Neonatal Resuscitation

Perspective

Approximately 10% of newborns require some resuscitative assistance at birth, and approximately 1% require extensive resuscitative measures.¹ Appropriate equipment and preparation, knowledge of neonatal physiology and response to stress, and skill in performing the necessary procedures are essential to successful resuscitation. Preparation for neonatal resuscitation requires an understanding of how it differs from pediatric and adult resuscitation, as follows:

1. Newborns have rapidly changing cardiopulmonary physiology, their own range of normal vital signs (Table 11-1), and unique responses to stress.^2,3

Table 11-1

Normal Vital Signs in the Newborn

2. The approach to newborn resuscitation focuses almost entirely on respiratory, not cardiac, management.²

3. Because of their small size, infants require special equipment.

Pathophysiology

Transition from Fetal to Extrauterine Life

The successful transition from the fetal to the extrauterine environment requires two major cardiorespiratory changes: (1) removal of fluid from unexpanded alveoli to allow ventilation and (2) redistribution of cardiac output to provide lung perfusion. Failure of the development of either adequate ventilation or adequate perfusion leads to shunting, hypoxia, and ultimately reversion to fetal physiology.²

In utero, the pulmonary alveoli are filled with pulmonary fluid and amniotic fluid. Removal of this fluid is partially accomplished by vaginal delivery, which compresses the fluid out of the alveoli into the bronchi, trachea, and pulmonary capillary bed. Most fluid is removed by the first few breaths. Expansion of alveoli requires the generation of high intrathoracic pressures and the presence of surfactant to maintain alveolar patency. The quality of the first few breaths is crucial to the establishment of adequate ventilation.

The fetal lung is poorly perfused. Because the pulmonary arterial bed is intensely vasoconstricted, the fetal lung receives only 40% of the right ventricular cardiac output; most of the right ventricular output is shunted from the pulmonary artery through the ductus arteriosus to the descending aorta.⁴ After the first few breaths, with exposure to alveolar oxygen, pulmonary vascular resistance decreases. The fetal shunt through the ductus arteriosus reverses as systemic vascular resistance increases; then the shunt usually ceases by 15 hours of age as the ductus also constricts. This reversal of flow allows all right ventricular output to perfuse the lungs. If hypoxia or severe acidosis occurs, however, the muscular pulmonary vascular bed constricts again, and the ductus may reopen. The reinstitution of fetal circulation, with its attendant shunting, leads to ongoing hypoxia and is termed persistent fetal circulation.^2,4 Resuscitation facilitates the first few breaths, prevents and reverses ongoing hypoxia and acidosis, and assists the newborn in the transition to extrauterine life.

Indications for Resuscitation

Any infant born outside of the controlled environment of the delivery room should be considered in need of resuscitation.1–3 Minimal intervention may be required, but a standardized approach as described in this chapter should be followed. Adequate ventilation and warming are essential to a successful resuscitation. Some specific conditions such as the ones presented here increase the likelihood that resuscitation will be required.

Premature infants, especially those born before 34 weeks of gestational age, pose a special problem because of their immature lungs and susceptibility to hypothermia. Rapid intubation should be initiated if the premature infant appears to be in respiratory distress with signs of retractions, desaturation, or tachypnea. Surfactant (approximately 100 mg/kg divided in four doses) may be delivered via the endotracheal tube (ETT) shortly after birth. Premature infants are also more susceptible to infection, so blood cultures and a complete blood count should be drawn, followed by intravenous antibiotics. The gastrointestinal system of the premature infant may not be capable of digesting maternal breast milk, so total parenteral nutrition is often required until the infant matures.

The presence of meconium in the amniotic fluid at delivery indicates that the infant has been stressed before delivery and warrants special consideration in resuscitation. When delivered, a nonvigorous infant with meconium in the amniotic fluid has the trachea suctioned before other steps in resuscitation are taken, to prevent aspiration of meconium.

Medications given to the mother or illicit drugs taken before delivery can lead to respiratory depression in the newborn. Maternal opioid administration or opioid use should be considered in any newborn with isolated respiratory depression that persists after successful initial resuscitation. As in adults, 0.1 mg/kg of naloxone administered to newborns may reverse respiratory depression caused by opioids. Naloxone may have a shorter half-life than the original maternal opioid; therefore the neonate should be monitored closely for recurrent apnea or hypoventilation, and subsequent doses of naloxone may be required.9,10 However, use of naloxone may precipitate acute withdrawal, seizures, or both in infants who have had prolonged intrauterine opioid exposure, and the overall effect and side effects of naloxone in the newborn are not fully known.^9,10 Therefore naloxone is not recommended as a first-line treatment in the initial resuscitation efforts. Support of ventilation may be preferable to reversal with naloxone.

Hemorrhage caused by abruptio placentae, placenta previa, trauma, or other complications can lead to respiratory depression and shock in the newborn. In the newborn, hemorrhage is one of the few situations in which fluid resuscitation is initially required.

No reliable set of parameters has been identified for newborns who should not receive resuscitative efforts.¹¹ Currently, resuscitation is not recommended for neonates with confirmed gestational age less than 23 weeks; those with birth weight less than 400 g; and those with confirmed anencephaly, trisomy 13, or trisomy 18.^11,12 If unsure of gestational age or birth weight limitations, the recommendation is to initiate resuscitation. In the out-of-hospital setting or in the emergency department, every attempt should be made to stabilize the neonate until it is clear that attempted or continued resuscitation would not improve the patient’s chance of survival. Infants with no signs of life (no heart beat and no respiratory effort) after 10 minutes of resuscitation show either a high mortality rate or severe later developmental delay. After 10 minutes of continuous and adequate resuscitative efforts, discontinuation may be justified if there are no signs of life.^12,13 It is important to communicate openly with the parent(s) and to acknowledge their opinions regarding risk of morbidity, including participation in the decision of whether or not to continue resuscitation.

Few specific disorders require deviations from the approach described here. The presence of meconium may necessitate intervention after delivery. Other anatomic anomalies require special care and include diaphragmatic hernia, meningomyelocele, abdominal anomalies (e.g., gastroschisis, omphalocele), and upper airway obstructive lesions (e.g., bilateral choanal atresia, Pierre Robin sequence).

Specific Disorders

Meconium Aspiration

Meconium in the amniotic fluid is a sign of in utero distress, and the presence of thick or particulate meconium before or at delivery should raise concern about the potential for aspiration. Aspiration of meconium and its consequences can be avoided by rapid intervention. Previous recommendations included suctioning meconium from the infant’s airway after delivery of the head but before delivery of the shoulders (intrapartum suctioning). However, evidence from a large multicenter trial did not show benefit from intrapartum suctioning.14–16 Therefore current recommendations no longer advise routine intrapartum suctioning for infants born to mothers with meconium-stained fluid. The decision to perform endotracheal intubation with tracheal suctioning after delivery of the infant should be made based on the vigor of the infant, rather than on the presence or consistency of the meconium (e.g., thick or particulate vs. thin). Infants with meconium-stained fluid and with any of the following are candidates for tracheal suctioning: (1) absent or depressed respirations, (2) poor muscle tone, or (3) HR less than 100 beats/min.² In such newborns, a meconium aspirator should be attached to the ETT and connected to wall suction at 100 mm Hg or less. The ETT is withdrawn as suction is being applied. After intubation, the ETT with meconium aspirator serves as the ideal suction catheter. Because of its narrower width, a suction catheter placed in the ETT does not suction meconium effectively. Reintubation and suction should be repeated until the meconium clears. Two passes of intubation and suctioning are usually sufficient. When these steps have been completed, the resuscitation should continue, beginning with the steps at the top of the neonatal flow algorithm (Fig. 11-1). If bradycardia or apnea continues beyond two passes, resuscitation should include bag-mask ventilation and consideration of intubation with ETT to secure the airway.

Figure 11-1 Neonatal resuscitation flow algorithm. Endotracheal intubation may be considered at several steps. CPAP, continuous positive airway pressure; HR, heart rate; IV, intravenous; PPV, positive pressure ventilation; SpO₂, oxygen saturation. (Modified from Kattwinkel J, et al: Part 15: Neonatal resuscitation: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation; 122:S909-S919, 2010. Copyright © 2010 American Heart Association.)

Anatomic Anomalies

Diaphragmatic Hernia

The neonate should be intubated as soon as possible if a prenatal diagnosis of diaphragmatic hernia has been made or if a diaphragmatic hernia is diagnosed on chest radiograph. Bag-mask ventilation distends the stomach and worsens respiratory distress because of the presence of the stomach in the chest cavity.

Meningomyelocele and Omphalocele

To avoid pressure on the defect, infants with meningomyelocele should not be placed on their backs but on their stomachs or sides. The resuscitation should be conducted in this position if possible. The spinal defect should be covered with sterile gauze pads soaked in warm sterile saline and covered with a plastic covering. Infants with gastroschisis or omphalocele should be resuscitated as needed, and the defect should be covered with an occlusive plastic covering to decrease water and heat loss.

Choanal Atresia

Because newborns are obligate nose breathers, bilateral choanal atresia causes upper airway obstruction and respiratory distress. It is diagnosed by the inability to pass a catheter through either naris into the oropharynx. An oral airway bypasses the obstruction.

Pierre Robin Sequence

Patients with Pierre Robin sequence have small jaws, and the relatively large tongue can lead to upper airway obstruction. A nasal or oral airway should be able to bypass the obstruction; if not, intubation may be necessary. It is technically difficult to intubate a patient with Pierre Robin sequence, so a laryngeal mask airway (LMA) may be placed instead.¹⁷ Consultation with anesthesiology may be needed.

Preparation

To maximize the effectiveness of resuscitation, the emergency department should have a prestocked drug pack, standardized equipment (Box 11-1), and staff familiar with newborn resuscitation.^1,3 The pediatric length-based resuscitation tape (Broselow-Luten tape) has a section that can be used to determine equipment size and drug dosages for newborn resuscitation for infants weighing 3 kg or more.^18,19

BOX 11-1 Equipment Needed for Neonatal Resuscitation