.
Jaundice or Hyperbilirubinemia
When red blood cells die and are broken down, a chemical called “bilirubin” is produced. Normally the bilirubin is processed by the liver and excreted from the body by the kidneys in the urine. The baby’s liver sometimes cannot process the bilirubin quickly enough and it begins to build up in the blood. Bilirubin is deposited in the skin, whites of the eyes, and mucous membranes (for example the inside of the mouth). When this occurs, the baby appears yellow and is said to be “Jaundiced”. Usually Jaundice disappears in 1-2 weeks and does not require special treatment. Some bilirubin in the blood is normal but when the concentration rises too high it is dangerous hyperbilirubinemia. An excessive level of bilirubin can lead to serious neurological damage such as brain damage and hearing loss.
WORKING OF PHOTOTHERAPY
During phototherapy the baby’s skin is exposed to blue light (420 – 500nm). The bilirubin deposited in the skin is “photoisomerised” (changed shape by the light) and becomes water soluble. This is a similar change that occurs normally in the liver. The photoisomerised bilirubin then dissolves back into the blood where it is excreted from the body in urine. The untreated bilirubin in the blood then deposits in the skin and the process continues until all or most of the bilirubin is removed. This happens over a long period of time, usually several days
The effectiveness of the phototherapy depends on:
– the intensity of the therapeutic light
– the wavelength (colour) of the light
– the surface area of skin exposed
(BLUE LIGHT PHOTOTHERAPY)
(PROTECTION OF BABY EYES IN PHOTOTHERAPY TREATMENT)
Some phototherapy lights use white light instead of pure blue. White light contains all the colours but it is only the blue wavelengths that treat the Jaundice.
(WHITE LIGHT PHOTOTHERAPY)
UNIT : mW/cm2
RANGE OF VALUES
Wavelength = 420-500 nm (with the most important wavelength of 470 nm)
Intensity = 8 uW/cm2/nm to 25 uW/cm2/nm
(or) 0.65 mW/cm2 to 2 mW/cm2 (with a blue filter of 80nm bandwidth)