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TAS Neonatal Medicine ✅ > Treatment of Jaundice ✅ > Flashcards

Treatment of Jaundice ✅ Flashcards

1
Q

What does the type of treatment for jaundice depend on?

A
  • Bilirubin level
  • Rate of rise of bilirubin
  • Gestational age
  • If other risk factors are present
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2
Q

What are current treatment thresholds for jaundice in neonates based on?

A

Consensus guidelines (NICE and AAP) - not evidence based

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3
Q

Is the albumin-bilirubin ratio used when determining treatment for neonates?

A

No

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4
Q

Why is the albumin-bilirubin ratio not used when determining treatment for neonates?

A

Most laboratories overestimate albumin, especially at low concentrations

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5
Q

Is management of jaundice based on total or conjugated bilirubin levels?

A

Total

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6
Q

Why is management of jaundice based on total bilirubin level?

A

There are rare cases of kernicterus with high conjugated bilirubin levels, and a theoretical risk that conjugated bilirubin can elevate free bilirubin levels

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7
Q

In theory, how can conjugated bilirubin cause an increase in free bilirubin?

A

By displacing unconjugated bilirubin from the binding sites

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8
Q

How does phototherapy work?

A

Through geometric photoisomerisation of unconjugated bilirubin

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9
Q

What is the normal bilirubin isomer?

A

4Z, 15Z

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10
Q

What wavelength of light is used in phototherapy?

A

460 +/- 10nm

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11
Q

What happens to bilirubin when it absorbs light of the specific wavelength used in phototherapy?

A

The light is absorbed and the bilirubin undergoes Z to E isomerisation

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12
Q

How does the E isomer of bilirubin differ from the Z isomer?

A

The E-isomer is more polar and water-soluble than the Z-isomer

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13
Q

What is the result of the E-isomer of bilirubin being more polar and water-soluble?

A

It can be excreted without conjugation

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14
Q

Other than the E-isomer of bilirubin, what else is produced when the Z-isomer absorbs light in phototherapy?

A

A small amount of structural isomer (lumirubin)

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15
Q

How is lumirubin formed in phototherapy?

A

Photo-oxidation

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16
Q

What does the effectiveness of phototherapy depend on?

A
  • Wavelength
  • Irradiance (dose of light)
  • Exposed body surface area
  • Distance from light source
  • Duration of treatment
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17
Q

What irradiance is optimal in phototherapy for jaundice?

A

30-40mwatts/cm^2/nm

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18
Q

What colour of light is most effective in phototherapy for jaundice?

A

Blue or blue-green light

19
Q

What is the wavelength of blue/blue-green light?

A

230-490nm

20
Q

How is intensive phototherapy achieved?

A
  • Using more than 1 light source
  • Bulbs held at close distance
  • Well-exposed body
21
Q

How do the measures used to provide intensive phototherapy maximise the effectiveness?

A

By increasing irradiance

22
Q

Why is insensible water loss during phototherapy now less of an issue than previously?

A

Increased used of LED lights that have a lower heat output

23
Q

What medications can be used in the treatment of jaundice?

A
  • Phenobarbitone
  • Metalloporphyrins
  • IV immunoglobulin
24
Q

How does phenobarbitone work in jaundice?

A
  • Induces hepatic UGT enzyme and hence the conjugation of bilirubin
  • May also increase hepatic uptake of bilirubin
25
Q

What is the limitation of the use of phenobarbitone in jaundice?

A

Acts very slowly, doesn’t lower serum bilirubin levels fast enough to be clinically helpful

26
Q

Which metalloporphyrins may help in jaundice?

A

Tin and zinc

27
Q

How do tin and zin protoporphyrins work in jaundice?

A

They inhibit haem oxygenate

28
Q

Why does the inhibition of haem oxygenase help in bilirubin?

A

It is the rate limiting step in the production of bilirubin for haem

29
Q

Are metalloporphyrins used clinically?

A

Their use is under investigation, and currently not recommended

30
Q

Which patients with jaundice might benefit from IVIG?

A

Neonates with rhesus or ABO immune haemolytic disease

31
Q

What is the benefit of IVIG for jaundice in neonates with rhesus or ABO haemolytic diease?

A
  • Reduces bilirubin levels

- Reduces need for exchange transfusion

32
Q

When is IVIG recommended in jaundice caused by rhesus or ABO haemolytic disease?

A

As an adjunct to intensive phototherapy if serum bilirubin continues to increase more than 8.5µmol/L/hour

33
Q

What is the mechanism of action of IVIG in jaundice caused by rhesus or ABO immune haemolytic disease?

A

Non-specific blockage of Fc receptors, which reduces red blood cell breakdown

34
Q

Why does the specific blockade of Fc receptors reduce RBC breakdown in rhesus or ABO haemolytic disease?

A

In isoimmune haemolysis, RBC are destroyed by an antibody-dependent cytotoxic mechanism mediated by Fc receptor-bearing cells of the neonatal reticuloendothelial system

35
Q

Can maternal IVIG administration reduce fetal haemolysis in rhesus or ABO immune haemolytic disease?

A

Yes

36
Q

When is exchange transfusion used?

A

Severe hyperbilirubinaemia

37
Q

What is the purpose of exchange transfusion in severe hyperbilirubinaemia?

A
  • Prevent kernicterus
  • Remove haemolytic antibodies
  • Correct anaemia
38
Q

What does exchange transfusion involve?

A

Removing aliquots of neonatal blood and replacing it with donor blood

39
Q

How much is the serum bilirubin reduced by following a double volume exchange transfusion?

A

50%

40
Q

What has happened to the need for exchange transfusion?

A

It has been markedly reduced

41
Q

Why has the need for exchange transfusion been markedly reduced?

A
  • Prevention and prenatal treatment of Rhesus disease

- Early treatment of jaundice with phototherapy

42
Q

What is the morbidity when exchange transfusion is required for jaundice?

A

5%

43
Q

What is the mortality when exchange transfusion is required for jaundice?

A

0.3%

44
Q

What causes morbidity and mortality in exchange transfusion?

A
  • Biochemical and haematological disturbances
  • Vascular accidents
  • Cardiac complications
  • Sepsis

TAS Neonatal Medicine ✅ (35 decks)

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