Problems with LBW and prematurity Flashcards
What is considered to be a low-birthweight/very low birthweight/extremely low birthweight?
Low birthweight: <2500 g
Very low birthweight: <1500 g
Extremely low birthweight: <1000 g
What is meant by small for gestational age?
Birthweight below the 10th centile for gestation
Define foetal growth restriction.
Failure to achieve normal rate of foetal growth - can be from uteroplacental insufficiency or from foetal infection
Why might a baby be small for gestation age?
Genetics:
- normal small baby
- chromosomal disorders (Edwards syndrome = trisomy 18)
- inherited disorders
Acquired:
- uteroplacental insufficiency
- congenital infection
- smoking
- maternal chronic illness (renal, sickle cell)
- multiple pregnancy (twins)
Why does uteroplacental insufficiency occur? How is it detected?
Failure of syncytiotrophoblast invasion of the high resistance spiral arteries (fail to transform into low resistance vessels)
Poor placental development with raised resistance in the placental vascular bed
Can be detected using doppler US of the uterine arteries + foetal circulation
During foetal hypoxia, what does increased blood flow to the MCA indicate? Is it a good sign? What artery might there be reduced blood flow in, at the same time?
It is a good sign
Indicates that the brain is being spared + prioritised over other organs
Most likely reduced blood flow to the SMA as a result
What problems might a SGA baby face?
- temperature control (increased surface area:volume; reduced adipose tissue insulation; reduced capacity for thermogenesis)
- polycythaemia (response to foetal hypoxia)
- poor nutritional status (hypoglycaemia = <2.6 mmol/L, treat with feed/IV dextrose)
- increased risk of necrotising enterocolitis
What adult diseases are associated with LBW?
Diabetes Hypertension Coronary heart disease Stroke Chronic bronchitis
Why might a baby be born prematurely?
Spontaneous:
- infection/ruptured membranes
- cervical incompetence
- polyhydramnios
Intentional:
- save mother (HTN, haemorrhage)
- save foetus (placental insufficiency)
What complications can arise with a premature baby?
- temperature control
- respiratory problems
- cardiovascular problems
- nutrition
- infection
- neurological
- LT consequences
What respiratory problems might a premature baby have?
Structural immaturity:
- primitive alveolar development
- susceptibility to O2 toxicity and barotrauma
Functional immaturity:
- surfactant deficiency
- lack of respiratory drive
Susceptibility to infection:
- immature immune system
- ineffective cilia
- instrumentation of airway
Short term clinical issues:
- Respiratory distress syndrome
- pneumonia
- apnoea of prematurity
Long-term clinical issues:
- chronic lung disease in infancy
What are the main components of surfactant?
Dipalmitylphosphaditylcholine
Phosphaditylglycerol
What stabilises surfactant?
Surfactant protein B
What is the clinical presentation of RDS? How soon does it occur? How is it diagnosed?
Clinical presentation:
- tachypnoea
- respiratory grunting
- recession
- use of accessory muscles
Onset is within 4 hours of birth
Diagnosed with bronchogram –> will show a hazy ‘ground glass’ appearance (surfactant deficiency)
What prevention and treatment options are there for RDS?
Prevention:
- Antenatal steroids (2 12h apart)
- avoidance of intrauterine hypoxia
- prophylactic surfactant treatment
- keep warm - avoid acidosis
Treatment:
- surfactant and respiratory support
What would the lungs/airways system of an infant with chronic lung disease look like?
- inflammation
- fibrosed
- emphysema-like appearance
What kind of cardiovascular problems occur with prematurity?
Persistent pulmonary hypertension of the newborn
Failure to maintain BP
Patent ductus arteriosus
How many calories and how many ml of milk does a preterm baby require in order to grow? What must be done if a baby cannot tolerate milk?
110-135 kcal/kg/day
160-200 ml/kg/day (milk)
If baby cannot tolerate milk = IV parenteral nutrition
What challenges might a preterm baby face in terms of nutrition?
Immature sucking = tube feeding
digestive enzymes are present
poor gut motility
may not tolerate enteral feeds
- if a baby is not fed it can lead to gut mucosa atrophy
- feeding may precipitate necrotising enterocolitis
What is necrotising enterocolitis? What are the risk factors?
Acute bacterial/inflammation/necrosis of the bowel with gas formation (pneumotosis)
RFs: prematurity, hypoxia, infection, enteral feeding
How does necrotising enterocolitis present? What is the treatment? What are the potential complications?
Presentation:
- Abdominal distension
- Tenderness
- Discolouration
- Blood in stools
- Collapse
Treatment:
- Stop feed and give antibiotics +/- surgery
Complications:
- Death (~25%)
- Short gut secondary to resection/strictures/late obstruction
What bacteria most commonly cause infection in newborns?
Early infections (<48 hours)
- Group B beta haemolytic streptococcus
- E coli
Late infections (>48 hours)
- Coagulase negative staphylococci
- Gram negative organisms that colonise the intestine
What defences against infection do full-term babies have?
- Transplacental IgG in 3rd trimester
- IgA + immunologically active cells in colostrum
- Skin barrier
- Acquisition of normal flora from mother to baby
*antibiotics and invasive procedures can breach host defences
What CNS issues can preterm babies have?
- Susceptibility to periventricular haemorrhage
(RFs: <34 weeks; RDS; pneumothorax; hypercapnia) - Risk of periventricular leucomalacia = ischaemia of periventricular white matter
What complications arise with intracerebral bleeding?
- collapse + death
- loss of brain parenchymal tissue with cyst development
- blockage of CSF circulation leading to hydrocephalus
