PHOTOTHERAPY
INTRODUCTION:
- Consists of application of fluorescent light to the infant’s skin
- Most commonly used treatment for unconjugated hyperbilirubinemia
MECHANISM OF ACTION:
- Geometric photoisomerization of unconjugated bilirubin resulting in a more soluble form of Bilirubin
- Accounts for 80% of conversion
- Converting bilirubin to lumirubin through structural isomerization which can be excreted into bile without need for further hepatic conjugation
- Oxidation mechanism resulting in colourless by products and excreted by liver and kidney without need for conjugation
INDICATIONS:
- Used when level of bilirubin may be hazardous to the infant(20mg% for full term baby)
- Prophylactic phototherapy may be indicated in circumstances like extremely low birth weight or severely bruised infants.
NURSING CARE:
- Keep the baby naked, except for diapers
- Eyes must be shielded to prevent potential adverse effects on the retina
- Closely monitor temperature for hyper/hypothermia
- Maintaining baby in a flexed position with rolled blankets along the sides helps to maintain heat and provide comfort
- Oily lubricants should be avoided to prevent tanning / frying effect
TECHNIQUE:
- Bilirubin absorbs light maximally in the blue light ranges ( 420-500 nm)
- Daylight and cool white lamps have a spectral peak between 550-600 nm & are less effective than special blue lamps, which have an average of 420-480 nm
- Blue lamps interfere with observation of skin colour in the baby and cause headache, & nausea to care givers. Hence a combination of white and blue lamps is preferred
- A unit with 4 special blue & 4 daylight lights will give an effective irradiance of 11 µW/cm2 /nm which is far above the required 4-6µW/cm2/nm.
- Distance of the baby from the light source affects the effectiveness i.e. 45cm
COMPLICATIONS:
- Increase in environment and body temperature
- Increase in insensible waterloss especially in premature infants
- Stools tend to be loose and more frequent
- This loss must be compensated by increasing fluid intake by 25%
- Monitor temperature frequently and check weight twice daily
- Retinal damage
- Retinal degeneration may occur after several days of continuous exposure
- Bronze baby syndrome
- Skin urine and serum becomes brownish black after several days of phototherapy
- Seen most often in babies with conjugated hyperbilirubinemia
- Babies recover fully several days after phototherapy is discontinued
- Electrolyte disturbance such as hypocalcemia
- Transient skin rashes
- Drying of skin which can lead to excoriation and breakdown
- Others
- Electric shock
- Unproven potential effects on endocrine and sexual maturation
Exam Important
- Structural isomerization in phototherapy is chiefly responsible for reduction in serum billirubin
- Bronze baby syndrome is due to Phototherapy
- For A full term, 80 hrs old new born baby develops jaundice 20mg% should be the minimum level of serum bilirubin to start phototherapy
- Infants receiving phototherapy Should have their eyes patched during therapy
- Infants receiving phototherapy May develop diaorrhea
- Ideal treatment of B/L retinoblastoma is phototherapy
- Ideal management for premature, healthy infant weighing less than 1 kg is having jaundice with serum bilirubin level of 5 mg% is phototherapy
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