From Superstition to Science - The History of Phototherapy
Rochford General Hospital, the summer of 1956.
Sister. J. Ward, heard muffled voices and shuffling footsteps of the pediatric consultants. She hurriedly brought in the infant she had taken outside the Premature Baby Unit. According to her, there was nothing that couldn’t be cured by “fresh air and warm sunlight.”
The consultants got to the baby that Sister Ward had just brought in, and they noticed that that specific infant had a rather odd triangular patch of yellow skin; darker than the rest of the baby’s premature skin. On observing this, Dr. R. H. Dobbs, the consultant pediatrician of the hospital asked her, “Sister, what did you paint the baby with - Iodine or flavine and why?”
Sister Ward felt instantly uncomfortable at being confronted about this, and resorted to being honest. “Sir, I had taken the infant out to get some fresh air, and sunlight; it must be the Sun”, she said, shrugging; Dr. Dobbs claimed that sun-tans usually take a longer time to develop. But Sister Ward corrected him, saying “But no sir, it’s the part of the body that I had covered when I took the child outside.” Though something about the claim seemed odd, the consultants, considering the number of babies that were in need of attention, and also the fact that this particular baby was doing well, decided not to probe it further.
A few weeks later, a blood sample was drawn from a jaundiced infant, and after an uncharacteristic delay of over a few hours, the serum bilirubin value was reported to be 13-14 mg/dL. This struck Dr. Dobbs as odd, for two reasons: one, that such a simple investigation took so long, and two, that the value reported did not, in his years of experience, correspond to how deeply icteric the infant clinically seemed; so he drew up a fresh blood sample and took it to the lab himself, and spoke to the biochemist in-charge, Mr. P. W. Perryman.
When asked, Mr. Perryman said, “I am truly sorry about the delay, sir, one of my assistants seem to have left it near the window sill and must’ve forgotten about it. But the value cannot be wrong! I ran the test myself!” checking the signature in the register, and went on to add, “I’ll repeat the test with whatever remaining sample there is, and also with the new sample that you have brought with you” and took the left over sample that was basking under the English sun by the window.
After a while, Mr. Perryman, looking rather flabbergasted, said, “I am not sure how, but this sample’s value reads 9mg/dL; the second sample you had brought with you reads 24mg/dL!”
This, is the story behind one of the revolutions in neonatology - Phototherapy.
What seemed to be chaotic, apparently unrelated events, took the genius minds of two pediatricians of the 1950s: Dr. D. H. Dobbs, and Dr.R. J. Kramer, Dr. Dobbs’ resident, to develop this to be clinically relevant and useful. But they did have their road-blocks to overcome.
Firstly, they needed to identify that some component of the sun’s rays, either the heat or the light, contributed to this reduction of bilirubin levels. Once they identified it was infact, the light rays, they needed to establish which infant with jaundice needed this “phototherapy", which infants needed exchange transfusion, and finally which of the icteric babies needed no intervention. Thirdly, they needed to establish if all forms of bilirubin were affected by this or if specific fractions of it only responded. Finally, proving to a peer group that it was scientific, and not just brute hunch.
After years of experimenting, finding out the exact wavelength of light (blue light in temperature controlled environments), creating safe electrical equipment for the babies while ensuring continued nursing and other care required were delivered, creating methods to identify serum bilirubin using a heel-prick blood sample, making a graph available to plot serial values (as opposed to single bilirubin values used as arbitrary cut-off points for commencement of treatment) to identify the infants needing phototherapy from the infants needing exchange transfusion, a lot of this were done under the vision of these two gentlemen, which effectively has altered the outcome of children, generations to come.
Nowadays, the physiological jaundice of the newborn isn’t something that is a cause of concern as opposed to how it was five or six decades ago.
But how does this happen? How does a specific wavelength of light reduce the levels of bilirubin in the baby, that would otherwise potentially lead to devastating consequences, either due to treatment with exchange transfusion or not instituting any form of treatment at all?
The basic principle is that unconjugated bilirubin, which is insoluble, needs to be made soluble in order to aid the infant’s developing conjugating systems in the liver.
On exposure to a wavelength of 420-470nm (blue light range in the visible spectrum), the bilirubin molecule undergoes photochemical reactions in the baby’s skin of which two of the following major reactions are important:
- The bilirubin which is in its predominant “Z” configuration, isomerizes to the “E” configuration, which can be excreted in the bile without conjugation. This is a reversible photoisomerisation reaction, and contributes to some of the bilirubin excretion.
- The bilirubin gets oxidized to “Lumirubin” which is a structural isomer. This is an irreversible reaction, and this lumirubin can be excreted in the kidneys without the need for conjugation.
During phototherapy, the baby needs to be fully exposed, including the genital area, but the eyes need to be sufficiently covered, while taking care of the nutrition and hydration of the baby with regular monitoring of the Total Serum Bilirubin.
Phototherapy, though a useful tool, should never be considered a replacement for Exchange Transfusion; but it definitely proved to reduce the number of times exchange transfusion was needed. A constant vigil is a must, with serial serum bilirubin plotting to make sure the infant isn’t going into the danger region.
So this is the story of how a supposedly innocent thought, armed with the quest to make a difference, changed the face of neonatology and the futures of generations to come.
Author: Anirudh Murali (Facebook)
Sources and citations
1) Dobbs RH, Cremer RJ: Phototherapy.Archives of Disease in Childhood 1975; 50:833-836.
2) Ambalavanan, Namasivayam, and Waldemar A. Carlo. “Chapter-102.4- Kernicterus.” Nelson Textbook of Pediatrics, 20th ed., Elsevier, 2016, pp. 874–877.