Adaptation at birth Flashcards
What is the placental function?
Foetal homeostasis Gas exchange Nutrient transport to foetus Waste product transport from foetus Acid base balance Hormone production; baby ready for labour Transport of IgG
What is the role of the foetal liver and kidney?
Liver; albumin, clotting factor, RBC
Kidney; excretes urine, contributes to amniotic fluid
What is the role of the foetal endocrine system?
Thyroid hormones Corticosteroids Mineralocorticoids PTH Insulin
What are the 3 shunts present in the foetal circulation?
Ductus venosus
Foramen ovale
Ductus arteriosus
What % of the foetal circulation goes to the lungs?
7%
What occurs in the 3rd trimester to prepare the foetus for birth?
Surfactant production
Accumulation of glycogen at liver, muscle and heart
Accumulation of brown fat; scapulae and internal organs
Accumulation of subcutaneous fat
Swallowing of amniotic fluid
What produces surfactant?
Type 2 pneumocytes
What is the role of surfactant?
Reduced surface tension
How much fluid is present in foetal lungs?
100ml
What is the benefit of vaginal delivery in terms of lung fluid?
Squeezes out 30%, this can be a reason for transient tachypnoea of the newborn in c/s babies (no squeezing)
How does the circulation transition as the baby is born?
Pulmonary vascular resistance drops Systemic vascular resistance rises Oxygen tension rises Circulating prostaglandins drop Duct constricts Foramen ovale closess
How does the arterial pO2 change as the baby is born?
Rises from 2-3.5 to 9-13 kPa
What factors allows for the duct closure in babies post birth?
Decreased flow due to decreased pulmonary vascular resistance
Increased pO2 (oxygen sensitive muscular layer)
Decreased circulating PGE2 due to increased lung metabolism
Shut becomes bidirectional then left-right
When is the physiological and anatomical closure of the ductus venous?
Physiological; few hours
Anatomic; 7-10 days
What is the fate of the foramen ovale?
Closes or persists as PFO (10%)
What is the fate of the ductus arteriosus?
Becomes ligamentum arteriosus
What is the fate of the ductus venosus?
Becomes ligamentum teres
What can result in failure of cardiopulmonary adaptation?
Asphxia; hypoxia/ acidosis Prematurity Sepsis Hypoxia - meconium aspiration Cold stress Chorioamnionitis Hypothermia
What is PPHN?
Lung vascular resistance fails to fall
Shunts remain; right to left at PFO, right to left at PDA
High pressure in the pulmonary vascular system
What is a good test to assess PPHN?
Pre and post ductal o2 sats
How is PPHN managed?
Ventilation Oxygen NO - vasodilator Sedation Inotropes ECLS/ ECMO
What adaptations occur within the first couple of hours?
Thermoregulation
Glucose homeostasis
Nutrition
Why is thermoregulation a problem for babies?
Large surface area
Wet when born
What are the 4 methods of heat loss?
Radiation
Convection
Conduction
Evaporation
Can babies shiver?
No; therefore main source of heat is non shivering thermogenesis
How do babies produce heat?
Breakdown of stored brown adipose tissue in response to catecholamines
Can babies breakdown brown adipose tissue in the first 12 hours of life?
No; peripheral vasoconstriction occurs
Newborns need help with maintaining temp; between 36.5-37.5
Who do small for dates/ preterms need help maintaining temp?
Low stores of brown fat
Little subcutaneous fat
Larger surface area:vol
How can hypothermia be prevented in newborns?
Dry Hat Skin to skin Blanket/ clothes Heated mattress Incubator
How does glucose homeostasis change in the first couple hours of life?
Interruption of glucose supply from placenta
Very little oral intake of milk
Drop in insulin, increase in glycogen
Mobilisation of hepatic glycogen stores for gluconeogenesis
Ability to use ketones for brain
What can predispose to hypoglycemia in a newborn?
Increased demands; unwell, hypothermia
Low glycogen stores; small/ prem
Inappropriate insulin/ glucagon ratio; maternal diabetes, hyperinsulinism
Beta blockers
How can hypoglycemia be avoided in newborns?
Identify those at risk
Feed effectively
Keep warm
Monitor
What are the different forms of breastmilk?
Colostrum
Foremilk
Hindmilk
What is a normal weight loss in the first week following birth?
10%
What can occur if more than 10% of weight is lost?
Hypernatremic
What chemical will result in the changes of foetal Hb?
2,3 BPG
Shifts curve to the right
Where will haematopoiesis move to/from after birth?
From liver to bone marrow
Why will there be a physiological anaemia at 8-10 weeks post birth?
Adult Hb is synthesised more slowly than foetal Hb is broken down
What type of bilirubin results in physiological jaundice?
Unconjugated as conjugating pathways are immature
What are the 2 methods of treating jaundice in babies?
Phototherapy
Exchange transfusion
What is a bad side effect of prolonged and high jaundice in a baby?
Kernicterus; bilirubin deposits in basal ganglia resulting in athetoid CP and deafness
What babies are at risk to maladaptation?
Hypoxia/ asphyxia during delivery SGA or LFD Prematures Maternal illness Ill babies; sepsis or congenital anomalies
