Prematurity

Question 1

Define prematurity and what proportion of babies in the UK are premature

Answer 1

Birth from 24-37+0 weeks
7.7%

Question 2

What are the physical/clinical features of extremely premature babies that differ from term babies

Answer 2

Lower birthweight
Very thin, dark red colouration
Ear pinnas are soft with no recoil
Genitalia: no testes in scrotum, labia major widely separated and prominent clitoris
Often requires respiratory support
No coordinated sucking → requires parenteral nutrition
Faint cry
eyelids may be fused

Question 3

What are the management steps in stabilising a preterm infant

Answer 3

1.Airway and breathing: check for respiratory distress and apnoea, consider LOW CONCENTRATION O2 support/CPAP/nasal cannula ± surfactant ± mechanical ventilation
2. Delayed cord clamping if resus not requred, monitor obs
3. <32w →Place in a plastic bag (wrap) to keep warm, stabilisation under a radiant warmer ± heated mattress or humidified incubator
4. Place a venous and arterial line ± PICC for parenteral nutrition
5. CXR ± AXR
5. Investigaitons
5. Consider Abx

Question 4

What is the purpose of delayed cord clamping

Answer 4

Better physiological transition if lungs are aerated before clamping
Increased peak Hb
Reduction in need for transfusion
Reduced necrotising enterocolitis and intraventricular haemorrhage

Question 5

What are the considerations for oxygen therapy in preterm infants

Answer 5

Excessive oxygen may cause tissue damage to the brain, lungs, and eyes from free radicals - avoid a pre-ductal saturation of 95%

Question 6

What are the possible complications of premature delivery

Answer 6

Circulatory: hypotension, PDA
Respiratory: RDS, pneumothorax, apnoea, bronchopulmonary dysplasia
Temperature: hypothermia
Infection
Brain: haemorrhage, ventricular dilatation, periventricular leukomalacia
GI: necrotising enterocolitis
Metabolic: hypoglycaemia, electrolyte disturbance, osteopenia
Eyes: retinopathy of prematurity
Jaundice
Anaemia

Question 7

What are the causes of premature delivery

Answer 7

Idiopathic
Uterine stretch: multiple gestation, polyhydramnios, uterine anomalies
Bleeding: abruption, APH
Infection: chorio, BV, PPROM
Foetal: IUGR, chromosomal/congenital anomalies
Maternal: PET, HTN, UTI, maternal infection, cervical weakness

Question 8

Describe respiratory distress syndrome

Answer 8

Aka hyaline membrane disease
Deficiency of surfactant (mixture of phospholipids and proteins excreted by type II pneumocytes of the alveolar epithelium), which lowers surface tension.
Risk increases with earlier age of gestation, being very common in infants <28w
More severe in boys than girls

Question 9

What are the signs of respiratory distress syndrome

Answer 9

Usually within 4 hours of birth:
Tachypnoea >60
Increased work of breathing
Chest wall recession (Sternal and subcostal)
Nasal flaring
Expiratory grunting (creates a positive airway pressure during expiration)
Cyanosis (severe)

Question 10

What are the management steps for respiratory distress syndrome and how can it be prevented

Answer 10

1. CXR (ground class apperance)
2. Supplemental oxygen (21-30% to avoid damage from excess free radicals)
   - Aim for sats 91-95%
3. CPAP or high flow nasal cannula
4. Surfactant therapy - instilling directly into the lungs via tracheal tube or catheter
5. Mechanical ventilation

Prevention is via antenatal steroid

Question 11

What is the complications of respiratory distress syndrome and what are the signs

Answer 11

Air from the overdistended alveoli (RDS) may track into the interstitium → pulmonary interstitial emphysema
Air may leak into the pleural cavity and cause a pneumothorax

Breath sounds and chest movement on the affected side are reduced
Transillumination with a bright fibre-optic light source applied to the chest

Question 12

What investigations and management should be done for pneumothorax in premature neonates and how could it be prevented

Answer 12

CXR: shows pneumothorax
Tension pneumothorax: decompression by needle aspiration + chest drain

Prevention: ventilate with the lowest pressures possible

Question 13

What are the causes of apnoea/bradycardia/desaturation

Answer 13

Immaturity of central respiratory control
Hypoxia
Infection
Anaemia
Electrolyte disturbance
Hypoglycaemia
Seizures
Heart failure
Aspiration due to reflux

Question 14

How should apnoea, bradycardia and desaturation be managed

Answer 14

Gentle physical stimulation
Caffeine (resp. stimulation)
Frequent: CPAP or mechanical ventilation

Question 15

Why are premature infants vulnerable to hypothermia

Answer 15

Large surface area:mass ratio - greater heat loss than generation
Skin is thin and heat permeable - transepidermal water loss is significant in the first week
Little SC fat for insulation
Nursed naked and cannot conserve heat by curling up or shivering

Question 16

How should heat be maintained in premature neonates

Answer 16

Wrapping in a plastic bag without drying
Placing under a radiant heater
Warmed humidified respiratory gases
Incubator (allows ambient humidity)
Cover the head
Nurse on a heated mattress

Question 17

What are the common brain lesions that may occur in premature neonates and how are they detected

Answer 17

Haemorrhage (IVH)
White matter injury
Abnormal cerebral development
Periventricular leukomalacia

Detection: cranial ultrasound

Question 18

Describe haemorrhage in preterm neonates

Answer 18

25% of very LBW infants
Typically in the germinal matrix above the caudate nucleus
Large haemorrhage → extends to ventricles → intraventricular haemorrhage (IVH) → infarction of brain parenchyma → hemiplegia
Large IVH → impairs drainage and reabsorption of CSF → accumulates under pressure → hydrocephalus → separation of cranial sutures → rapid increase in head circumference and tense fontanelle
Associated with cerebral palsy

Question 19

What is the management for Intraventricular haemorrhage

Answer 19

1. LP to relieve pressure
2. ventriculoperitoneal or subgaleal shunt

Question 20

Describe white matter injuries in premature infants

Answer 20

Usually follows ischaemia and inflammation
Cranial ultrasound: Cystic white matter lesions visible

Question 21

Describe periventricular leukomalacia in premature infants

Answer 21

Bilateral multiple cysts
80-90% risk of spastic diplegia + cognitive impairment if posteriorly sited

Question 22

What is retinopathy of prematurity

Answer 22

Vascular proliferation of blood vessels at the junction of the vascularised and non-vascularised retina → retinal detachment → fibrosis → blindness
Bilateral blindness in 1% of VLBW infants (<28w)

Question 23

What are the risk factors for retinopathy of prematurity

Answer 23

Uncontrolled use of high oxygen concentrations
Very low birth weight infants (35% prevalence)

Question 24

What is the sign of retinopathy of prematurity, how is it screened for and what is the management

Answer 24

S/S: loss of red reflex
Screening: for preterm infants <1500g or <32 by opthalmologist
Management: laser therapy (± intravitreal anti-VEGF)

Question 25

What is bronchopulmonary dysplasia

Answer 25

Infants who still have an oxygen requirement at 36 weeks
→ recurrent infection or pulmonary hypertension → mortality
→ pertussis and RTI → respiratory failure

Question 26

What investigations should be done for bronchopulmonary dysplasia and what is the management

Answer 26

CXR: widespread areas of opacification ± cystic changes
Management:
- Prolonged artificial ventilation
- CPAP or high flow nasal cannula therapy + supplemental oxygen
- Steroids may be used to facilitate weaning, but there is concern about risk of neurodevelopment e.g. cerebral palsy

Question 27

How does premature birth impact nutrition

Answer 27

Preterm infants have a high nutritional requirement as they grow rapidly.
Infants born at 35-36 weeks gestational age are mature enough to suck and swallow milk
Less mature infants will need feeding through an orogastric or nasogastric tube

Requires supplementation with phosphate, protein, calories, calcium, iron
(Cow’s milk based formula → risk of NEC)

Question 28

What is necrotising enterocolitis

Answer 28

Surgical emergency where a combination of insults (vascular, mucosal, toxic, other) damages an immature gut
3 in 10,000 (7% of those premature get NEC)

Question 29

What are the risk factors for NEC

Answer 29

Prematurity
Patient ductus arteriosus

Question 30

What are the signs and symptoms of necrotising enterocolitis

Answer 30

Early signs = biliary vomiting, feed intolerance
Abdomen distension
Blood-stained stool
Rapid deterioration and shock

Question 31

What are the investigations for necrotising enterocolitis

Answer 31

AXR – ‘gas cysts’ in bowel wall
Blood cultures

Question 32

What is the management for necrotising enterocolitis

Answer 32

Bowel rest (NPO (stop oral feed) and switch to parenteral nutrition)
Broad-spectrum antibiotics (cefotaxime/tazocin and vancomycin)
- Stage IA/IB (3 days), stage IIA (7-10 days), stage IIB, III (14 days)
Laparotomy (if perforated as seen on AXR)