Paediatrics

Question 1

What is the function of the placenta? (8)

Answer 1

Foetal homeostasisGas exchangeAcid base balanceNutrient transport to foetusWaste product transport from foetusHormone productionTransport of IgG (crosses the placenta from mother to baby protecting the baby while their humoral response is developing)PGE2 (helps to maintain duct potency in utero.)

Question 2

In utero, what is the state of the baby’s lungs?

Answer 2

Fluid filled and unexpanded (the liver has little role in nutrition and waste management and the gut is not in use)

Question 3

What blood vessels carry blood to and from the foetal heart to the placenta?

Answer 3

The foetal heart pumps blood to the placenta via the umbilical arteries and blood from the placenta returns to the foetus via the umbilical vein

Question 4

What are the 3 blood vessels in the umbilical cord?

Answer 4

2 umbilical arteries1 umbilical vein(some babies can only have one artery and one vein - this can be normal but can also be a sign that there are other problems)

Question 5

What are the 3 foetal shunts?

Answer 5

The ductus venosusThe foramen ovalThe ductus arteriosus

Question 6

In the foetal circulation, does the right heart or left heart have higher pressure?

Answer 6

The right heart

Question 7

Which ventricle is dominant in the foetus?

Answer 7

The right ventricle

Question 8

What does the ductus venous do?

Answer 8

Connects the umbilical vein to the inferior vena cava

Question 9

What does the foramen ovale do?

Answer 9

Opening in atrial septum connecting RA to LA

Question 10

What does the ducts arteriosus do?

Answer 10

Connects pulmonary bifurcation to the descending aorta

Question 11

Why does the ductus venosus exist?

Answer 11

Nutrients coming from placenta don’t need further processing in the liverDuctus venosus carries the majority of the placental blood straight into the IVC bypassing portal circulation

Question 12

What does foramen ovale allow?

Answer 12

Blood to flow from right to left atriumAllows the best oxygenated blood to enter left atrium then on to LV, ascending aorta, carotidsMembrane flap on left atrium side

Question 13

Where does the output from the RV go?

Answer 13

Only 7% goes to the lungsThe restless via ductus arteriosus to join descending aorta

Question 14

What maintains the potency of the ductus arteriosus?

Answer 14

Circulating prostaglandin E2 produced by the placenta

Question 15

Summary of foetal circulation?

Answer 15

Oxygenated comes from the placenta to the foetus via the umbilical vein.In the liver, the ductus venosus connects the umbilical vein to the IVCThe blood passes into the right sides of the heart and the oxygenated blood passes through the foramen ovale into the left atriumThe blood then passes into the left ventricle and out the aortaBlood coming from the body also enter the right atriumThis deoxygenated blood passes to the right ventricleThe blood is pumped via the pulmonary artery Most of the blood bypasses the lungs and is pumped through the ductus arteriosus where the deoxygenated blood is pumped to the lower half of the foetal body where it leaves via the umbilical arteriesSome blood does pass to the lungs

Question 16

Why do babies cry when they are first born?

Answer 16

It creates back pressure opening up the alveoli

Question 17

What are the circulation changes during the first few mins after birth? (3)

Answer 17

First breath = lungs open up, pO2 increases and causes pulmonary vasodilationDecrease in resistance to flow to lungsCord clamping = large, low resistance vascular bed removed from circulation, systemic vascular resistance increasesBaby going pink = more blood circulating to lungs, progressively increasing pO2

Question 18

What are the O2 sats of the foetus in the womb?

Answer 18

60 - 70%

Question 19

What causes the foramen ovale flap to close?

Answer 19

As PVR falls and SVR rises, LA pressure exceeds the RA pressure = the flap is pushed closed (stays open in up to 35% of the population = implicated in stroke and migraine)

Question 20

What causes the ductus arteriosus to close? (3)

Answer 20

Fall in pulmonary vascular resistance reduces blood flow through the ductRising oxygen tension has a direct effect on the duct smooth muscle causing constrictionThe loss of circulating PGE2 from the placenta and increased PGE2 metabolism in the lung

Question 21

How long does it take for the ductus arteriosus to functionally close?To anatomically close?

Answer 21

hours to days7-10 dats

Question 22

What does the ductus arteriosus end up as when it closes?

Answer 22

Fibrous ligament called the “ligamentum arteriosum”

Question 23

What type of babies have a very high incidence of failure of ductus arteriosus closure?

Answer 23

Preterm infants

Question 24

Treatment options for failure of ductus arteriosus to close?

Answer 24

Wait and seeNSAIDs (cause the duct to close)Surgery (if NSAIDs don’t work)

Question 25

How are “duct dependent circulations” managed in babies with congenital heart disease?

Answer 25

IV prostaglandin E2 is used to keep the duct open until an alternative shunt is established or definitive surgery is carried out

Question 26

What can cause persistent pulmonary hypertension of the newborn? (failure of adaption)

Answer 26

(vascular resistance in the lungs fails to drop when baby is born)More likely in sick babies e.g. sepsis, hypoxic ischaemic insult, meconium aspiration syndrome, cold stress)Can be related to underlying anatomical abnormality such as congenital diaphragmatic hernia

Question 27

What type of circulation will you get in a newborn if there is persistent pulmonary hypertension?

Answer 27

Persistence of foetal circulation = shunts remain

Question 28

What will the baby look like if they persistent pulmonary hypertension?

Answer 28

Blue(baby will have a large difference between their pre and post ductal oxygen saturation)

Question 29

Treatment of persistent pulmonary hypertension of the newborn?

Answer 29

VentilationOxygenationHigh systemic blood pressureInhaled NO (potent vasodilators)ECMO

Question 30

Where is pre and post ductal saturation measurements taken?

Answer 30

Pre = right handPost = left foot