Respiratory Distress in the Neonate

Question 1

What is meconium aspiration syndrome?

Answer 1

Occurs when meconium is passed in utero and then aspirated by the baby resulting in respiratory distress when born. The meconium leads to airway obstruction, irritation surfactant dysfunction, pulmonary vasoconstriction. Obstruction may lead to a right to left shunt (via patent DA or FO) as pulmonary pressure increases. V:Q mismatch creates a downward spiral.

Question 2

What are the risk factors for meconium aspiration syndrome?

Answer 2

Foetal maturity i.e. >42 weeks gestation
Foetal distress
Oligohydramnios
Maternal hypertension, diabetes, Pre-eclampsia, smoking and substance abuse
Chorioamnionitis
IUGR

Question 3

What are the clinical features of meconium aspiration syndrome?

Answer 3

Clinical diagnosis – baby in respiratory distress following meconium stained amniotic fluid.
Tachypnoea, tachycardia, cyanosis, grunting, nasal flaring, recessions and hypotension

Question 4

How should a child suspected of having meconium aspiration syndrome be investigated?

Answer 4

CXR – increased lung volume, asymmetrical opacities, pleural effusions, pneumothorax and multifocal consolidation.
Bloods – CRP, FBC and Blood cultures
Blood gas
Sats

Question 5

What differentials should be considered in a child suspected of having meconium aspiration syndrome?

Answer 5

Transient tachypnoea of the new-born – usually resolves after 24 hours
Surfactant deficiency

Question 6

How is meconium aspiration syndrome managed?

Answer 6

Oxygen +/- ventilation if needed – nasal cannula, CPAP, intubation
Keep warm in an infant warmer
Endotracheal suctioning only needed if baby not vigorous at birth
Surfactant
Antibiotics – ampicillin and gentamicin
Inhaled nitric oxide

Question 7

What complications can occur from Meconium aspiration syndrome?

Answer 7

Ball valve if thick meconium leading to pneumothorax or pneumomediastinum
Persistent pulmonary hypertension due to airway remodelling
Chronic lung disease from barotrauma and oxygen toxicity

Question 8

What causes respiratory distress syndrome (RDS)?

Answer 8

This occurs due to a deficiency in alveolar surfactant and so most common in premature babies. Insufficient surfactant leads to atelectasis and reinflation with each breath exhausts the baby leading to respiratory failure.

Question 9

What are the main risk factors for RDS?

Answer 9

Prematurity
Maternal diabetes
Males 
2nd twin 
Caesarean

Question 10

What are the clinical features of RDS?

Answer 10

Increased exertion when breathing 
Tachypnoea 
Grunting
Nasal flaring 
Intercostal recession 
Cyanosis

Question 11

What is the appearance of RDS on X-ray?

Answer 11

On CXR there with be diffuse granular patterns and air bronchograms

Question 12

What differentials should be considered alongside RDS?

Answer 12

Important differentials to rule out – transient tachypnoea of the new-born (resolves after 24hrs), meconium aspiration, congenital pneumonia (GBS), tracheoesophageal fistula and congenital lung abnormalities.

Question 13

What drugs can be used to prevent RDS in a child this is likely to be born premature?

Answer 13

Prevention with betamethasone or dexamethasone steroid maternally

Question 14

How is RDS managed in a premature new born ?

Answer 14

Delay clamping of cord to promote placenta-foetal transfusion

Give oxygen via an air blender starting at 21% and increasing as necessary

Attach oximeter – 85% normal in first 10mins of life if active, If not increase oxygen by 10% every minute until improving.

If spontaneously breathing, then stabilise with CPAP

If gestation <26 weeks, then intubate and give prophylactic surfactant. Aim for sats of 85-93% to avoid retinopathy of prematurity or bronchopulmonary dysplasia
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Wrap up warm and take to incubator

If blood gases worsen intubate and support ventilation.

Fluids – 10% glucose IVI. Nutrition – seek help but inositol is essential for surfactant

Question 15

If a child deteriorates after being managed for RDS what should be checked?

Answer 15

If any deterioration check DOPE:

Displaced ET tube, Obstructed, Pneumothorax or Equipment Failure

Question 16

What is broncho pulmonary dysplasia?

Answer 16

This occurs due to barotrauma and oxygen toxicity. There is persistent hypoxia and difficult ventilator weaning e.g. still requiring ventilation at 36 weeks postmenstrual age.

This can cause feeding issues, severe RDS bronchiolitis and GORD. Long term this may lead to reduced IQ, cerebral palsy, asthma and exercise limitation.

Question 17

What does broncho pulmonary dysplasia appear as on X-ray?

Answer 17

CXR will show hyperinflation and histology will show necrotising bronchiolitis with alveolar fibrosis.

Question 18

When should you suspect pulmonary hypoplasia?

Answer 18

Very rare but suspect in infants with persisting neonatal tachypnoea and feeding difficulties particularly if prenatal oligohydramnios. Can also occur as a consequence of diaphragmatic hernia.

Post-natal catch up growth is possible

Question 19

What is HFNC?

Answer 19

HFNC (high flow nasal cannula) – delivery positive airway pressure similar to CPAP. Air should be humidified to prevent mucosal drying.

Question 20

What is CPAP?

Answer 20

CPAP – pressure delivered throughout the airway cycle preventing airway collapse. Can cause pneumothorax, nasal trauma, feed intolerance and reflux. Indicated in RDS, for respiratory support, post extubation and upper airway obstruction.

Question 21

What is NIPPV?

Answer 21

NIPPV (nasal intermittent positive pressure ventilation) – combined nasal CPAP with superimposed ventilator breathing. It can be used to bridge between invasive ventilation and nasal CPAP.

Question 22

What is TCPL?

Answer 22

Invasive Ventilation
TCPL (time cycled pressure limited ventilation)
Continuous flows of heated humidified gas passed through an endotracheal tube. Breath delivered by peak inspiratory pressure, and inspiratory time or ratio of inspiration to expiration. Allows infants to give some effort between breaths which may lead to desynchrony.

Question 23

What is PTV?

Answer 23

Invasive Ventilation
PTV (patient-triggered ventilation)
Combined TCPL with a sensor to when the patient attempts to breath. Pressures set by operator but rate set by infant.

Question 24

What is HFV?

Answer 24

HFV (high-frequency ventilation)

Small volumes at a very high rate in an aim to reduce ventilator injuries.

Question 25

How should infants be sedated prior to invasive ventilation insertion?

Answer 25

Infants should be sedated prior to elective intubation with an opiate and a muscle relaxant.

Question 26

What complications can occur from ventilation?

Answer 26

Lung: pneumothorax, pulmonary haemorrhage, bronchopulmonary dysplasia, interstitial pulmonary emphysema and pneumonia.
Airways may become obstructed – consider bronchoscopy.
Other: patent DA, raised intracranial pressure and intraventricular haemorrhage, retinopathy of prematurity, subcutaneous emphysema, pneumomediastinum, pneumopericardium and pneumoperitoneum.

Question 27

How should a neonate be weaned from positive pressure ventilation?

Answer 27

Oxygen should first be reduced by as much as possible to reduce risk of retinopathy. Slowly reduce the amount of time being ventilated and the pressure they are being ventilated at.