Meconium Aspiration Syndrome Treatment & Management

Updated: Jan 14, 2014
  • Author: Melinda B Clark, MD; Chief Editor: Ted Rosenkrantz, MD  more...
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Treatment

Medical Care

The American College of Obstetricians and Gynecologists continues to provide guidance regarding the appropriate indications for delivery to prevent neonatal complications of a prolonged pregnancy as well as avoiding the unnecessary delivery of a preterm baby. [10, 11]

In patients with meconium aspiration syndrome (MAS), thorough cardiac examination and echocardiography are necessary to evaluate for congenital heart disease and persistent pulmonary hypertension of the newborn (PPHN).

Confirming the degree of pulmonary hypertension, prior to instituting therapy, is extremely important.

Prevention of meconium aspiration syndrome (MAS)

Prevention is paramount. Obstetricians should closely monitor fetal status in an attempt to identify fetal distress.

When meconium is detected, amnioinfusion with warm, sterile saline is theoretically beneficial to dilute the meconium in the amniotic fluid, thereby minimizing the severity of the aspiration. However, current evidence does notsupport routine amnioinfusion to prevent meconium aspiration syndrome. [12, 13, 14] One large, multicenter study determined that amnioinfusion did not reduce the risk of moderate or severe meconium aspiration syndrome or meconium aspiration syndrome–related death. [15]

Current recommendations no longer advise routine intrapartum suctioning for infants born to mothers with meconium staining of the amniotic fluid. [16, 17]

When aspiration occurs, intubation and immediate suctioning of the airway can remove much of the aspirated meconium.

No clinical trials justify suctioning based on the consistency of meconium. Do NOT perform the following harmful techniques in an attempt to prevent aspiration of meconium-stained amniotic fluid:

  • Squeezing the chest of the baby
  • Inserting a finger into the mouth of the baby

The American Academy of Pediatrics Neonatal Resuscitation Program Steering Committee and the American Heart Association have promulgated guidelines for management of the baby exposed to meconium. The guidelines are under continuous review and are revised as new evidence-based research becomes available. The guidelines are as follows [18] :

  • If the baby is not vigorous (defined as depressed respiratory effort, poor muscle tone, and/or heart rate < 100 beats/min): Use direct laryngoscopy, intubate, and suction the trachea immediately after delivery. Suction for no longer than 5 seconds. If no meconium is retrieved, do not repeat intubation and suction. If meconium is retrieved and no bradycardia is present, reintubate and suction. If the heart rate is low, administer positive pressure ventilation and consider suctioning again later.
  • If the baby is vigorous (defined as normal respiratory effort, normal muscle tone, and heart rate >100 beats/min): Do not electively intubate. Clear secretions and meconium from the mouth and nose with a bulb syringe or a large-bore suction catheter.
  • In both cases, the remainder of the initial resuscitation steps should ensue, including drying, stimulating, repositioning, and administering oxygen as necessary.

Continued care in the neonatal ICU (NICU)

Maintain an optimal thermal environment to minimize oxygen consumption.

Minimal handling is essential because these infants are easily agitated. Agitation can increase pulmonary hypertension and right-to-left shunting, leading to additional hypoxia and acidosis. Sedation may be necessary to decrease agitation.

An umbilical artery catheter should be inserted to monitor blood pH and blood gases without agitating the infant.

Continue respiratory care. Oxygen therapy via hood or positive pressure is crucial in maintaining adequate arterial oxygenation. Mechanical ventilation is required by approximately 30% of infants with meconium aspiration syndrome. [5] Make concerted efforts to minimize the mean airway pressure and to use as short an inspiratory time as possible. Oxygen saturations should be maintained at 90-95%.

Surfactant therapy is commonly used to replace displaced or inactivated surfactant and as a detergent to remove meconium. [19, 20, 21] Although surfactant use does not appear to affect mortality rates, it may reduce the severity of disease, progression to extracorporeal membrane oxygenation (ECMO), [22] and decrease length of hospital stay.

Although conventional ventilation commonly is initially used, high-frequency oscillation and jet ventilation are alternative effective therapies. Hyperventilation to induce hypocapnia and compensate for metabolic acidosis is no longer a primary therapy for pulmonary hypertension because hypocarbia often results in decreased cerebral perfusion (PaCO2 < 30 mm Hg). Prolonged alkalosis has been shown to cause neuronal injury in animals and humans, providing another reason to avoid alkalosis in these patients. [23]

Ventilator therapy aimed at minimizing mean airway pressure and tidal vlume should be used if pulmonary interstitial emphysema or a pneumothorax is present.

For treatment of persistent pulmonary hypertension of the newborn (PPHN), inhaled nitric oxide is the pulmonary vasodilator of choice. [24] Oxygen is also a potent pulmonary vasculature vasodilator. Phosphodiesterase inhibitors, including sildenafil and milrinone, are being increasingly used as adjunctive therapies for PPHN.

Pay careful attention to systemic blood volume and blood pressure. Volume expansion, transfusion therapy, and systemic vasopressors are critical in maintaining systemic blood pressure greater than pulmonary blood pressure, thereby decreasing the right-to-left shunt through the patent ductus arteriosus. Dopamine is often the first-line vasopressor for neonates with meconium aspiration syndrome requiring vasopressor support.

Ensure adequate oxygen carrying capacity by maintaining the hemoglobin concentration of at least 13 g/dL.

Corticosteroids are not recommended. Evidence supporting the use of steroids in the management of meconium aspiration syndrome is insufficient. [25]

Neonates with meconium aspiration syndrome have historically been routinely treated with empiric broad-spectrum antibiotics, but this practice is being increasingly called into question. No studies have shown prophylactic antibiotics to reduce the incidence of sepsis in neonates born through meconium-stained amniotic fluid; thus, antibiotic use may be reserved for suspected or documented infections.

Extracorporeal membrane oxygenation (ECMO) is used if all other therapeutic options have been exhausted. Although effective in treating meconium aspiration syndrome, ECMO is associated with a high incidence of poor neurologic outcomes.

Consultations

Evaluation by a pediatric cardiologist is necessary for echocardiographic assessment of the cardiac structures and to assess the severity of pulmonary hypertension and right-to-left shunting.

Evaluation by a pediatric neurologist is helpful in the presence of neonatal encephalopathy or seizure activity.

Transfer

Although initial stabilization is necessary at community hospitals, infants with meconium aspiration syndrome frequently require high-frequency ventilation, inhaled nitric oxide (NO), or extracorporeal membrane oxygenation (ECMO). Therefore, infants with a significant aspiration should be transferred to a regional neonatal ICU (NICU) as soon as possible.

Diet

Perinatal distress and severe respiratory distress preclude feeding.

Intravenous fluid therapy begins with adequate dextrose infusion to prevent hypoglycemia. Intravenous fluids should be provided at mildly restricted rates (60-70 mL/kg/d).

Progressively add electrolytes, protein, lipids, and vitamins to ensure adequate nutrition and prevent essential amino acid and essential fatty acid deficiencies.

Outpatient care

Infants with meconium aspiration syndrome are at increased risk for adverse developmental outcomes and should be referred for developmental assessment as an outpatient

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Surgical Care

Although primary management of air block syndromes (pneumothorax or pneumopericardium) is achieved by thoracic drainage tubes inserted by a neonatologist, a pediatric surgical consultation may be necessary in severe cases. Therapy with fibrin glue has been shown to be effective in patients with a persistent air leak. [26]

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