Prematurity

Question 1

List the common medical problems for the preterm infant

Answer 1

• 23- 26 weeks: require weeks of intensive support, high overall mortality rate
• after 32 weeks: prognosis is excellent with modern intensive support
• problems:
  
  • _​_resuscitation need
  • RDS
  • pneumothorax
  • apnoea/ bradycardia
  • hypotension
  • PDA
  • temperature control problems
  • hypoglycaemia
  • hypocalcaemia
  • electrolyte imbalance
  • osteopenia of prematurity
  • nutrition problems
  • infection
  • jaundice
  • IVH/ periventricular leukomalacia
  • necrotising enterocolitis
  • retinopathy
  • anaemia
  • iatrogenic
  • bronchopulmonary dysplasia- chronic lung disease
  • inguinal hernias

Question 2

Presentation and management of RDS

Answer 2

Cause: lack of surfactant (phosphlipids and proteins secreted by T2 pneumocytes of alveolar epithelium- lowers surface tension), leads to widespread alveolar collapse and therefore, insufficient gas exchange.

Presentation:

• tachypnoea >60/min
• laboured breathing: subcostal, sternal recession, nasal flaring, expiratory grunt, cyanosis (late stage)

Management:

• glucocorticoids- given antenatally to mother, stimulate surfactant production
• surfactant therapy- pig/ calf lung surfactant
• oxygen -nasal cannula deilvery or artificial/ mechanical ventilation

Question 3

Presentation and management of necrotising enterocolitis

Answer 3

Cause: bacterial invasion of the ischaemic bowel wall. More likely to develop in preterms fed cow’s milk formula vs. breast milk.

Presentation:

• not tolerating feeds
• milk aspirated from stomach
• vomiting (+/- bile stained)
• distended abdomen
• fresh blood in stool

Management:

• stop oral feeding
• give broad spectrum ABx
• PEN
• atrifical ventilation
• circulatory support
• surgery (bowel perforation)

Question 4

Presentation and management of infection

Answer 4

Cause: preterms more at risk of infection as IgG mostly transferred across placenta in last trimester. No IgA/M transferred. Plus, infection in and around cervix often cause for preterm labour. Hospital-derived- indwelling catheters, ventilation.

Infection in preterms can contribute to bronchopulmonary dysplasia, white matter injury and latuer disability.

Presentation/ management: see infection cards.

Question 5

Presentation and management of hypoglycaemia

Answer 5

Cause: poor glycogen stores. No agreed definition for ‘hypoglycaemia’ in newborn however (due to use of lactate and ketones in first few days of life). > 2.6 mmol/L desirable. Prolonged hypoglycaemia–> neurological disability.

Presentation:

• jitteriness
• irritability
• apnoea
• lethargy
• drowsiness
• seizures

Management

• early, frequent milk feeding
• IV glucose infusion- dextrose 10, 15 or 20% - higher concentrations should be delivered by central venous catheter to avoid extravasion into the tissues/ reactive hypoglycaemia
• glucagon/ hydrocortison if IV not possible/ difficult

Question 6

Presentation and management of temperature control

Answer 6

Cause: vulnerable to hypothermia because…

• large SA:V ratio
• skin is thin- transepidermal water loss important in first week of life
• little subcutaneous fat for insulation
• cannot conserve heat by curling up/ generating heat by shivering

Presentation: hypothermia causes increased energy consumption and therefore may result in hypoxia, hypoglycaemia, failure to gain weight and increased mortality.

Management:

• incubators
• overhead radiant heater
• clothing- esp. covering head
• avoid draughts
• heated mattresses
• plastic bag straight after birth in extremely preterm

Question 7

Presentation and management of apnoea of prematurity

Answer 7

Cause: hypoxia, infection, anaemmia, electrolyte disturbance, hypoglycaemia, seizures, HF, aspiration due to GORD. Many cases = immaturity of central respiratory control

Presentation:

• usually occur up to 32 weeks life
• bradycardia may occur in apnoea > 20-30 secs or when breathing continues but against closed glottis

Management

• physical stimulation
• respirstory stimulant- caffiene
• CPAP- if apnoeic episodes frequent

Question 8

Presentation and management of retinopathy of prematurity

Answer 8

Cause: blood vessels at junction of vascular and non-vascular retina. Vascular proliferation–> retinal detachment, fibrosis and blindness.

Management:

• avoid high conc. O2 (risk factor)
• screening in those susceptible (<32 wks, <1500g)- opthalmologist
• laser therapy (reduces visual impairment)

Question 9

Presentation and management of intraventricular haemorrhage

Answer 9

Cause: typically occur germinal matrix above caudate nucleus (fraglie network of blood vessels). Common in first 72 hrs life. Haemorrhage can occur in ventricles.

• Most severe = unilateral haemorrhagic infarction (parenchyma of brain involvement) –> hemiplegia.
• Large intraventricular haemorrhage = impairs drainage/ reabsorption of CSF
• Post-haemorrhagic ventricular dilatation= cerebral palsy
• Peri-ventricular white matter brain injury= ischaemia/ injury. May resolve in a week.
• Cystic lesions 2-4 weeks later= definite loss of white matter
• Bilateral, multiple cysts (periventricular leukomalacia) = 80-90% risk of spasti diplegia (with cognitive impairment if posterior placed)

RFs: perinatal asphyxia, severe RDS, pneumothorax

Presentation:

• large intraventricular haemorrhage
  
  • hydrocephalus
    
    • _​_cranial suture separation
    • HC rapidly increases
    • tense anterior fontanelle

Management:

• large intraventricular haemorrhage
  
  • _​_VP shunt

Question 10

Nutrition in the premature infant

a) principles
b) method of delivery

Answer 10

• preterms have high nutritional requirements
  
  • due to rapid growth
  • 28 weekers- double birthweight in 6w, treble it in 12w
  • term babies- double their weight in 4.5m, treble it in 1yr
• methods
  
  • ​35-36 weeks: mature enough to suck and swallow milk from bottle/ breast
  • less than 35 weeks: oro- or nasogastric tube
  • very preterm: enteral feeds (breast milk supplemented with phosphate +/- protein, calories and calcium preferable)
  • very immature/ sick: parenteral feeds via peripheral vein. PICC lines have risks of septicaemia, thrombosis
• benefits of breast milk for preterms
  
  • ​immune protection
  • decreased risk of necrotising enterocolitis
  • risk of septicaemia from PICC
• osteopenia of prematurity used to be common but now prevented by adequate provision of phosphate, calcium and vitamin D
• iron deficiency can be a problem as:
  
  • most iron transferred in last trimester
  • constant sampling and inadequate erythropoietin response
  • iron supplements started at several weeks of life and continued at home

Question 11

• Impact of prematurity on lung development
• Risk of chronic lung disease and other respiratory morbidity

Answer 11

• Bronchopulmonary dysplasia/ chronic lung disease: infants who have oxygen requirement at post-menstrual age of 36 weeks
• Aetiology: pressure/ volume trauma from artificial ventilation; oxygen toxicity and infection
• Weaning: artificial ventilation –> CPAP –> additional ambient oxygen (sometimes over sveral months)​
• Corticosteroids = earlier weaning and reduces infants oxygen requirements short term (risk re cerebral palsy)
• Cause of death: intercurrent infection (pertussis and RSV), pulmonary HTN
• Lung problems throughout life: pneumonia, wheezing, asthma, bronchiolitis (RSV), may require oxygen for many months

Question 12

Outline the neurodevelopmental complications in prematurity

Answer 12

• 5-10% LBW infants will develop cerebral palsy
  
  • More commonly learning difficulties
    
    • the prevelance of this increases with descreaing gestational age (<26w)
    • trouble with: fine motor skills, concentration, behaviour problems, (ADHD), abstract reasoning (maths) and processing tasks simultaneously
• small proportion of hearing impairment
  
  • ​1-2% requiring amplification
• visual impairments
  
  • ​1% blind both eyes
  • greater proportion have refractive errors and squints