Emergencies

James M. Greenberg

Certain medical and surgical conditions presenting at delivery or during the neonatal period require prompt diagnosis and timely treatment to effect a good outcome. Recent advances in prenatal diagnostic technology, including ultrasound techniques, fetal echocardiography, and fetal MRI imaging, can facilitate prenatal counseling as well as plans for delivery room and neonatal management. However, these techniques do not substitute for a careful newborn assessment and postnatal imaging to confirm and expand upon any prenatal diagnostic studies. Coordination of care is essential, because these conditions typically require the involvement of surgical and medical subspecialty providers. The neonatologist or pediatrician should ensure intervention is timely and in the patient’s best interest, and should facilitate appropriate communication with family.

RESPIRATORY DISTRESS

The successful transition to extrauterine life depends upon patent, structurally intact airways and specific physiologic shifts in pulmonary vascular resistance and parenchymal water transport. Upper airway obstruction is usually evident at or shortly after birth by increased work of breathing, diminished air entry, poor perfusion, and in extreme cases, cyanosis. Craniofacial anomalies can affect nasopharyngeal patency. Choanal atresia usually involves the posterior nasal septum of one or both choanae and can be anticipated by inability to pass a 5-Fr. catheter into the posterior pharynx. Micrognathia associated with conditions such as Pierre Robin syndrome may be sufficiently severe to cause posterior displacement of the tongue and airway obstruction. Similarly, severe macroglossia seen in association with Beckwith-Wiedemann syndrome or subglossal cysts such as cannulae can cause functional obstruction of the proximal airway. In many instances of proximal airway obstruction, prone positioning and placement of an oral airway may relieve symptoms until surgical correction is possible. Severe cases may require tracheostomy. Antenatal diagnostic studies may facilitate delivery room management. Several centers report successful treatment of upper airway obstruction prior to delivery with the infant still attached to the placental circulation.^1,2

Anomalous development of the larynx and proximal trachea may present with symptoms ranging from subtle stridor to acute catastrophic respiratory distress. Inspiratory stridor is most often associated with laryngomalacia due to redundant aryepiglottic folds or an enlarged, floppy epiglottis. Despite the stridor, respiratory compromise is less common. If feeding problems or respiratory distress persist, surgical laryngoplasty often yields good results. Unilateral vocal cord paralysis usually presents with stridor, while bilateral cord paralysis often presents as acute airway obstruction with severe respiratory distress requiring urgent intervention.

Unusual anomalies of the upper airway include laryngeal cysts, tracheal stenosis, and laryngotracheal clefts. The extent of symptoms and extent of intervention are functions of the severity of the defect. Tracheal atresia with complete high airway obstruction syndrome (CHAOS) is not compatible with survival unless diagnosed during the prenatal period. Extended survival beyond the delivery room has been reported in patients treated with tracheostomy at the time of delivery.³

Extrinsic compression of conducting airways can occur with congenital tumors of the neck or mediastinum. Cystic hygromas and cervical teratomas are most often implicated. Optimal management depends upon prenatal diagnosis that allows for careful planning for delivery room management and parental guidance. Those with associated polyhydramnios or hydrops are at highest risk for critical airway compromise.

Lesions of pulmonary parenchyma may cause respiratory distress during the neonatal period. These include congenital cystic adenomatoid malformations, pulmonary sequestration, congenital lobar emphysema, and bronchogenic cysts. Often, the respiratory distress is related to ball-valve phenomena and progressive air trapping. Pulmonary hypoplasia should be considered in any newborn with hypoxic respiratory distress, especially with an associated history of oligohydramnios or findings of skeletal dysplasia. The spectrum of severity is broad, which may make immediate decisions regarding care difficult. A newborn presenting with profound respiratory distress and a prenatal diagnosis of renal agenesis with associated anhydramnios will not survive and should receive only comfort care in the delivery suite. Other cases are more ambiguous. Prenatal imaging techniques to assess lung volume are improving but still have intrinsic variability and require more study. It is important to remember that such studies evaluate volume but not function. Similarly, the relationship between renal function and lung growth is well documented but remains difficult to quantify. Often, the best approach in the delivery room involves expectant management and continuous assessment of the neonate’s clinical course and response to treatment.

Congenital diaphragmatic hernia represents a specific form of pulmonary hypoplasia caused by herniation of abdominal contents into the chest through a defect in the diaphragm. Approximately 90% of congenital diaphragmatic hernias occur on the left side. Improvement in the medical and surgical management of this congenital malformation has improved published survival rates to as high as 80% in some centers.⁴ Optimal delivery room management depends upon prenatal diagnosis. With advance warning, the appropriate team of delivery room personnel can be assembled. After delivery, the infant is immediately intubated with simultaneous placement of a suction catheter for gastric decompression. Positive pressure is provided to achieve sufficient postductal oxygenation and ventilation to prevent metabolic acidosis and support normal major organ system function. Early management focuses on treatment of any pulmonary hypertension. Surgical correction typically takes place only after stabilization of respiratory function and pulmonary artery pressure, often many days after delivery (see Chapter 50).

Most neonates presenting with early-onset respiratory distress have residual lung fluid or parenchymal lung disease that will respond to treatment with supplemental oxygen and, if needed, positive pressure. Available history and physical examination, along with judicious diagnostic testing, directs subsequent management. Noninvasive monitoring of oxygen saturation via pulse oximetry is a useful adjunct for screening the newborn infant with respiratory distress. If pulmonary hypertension is suspected, the application of pulse oximetry probes in preductal and postductal locations can provide rapid detection of right-to-left shunting. Often, blood gas analysis and chest x-ray provide sufficient information to make a diagnosis and initiate an appropriate treatment plan. Early-onset respiratory distress due to delayed clearance of alveolar lung fluid is most often seen in association with cesarean or precipitous deliveries. Comfortable tachypnea is typical. Ventilation is usually normal, with a transient oxygen requirement for less than 24 hours.

Respiratory distress syndrome due to pulmonary surfactant deficiency presents as early-onset respiratory distress characterized by a prolonged expiratory phase, grunting, and retractions (see Chapter 54). Progressive hypoxia and hypercarbia are the norm. The natural clinical course of respiratory distress syndrome peaks in severity at 24 to 48 hours, followed by gradual resolution. Severe cases require positive pressure support as continuous positive airway pressure or time-cycled intermittent mandatory ventilation and surfactant replacement therapy.

Pneumothorax during the early neonatal period may occur spontaneously or following administration of positive pressure.⁵ The amount of positive pressure needed to produce a pneumothorax is variable, but in general, the risk increases with increasing mean airway pressure. Diseased or hypoplastic lungs are more prone to this complication. Diagnosis is made on the basis of asymmetric breath sounds and transillumination of the affected hemithorax and may require confirmation by chest radiograph. Needle aspiration of a suspected pneumothorax is indicated with a high index of clinical suspicion and severe respiratory distress. Chest tube placement for continuous evacuation of free air may be required for patients receiving positive pressure ventilation.

For further discussion of many of the above disorders see Chapters 50, 54, 370, and 371.

CYANOSIS WITHOUT RESPIRATORY DISTRESS

Cyanosis without respiratory distress usually implies the presence of a fixed cardiopulmonary shunt allowing deoxygenated blood draining into the right atrium to bypass the pulmonary circulation. Occasionally, a newborn experiencing a delayed decrease in pulmonary vascular resistance may appear cyanotic without associated respiratory problems. A cyanotic appearance is also noted in some infants with polycythemia. A neonate with early-onset sepsis may appear cyanotic prior to demonstrating other signs or symptoms of infection. As with clinical respiratory distress, evaluation of the cyanotic infant is facilitated by careful history and physical examination, pulse oximetry, blood gas analysis (preferably from an arterial source with attention to preductal or postductal location), and a chest x-ray. Patients with suspected fixed intracardiac shunts should be started on prostaglandin E1 infusion at 0.05 μg/kg/min to maintain ductal patency until additional diagnostic studies can be performed.⁶ Fluid boluses may also improve oxygenation by enhancing mixing via the ductus arteriosus. For further details, see Chapter 49.

GASTROINTESTINAL EMERGENCIES

Transient feeding difficulties and emesis are typical during the neonatal period. These must be distinguished from pathologic gastrointestinal problems that require immediate evaluation. Congenital obstruction of the alimentary tract may occur at any location from esophagus to distal colon. Symptoms may vary. Any infant presenting with bilious emesis of any volume or recurrent emesis with volumes in excess of 20 to 25 ml requires evaluation (see Chapter 389). Other symptoms requiring immediate attention include abdominal distention, absence of stool passage within the first 48 hours of delivery, hematochezia, discoloration of the abdominal wall, and persistent lack of feeding interest, especially after 24 hours of age. The presence or absence of bowel sounds has limited diagnostic value because neonates with pathologic bowel obstruction may still have audible bowel sounds of normal quality. In addition to a careful feeding history and physical examination, an abdominal radiograph is a useful screening test. However, bowel gas patterns may appear normal in certain pathologic conditions. It is always important to integrate the entire clinical presentation, physical examination, and screening tests to develop an appropriate management strategy.

Esophageal atresia presents within 24 hours of delivery with feeding intolerance, excess salivation, and respiratory distress. A chest radiograph obtained after placement of a nasoenteric feeding tube can be diagnostic, demonstrating the tip in the proximal esophageal pouch. A neonate with suspected esophageal atresia should be referred to a tertiary center for comprehensive diagnostic evaluation and surgical management. Stabilization includes decompression of the proximal pouch and provision of intravenous fluids. A detailed discussion of anatomic disorders of the esopahgus is provided in Chapter 392.

Abdominal wall defects include omphalocele, gastroschisis, and bladder and cloacal exstrophies.⁸ These are discussed in Chapter 396.

Early management of abdominal wall defects includes immediate covering of herniated abdominal contents. Saline-soaked dressing have been traditionally used, but a preferable alternative involves placing the caudal portion of the infant, including the abdominal wall defect, into a sterile bag partially filled with warmed, sterile saline solution. The opening of the bag can be gently cinched around the chest of the infant. This approach minimizes insensible water loss, prevents desiccation injury of exposed bowel or bladder mucosa, and reduces the potential for injury from directly contacting the exposed tissue with gauze. Newborn infants with abdominal wall defects should have intravenous fluids started in the delivery room. Those with gastroschisis or omphalocele require placement of a nasogastric tube to minimize bowel distention. Immediate surgical evaluation and management is essential for successful treatment.

NEUROLOGIC EMERGENCIES

Assessment of neurologic status in the newborn infant is nonspecific with limited specificity and sensitivity. However, certain signs of neurologic dysfunction require immediate evaluation. Apnea is common, especially in preterm infants. Sustained apnea must be distinguished from periodic breathing. Sustained or pathologic apnea is accompanied by changes in color and perfusion. Any suspicious apnea must be evaluated with pulse oximetry and blood gas analysis. Apnea may be a reflection of systemic disease, heralding sepsis, meningitis, or pulmonary pathology. Apnea may also indicate a primary neurologic problem. Neonatal seizures may present as apnea. Hypoxicischemic insults or intracranial hemorrhage may result in apnea at delivery. Maternal medications such as narcotics or barbiturates may cross the placenta and blunt respiratory drive. Therapeutic intervention is based on supporting appropriate ventilation and oxygenation. In some instances, tactile stimulation is sufficient to address apneic events. However, persistent apnea should be treated with positive pressure ventilation (not necessarily with tracheal intubation) to maintain normal acid-base balance and normocarbia and to prevent hypoxia until the cause can be determined or eradicated. Diagnostic evaluation should be developed on the basis of presenting signs and symptoms and may include imaging studies of the brain, diagnostic studies of cerebral spinal fluid, blood gas analysis, and evaluation for infection.

Seizures may have infectious, metabolic, traumatic, or structural origins. Clinical seizure activity is often subtle and may be mistaken for normal movement. Rhythmic, repetitive movements with an unresponsive affect should alert caregivers, especially if the clinical history implies increased risk for a neurologic insult. Treatment with anticonvulsants such as phenobarbital is indicated if seizure activity is suspected. Diagnostic evaluation should always accompany therapeutic intervention. Screening includes evaluation for disturbances of electrolytes (particularly Na⁺) and glucose, cerebral spinal fluid studies, intracranial imaging, and electroencephalography. In many instances, etiologic studies fail to identify a cause.

Neural tube defects must be urgently addressed unless completely covered by intact skin. The exposed area should be covered with an occlusive, sterile, saline-soaked dressing to ensure that exposed membranes and neuronal tissue do not desiccate. Lesions with ruptured coverings or those leaking spinal fluid are at particular risk for infection. Initiation of antibiotic treatment is important. Prompt neurosurgical evaluation and treatment is essential to optimize neurodevelopmental prognosis. Management of these disorders is further discussed in Chapter 549.

REFERENCES

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