Adaptation at Birth

Question 1

what are the functions of the placenta

Answer 1

fetal homeostasis
gas exchange 
nutrient transport to fetus 
waste product transport from fetus 
acid base balance 
hormone production 
transport of IgG

Question 2

what does the fetal liver do

Answer 2

produces albumin, clotting factors and RBCs

Question 3

what does the fetal kidney do

Answer 3

excretes urine, contributes to amniotic fluid

Question 4

describe the fetal circulations

Answer 4

The oxygenated blood is carried from the placenta to the fetus via the umbilical vein. About half of this blood passes through the hepatic capillaries and the rest flows through the ductus venosus into the inferior vena cava. Blood from the vena cava is mostly deflected through the foramen ovale into the left atrium, then to the left ventricle, into the ascending and descending aorta to supply to the fetus
goes back to placenta via the pulmonary arteries (branches of descending aorta)
Deoxygenated blood from the superior vena cava flows into the right atrium, right ventricle, and then into the pulmonary artery. Because of high pulmonary vascular resistance, only about 5 to 10 per cent of the blood in the pulmonary artery flows to the lungs, the majority of it being shunted through the patent ductus arteriosus and then down the descending aorta

Question 5

name the three shunts in the fetal circulation and what they allow

Answer 5

ductus venosus (allows umbilical vein to pass through liver)
foramen ovale (right to left shunt in heart, reduced blood going to lungs)
ductus arteriosus (reduces blood going to lungs, mean oxygenated and deoxygenated blood mix in descending aorta)

Question 6

what does the fetus do in the 3rd trimester to prepare for birth

Answer 6

produce surfactant
accumulation of glycogen - liver, muscle, heart (to prepare for starvation state)
accumulation of brown fat- between scapular and around internal organs (insulating fat)
accumulation of subcutaneous fat
swallowing amniotic fluid and ‘practise breathing’

Question 7

where is surfactant produced

Answer 7

type 2 pneumocytes in alveoli

Question 8

what is the role of surfactant

Answer 8

needed for gas exchange

reduces surface tension of alveoli allowing them to expand

Question 9

what adaptations happen to the fetus during labour

Answer 9

increased catecholamine and cortisol at the onset of labour
synthesis of lung fluid stop
during vaginal delivery lung fluid gets squeezed out
first cry helps absorb left over fluid into lymphatic system

Question 10

what colour do babies come out

Answer 10

blue/ pale

gradually goes pink after starts to breath/ cry

Question 11

why is delayed cord clamping important

Answer 11

allows blood volume and immunoglobulin transfer to baby, helps prevent amaemia

Question 12

what happens to the circulation after birth

Answer 12

pulmonary vascular resistance drops (onset of breathing expands and aerates the lungs)
systemic vascular resistance rises (cord clamped, placenta =low resistance vascular bed removed)
oxygen tension rises (pO2 rises from 2-3.5 kPa to 9-13kPa)
duct (venosus and arteriosus) constricts
foramen ovale closes

Question 13

what is the fetal level of oxygen (pO2)

Answer 13

2-3.5 kPa

Question 14

what causes duct constriction in fetal adaptation

Answer 14

increased pO2 (muscle layer is oxygen sensitive)
decreased flow of blood
decreased prostaglandins

Question 15

when does the ductus close

Answer 15

physiological closure within first few hours/ days

anatomical closure within 7-10 days

Question 16

what happens to the foramen ovale

Answer 16

closes or persists as PFO (10%)

Question 17

what happens to the ductus arteriosus

Answer 17

becomes ligamentum arteriosus or persists as duct

Question 18

what happens to the ductus venosus

Answer 18

becomes ligamentum teres

Question 19

what can cause failure of cardiorespiratory adaptation

Answer 19

asphyxia (causing hypoxia/ acidosis) 
prematurity 
sepsis 
hypoxia (meconium aspiration) 
cold stress

Question 20

what is persistent pulmonary hypertension of the newborn

Answer 20

when lung vascular resistance fails to fall meaning the shunts stay open (right to left flow at PFO and PDA)
Any oxygenated blood comes back into La however PFO and PDA means the oxygenated blood mix with deoxygenated meaning majority of circulation will be deoxygenated blood

Question 21

what direction of flow in the shunts

Answer 21

right to left

Question 22

what can cause persistent pulmonary hypertension

Answer 22

asphyxia (causing hypoxia/ acidosis) 
prematurity - lack of surfactant 
sepsis 
hypoxia (meconium aspiration) 
cold stress

Question 23

what is a way of diagnosing PPHN

Answer 23

compare oxygenation of blood in right upper limb to left lower limb
branches that supply the right upper limb are pre ductal (will receive oxygenated blood) where as branches to other three limbs are post ductal (will be deoxygenated)
anything more than 3% difference = PPHN

Question 24

what is the management for PPHN

Answer 24

ventilation
oxygen
nitric oxide (given through ventilator, dilates pulmonary arteries to decreased vascular resistance)
sedation (so dont breath against ventilator)
inotropes (cardiac contractility will be impaired)
ECLS- membranous oxygenation, very invasive, only done in glasgow

Question 25

what is the presentation of transient tachypnoea

Answer 25

usually healthy babies born by c section tachypnoeic can grunt is transient a diagnosis of exclusion, will have fluid in horizontal fissure on x ray

Question 26

what causes transient tachypnoea

Answer 26

baby taking longer to absorb fluid in lungs - eg not squeezed out when birth via c section

Question 27

why do babies loose so much heat

Answer 27

``` large surface area wet and naked when born big head if premature will have very thin epithelial layer - more evaporation have no shivering mechanism ```

Question 28

what are the 4 ways babies loos heat

Answer 28

convection evaporation conduction radiation

Question 29

how do babies thermoregulate

Answer 29

non shivering thermogenesis: -heat produced by breakdown of stored brown adipose tissue in response to catecholamines -not efficient in first 12 hours of life =peripheral vasoconstriction

Question 30

what temperature should you aim for babies to be

Answer 30

36-5 to 37.5

Question 31

what is acrocynosis

Answer 31

when hands a feet of baby stay blue for a couple days- is normal, heat is important to fix it though

Question 32

what are small for dates/ preterm babies at higher risk of hypothermia

Answer 32

low stores of brown and subcutaneous fat larger surface area to volume ratio thin epithelial layer

Question 33

how do you prevent hypothemia in babies

Answer 33

``` dry hat skin to skin blanket/ clothes heated mattress incubator ```

Question 34

how do neonates maintain glucose homeostasis

Answer 34

interruption of glucose from placenta + little oral intake of milk= drop in insulin and increase in glycogen mobilisation of hepatic glycogen stores for gluconeogenesis ability to use ketones as brain fuel

Question 35

what can cause hypoglycaemia in a neonate

Answer 35

increased energy demands: - unwell - hypothermia low glycogen stores: - small/ premature - high circulating maternal glucose inappropriate insulin/ glucagon ration: - maternal diabetes - hyperinsulinism some drugs

Question 36

how do you avoid/ treat hypoglycaemia

Answer 36

identify those at risk feed effectively keep warm monitor

Question 37

what is the difference between foremilk and hindmilk

Answer 37

foremilk has more glucose, water and antibodies | hindmilk has more protein, fat and calories

Question 38

what does the suckling stimulus cause in breastfeeding mothers

Answer 38

posterior pituitary releases oxytocin = milk ejection | anterior pituitary releases prolactin= milk production

Question 39

what does colostrum contain

Answer 39

IgA, cellular immunity, growth factors

Question 40

is weight loss normal after birth

Answer 40

up to 10% normal - due to fluid loss

Question 41

what is the risk of dehydration in babies

Answer 41

hypernatraemia | usually due to delayed lactation

Question 42

how is fetal haemoglobin different from adult

Answer 42

higher affinity | lower oxygen delivery power

Question 43

what does increased 2,3 BPG do to Hb oxygen curve

Answer 43

shifts it to the tight

Question 44

what causes physiological anaemia

Answer 44

adult Hb synthesised more slowly than fetal Hb is broken down causes a physiological anaemia - lowest level at 8-10 weels

Question 45

what does good recticulocyte (immature red blood cells) levels in babies mean

Answer 45

bone marrow working (haematopoiesis)

Question 46

what causes physiological jaundice

Answer 46

breakdown of fetal haemoglobin Conjugating (liver enzymes) pathways immature Rise in circulating unconjugated bilirubin not harmful unless very high levels

Question 47

what suggests jaundice is pathological

Answer 47

if early (<24 hrs) or prolonged

Question 48

what is the treatment for jaundice

Answer 48

phototherapy (blue light converts unconjugated bilirubin into excrete-able form and is peed out) if severe exchange transfusion

Question 49

what might very high levels pf unconjugated bilirubin cause

Answer 49

cross BBB, goes to basal ganglia and can cause significant cerebral changes leading to cerebral palsy

Question 50

what babies are most at risk of adaptation problems

Answer 50

``` Hypoxia / asphyxia during delivery Particularly small or large babies Premature babies Some maternal illnesses and medications Ill babies – sepsis, congenital anomalies ```