Meconium aspiration syndrome: Difference between revisions
No edit summary |
No edit summary |
||
| Line 3: | Line 3: | ||
*Presentation ranges from mild respiratory distress to life-threatening respiratory failure | *Presentation ranges from mild respiratory distress to life-threatening respiratory failure | ||
*Incidence is 2-10% of infants born through MSAF | *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 | *Causes hypoxemia and acidosis via airway obstruction, chemical irritation/inflammation, infection, and surfactant inactivation | ||
*Associated with persistent pulmonary hypertension of the newborn (PPHN) | *Associated with persistent pulmonary hypertension of the newborn (PPHN) | ||
| Line 24: | Line 25: | ||
*Pulmonary edema | *Pulmonary edema | ||
*Blood aspiration | *Blood aspiration | ||
*Pulmonary hypertension | |||
*Congenital heart disease | |||
*Respiratory distress syndrome | |||
==Evaluation== | ==Evaluation== | ||
| Line 48: | Line 52: | ||
==Management== | ==Management== | ||
*Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially) | *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 | |||
==Disposition== | ==Disposition== | ||
Revision as of 18:42, 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