Meconium aspiration syndrome

Question 1

What is meconium aspiration syndrome?

Answer 1

Term used to describe a spectrum of disorders, marked by various degrees of respiratory distress in the new born infant. This follows the aspiration of meconium stained amniotic fluid

Question 2

How does meconium aspiration occur?

Answer 2

Antenatally 2.8%

During birth 23%

Question 3

Describe meconium

Answer 3

Dark green, sticky, lumpy faecal material produced during pregnancy

Question 4

When is meconium release?

Answer 4

After birth but sometimes in utero or during birth

Question 5

Describe the pathophysiology of meconium aspiration syndrome

Answer 5

After effect of in-utero peristalsis

Result of foetal hypoxic stress or vagal stimulation due to cord compression

Question 6

What does meconium stimulate release of once aspirated?

Answer 6

Vasoactive and cytokine substances that activate inflammatory pathways and trigger vascular changes

Question 7

What does meconium inhibit?

Answer 7

Effect of surfactant on the lungs

Question 8

What features are seen with MAS-related respiratory distress of the newborns?

Answer 8

Partial/total airway obstruction

Foetal hypoxia

Pulmonary inflammation

Infection

Surfactant inactivation

Persistent pulmonary hypertension

Question 9

List some risk factors for meconium aspiration

Answer 9

Gestational age >42 weeks

Foetal distress - tachycardia/bradycardia

Intrapartum hypoxia secondary to placenta; insufficiency

Thick meconium particles

APGAR <7

Chorioamnionitis and prolonged pre-rupture

Oligohydramnios

In utero growth restriction

Maternal HTN, DM, pre-eclampsia, eclampsia, smoking or drug abuse

Question 10

What may be noted on examination of a newborn with MAS?

Answer 10

Tachycardia
Tachypnoea
Cyanosis
Grunting
Nasal flaring
Recessions
Hypotension

Question 11

Describe the investigations and findings for MAS

Answer 11

CXR - increased lung volumes, pleural effusions, asymmetrical patchy pulmonary opacities, pneumothorax/mediastinum, multifocal consolidation

Infection markers - FBC, CRP, blood culture

ABG

Dual pulse oximetry - difference of 5-10% between limbs is significant of pathology

Echo - rule out CHD

Cranial ultrasound - hypoxic damage

Question 12

Describe the management of MAS

Answer 12

Careful observation

Infant warmer

O2 sat monitoring

Blood glucose, UE, FBC, CRP,
calcium

Nutritional support commenced on day 1 in form of IV fluids with aim to switch to NGT or oral feeds

Antibiotics if clinical suspicion of infection

Oxygen - nasal cannula, CPAP

Surfactant bolus

Inhaled nitric oxide

Corticosteroids

Question 13

List the complications of meconium aspiration

Answer 13

Air leak - pneumothorax or pneumomediastinum

PPHN

Cerebral palsy

Chronic lung disease