Neonatology Flashcards
What is neonatology?
Speciality of new-born medical care
When does the CVS develop?
- 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 circulation of the foetus.
- Sats 60-70%
- Oxygenated blood via umbilical vein through ductus venosus
- Blood shunted through foramen ovale
- Blood flow through ductus arteriors
What is the function of the ductus arteriosus?
- Protects lungs against circulatory overload
- Allows the right ventricle to strengthen
- Carries low oxygen saturated blood
What is the function of the ductus venosus?
- Foetal blood vessel connecting the umbilical vein to the IVC
- Blood flow regulated via sphincter
- Carries mostly oxygenated blood
What are the normal blood pressure or a new-born?
1 hour old
- Systolic 70
- Diastolic 44
1 day old
- Systolic 70+/-9
- Diastolic 42+/-12
3 days old
- Systolic 77+/-12
- Diastolic 49+-10
What is the usual respiratory rate of a new-born?
- 30-60 per minute
- Periodical breathing pattern
What is considered normal HR in a new-born?
120-160bpm
What is considered tachycardia in a new-born?
> 160bpm
What is considered bradycardia in a new-born?
<100bpm
What does cold stress in new-borns lead to?
Lipolysis and heat production
What is brown fat innervated by?
Well innervated by sympathetic neurones
Why do new-borns need a metabolic production of heat?
They lack shivering thermogenesis
How do babies lose 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
How can new-born breathing be assessed non-invasively?
Blood gas determination
- PaCO2 5-6 kPa,
- PaO2 8-12 kPa
Trans-cutaneous pCO2/O2 measurement
How can new-born breathing be assessed invasively?
- Capnography
- Tidal volume 4-6 ml/kg
- Minute ventilation: (Tidal Volume ml/kg x respiratory rate)
- Flow-volume loop.
When does physiological jaundice occur?
- Appears on Day of life (DOL) 2-3.
- Disappears within 7-10 DOL in term infants and up to 21 DOL in premature infants.
What is the incidence of physiological jaundice?
Up to 60% of term babies and 80% of premature babies
What affect does blue light have on bilirubin/
Converts it to water soluble form and increases oxidation of bilitubin
How does kernicterus occur?
- Unconjugated bilirubin is lipid soluble and can cross the BBB
- At high concentrations it can cause irreversible brain changes
Why is 10% weight loss of a term baby normal?
Loss is due to natural
- Shift in interstitial fluid to intravascular
- Diuresis
When is it normal not to pass urine?
Term baby for the first 24 hours
Why is it difficult for a premature infant to maintain fluid balance?
- Less fat in body composition
- Increased loss through kidney
- Increased insensible water loss
Why do premature infants lose more water through their kidneys?
- Slower GFR
- Reduced Na reabsorption
- Decreased ability to concentrate or dilute urine
What insensible water loss do premature babies have?
- 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
What are the causes of anaemia of prematurity?
- Reduced erythropoesis.
- Infection
- Blood letting – most important cause!
What physiological anaemia occurs in new-borns?
- RBC production is 10% of in uterus DOL 7
- Born with - Hb 15-20 g/l
- Week 10 - Hb 11.4 g/l
- Increase production of Erythropoetin
- Week 20 - Hb 12.0 g/l
What is considered IUGR?
<10th centile
What is considered severe IUGR?
<0.4th centile
What are the categories of causes of babies being small for dates?
- Maternal
- Foetal
- Placental
- Other
- Normal
- MIxed
What maternal causes of small for dates are there?
- Alcohol
- Smoking
- Pre-eclamptic toxaemia
What foetal causes of small for dates are there?
-Chromosomal (Edwards’ syndrome)-Infection (CMV)
What placental causes of small for date are there?
- Placental abruption
- Anything that affects placental perfusion
Why can small for dates occur with twins?
Twin to twin transfusion syndrome
What are some common problems experienced by small for date babies?
- Perinatal Hypoxia
- Hypoglycaemia
- Hypothermia
- Polycythaemia
- Thrombocytopenia
- Hypoglycaemia
- Gastrointestinal problems (feeds, NEC)
- RDS, Infection
What long term problems can babies that are small for dates experience?
- Hypertension
- Reduced growth
- Obesity
- Ischaemic heart disease
Premature
Baby delivered <37 weeks
Extremely preterm
Baby delivered <28 weeks
Low birth weight
<2500g
Very low birth weight
<1500g
Extremely low birth weight
<1000g
What is the incidence of prematurity?
5-12%
What systems can be affected in preterm babies?
Any system
- Respiratory
- Circulation
- Metabolic / Nutrition
- Immune / Infection
- Brain
- Gastrointestinal
- Haematology
- Renal
- Skin
What does RDS stand for?
Respiratory distress syndrome
What does IVH stand for?
Inter-ventricular haemorrhage
What does PVL stand for?
Peri-ventircular leucomalacia
What does NEC stand for?
Necrotising entero-colitis
What does PDA stand for?
Patent ductus arteriosus
What does BPD stand for?
Broncho pulmonary dysplasia
What does ROP stand for?
Retinopathy of prematurity
What does PHH stand for?
Post haemorrhagic hydrocephalus
What does NAS stand for?
Neonatal abstinence syndrome
What does HIE stand for?
Hypoxic-ischaemic encephalopathy
How is RDS prevented?
Antenatal steroids
What early treatment is there for RDS?
- Surfactant
- Early extubation
- N-CPAP
- Minimal ventilation
What can cause BPD?
- Overstretch by volu-baro-trauma
- Atelectasis
- Infection via ETT
- O2 toxicity
- Inflammatory changes
- Tissue repair - scarring
How is BPD treated?
- Patience
- Nutrition and growth
- Steroids ?
What minor respiratory problems can premature babies face?
- Apnoea
- Irregular breathing
- Desaturations
How can minor respiratory problems be managed in premature babies?
- Caffeine
- NCPAP
What is the most common limiting factor for good prognosis for premature babies?
IVH
How is IVH graded/
I-IV
-Grad IV has a 75% adverse outcome
How can IVH be prevented?
Antenatal steroids
How can IVH be treated?
- Symptomatic
- Drainage
What is the pathophysiology of PDA
- Pressure of aorta> PA leading to LR shunt
- Additional blood to pulmonary circulation leads to over-perfusion of lungs and lung oedema
- Steal from systemic circulation leads to systemic ischaemia
What are the consequences of PDA?
- Worsening of respiratory symptoms
- Retention of fluids (poor renal perfusion)
- GI problems (ischaemia)
What is NEC?
-Ischaemic and inflammatory changes leading to necrosis of the bowel
How is NEC managed?
- Surgical intervention is often required
- Conservative management is sometimes possible by antibiotics and parenteral nutrition
What are the outcomes of extreme prematurity?
- Unpredictable at birth
- US of brain by day 7
- Can deteriorate even on discharge (up to age 6)
- May be some unexpected improvements
- I/3 die
- 1/3 have normal life/mild disability
- 1/3 have moderate/severe disability
