Respiratory disease in a neonate (CLD of prematurity, RDS, PPH, transient tachypnoea) Flashcards
What is VLBW?
<1.5kg
What are the most common respiratory complications in VLBW infants?
- Respiratory distress syndrome (surfactant deficiency) 74%
- Pneumothorax 4%
- Apnoea and bradycardia and desaturations
- Bronchopulmonary dysplasia (BPD) - O2 requirement at 36 weeks in 27%
Define bronchopulmonary dysplasia/chronic lung disease in the newborn.
Infants who still have an oxygen requirement at a postmenstrual age of 36 weeks
What is the aetiology of bronchopulmonary dysplasia?
Damage is mainly due to:
- delay in lung maturation
- pressure and volume trauma from artificial ventilation
- oxygen toxicity
- infection
What can be seen on an x ray of brochopulmonary dysplasia?
Widespread areas of opacification, sometimes with cystic changes.
What is the management of bronchopulmonary dysplasia and its complications?
- Wean from prolonged artificial ventilation –> CPAP or high flow nasal cannula therapy –> ambient oxygen (over several months)
- Corticosteroid therapy - may facilitate earlier weaning but risk of neurodevelopmental abnormalities like cerebral palsy
What are the complications of bronchopulmonary dysplasia?
Severe disease may follow intercurrent infection or pulmonary hypertension, causing respiratory failure and necessitating ICU.
What is the aetiology of retinopathy of prematurity?
Uncontrolled use of high concentrations of oxygen
Now, even with careful monitoring 35% of infants still develop this
What is the pathophysiology of retinopathy of prematurity?
- Vascular proliferation
- Retinal detachment
- Fibrosis
- Blindness
What is the management of retinopathy of prematurity?
If <1.5kg at birth or <32 weeks gestation then refer to be screened by ophthalmologist
Laser therapy if required
Define respiratory distress syndrome.
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.
What are the risk factors for RDS?
- 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
What is seen on histology in RDS?
hyaline membrane disease - there is a proteinaceous exudate seen in airways on histology
What is the prevention treatment for RDS?
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.
What is the typical presentation of respiratory distress syndrome?
Within 4 hours:
- tachypnoea over 60 breaths/min
- laboured breathing with chest wall recession (sternal+ subcostal indrawing) and nasal flaring
- expiratory grunting (attempt to create +ve airway pressure during expiration and maintain functional residual capacity)
- cyanosis in severe cases
What is the management of RDS?
- Oxygen
- Surfactant therapy - instilled directly into lungs via a tracheal tube or catheter.
- 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
What are the benefits of surfactant therapy in RDS?
reduces morbidity and mortality of preterm infants with respiratory distress syndrome
What is seen on this CXR?
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
What conditions is peristent pulmonary hypertension associated with in a newborn?
Secondary to:
- birth asphyxia
- meconium aspiration
- septicaemia
- RDS
Or can be a primary disorder.
What is the pathophysiology of PPH?
high pulmonary vascular resistance –> right-to-left shunting within lungs, atria and ducts –> cyanosis soon after birth
What are the clinical features of PPH? Would heart murmurs or signs of heart failure be present?
No murmurs or signs of heart failure would be present
- Cyanosis soon after birth
- CXR - pulmonary oligaemia, normal sized heart
- Echo - raised pulmonary pressures and tricuspid regurgitation due to pulmonary hypertension
What is the management of PPH?
- Mechnical ventilation - high frequency or oscillatory ventilation may be helpful.
- Circulatory support - e.g. inhaled nitrix oxide or sildenafil (viagra) which are potent vasodilators
- ECMO - heart and lung bypass (if severe)
Which ECG finding indicates pulmonary hypertension?
Upright T waves
What are the causes of respiratory distress in term infants?
What is the most common cause of respiratory distress in term infants?
Transient tachypnoea of the newborn
What is the cause of transient tachypnoea of the newborn?
delayed resorption of fluid in the lungs
What is the main risk factor for TTN development?
It is more common following Caesarean sections, possibly due to the lung fluid not being ‘squeezed out’ during the passage through the birth canal
How can TTN be diagnosed?
Chest x ray - shows fluid in the horizontal fissure and hyperinflation of the lungs
NB: must exclude other causes such as infection.
What is the management of TTN? What is the prognosis?
Supplementary oxygen - may be required to maintain oxygen saturations.
Prognosis - usually settles within 1-2 days
