Respiratory disease in a neonate (CLD of prematurity, RDS, PPH, transient tachypnoea)

Question 1

What is VLBW?

Answer 1

<1.5kg

Question 2

What are the most common respiratory complications in VLBW infants?

Answer 2

• Respiratory distress syndrome (surfactant deficiency) 74%
• Pneumothorax 4%
• Apnoea and bradycardia and desaturations
• Bronchopulmonary dysplasia (BPD) - O2 requirement at 36 weeks in 27%

Question 3

Define bronchopulmonary dysplasia/chronic lung disease in the newborn.

Answer 3

Infants who still have an oxygen requirement at a postmenstrual age of 36 weeks

Question 4

What is the aetiology of bronchopulmonary dysplasia?

Answer 4

Damage is mainly due to:

• delay in lung maturation
• pressure and volume trauma from artificial ventilation
• oxygen toxicity
• infection

Question 5

What can be seen on an x ray of brochopulmonary dysplasia?

Answer 5

Widespread areas of opacification, sometimes with cystic changes.

Question 6

What is the management of bronchopulmonary dysplasia and its complications?

Answer 6

1. Wean from prolonged artificial ventilation –> CPAP or high flow nasal cannula therapy –> ambient oxygen (over several months)
2. Corticosteroid therapy - may facilitate earlier weaning but risk of neurodevelopmental abnormalities like cerebral palsy

Question 7

What are the complications of bronchopulmonary dysplasia?

Answer 7

Severe disease may follow intercurrent infection or pulmonary hypertension, causing respiratory failure and necessitating ICU.

Question 8

What is the aetiology of retinopathy of prematurity?

Answer 8

Uncontrolled use of high concentrations of oxygen

Now, even with careful monitoring 35% of infants still develop this

Question 9

What is the pathophysiology of retinopathy of prematurity?

Answer 9

1. Vascular proliferation
2. Retinal detachment
3. Fibrosis
4. Blindness

Question 10

What is the management of retinopathy of prematurity?

Answer 10

If <1.5kg at birth or <32 weeks gestation then refer to be screened by ophthalmologist

Laser therapy if required

Question 11

Define respiratory distress syndrome.

Answer 11

AKA hyaline membrane disease, is a deficiency of surfactant which lowers surface tensions. Surfactant* deficiency causes alveolar collapse and inadequate gas exchange.

*Surfactant = mix of phospholipids and proteins excreted by type II pneumocytes of the alveolar epithelium.

Question 12

What are the risk factors for RDS?

Answer 12

• risk of RDS decreases with gestation
  
  • 50% of infants born at 26-28 weeks
  • 25% of infants born at 30-31 weeks
• boys > girls
• diabetic mothers
• second born of premature twins
• cesarean section
• genetic mutation in the surfactant genes

Question 13

What is seen on histology in RDS?

Answer 13

hyaline membrane disease - there is a proteinaceous exudate seen in airways on histology

Question 14

What is the prevention treatment for RDS?

Answer 14

Glucocorticoids ANTENATALLY given to mother - stimulate fetal surfactant production if preterm birth is anticipated; significantly reduces RDS, BPD and intraventricular haemorrhage in those <34 weeks’ gestation.

Question 15

What is the typical presentation of respiratory distress syndrome?

Answer 15

Within 4 hours:

1. tachypnoea over 60 breaths/min
2. laboured breathing with chest wall recession (sternal+ subcostal indrawing) and nasal flaring
3. expiratory grunting (attempt to create +ve airway pressure during expiration and maintain functional residual capacity)
4. cyanosis in severe cases

Question 16

What is the management of RDS?

Answer 16

1. Oxygen
2. Surfactant therapy - instilled directly into lungs via a tracheal tube or catheter.
3. Respiratory support:

• Non-invasive CPAP or high-flow nasal cannula therapy (preferable)
• Invasive with mechanical ventilation via tracheal tube, intermittent +ve pressure or high frequency oscillation, adjucted according to infant’s oxygenation, chest wall movements and blood gas analyses

Question 17

What are the benefits of surfactant therapy in RDS?

Answer 17

reduces morbidity and mortality of preterm infants with respiratory distress syndrome

Question 18

What is seen on this CXR?

Answer 18

Chest X-ray in respiratory distress syndrome showing:

• a diffuse granular or ‘ground glass’ appearance of the lungs
• and an air bronchogram, where the larger airways are outlined.
• heart border is indistinct
• tracheal tube is present

Question 19

What conditions is peristent pulmonary hypertension associated with in a newborn?

Answer 19

Secondary to:

• birth asphyxia
• meconium aspiration
• septicaemia
• RDS

Or can be a primary disorder.

Question 20

What is the pathophysiology of PPH?

Answer 20

high pulmonary vascular resistance –> right-to-left shunting within lungs, atria and ducts –> cyanosis soon after birth

Question 21

What are the clinical features of PPH? Would heart murmurs or signs of heart failure be present?

Answer 21

No murmurs or signs of heart failure would be present

1. Cyanosis soon after birth
2. CXR - pulmonary oligaemia, normal sized heart
3. Echo - raised pulmonary pressures and tricuspid regurgitation due to pulmonary hypertension

Question 22

What is the management of PPH?

Answer 22

1. Mechnical ventilation - high frequency or oscillatory ventilation may be helpful.
2. Circulatory support - e.g. inhaled nitrix oxide or sildenafil (viagra) which are potent vasodilators
3. ECMO - heart and lung bypass (if severe)

Question 23

Which ECG finding indicates pulmonary hypertension?

Answer 23

Upright T waves

Question 24

What are the causes of respiratory distress in term infants?

Answer 24

Question 25

What is the most common cause of respiratory distress in term infants?

Answer 25

Transient tachypnoea of the newborn

Question 26

What is the cause of transient tachypnoea of the newborn?

Answer 26

delayed resorption of fluid in the lungs

Question 27

What is the main risk factor for TTN development?

Answer 27

It is more common following Caesarean sections, possibly due to the lung fluid not being ‘squeezed out’ during the passage through the birth canal

Question 28

How can TTN be diagnosed?

Answer 28

Chest x ray - shows fluid in the horizontal fissure and hyperinflation of the lungs

NB: must exclude other causes such as infection.

Question 29

What is the management of TTN? What is the prognosis?

Answer 29

Supplementary oxygen - may be required to maintain oxygen saturations.

Prognosis - usually settles within 1-2 days