Small / Preterm baby

Question 1

What is RDS?

Answer 1

Hyaline membrane disease or respiratory distress syndrome

Occurs when there is a deficiency of sufactant which lowers surface tension. Deficiency causes widespread alveolar collapse and inadequate gas exchange.

The more preterm the infant the greater the risk of RDS

Question 2

What are the RFs for RDS?

Answer 2

• Prematurity
• Diabetic mother
• Genetic mutations in surfactant genes
• Boys > girls

Question 3

What can be done to prevent RDS?

Answer 3

Glucocorticoid administration to mother if preterm delivery is anticipated- stimulates surfactant production; substantial benefit:

• reduces RDS
• bronchopulmonary dysplasia
• intraventricular haemorrhage in infants <34 weeks’ gestation

Question 4

What are the clinical features of RDS?

Answer 4

Within 4 hours of birth there will be:

• tachypnoea >60 breaths/min
• laboured breathing with chest wall recession (particularly sternal and subcostal indrawing) and nasal flaring
• expiratory grunting to create +ve airway pressure during expiration and maintain functional residual capacity
• cyanosis if severe

Question 5

What is the management of RDS?

Answer 5

Surfactant therapy - reduces morbidity of preterm infants with RDS; given via tracheal tube or catheter directly into lungs

Oxygenation - NIV with CPAP or high-flow nasal cannulae; or mechanical ventilation adjusted according to infant oxygenation, chest wall movements and blood gas measurements; but NIV used where possible.

Question 6

What is a common complication of RDS? What is the pathophysiology of this?

Answer 6

Pneumothorax - occurs in up to 10% of infants ventilated for RDS as overdistended alveoli may track into interstitum resulting in pulmonary interstitial emphysema.

Question 7

What are the clinical features of pneumothorax in a preterm infant? What simple investigation may be used?

Answer 7

Oxygen requirements increase

Chest wall movement and breath sounds are reduced on that side.

Transillumination with bright fibre optic light source applied to chest wall can be used to confirm diagnosis. Alternatively CXR.

Question 8

What is the management of pneumothorax in an infant?

Answer 8

Urgent decompression by inserting a chest drain

Prevention - using lowest pressures for ventilation that provide adequate chest movement and satisfactory blood gases

Question 9

Until what age are episodes of apnoea and bradycardia common in preterm infants?

Answer 9

Until 32 weeks’ gestational age

Question 10

Why does bradycardia occur in preterm infants?

Answer 10

• Apnoea for 20-30 seconds
• Breathing against a closed glottis
• Underlying pathology e.g. hypoxia, infection, anaemia, electrolyte disturbance, hypoglycaemia, seizures, HF or aspiration due to GOR.

MOST: immaturity of central respiratory control

Question 11

What is the management of apnoea in prematurity?

Answer 11

1. Gentle physical stimulation - to restart breathing
2. Caffeine - respiratory stimulant, improves outcommes
3. If frequent apnoea- CPAP or mechanical ventilation

Question 12

Why are preterm babies vulnerable to hypothermia?

Answer 12

1. Large surface area relative to mass - so greater heat loss than generation
2. Skin is thin and heat permeable - so there is also transepidermal water loss in 1st week of life
3. Little subcutaneous fat for insulation
4. Often nursed naked and cannot curl up to conserve heat or shiver to generate heat

Question 13

How do you manage hypothermia in preterm infants?

Answer 13

Incubators - a neutral temperature range is calculated which is highest in the first few days of life and then declines; allow ambient humidity to be provided which reduces transepidermal heat loss

Overhead radiant heaters can alos be used

Question 14

What is the pathophysiology of PDA?

Answer 14

Causes left to right shunt

Common in infants with RDS