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Define what the perinatal period is 

This is the period from 22+0 wks until 7 days after birth 


What is the function of the placenta ?

  • Gas exchange - supply O2 & clearance of CO2 
  • Nutrients supplied to fetus - H2O, glucose, electrolytes (iron,Ca2+), free fatty acids 
  • Waste product removal 
  • Acid-base balance 
  • Hormone production - oestrogen, progesterone, HCG, Human chorionic somatotropin, human placental lactogen, placental growth hormone, relaxin & kisseptin
  • Transport of IgG - mainly in the 3rd trimester 


When in utero does the fetal lungs carry out gas exchange ?

No, there alveoli are filled with fluid 


What is the function of IgG transport during the 3rd trimester ?

To give the baby passive immunity to everything the mother is immune to (passive immunity continued with breastfeeding upto 6 months)


Describe the fetal circulation 

  1. 2 umbilical arteries take deoxygenated blood from the fetus to the placenta, to be reoxygenated
  2. Oxygenated blood is then transported from the placenta to the fetus via the umbilical vein
  3. Blood then enters the R side of the fetal heart 
  4. Blood then passes through one of the 2 extra connections in the fetal heart (they close when born)
  5. Some blood goes through the foramen ovalae travelling from R to L atrium then to L venitrcle & subsequently the aorta & then the rest of the body (blood travelling this route is the most oxygenated 
  6. Blood coming back from the fetus' body also entres the R atrium (so essentially have oxygenated & deoxygenated blood entering the R atrium, with oxygenated blood passing through the foramen ovalae), deoxygenated blood passes through to pulmonary artery & bypasses lungs through ductus arteriosus
  7. Some blood then transported to lower half of fetal body but most deoxygenated blood leaves fetus to placenta via the umbilical arteries   


What 3 shunts exist in the fetal circulation ?

  1. Foramen ovalae 
  2. Ductus arteriousus
  3. Ductus venosus - this shunts a portion of umbilical vein blood flow directly into IVC ==> bypassing the liver 


How do the fetal lungs remain perfused ?

7% of the fetal circulation does actually pass into the lungs but this is to just keep them perfused (==> not all the blood actually bypasses the lungs) 


What are the main fetal changes which occur during the 3rd trimester in preparation for birth ?

  • Surfactant production - produced by type 1 pnuemocytes to aid fetal alveoli/lung patency 
  • Accumulation of glycogen 
  • Accumulation of brown fat 
  • Accumulation of subcutaneous fat
  • Swallowing amniotic fluid - this helps drive fetal lung development 


What is the importance of the accumulation of fat during the 3rd trimester ?

  • It is important because once delivered the baby will no longer have a continuous supply of nutrients from the placenta, so they need to use fat stores in the inital stages for energy following birth (why breastfeeding babies often loose weight first) 
  • It is also important for insulation/ breakdown for heat production 


What changes occur during labour & delivery which help prepare the baby for birth ?

  • Increased catecholamines (adrenaline, noradrenaline, dopamine), cortisol & T3 (thyroid hormone) - all required for gluconeogenesis & thermogenesis after birth to help keep the baby fed & warm whilst breastfeeding kicks in 
  • Sythesis of lung fluid stops 
  • Vaginal delivery squeezes the babies lungs helping alveolar cells to switch from fluid production to reasorption (so they can inflate & arent filled with fluid) 


What is the normal appearance of a baby in the first few seconds after birth ?

  • Appears blue initially then gradually goes pink 
  • Starts to breath & cries 


What is the purpose of delayed cord clamping ?

To allow the cord to pulsate for a few mins - this improves iron stores, Hb & transition to life outside the uterus 


Describe the transition from fetal to normal circulation after delivery 

  • There is decreased pulmonary vascular resistance (fluid in alveoli removed within first few breaths) 
  • Systemic vascular resistance increases (this is resistance to blood flow offered by all the systemic vasculature except pulmonary vasculature) 
  • O2 tension in blood rises (dilating pulmonary vessels) 
  • Decreased prostaglandins 
  • Ducts constrict 
  • Foramen ovalae closes 


What happens to each of the 3 fetal shunts following birth ?

  1. Foramen ovalae closes (persists in 10% of people = patent foramen ovalae PFO)
  2. Ductus arteriosus becomes ligamentum arteriosus or persistent ductus arteriosus 
  3. Ductus venosus becomes ligamentum teres 


List the risk factors for failure of cardiorespiratory adaptation at birth i.e. PPHN

  • Pre-term 
  • Babies that pass meconium prior to birth 
  • Babies which get cold during delivery (hypothermia) 
  • Babies with infections 
  • Congenital disorders that cause underdeveloped lungs or CHD 


Define what persistent pulmonary hypertension of the newborn is (PPHN)

  1. This is when the babys circulation does not change over from fetal to normal newborn circulation. 
  2. Essentially the pulmonary arteries are narrowed & obstructed (shunts persist) resulting in the R ventricle having to pump harder to properly pump the blood ==> pulmonary HTN
  3. This can result in R to L intracardiac shunting of blood at the foramen ovalae & ductus arteriosus resulting in hypoxaemia 


What are the signs & symptoms of PPHN?

  • Asphyxia - O2 deprivation causing unconciousness or death 
  • Tachypnoea, resp distress
  • Resp acidosis 
  • Loud, single second heart sound or harsh systolic murmur 
  • Low APGAR score 
  • Cyanosis due to poor cardiac function 
  • Systemic hypotension 
  • Symptoms of shock


How is PPHN diagnosed ?

  1. Preductal & postductal O2 sats via pulse oximetry show a 5-10% gradient difference, with preductal O2 5-10% higher 
  2. Echocardiography is the gold standard test to establish diagnosis 


What is the management of PPHN ?

  • Ventilation - O2 
  • Nitric oxide (pulmonary vasodilator) 
  • Ionotropes - dopamine 1st line 
  • Sedation 
  • ECLS (Extracorporeal membrane oxygenation) used 
  • Give surfactant - if evidence of parenchhymal lung disease 


What is transient tachyponea of the newborn (TTN)?

  • This is when extra fluid stays in the lungs or is cleared out too quickly. 
  • This as a result makes it harder for the baby to breathe 


How long does TTN last ?

< 24hrs 


What are the risk factors for TTN development ?

  • Preterm 
  • C-section (because fluid not been squeezed out like in SVD)
  • Mother has asthma or DM 


What are the signs/symptoms of TTN ?

  • RR > 60
  • Grunting or moaning on exhalation 
  • Flaring nostrils 
  • Use of excessory resp muscles (skin pulling between ribs) 
  • Central cyanosis 


How is TTN diagnosed ?

  • Physical exammination +/- CXR 
  • O2 sats monitoring 


What does this CXR show ?

TTN - interstitial oedema - predominantly perihilar often seen as perihilar streakiness


What is the management of TTN ?

  • Conservative - if O2 sats are low, then give O2 
  • Ensure adequate nutrition 


Following starting to breath and successfully switching to normal circulation, what 3 things does the baby now need to establish ?

  1. Thermoregulation 
  2. Ensure glucose homeostasis 
  3. Feed/nutrition 


Why are babies prone to becoming cold (hypothermia)? 

  • Because they have: 
  • A large surface area to volume ratio 
  • They are wet & naked 
  • They cannot shiver 
  • There main source of heat is non-shivering thermogenesis = heat produced by the breakdown of adipose tissue in response to catecholamines which is not efficient 
  • Peripheral vasocontriction 


Why do you want to avoid hypothermia in babies ?

Becuase it predisposes them to other problems 


Why are SGA/preterm babies more predisposed to hypothermia ?

  1. Low stores of brown fat 
  2. Little S/C fat 
  3. Larger surface area to volume ratio