Wk 3: Jaundice, prematurity and low birth weight/IUGR Flashcards
What jaundice?
= juandice/hyperbilirubinaemia as a result from an imbalance between bilirubin production, conjugation and elimination.
Presents as yellow discolouration of the skin, mucous membranes and sclera/conjunctiva.
Explain the pathophysiology of general jaundice.
- Jaundice/hyperbilirubinaemia is a results from an imbalance between bilirubin production, conjugation and elimination.
- The breakdown of RBCs and haemoglobin causes unconjugated bilirubin to accumulate in the blood (not water soluble) and is neurotoxic.
- Unconjugated bilirubin binds to albumin and is transported to the liver where it is converted to conjugated bilirubin.
- Conjugated bilirubin is water soluble and able to be eliminated via urine and faeces
What is the difference between pathological and physiological jaundice and when do they most commonly occur?
Pathological jaundice occurs when the liver correctly conjugated bilirubin for excretion, however there is a problem with excretion.
- an issue of once conjugated
- occurs within 24hrs and can persist greater than 14 days
Physiological is related to the immaturity of the liver and inability to process bilirubin at a rate that is equating to its production.
- an issue before conjugated thus more dangerous
Why is jaundice dangerous?
- if left unbound and thus uncongufated, bilirubin can cross the blood-brain barrier as it is lipid soluble and thus be toxic to the brain protetially causing Kernicterus.
What can factors impact severity of jaundice?
- gestation (relateing to lover development)
- trauma (relating to increased brusing and thus dead blood cells)
- feeding ability
- race
- family factors
- gener (more common in males)
- time of first breastfeed (earlier the better)
Should breastfeeding be stopped if a baby has breast milk jaundice?
- Not neccessarity
Other than immature liver and compromised excretion, what are some other causes of jaundice?
- Spesisi, though neoate usually presents unwell as well as jaundice
- Haemolysis from blood group incompatability and red cell defects e.g. ABO incompatibility, Rh isoimmunised
- Excessive, non-haemolytic red cell destruction e.g. bruising, cephalhaematoma
- GI tract obstruction or ileus
- Prematurity
- Hypothyroidism
Why is conjugated bilirubinemia (pathological) a risk?
- because we are unsure what is causing it. It is the underlying obstruction in excretion that is of concern.
What are some key differentiations making a jaundice an issue of pathological vs physiological? and what are their respective risks.
Pathological: only related to issues of congugated bilirubin.
- risk of underlying cause
- if jaundice present before - 24hrs or after 24 days it is likely pathological.
Physiological: always an issue of uncongugated.
- risk of toxic uncongugated crossing the blood brain barrier.
What are some causes of pathological jaundice?
- Obstruction of the large and/or small branches of the biliary tree.
- biliary atresia
- Result in bile ducts being absent causing an obstructive jaundice
- Best operated before 45-60 days of life
- These newborns usually have pale, clay-coloured stools and dark urine. - Choledochal/Common bile duct cyst
- Neonatal hepatitis e.g. congenital infection - toxoplasmosis, rubella, cytomegalovirus, herpes, syphilis
Metabolic
- galactossaemia
- fructose intolerance - Complication of Total Parental Nutrition (TPN)
What are some diseases resulting in hyperbilirubinaemia?
Glucose-6-Phosphate Dehydrogenase deficiency (G6PD)
Pyruvate Kinase Deficiency (PK)
Hereditary spherocytosis (HS)
Explain Glucose-6-Phosphate Dehydrogenase deficiency (G6PD)
= common enzyme deficiency
the primary function of G6PD is to stabilise the RBC membrane and protect it from oxidative damage which may lead to haemolysis if damage occurs.
- can cause extreme hyperbilirubinaemia +/- acute bilirubin encephalopathy.
- X-linked recessive disorder mostly affecting males
- complete absence of G6PD is incompatible with life
- jaundice may subside spontaneously, require phototherapy and occasionally require an exchange transfusion.
Explain Pyruvate Kinase Deficiency (PK)
= common glycolytic (relating to or causing glycolysis) defect causing non-spherocytic haemolytic anaemia
- PK is crucial to energy production, responsible for nearly 50% of the neonates total ATP
- Lack of ATP may lead to severe neonatal anaemia and early hyperbilirubinaemia
- DAT negative
results in severe haemolytic crises and hyperbilirubinaemia
- in some circumstances, newborns may be severely anaemic or even die in-utero
- in those born alive, anaemia and severe jaundice may result.
Explain hereditary spherocytosis (HS)
- common hereditary RBC membrane defect leading to acute haemolysis in the newborn
- this condition results in RBC shape being spherical instead of biconcave as a result of loss of membrane surface area relative to intracellular volume
- autosomal dominant condition predominantly but at times may be recessive or due to mutations
- the deficiency results in RBC with higher metabolic requirements that are trapped prematurely in the spleen and destroyed.
- may be associated with hyperbilirubinaemia in the first day of life or kernicterus which occurs suddenly as the immune system recognises the abnormal cells.
a blood test will show spherocytes
Explain the pathophysiology of bilirubin-induced neurotoxicity and encephalopathy
= The “blood-brain barrier” of the neonate, especially the premature neonate, is unable to defend the brain against unconjugated bilirubin, which is toxic to the nerve cells in the basal ganglia, hippocampus and substantia nigra as well as the auditory pathways and oculomotor nucleus.
- may leads to kernicterus
What are some signs of acute bilirubineia encephalopathy?
- Lethargy
- Poor feeding
- Temperature instability
- Hypotonia
- Arching of the head, neck and back
- Spasticity
- Seizures
Define kernicterus
= yellow staining of the brain cells and even permanent death, particularly in the grey matter of the brain.
- There is necrosis of the neurons in the basal ganglia leading to irreversible neuro disabilities.
- Kernicterus is the chronic and permanent result of bilibilirubin-induced neurological dysfunction
- There is no safe level of Serum bilirubin for where toxicity occurs and pre-term neonates are more susceptible than term neonates due to an immature central nervous system and neuronal pathways.
Explain the cephalocaudal manner and kramers rule
the progression of jaundice yellowing from the
- eyes and face (1 ~100)
- chest and upper abdo (2 ~150)
- lower abdo/pelvis (3 ~200)
- legs and upper arms (4 ~250)
- hands a feets (5 ~>257)
What are the benififts of a TCB?
- fast
- non invasive
- most accurate at the lower levels of hyperbilirubinaemia
- useful for assessing infants who are jaundiced and more than 24 hours of age without risk factors for developing severe hyperbilirubinemia.
- if within 50mmol/L of threshold then do formal SBR
What is the treatment of jaundice?
- Treating cause e.g. infection
- Ascertain adequate and effective breast/bottle feeding to reduce the enterohepatic circulation of bilirubin.
- Breast fed newborns should feed effectively 8-12 times per day
- IV fluids may be considered if oral input poor
- Phototherapy
- Exchange transfusion
- IV immunoglobulin to newborns with isoimmune haemolytic disease and rising bilirubin despite intensive phototherapy or in close range for an exchange transfusion
What is the JAUNDICE neumonic for remebering risk of jaundice?
J - jaundice within the first 24 hours
A - a sibling who required phototherapy in the neonatal period
U - unrecognised haemolysis
N - non-optimal sucking/feeding
D - deficiency of G6PD
I - infection
C - Cephalhaematoma of bruising
E - ethnicity in particular East Asian heritage, Mediterranean, African. Early birth-preterm .
What are some key practice point of phototherapy?
- Position phototherapy units no more than 30.5cm from the patient
- expose as much skin as possible
- cover eyes but remove to feed and every 6-8hours
- 4/24 vitals
- turn unti of when doing TCB or SBR
What are some side effects of phototherapy?
- Overheating or hypothermia
- Waterloss
- Diarohoea
- Ileus in perterm newborn
- Rash- no treatment required
- Parental separation
- ‘Bronzing’ of infants with conjugated - hyperbilirubinaemia
When to cease phototherapy and rechecking protocol?
- when under 50mmol/L of the range.
- no need to reck check unless risk of rebound including;
- haemolytic disease
- gestation less than 37 weeks
- cessation of phototherapy at less than 72 hours of age.
What is an exchange transfusion?
= The procedure involves slowly removing the person’s blood and replacing it with fresh donor blood or plasma.
- reccomended to commence in tertiary center
- if TCB>/ exchange line= medical emergency and get baby on intensive phototherapy
What is the indication for an exchange transfusion?
- Alloimmune haemolytic disease of the newborn
- Remove circulating bilirubin to reduce levels and prevent kernicterus
- Replace antibody-coated red cells with antigen-negative red cells
- Sever herperbilirubinaemia secondary to alloimmune heamolytic disease is the most common reason for excahnge transfusion in the NICU.
- Significant unconjugated hyperbilirubinaemia with risk of kernicterus due to any cause when intensive phototherapy is unsuccessful
- Severe anaemia (where there is normal or increased circulating blood volume)
- Antibodies in maternal autoimmune disease
- Polycythaemia (to reduce haematocrit, usually accomplished with partial exchange transfusion using normal saline replacement)
- Severe disturbances of body chemistry
What are some complications of exchange transfusion?
- Catheter related complications
- air emboli
- Thrombosis
- haemorrhage
Other;
- Haemodynamic (related to excess removal of injection of blood)
- hypo or hypertension, intraventricular haemorrhage (preterm)
- Hypo or hyperglycaemia
- Hypocalcaemia
- Hyperkalaemia,
- Acidaemia
What is breastmilk jaundice? what is the cause and what is the teartment?
= higher serum bilirubin peaks and slower decline, compared to the hyperbilirubinemia trend associated with other etiologies, leading to longer resolution time.
Cause: exact is unknown. Some evidence to suggest breast milk inhibits the newborn’s liver to process bilirubin and other suggest it is a genetic mutation or delay in entric flora in the breastfed newborns gut.
- occurs typically in the second week of life.
- spontaneously resolves even without discontinuation of breastfeeding.
It can persist for 8-12 weeks of life before resolution.
Treatment: none
