Neonatology, preterm & low birth weight babies

Question 1

Primary cause of death in preterm infants (<26wks)

Answer 1

RDS+-IVH+-Infection (29%) - down from 31% in 1995
Pulmonary insufficiency (22%) - down from 34% in 1995
Infection (16%) - up from 8% in 1995
NEC (12%) - up from 4% in 1995

Question 2

Causes of Mortality in low birth weight infants

Answer 2

Prematurity – System immaturity or complications of prematurity
Small for gestational age – Underlying cause of prematurity or inadequate growth

Question 3

Regulatory problems in preterm infants

Answer 3

Homeostasis - skin integrity, heat loss & energy use

Fluid Balance - skin integrity or renal immaturity

Question 4

Respiratory problems in preterm infants

Answer 4

Apnoea/poor respiratory effort (central factors) or poor muscle bulk (peripheral)
Surfactant deficiency or bronchopulmonary dysplasia
Infections or air leak leading to pneumothorax

Question 5

Respiratory/Hyaline distress syndrome (RDS)

Answer 5

Surfactant deficiency – common cause of death
Worse with: greater prematurity, boys, caucasians, second twins
Worsened by: Hypothermia, treatment delay, infection

Question 6

Chronic lung disease of prematurity

Answer 6

A broad term used to describe ongoing respiratory symptoms at 36wks post-menstrual age most commonly in infants who have needed mechanical ventilation - used to be called chronic pulmonary dysplasia

Question 7

Respiratory/Hyaline distress syndrome - management

Answer 7

Antenatal steroids to mature the lungs – reduces RDS and mortality by 50%
Surfactant replacement – reduces mortality & pneumothorax by 40%
Ventilation – CPAP, conventional ventilation, high frequency oscillation

Question 8

Gastro-intestinal problems in preterm infants

Answer 8

Feed intolerance
Poor growth
Gastro-oesophageal reflux
Necrotising enterocolitis (NEC)

Question 9

Causes of Chronic lung disease of prematurity (5)

Answer 9

Immature lungs, surfactant deficiency, ventilator induced lung injury (barotrauma, volutrauma, atelectotrauma)
Infection or inflammation

Question 10

Breast milk in preterm babies

Answer 10

Better feeding tolerance and trophic to immature gut –> Reduces infection and NEC risk. Nutritionally matched to gestation
Possibly improves metabolic/endocrine adaptation to life ex-utero and promotes brain growth

Question 11

Necrotising Enterocolitis (NEC)

Answer 11

4-8% of preterm babies, 10% of those under 1.5kg
Increased risk with increasing immaturity & IUGR
Pathogenesis –> Mucosal injury, bowel ischemia, presence of bacteria. 20-40% mortality

Question 12

Intraventricular haemorrhage (IVH)

Answer 12

– 25% of VLBW babies
Post IVH - 15% Haemorrhagic parenchymal infarction (HPI)
- 14% Post-haemorrhagic hydrocephalus (PHH)

Question 13

Periventricular leuomalacia

Answer 13

2-10% of VLBW babies – depending on maturity

Necrosis and coagulation of periventricular white matter

Question 14

Risk of brain injury in premature infants is increased by?

Answer 14

Increasing immaturity. Infection. Ischaemia . Hypotension. Antenatal steroids are protective

Question 15

Long term prognosis of brain injury in premature infants?

Answer 15

Cerebral palsy – spastic diplegia or hemiparesis. Cognitive impairments or learning difficulties. Visuospatial problems
Attention deficit and behavioural problems. Require multi-disciplinary support at home and at school

Question 16

Retinopathy of prematurity

Answer 16

60-70% of VLBW babies – only 6% require treatment
untreated 50% will progress to retinal detachment and visual loss
Risk increased by prematurity, hypoxia and severe illness

Question 17

Retinopathy of prematurity – screening

Answer 17

All babies under 31wks or under 1500g

Question 18

Retinopathy of prematurity – treatment

Answer 18

Start at 6-7wks post-natal age

Use lasers for stage 3 and worse or for progressive disease

Question 19

Long term prognosis for respiratory disease

Answer 19

May require long term domiciliary oxygen
50% will have persistent wheeze or respiratory symptoms during infancy
50% will be rehospitalised for viral infections
The impact on lung function is still detectable at school age

Question 20

Long term prognosis for gastrointestinal disease

Answer 20

Persistent growth restriction and poor nutrition
Poor feeding due to: aversion, reflux, respiratory compromise, neurological problems, malabsorption after intestinal surgery

Question 21

IUGR

Answer 21

Due to placental insufficiency (illness or smoking)
Have general problems from being small (temp control or hypoglycaemia) and specific issues (NEC, HIE, haematological problems)
Can lead to preterm birth

Question 22

Physiological changes at birth

Answer 22

Cry in response to trauma –> fluid in the alveoli is rapidly absorbed
Clamping the cord –> removes low pressure umbilical circulation increasing systemic blood pressure

Question 23

Perinatal asphyxia

Answer 23

1 in 10 term babies need assistance – 1% need prolonged resuscitation – 30% of these have multi-organ hypoxia
Biggest risk is HIE

Question 24

Sarnat classification of HIE

Answer 24

Grade 1 – Mild (irritable, hyperalert)
Grade 2 – Moderate (lethargy, hypotonia, seizures)
Grade 3 – Severe (stuporous, absent reflexes, reduced background EEG activity)

Question 25

Neonatal sepsis

Answer 25

Before 7 days old implies vertical transmission (Group B strep or E coli) clinical signs are subtle and non-specific - insidious onset Beware meningitis

Question 26

Risk factors for neonatal sepsis

Answer 26

PROM >24hrs Prematurity or low birth weight Maternal GBS or infection, intrapartum pyrexia Confirmed chorioamnionitis

Question 27

Group B strep (GBS) (6)

Answer 27

Most common cause of neonatal sepsis at term (within 24hrs) -- very sensitive to penicillin. From the genital tract of asymptomatic mother Rapid respiratory deterioration -- lead to pulmonary HTN and possible shock or DIC. Can also have late (4-6wks) insidious onset with a poor prognosis

Question 28

Neonatal hypoglycaemia

Answer 28

Glucose below 2.6mmol/L -- give 10% IV dextrose Only need to test at risk babies -- increased demand (macrosomia, polycythemia, infection, asphyxia) or decreased supply (poor feeding, IUGR, preterm, hypothermia)

Question 29

Neonatal jaundice

Answer 29

Common (60%) of term babies -- if early (<48hrs) indicates infection or haemolysis and should be investigated Can be conjugated (biliary atresia) or unconjugated

Question 30

Causes of unconjugated neonatal jaundice (4)

Answer 30

Isoimmunisation (ABO, rhesus or anti-C) RBC defects -- G6P deficiency or spherocytosis/epllipocytosis Infection Sequestered blood - cephalohematoma, large IVH, subdural

Question 31

Spherocytosis

Answer 31

A haemolytic anaemia where a autosomal dominant defect in the cytoskeleton of RBCs causes them to be spherical leading to splenic destruction and osmotic fragility -- this causes chronic haemolytic anaemia. Northern european descent. Can also have gallstones, splenomegaly, chronic symptoms through haemolytic crises can be triggered by infection.

Question 32

Treatment for neonatal jaundice

Answer 32

Milk -- increases bile excretion Adequate hydration phototherapy Rarely exchange transfusions are required.

Question 33

Breast feeding jaundice vs breast-milk jaundice

Answer 33

Breast feeding jaundice is an early onset jaundice due to poor milk supply from first time mothers causing mild dehydration Breast-milk jaundice is late onset where maternal hormones in breast milk slow bilirubin metabolism

Question 34

Common neonatal viral infections

Answer 34

Herpes simplex (local or disseminated) CMV -- most common Varicella -- should be protected by maternal IgG Also -- rubella, hepatitis A, B ,C and HIV

Question 35

Risks of maternal HIV

Answer 35

Maternal screening and treatment will reduce risk Vertical transmission reduced with -- keeping maternal viral load low, prevent PROM but early elective C-section Post natal AZT therapy for 4 weeks and avoid breast feeding