Adaptation at Birth Flashcards
How does the meconium aspiration syndrome present as?
- streaky lung fields
- —not black as it should be
PLacental fxn?
Fetal homeostasis Gas exchange Nutrient transport to fetus Waste product transport from fetus Acid base balance Hormone production Transport of IgG
Name the 3 major shunts in fetal circulation.
- Ductus arteriosus
- Foramen Ovale
- Ductus venosus
What % of maternal blood goes to the fetal lungs and why?
7%
—-because the lungs is not yet filled with oxygen
How is the baby prepped for birth in the 3rd trimester?
- Surfactant production (allows gas exchange)
- Accumulation of glycogen – liver, muscle, heart
- Accumulation of brown fat – between scapulae and around internal organs; Insulation
- Accumulation of subcutaneous fat
- Swallowing amniotic fluid
What produces surfacant? What is the role of surfacant?
- by type 2 Pneumocytes
- reduces the surface tension; allows the lungs to fill up easily with air (no collapse of alveoli)
What occurs with reduced amniotic fluid around the baby?
Small Hypoplastic lungs
What occurs to the fetus during delivery and labour?
Onset of labour – increased catecholamines / cortisol
Synthesis of lung fluid stops
Vaginal delivery – uterine contractions help squeeze out liquid
from lungs
What is the appearance of the baby in the first few secs?
Blue Starts to breathe Cries---helps oxygen get into the lungs? Gradually goes pink Cord cut
What affects fetal circulation?
- cord clamped (INCR. placental resistance) and first breath ( decr. resistance)
What occurs with circulatory transition? –search up
Pulmonary vascular resistance drops Systemic vascular resistance rises Oxygen tension rises Circulating prostaglandins drop Duct constricts Foramen ovale closes
What occurs to the ductus arteriosus ?
- ductus arteriosus becomes ligamentum arteriosus
Ductus venosus becomes_______
Ligamentum teres
What may occur to the foramen ovale?
- may persist as Patent Foramen Ovale (10%)
What may occur to the foramen ovale?
- may persist as Patent Foramen Ovale (10%)
WHat occurs with persistent pulmonary hypertension?
- FAILURE of normal circulatory transition d.t Lung vascular resistance failing to fall; SHUNTS remain
(surfacant deplete; lungs full of fluid)
What is a sig. finding for PPH?
- anything more than 3% difference between the pre and post ductal saturation
= PPH
What is the management of PPHN?
- dialyate given direct to the fetal lungs
- ventilation
- oxygen
- nitric oxide
- sedation
- inotropes
- ECLS
What does Transient Tachypnea present as? And Why?
- in big healthy bbies
- —grunt and breathe faster
- born by C-section
- no lung squeeze!
- —-recovers quickly
What should be done in the first few hrs, post delivery?
Thermoregulation
Glucose homeostasis
Nutrition
How to keep bbies warm?
- cover the HEAD and BODY to stop radiation of body
as bbies have a LARGE surface area and they are wet post-delivery
How do bbies attempt to keep warm?
- non shivering thermogenesis
Heat produced by breakdown of stored brown adipose tissue in response to catecholamines - Not efficient in the first 12 hours of life
Peripheral vasoconstriction
—why Newborn babies need help with maintaining temperature
Which particular bby has to be kept warm?
- SGA bbies and preterm bbies
- Low stores of brown fat
- Little subcutaneous fat
- Larger surface area:vol
How to keep warm?
Dry Hat Skin to skin Blanket / clothes Heated Mattress Incubator
How does glucose homeostasis occur?
- Interruption of glucose supply from placenta
- Very little oral intake of milk (~5 days for breast milk to set in)
- Drop in insulin, increase in glycogen
- Mobilisation of hepatic glycogen stores for gluconeogenesis
- Ability to use ketones as brain fuel
Why may hypoglycemia occur in bbie?
- incr. energy demands (unwell, hypothermia)
- low glycogen levels (preterm, small bby)
- Inappr. insulin/glucagon ratio (hyperinsulinism/ maternal diabetes)
- Some drugs
How to avoid hypoglycemia
Identify those at risk
Feed effectively
Keep warm
Monitor
Expectant wgt loss that is normal in bbies?
10% wgt loss
—-some may lose more that 10% —RISK of HYPERNATREMIC dehydration > usually d/t delayed lactation
Why is it important to change the fetal Hb to change to adult Hb?
- to high O2 affinitt (hard to oxygenate fetal tissues)
- fetal Hb break quickly
What helps shift the curve to the right?
Incr. in 2,3 BPG helps move the curve to the right
What form of JAUNDICE is seen in the first few days of the bby?
- Unconjugated Jaundice; V. high level is DANGEROUS
Why does fetal jaundice occur?
Breakdown of fetal haemoglobin
Conjugating pathways immature
Rise in circulating unconjugated bilirubin
early or prolonged jaundice = pathologocical
Which bbies are at risk?
Hypoxia / asphyxia during delivery Particularly small or large babies Premature babies – a whole other lecture Some maternal illnesses and medications Ill babies – sepsis, congenital anomalies
What shunts oxygenated blood from the RA to the LA in the fetal circulation?
Foramen Ovale (bypasses pulmonary circulation; which is fine as the RA of the fetal heart recieves oxygenated blood)
What does Ductus Arteriosus shunt blood to and from?
- it shunts blood from the Pulmonary artery to the aorta
How is it possible for blood to BYPASS the lungs?
- d.t high pulmonary resistance
Name 2 right-to-left shunts in fetal circulation.
- Patent FO and Patent D.A
What does blood is shunted to and from in the Ductus Venosus?
-shunts blood from the Umbilical vein to the IVC
Does the percentage of blood directed to the lungs increase with gestational age?
YES
becomes 80% of blood redirected to the liver by week 32
In utero the patency of Ductus Arteriosus depends on what?
- maintained by HIGH levels of Prostaglandins —-METABOLIZED by the lung (level drops with incr. blood flow to lungs)
- low fetal pO2
Explain how the ductus arteriosus closes?
- physiological closure in first few hrs/ days
- (anatomical closure in 7-10 days)
- reduced PVR = Reduced flow
- decr. PGE2 circulation d.t INCR. lung metabolism
- rising arterial concentrations in blood
What occurs with failure of hte cardiorespiratory adaptation?
- Asphyxia
- Prematurity
- sepsis
- hypoxia
- cold stress
What are the signs of PPHN?
- asphyxia
- tachypnea
- Respiratory acidosis
- Loud, single second heart sound (S2) or a harsh systolic murmur (secondary to tricuspid regurgitation)
- Low Apgar scores
- Meconium staining
- Cyanosis; poor cardiac function and perfusion
- Systemic hypotension
- Symptoms of shock
Where are the pre and post ductal sats taken from and what is a concerning finding?
- Pre-ductal= right hand
- Post- ductal= Left foot
—-diff. of >10% indicative of Pulmonary hypertension !
What are the 3 methods of heat loss in a baby?
- radiation
- convection
- conduction
- evaporation
What does suckling of the mother’s nipple stimulate?
- the HYPOTHALAMUS
>then stimulates Posterior Pituitary> Oxytocin release> milk ejection - Hypothalamus also stimulates the anterior pituitary gland> stimulates PROLACTIN release and MILK prodn
Does breast milk have diff. forms of composition?
- Colostrum (lots of IgA, cellular immunity and growth factors)
- foremilk
- hindmilk
