Neonates Flashcards
2008A Q21
Which one of the following is the major determinant of risk of perinatal transmission of hepatitis C virus?
A. Breastfeeding.
B. Concomitant hepatitis B infection.
C. Concomitant human immunodeficiency virus (HIV) infection.
D. Maternal viral load.
E. Mode of delivery.
D. Maternal viral load.
2008A Q27
Which of the following coagulation factors is most likely to be relatively decreased in the healthy newborn compared to older infants?
A. factor V.
B. factor VII.
C. factor VIII.
D. Fibrinogen.
E. von Willebrand factor.
B. factor VII.
What must you look for in a newborn with respiratory alkalosis?
Hyperammonemia
2008A Q 31
Phototherapy is commonly used in the management of unconjugated hyperbilirubinaemia. The predominant mechanism of action of phototherapy is:
A. decreased binding of bilirubin to albumin.
B. destabilisation of photoisomers by bile acids.
C. geometric photo-isomerisation of unconjugated bilirubin to more soluble isomers.
D. intramolecular cyclisation to form lumirubin.
E. oxidation of bilirubin to form biliverdin and dypyrroles allowing excretion.
C. geometric photo-isomerisation of unconjugated bilirubin to more soluble isomers.
The specific wavelength of phototherapy decreases total bilirubin in three ways:
- Non reversible conversion from bilirubin to lumirubin. Lumirubin is more soluble and is excreted unconjugated into bile and urine. Principle mechanism TB concentration reduced by phototherapy.
- Reversible photo-isomerisation to less toxic form of bilirubin.
- Photo-oxidation to polar molecules – converts bilirubin to colorless, polar compounds that are excreted primarily in the urine. This is a slow process and accounts for a small proportion of bilirubin elimination
2008A Q38
Which of the following provides the strongest stimulus for postnatal closure of the ductus arteriosus in a term infant?
A. Decreased circulating prostaglandin levels.
B. Decreased pulmonary vascular resistance.
C. Increased pulmonary blood flow.
D. Increased systemic oxygen saturation.
E. Sympathetic stimulation.
Correct Answer D. Increased systemic oxygen saturation
With the clamping of the umbilical cord, the placenta with its low vascular resistance is removed from the neonatal circulation, resulting in a rise in neonatal systemic blood pressure. At the same time, lung expansion reduces both pulmonary vascular resistance and the pulmonary artery pressure.
These two changes decrease the right-to-left shunt at the ductus arteriosus, resulting in an increased blood flow through the pulmonary arteries and lungs. With increased lung perfusion and expansion, neonatal oxygenation saturation is increased, which stimulates closure of the ductus arteriosus.
In addition, the increased pulmonary arterial blood flow raises pulmonary venous return to the left atrium and left atrial pressure. As the left atrial pressure increases and the right atrial pressure falls, right-to-left shunting across the foramen ovale decreases. Closure of the foramen ovale occurs when the left atrial pressure exceeds the right atrial pressure.
A. Decreased circulating prostaglandin levels -Prostaglandins (PGE2) are important for duct patency. A few hours after delivery, PGE2 levels drop to maternal levels. The degree of patency correlates with PGE2 levels. PGE2 is given to keep duct patent. Conversly, indomethacin and ibuprofen are inhibitors of progstaglandin synthesis and are used in the treatment of PDA.
B. Decreased pulmonary vascular resistance - occurs due to lung expansion leading to increased oxygenation stimulating duct closure.
C. Increased pulmonary blood flow - results from decreased blood flow through DA
E. Sympathetic Stimulation - no role
Why does macrosomia occur in infants of insulin dependant diabetic mothers?
Raised BSL from mother crosses placenta but insulin doesn’t. Babe’s own insulin increases in response. Raised glucose + insulin leads to macrosomia.
What are early signs of congenital hypothyroidism?
- Prolonged jaundice
- poor suck/feeding
- bradycardia
- constipation
Does insulin cross the placenta in pregnancy?
No, its too big.
Is the risk of developing DM higher for those infants of diabetic mothers.
Yes. Infants born to mothers post diagnosis of DM have a higher risk of developing DM than those born prior to the diagnosis of DM.
Which part of the brain is most vulnerable to the effects of hypoglycaemia in the newborn period?
Occipital lobe.
Now thought to be parieto-occiptal lobes.
If mother has active TB and the newborn is clear, should the baby receive any treatment for TB?
Baby should still receive isoniazid for 6/12 + BCG.
If BCG delayed after 3 months, it should be preceeded by the Mantoux.
If a mother has untreated HIV, what is the risk of transmission to the fetus?
15-18%
If a mother has an undetectable viral HIV load, should treatment during pregnancy be commenced?
Yes, start at 20/40.
HIV and breastfeeding?
Contraindicated
What is more likely to result in vertical transmission of HIV, breastfeeding alone, or breast and BMS?
Mixed breast and BMS as BMS breaks down some of the guts immune barrier then the virus is provided via breastfeeding.
Describe head shapes with early suture closure
Describe the cranial sutures
