Physiology of Neonates Flashcards by Eilidh Seaton

What carries oxygenated blood to the baby

What carried deoxygenated blood

Umbilical vein
Carries O2 blood from placenta to foetus

Umbilical artery x2 - from bifurcation of aorta - placenta

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What is the ductus venous and what type of blood

Foetal blood vessel connecting umbilical vein from placenta to IVC of baby
Mostly oxygenated
Liver gets most oxygenated blood as first organ where umbilical vein goes

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What is the foramen ovale

Hole connecting RA-LA

Bypass immature lungs which have a very high pressure

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What is the ductus arteriosus

Allows blood flow from Pulmonary artery to aorta without travelling through foetal inadequate lungs
If it doesn’t close blood flows from aorta -> Pa

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What does ductus arteriosus allow

RV to strengthen

Protect lungs from circulatory overload

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What does ductus arteriosus carry

Low oxygen saturated blood

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What is the saturation in a foetus

60-70%

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When does CVS start to develop

End of third week

Heart beats at 4th week

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What happens at first breath

Move fluids out of lungs and arteries / alveoli in lungs open
Decreases pulmonary vascular resistance
LA pressure > RA pressure which squishes atrial septum closing foramen oval
Foramen ovale closes - hard top open after 14 days
PDA stays open 1-2 days
Others all become ligaments

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What are vital signs of newborn

BP 70/40ish 
RR - 30-60
HR- 120-160
Tachy >160
Brady <100

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How do new born babies thermoregulate

Lack shivering thermogenesis
Rely on metabolic heat
Brown fat innervated by sympathetic
If premature lack brown fat

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What are the 4 ways to lose heat

Radiation - to colder
Convection - moving air
Evaporation - to water
Conduction - to surface you touch

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How do you assess newborn breathing non-invasively

Clinical - RR
Blood gas determination - take capillary blood + analyser
Trans-cutaneous PCO2,O2

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What should the PaCo2 and PaO2 be in a newborn

PaCO2 - 5-6

PaO2 - 8-12

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How do you assess breathing invasively

Capnography - monitors PaCO2 in intubation

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What is TV average and minute volume

TV = 4-6ml / kg

Minute ventilaiton = TV x RR

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Physiological jaundice

Day 2-3 and disappears in 7-10 days or three weeks in prem

Breast feed increases duration

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Fluid balance in newborn term

Should be able to maintain fluid and electrolyte balance
U+E may be of first 24 hours as mother may have had IV fluids
Normal not to pass urine for 24 hours
Weight loss up to 10% is normal

Fluid balance in premature ?

Less fat
Increased loss through kidney
Increased insensible water loss

Why is there increased loss through kidney in premature

Slower GFR
Reduced Na reabsorption
Decreased ability to concentrate or dilute urine

Physiological anaemia

Reduced RBC production when born then increases

What is physiological of anaemia in prematurity

Reduced erythropoiesis when first born
Can’t keep up with rapid growth
Blood letting / tests remove blood volume
Infections

How do you treat

Give iron at 28 days if premature

What should happen to Hb when born

Should go up to provide O2

What do you do if low

Look at reticulocyte count to see if haemolytic

Why are bloods not accurate 1st 24 hours

Affected by mother e.g. if had IV fluid | Repeat

What happens if ductus arteriosus doesn't close

Blood goes from aorta to lungs as higher pressure

When is surfactant produced

24-34 weeks gestation

Role of surfactant

Reduces force needed to expand the alveoli which reduces lung compliance

Why is hypoxia in baby common

Normal labour and birth cause hypoxia as contractions stop gas exchange with placenta

What does extended hypoxia lead too

``` Anaerobic respiration Bradycardia Reduced consciousness Drop in RR Eventually HIE ```

Other issues in neonatal resus

Large S/A to weight = cold easily Born wet so lose heat May have meconium in airway

What do you do if baby comes out not crying

Dry baby and stimulate Keep warm under heat lamp or plastic bag if <28 weeks Stimulate Calculate APGAR - tone, RR, HR, colour, activity Given a score for each 0-2

When is APGAR carried out

1,5 and 10 minutes

If not breathing what do you do or HR low

5 inflation breaths - First breath to open up lungs so want large pressure - Put pressure on mask Aim is to sustain pressure to get fluid out

If this doesn't work what do you do

Continuous pressure

What do you do if not improving or HR <60

``` CPR Ratio 3:1 with ventilation breaths IV access and drugs Intubation May benefit from hypothermia to prevent HIE ```

How often do you assess

30 seconds

What does APGAR look at

``` Appearance 0 =pale / blue 1 = pink with blue Pulse 0 =absent 1 = <100 Grimmace / activity - response to stimulation 0 = floppy 1 = minimal Tone 0 = absent 1 = flexed Respiration 0 = absent 1 = irregular ``` Given a score 0-2

Delayed cord clamping ?

If uncompromised wait 1 minute Allows blood from placenta to enter baby Reduce IVH, NEC and improve BP, iron and Hb

What are other causes of anaemia

Prematurity Haemolysis Blood loss Twin-twin transfusion

What causes haemolytic

ABO or Rhesus G6PD Heriditary spherocytosis

What do you do if low blood sugar after birth

``` Encourage feeding Observe Trnasient hypo = common If DM mother start hypoglycaemic protocol - Dextrogel - IV dextrose - IV fluid ```