Neonatology 1 Flashcards
What are the significant development times of the heart of a foetus?
- Begins to develop toward the end of the third week.
- Heart starts to beat at the beginning of the fourth week.
- The critical period of heart development is from day 20 to day 50 after fertilization.
Describe the foetal circulation
○ Oxygenated blood via umbilical vein – Ductus Venosus.
- Foetal blood vessel connecting the umbilical vein to the IVC
- Blood flow regulated via sphincter
- Carries mostly oxygenated blood
○ Some blood via Foramen Ovale to Left Atrium – Left Ventricle – Aorta (Ao).
○ Some of blood to Right Ventricle – Pulmonary Artery (PA) - Patent Ductus Arteriosus (PDA) from PA to Ao.
○ Saturation SaO2 in foetal body is 60-70%.
○ Ductus arteriosus
- Protects lungs against circulatory overload
- Allows the right ventricle to strengthen
- Carries low oxygen saturated blood
What is the normal blood pressure of a newborn at 1 hour, 1 day and 3 days?
- 1hr: 70/44
- 1 day: 70(+/-9)/42(+/-12)
- 3 days: 77(+/-12)/49(+/-10)
What is the normal respiratory signs in a newborn?
- 30-60
- Periodical breathing
- Difficult to assess if spontaneous breathing.
□ Research rather clinical devices - Non-invasive:
□ Blood gas determination
□ PaCO2 5-6 kPa, PaO2 8-12 kPa
□ Trans-cutaneous pCO2/O2 measurement - Invasive:
□ Capnography
□ Tidal volume 4-6 ml/kg
□ Minute ventilation:
® Tidal Volume ml/kg x respiratory rate
□ Flow-volume loop
What is the normal heart rate of a newborn?
120-160bpm
What counts as tachycardia and bradycardia in a newborn?
- Tachycardia
□ >160bpm - Bradycardia
□ <100bpm
How does a newborn thermoregulate?
- Maternal thermoregulation in the womb.
- New born babies lack shivering thermo genesis thus need a metabolic production of the heat.
- Brown fat well innervated by sympathetic neurons.
- Cold stress leads to lipolysis and heat production.
Where does a newborn loose heat?
- Radiation: □ Heat dissipated to colder objects. - Convection: □ Heat loss by moving air. - Evaporation: □ We are born in the water. - Conduction: □ Heat loss to surface on which baby lies
Describe fluid balance in a newborn (full term)
- Full term infant is able to maintain fluid / electrolyte balance
- Weight loss up to 10% is normal
- Loss is due to:
□ Shift of interstitial fluid to intravascular compartment
□ Diuresis - It is normal not to pass urine for the first 24 hrs!
Descibe fluid balance in pre-term infants
- Less fat in body composition
- Increased loss through kidney:
□ Slower GFR
□ Reduced Na reabsorption
□ Decreased ability to concentrate or dilute urine - Increased Insensible Water Loss (IWL)
□ Via immature skin and breathing
□ Physiological IWL is 20-40 ml/kg/day but could be up to 82 ml/kg/day in 750-1000 g
Why might a baby be small for its gestational age?
- Maternal □ Smoking □ Drinking □ Pre-eclampsia toxaemia - Foetal □ Chromosomal e.g. Edward's syndrome (trisomy 18) □ Infection e.g. CMV - Placental □ Placental abruption - Other □ Twin pregnancies
What are the common problems presentated by a infant who is small for gestational age?
□ Perinatal hypoxia □ Hypoglycaemia □ Hypothermia □ Polycythaemia □ Thrombocytopaenia □ Gastrointestinal problems (feed, NEC) □ RDS, infection
What are the long term problems in newborns who are small for gestational age?
□ Hypertension
□ Reduced growth
□ Obesity
□ Ischaemic heart disease
What counts as preterm and extremely preterm babies?
○ Preterm <37 weeks
○ Extremely preterm <28 weeks
What counts as low birth weight and very low birth weight in newborns?
○ Low weight <2500g
○ Very low birth weight <1500g
What are the common prolems in preterm babies?
○ Respiratory distress syndrome (RDS) ○ BPD (Broncho-pulmonary dysplasia)/ CLD (chronic lung disease) ○ Minor respiratory problems ○ Intra-ventricular haemorrhage (IVH) ○ Peri-ventricular leukomalacia (PVL) ○ Post haemorrhagic hydrocephalus (PHH) ○ Necrotising enterocolitis (NEC) ○ Persistent ductus arteriosus (PDA) ○ Retinopathy of prematurity (ROP) ○ Neonatal abstinence syndrome (NAS) ○ Hypoxic-ischemic encephalopathy (HIE)
How is respiratory destress syndrome managed?
□ Prevention ® Antenatal steroids □ Early treatment ® Surfactant ® Then as little as possible ◊ Early extubation ◊ Non-invasive support (N-CPAP) ◊ Minimal ventilation (low tidal volume and good inflation)
Talk about BPD (Broncho-pulmonary dysplasia)/ CLD (chronic lung disease)
□ Overstretch by volu-baro-trauma □ Atelectasis- collapse of the lung □ Infection via ETT □ O2 toxicity □ Inflammatory changes □ Tissue repair- scarring □ Treatment ® Patience ® Nutrition and growth ® Steroids
What minor respiratory problems happen in premature babies and how are they managed?
□ Apnoea/ irregular breathing/ desaturations
□ Treatment
® double expresso (caffeine)
® N-CPAP
Talk about intraventricular haemorrhage and the premature baby
□ Most common limiting factor for good long term prognosis
□ Grades I-IV
□ Under 28 weeks fairly common
□ Not so common 28-37 weeks
□ Bleed happens in the first 3 days of life
□ Prevention: AN steroids
□ Treatment
® Symptomatic
® Drainage
□ On the 21st day of life macrophages come up and clean the dead tissues
Talk about peri-ventricular leukomalacia in premature babies
□ 95% adverse outcome
□ Not dangerous immediately but then starts pushing the tissue
® The brain is pushed becoming thinner and thinner
□ Outcome
® No new production of neurons
® They will wither have paraplegia or quadriplegia
How is post haemorrhagic hydrocephalus treated in premature babies?
BP shunt
Talk about patent ductus arteriosus in premature babies
□ Pressure in the left side of the heart is higher
□ You flood the lungs from left to right
□ The lungs overflow with blood which steals blood from the peripherals and causes ischaemia
® Worry about the gut and kidney
® Lung oedema
□ Additional blood to pulmonary circulation
® Overperfusion of the lungs
® Lung oedema
□ Steal from systemic circulation
® Systemic ischaemia
□ Consequences
® Worsening of respiratory symptoms
® Retention of fluids (low renal perfusion)
® Gastrointestinal problems (GE ischaemia)
Talk about necrotising entro-colitis in premature babies
□ Bubbles that are lined up are pneumatosis
□ You see oedema which means they are already retaining fluid
□ Ischaemia and inflammatory changes
□ Necrosis of the bowel
□ Surgical intervention is often required
□ Conservative management is sometimes possible
® Antibiotics
® Parenteral nutrition
Talk about nutrition in premature babies
- Enormous nutritional requirements unparalleled
- Patients often triple their size during hospital stay
- Building new functional tissues from compounds provided artificially
What are the ourcomes of extreme prematurity?
- Unpredictable at the time of birth
- Ultrasound of brain by the end of the 1st week
- Often very uncertain even on discharge home
- Surprising deterioration (cognitive and behavioural) between 2nd and 6th year
- Also some unexpected improvement between 2nd and 6th year of life
- Extremely limited data on subjective quality of life in adulthood
What fraction of premature babies:
- Die
- Have a normal life or mild disability
- Have severe or moderate disability?
- 1/3 dies
- 1/3 have normal life or mild disability
- 1/3 have severe or moderate disability
