Meconium aspiration syndrome: Difference between revisions
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==Differential Diagnosis== | ==Differential Diagnosis== | ||
*Transient tachypnea of the newborn (TTN) | *[[Transient tachypnea of the newborn]] (TTN) | ||
*Sepsis | *[[Sepsis]] | ||
*Pneumonia | *[[Pneumonia]] | ||
*Delayed transition from fetal circulation | *Delayed transition from fetal circulation | ||
*Pneumothorax | *[[Pneumothorax]] | ||
*Pulmonary edema | *[[Pulmonary edema]] | ||
*Blood aspiration | *Blood aspiration | ||
*Pulmonary hypertension | *[[Pulmonary hypertension]] | ||
*Congenital heart disease | *[[Congenital heart disease]] | ||
*Respiratory distress syndrome | *[[Respiratory distress syndrome]] | ||
==Evaluation== | ==Evaluation== | ||
Revision as of 20:56, 11 October 2017
Background
- May cause meconium aspiration syndrome (MAS) in a newborn infant that was born through meconium-stained amniotic fluid (MSAF)
- Presentation ranges from mild respiratory distress to life-threatening respiratory failure
- Incidence is 2-10% of infants born through MSAF
- Thought to be associated with fetal hypoxia and post-term delivery
- Causes hypoxemia and acidosis via airway obstruction, chemical irritation/inflammation, infection, and surfactant inactivation
- Associated with persistent pulmonary hypertension of the newborn (PPHN)
Clinical Features
- Tachypnea
- Cyanosis
- Accessory muscle use (intercostal/subxiphoid retractions, paradoxical breathing, grunting, nasal flaring)
- Barrel-shaped chest
- Rales and rhonchi on lung auscultation
- Pneumothorax
- Pneumomediastinum
- Usually develop symptoms immediately after birth, but sometimes are born asymptomatic and develop symptoms as meconium moves into lower tracheobronchial tree
Differential Diagnosis
- Transient tachypnea of the newborn (TTN)
- Sepsis
- Pneumonia
- Delayed transition from fetal circulation
- Pneumothorax
- Pulmonary edema
- Blood aspiration
- Pulmonary hypertension
- Congenital heart disease
- Respiratory distress syndrome
Evaluation
- Workup
- CXR
- ABG
- Echocardiogram
- Blood and sputum cultures
- Clinical diagnosis based on the following:
- Evidence of meconium on infant
- Respiratory distress shortly after birth
- Characteristic CXR findings
- Initially, streaky, linear densities
- Next, development of hyperinflated lungs and flattened diaphragm
- Finally, diffuse patchy opacities (may appear similar to ARDS if severe)
- If intubation required, meconium visualized in trachea
- Ways to differentiate between other causes of respiratory distress in a neonate:
- TTN is more common in late preterm infants (34-37 weeks) and RDS in preterm infants, whereas MAS more common in postmature infants (>41 weeks)
- Delayed transition from fetal circulation symptoms improve more quickly than those of MAS
- Congenital cyanotic heart disease is differentiated by physical exam (murmurs, hepatomegaly), CXR (cardiac size/shape), and echocardiogram (cardiac anatomy and function)
Management
- Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially)
- Prevention
- Fetal heart rate monitoring intrapartum to reduce risk of fetal hypoxia
- Induction of labor after 41 weeks gestation to reduce postmature delivery
- Amnioinfusion with isotonic fluid to dilute thick meconium is NOT routinely recommended