Neonatology, preterm & low birth weight babies Flashcards
Primary cause of death in preterm infants (<26wks)
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
Causes of Mortality in low birth weight infants
Prematurity – System immaturity or complications of prematurity
Small for gestational age – Underlying cause of prematurity or inadequate growth
Regulatory problems in preterm infants
Homeostasis - skin integrity, heat loss & energy use
Fluid Balance - skin integrity or renal immaturity
Respiratory problems in preterm infants
Apnoea/poor respiratory effort (central factors) or poor muscle bulk (peripheral)
Surfactant deficiency or bronchopulmonary dysplasia
Infections or air leak leading to pneumothorax
Respiratory/Hyaline distress syndrome (RDS)
Surfactant deficiency – common cause of death
Worse with: greater prematurity, boys, caucasians, second twins
Worsened by: Hypothermia, treatment delay, infection
Chronic lung disease of prematurity
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
Respiratory/Hyaline distress syndrome - management
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
Gastro-intestinal problems in preterm infants
Feed intolerance
Poor growth
Gastro-oesophageal reflux
Necrotising enterocolitis (NEC)
Causes of Chronic lung disease of prematurity (5)
Immature lungs, surfactant deficiency, ventilator induced lung injury (barotrauma, volutrauma, atelectotrauma)
Infection or inflammation
Breast milk in preterm babies
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
Necrotising Enterocolitis (NEC)
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
Intraventricular haemorrhage (IVH)
– 25% of VLBW babies
Post IVH - 15% Haemorrhagic parenchymal infarction (HPI)
- 14% Post-haemorrhagic hydrocephalus (PHH)
Periventricular leuomalacia
2-10% of VLBW babies – depending on maturity
Necrosis and coagulation of periventricular white matter
Risk of brain injury in premature infants is increased by?
Increasing immaturity. Infection. Ischaemia . Hypotension. Antenatal steroids are protective
Long term prognosis of brain injury in premature infants?
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
Retinopathy of prematurity
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
Retinopathy of prematurity – screening
All babies under 31wks or under 1500g
Retinopathy of prematurity – treatment
Start at 6-7wks post-natal age
Use lasers for stage 3 and worse or for progressive disease
Long term prognosis for respiratory disease
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
Long term prognosis for gastrointestinal disease
Persistent growth restriction and poor nutrition
Poor feeding due to: aversion, reflux, respiratory compromise, neurological problems, malabsorption after intestinal surgery
IUGR
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
Physiological changes at birth
Cry in response to trauma –> fluid in the alveoli is rapidly absorbed
Clamping the cord –> removes low pressure umbilical circulation increasing systemic blood pressure
Perinatal asphyxia
1 in 10 term babies need assistance – 1% need prolonged resuscitation – 30% of these have multi-organ hypoxia
Biggest risk is HIE
Sarnat classification of HIE
Grade 1 – Mild (irritable, hyperalert)
Grade 2 – Moderate (lethargy, hypotonia, seizures)
Grade 3 – Severe (stuporous, absent reflexes, reduced background EEG activity)
Neonatal sepsis
Before 7 days old implies vertical transmission (Group B strep or E coli)
clinical signs are subtle and non-specific - insidious onset
Beware meningitis
Risk factors for neonatal sepsis
PROM >24hrs
Prematurity or low birth weight
Maternal GBS or infection, intrapartum pyrexia
Confirmed chorioamnionitis
Group B strep (GBS) (6)
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
Neonatal hypoglycaemia
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)
Neonatal jaundice
Common (60%) of term babies – if early (<48hrs) indicates infection or haemolysis and should be investigated
Can be conjugated (biliary atresia) or unconjugated
Causes of unconjugated neonatal jaundice (4)
Isoimmunisation (ABO, rhesus or anti-C)
RBC defects – G6P deficiency or spherocytosis/epllipocytosis
Infection
Sequestered blood - cephalohematoma, large IVH, subdural
Spherocytosis
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.
Treatment for neonatal jaundice
Milk – increases bile excretion
Adequate hydration
phototherapy
Rarely exchange transfusions are required.
Breast feeding jaundice vs breast-milk jaundice
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
Common neonatal viral infections
Herpes simplex (local or disseminated)
CMV – most common
Varicella – should be protected by maternal IgG
Also – rubella, hepatitis A, B ,C and HIV
Risks of maternal HIV
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
