Meconium aspiration syndrome: Difference between revisions
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==Background== | ==Background== | ||
*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 (meconium-stained amniotic fluid) | ||
*Thought to be associated with fetal hypoxia and post-term delivery | *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) | ||
{{Newborn vital signs}} | |||
==Clinical Features== | ==Clinical Features== | ||
*Tachypnea | *Usually develop symptoms within 15 minutes after birth | ||
*[[Tachypnea]] | |||
*Cyanosis | *Cyanosis | ||
*Accessory muscle use (intercostal/subxiphoid retractions, paradoxical breathing, grunting, nasal flaring) | *[[Shortness of breath (peds)|Accessory muscle use]] (intercostal/subxiphoid retractions, paradoxical breathing, grunting, nasal flaring) | ||
*Barrel-shaped chest | *Barrel-shaped chest | ||
*Rales and rhonchi on lung auscultation | *Rales and rhonchi on lung auscultation | ||
*Pneumothorax | *[[Pneumothorax]] | ||
*Pneumomediastinum | *[[Pneumomediastinum]] | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
*[[Sepsis]] | *[[Sepsis]] | ||
*[[Pneumonia]] | *[[Pneumonia]] | ||
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*[[Pulmonary hypertension]] | *[[Pulmonary hypertension]] | ||
*[[Congenital heart disease]] | *[[Congenital heart disease]] | ||
{{Newborn DDX}} | |||
==Evaluation== | ==Evaluation== | ||
* | ===Workup=== | ||
** | *[[CXR]] | ||
** | **Streaky, linear densities | ||
** | **Hyperinflated lungs and flattened diaphragm | ||
**Blood and sputum cultures | **Diffuse patchy opacities (may appear similar to RDS if severe) | ||
*[[ABG]] | |||
*[[Echocardiography]] | |||
*Blood and sputum cultures | |||
===Diagnosis=== | |||
*Clinical diagnosis based on the following: | *Clinical diagnosis based on the following: | ||
**Evidence of meconium on infant | **Evidence of meconium on infant | ||
**Respiratory distress shortly after birth | **Respiratory distress shortly after birth | ||
**Characteristic CXR findings | **Characteristic CXR findings | ||
**If intubation required, meconium visualized in trachea | **If intubation required, meconium visualized in trachea | ||
*Ways to differentiate between other causes of respiratory distress in a neonate: | *Ways to differentiate between other causes of respiratory distress in a neonate: | ||
** | **[[Transient tachypnea of the newborn]] 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 | **Delayed transition from fetal circulation symptoms improve more quickly than those of MAS | ||
**Congenital cyanotic heart disease is differentiated by physical exam ( | **[[Congenital heart disease|Congenital cyanotic heart disease]] is differentiated by physical exam ([[murmur]]s, [[hepatomegaly]]), CXR (cardiac size/shape), and echocardiogram (cardiac anatomy and function) | ||
==Management== | ==Management== | ||
*Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially) | *Supportive care: see [[newborn resuscitation]] | ||
**Adequate oxygenation and ventilation | |||
***Supplemental [[oxygen]] to keep saturation >99% and PaO2 55-90 | |||
***Assisted ventilation with [[CPAP]] if FiO2 exceeds 0.4 to 0.5 | |||
* | ***High frequency oscillatory ventilation or ECMO for those who fail conventional mechanical ventilation | ||
***Goal PaCO2 50-55 mmHg | |||
**Maintain blood pressure and perfusion | |||
***Umbilical lines to monitor blood gases and BP | |||
**Correct metabolic abnormalities | |||
*Empiric [[pediatric antibiotics|antibiotics]] while awaiting culture results (because of difficulty differentiating between pneumonia initially) | |||
*Surfactant administration for severe disease requiring mechanical ventilation, FiO2>0.5, and mean airway pressure >10-12 | |||
==Disposition== | ==Disposition== | ||
*Admit to NICU | |||
==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 | |||
==See Also== | ==See Also== | ||
*[[Newborn resuscitation]] | |||
==External Links== | ==External Links== | ||
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==References== | ==References== | ||
<references/> | <references/> | ||
[[Category:Pediatrics]] |
Revision as of 16:56, 1 July 2020
Background
- Presentation ranges from mild respiratory distress to life-threatening respiratory failure
- Incidence is 2-10% of infants born through MSAF (meconium-stained amniotic fluid)
- 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)
Newborn Vital Signs[1]
Age | Pulse^ | Respiratory Rate | Systolic BP |
Preterm < 1 kg | 120-160 | 30-60 | 36-58 |
Preterm 1 kg | 120-160 | 30-60 | 42-66 |
Preterm 2 kg | 120-160 | 30-60 | 50-72 |
Newborn | 126-160 | 30-60 | 60-70 |
Min of life | Target sat^^ |
---|---|
1 min | 60-65% |
2 min | 65-70% |
3 min | 70-75% |
4 min | 75-80% |
5 min | 80-85% |
10 min | 85-95% |
^Fever directly causes an increase in heart rate of 10 beats per minute per degree centigrade[2] ^^Hyperoxia can be harmful
Clinical Features
- Usually develop symptoms within 15 minutes after birth
- Tachypnea
- Cyanosis
- Accessory muscle use (intercostal/subxiphoid retractions, paradoxical breathing, grunting, nasal flaring)
- Barrel-shaped chest
- Rales and rhonchi on lung auscultation
- Pneumothorax
- Pneumomediastinum
Differential Diagnosis
- Sepsis
- Pneumonia
- Delayed transition from fetal circulation
- Pneumothorax
- Pulmonary edema
- Blood aspiration
- Pulmonary hypertension
- Congenital heart disease
Newborn Problems
- Newborn resuscitation
- Hypoxia
- Primary apnea
- Secondary apnea
- Hypothermia
- Hypoglycemia
- Meconium aspiration syndrome
- Anemia (abruption)
- Infant scalp hematoma
- Transient tachypnea of the newborn
- Respiratory distress syndrome
- Congenital pneumonia
- Congenital heart disease
- Neonatal sepsis
- Pneumothorax
- Pulmonary hypertension
Evaluation
Workup
- CXR
- Streaky, linear densities
- Hyperinflated lungs and flattened diaphragm
- Diffuse patchy opacities (may appear similar to RDS if severe)
- ABG
- Echocardiography
- Blood and sputum cultures
Diagnosis
- Clinical diagnosis based on the following:
- Evidence of meconium on infant
- Respiratory distress shortly after birth
- Characteristic CXR findings
- If intubation required, meconium visualized in trachea
- Ways to differentiate between other causes of respiratory distress in a neonate:
- Transient tachypnea of the newborn 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
- Supportive care: see newborn resuscitation
- Adequate oxygenation and ventilation
- Maintain blood pressure and perfusion
- Umbilical lines to monitor blood gases and BP
- Correct metabolic abnormalities
- Empiric antibiotics while awaiting culture results (because of difficulty differentiating between pneumonia initially)
- Surfactant administration for severe disease requiring mechanical ventilation, FiO2>0.5, and mean airway pressure >10-12
Disposition
- Admit to NICU
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
See Also
External Links
References
- ↑ National-Model-EMS-Clinical-Guidelines-23Oct2014
- ↑ Davies P, Maconochie I. The relationship between body temperature, heart rate and respiratory rate in children. Emerg Med J. 2009 Sep;26(9):641-3. doi: 10.1136/emj.2008.061598.