Meconium Aspiration Syndrome Flashcards
1
Q
What is Meconium?
A
- Meconium is the dark green, sticky and lumpy faecal material produced during pregnancy
- It is usually released from the bowels after birth
- But in some pregnancies the baby can pass meconium in utero
2
Q
What is Meconium Aspiration Syndrome?
A
- When the baby passes meconium in utero which causes aspiration of meconium-stained amniotic fluid and then the baby develops Meconium Aspiration Syndrome.
- This causes the new-born to develop respiratory distress
3
Q
What is the Pathophysiology of Meconium Aspiration Syndrome?
A
- Aspiration of Meconium-Stained Amniotic Fluid causes in utero peristalsis
-Once the Meconium is aspirated it can stimulate the release of vasoactive and cytokine substances that activate inflammatory pathways and triggering vasculature changes - It also inhibits the effect of surfactant
4
Q
What are the common complications of MAS related respiratory distress?
A
PPIPS
- Partial/ Complete Airway Obstruction
- Pulmonary Inflammation
- Infection
- Persistent Pulmonary Hypertension
- Surfactant Inactivation
+ Foetal Hypoxia
5
Q
What is Partial/ Total Airway Obstruction?
A
- Due to the thick and sticky consistency of meconium it can cause partial/ total mechanical airway obstruction
- This leads to a decrease in pulmonary ventilation and may lead to atelectasis with air trapping
- There is an increase in the pulmonary pressure which creates a V/Q mismatch leading to severe foetal hypoxia
6
Q
What is Foetal Hypoxia?
A
- Caused by: V/Q mismatch, increase of pulmonary vascular pressures, mechanical obstruction, airway oedema or surfactant inactivation
7
Q
What is Pulmonary Inflammation?
A
- Meconium contains many pro-inflammatory cytokines such as TNF and Interleukins that directly/ indirectly contribute to lung tissue injury, surfactant inactivation and infection
8
Q
What is Infection in MAC?
A
- The inflammation process predisposes the foetal lung to a risk of infection
9
Q
What is Surfactant Inactivation?
A
- The inflammatory reaction caused by meconium deactivates surfactant which increase the surface tension of the alveoli. This reduces the efficiency of gas exchange.
10
Q
What is Persistent Pulmonary Hypertension?
A
- PPHN, results from remodelling of the pulmonary vascular bed in response to hypoxia
11
Q
What are the risk factors of MAS?
A
- Gestational Age >42 weeks
- Foetal Distress
- Thick Meconium Particles
- Apgar Score <7
- Chorioamnionitis
- Oligohydramnios
12
Q
What are the clinical features of MAS?
A
- Signs of Respiratory Distress:
- Tachypnoea >60
- Tachycardia >160
- Cyanosis
- Grunting
- Nasal Flaring
- Recessions (Subcostal, Intercostal)
- Hypotension
13
Q
What are the Investigations for MAS?
A
- Chest X-Ray: increased lung volumes, pleural effusions, Pneumothorax and multifocal consolidation
- Infection Markers: FBC, CRP, Blood Cultures
- ABG (check for any metabolic acidosis - sample taken from umbilical artery catheter)
- Dual Pulse Oximetry
- ECHO (used to exclude any heart abnormalities)
- Cranial USS (used to assess for any hypoxic damage to the brain)
14
Q
What is the differential Diagnosis?
A
- Transient Tachypnoea of the Newborn
- Surfactant Deficiency
- Persistent Pulmonary Hypertension
15
Q
What is the management of MAS?
A
- Observation for respiratory distress need to be taken with Newborns
- Routine Care: Newborns should be under an infant warmer (hypothermia inhibits surfactant), Continuous oxygen sats should be monitored, Blood Glucose, U+Es, FBC, CRP and Calcium may need to be assessed and Nutritional Support commenced in the form of IV fluids
- Ventilation and Oxygen therapy
- Antibiotics (clinical suspicion of infection)
- Surfactant: bolus administered in new-borns if pneumothorax is present
- Inhaled Nitric Oxide: In new-borns with pulmonary hypertension iNO should be considered
