Cyanosis is a common finding in the newborn. The first step is differentiating central cyanosis from peripheral cyanosis.
Peripheral cyanosis, or acrocyanosis, is a normal finding in the first few days of life secondary to vasomotor instability and requires no specific evaluation or intervention. Central cyanosis is cyanosis involving the mucous membranes/lips, tongue, and skin. It indicates the presence of at least 4 to 5 grams/dL of unsaturated hemoglobin. The very anemic newborn may present as pale but not cyanotic if the level of unsaturated hemoglobin is below the 4 to 5 grams/dL threshold.
The breathing pattern often provides valuable clues to the cause of cyanosis (Table 108-6). On auscultation, unilaterally decreased breath sounds with retractions are associated with a pneumothorax or a space-occupying lesion of the chest. Bilaterally decreased breath sounds with retractions may suggest upper airway obstruction. Stridor also suggests an upper airway cause. Rales and rhonchi may be heard with pneumonia, respiratory distress syndrome, or meconium aspiration syndrome.
TABLE 108-6Causes of Neonatal Central Cyanosis ||Download (.pdf) TABLE 108-6 Causes of Neonatal Central Cyanosis
|Airway Obstruction (retractions and/or grunting respirations; stridor) ||Cardiac Disorders (tachypnea*, no grunting or retractions) ||Pulmonary Disorders (tachypnea* with grunting and/or retractions; rales or rhonchi) ||CNS and Metabolic Disorders (slow, shallow respirations without retractions) |
|Choanal atresia ||Transposition of great arteries ||Respiratory distress syndrome ||Intracranial hemorrhage |
|Laryngeal web/cyst ||Tricuspid atresia ||Meconium aspiration syndrome ||Brain anomalies (Dandy-Walker malformation, congenital hydrocephalus) |
|Tracheal stenosis ||Truncus arteriosus ||Pneumonia ||Central hypoventilation syndrome |
|Pierre Robin sequence ||Total anomalous pulmonary venous return ||Congenital diaphragmatic hernia ||Polycythemia |
|Cystic hygroma/goiter ||Pulmonary atresia ||Pulmonary hypoplasia ||Hypoglycemia |
| ||Coarctation of aorta ||Congenital lobar emphysema ||Sepsis/shock |
|Hypoplastic left heart syndrome ||Congenital cystic adenomatoid malformation ||Methemoglobinemia |
|Primary pulmonary hypertension of the newborn || || |
A thorough knowledge of the differential diagnosis for cyanosis allows for quick, organized assessment, diagnosis, and treatment (Table 108-6).
Obtain simultaneous preductal (e.g., right radial) and postductal (e.g., lower extremity) or arterial blood gases to help diagnose persistent pulmonary hypertension of the newborn: the postductal Pao2 is significantly lower than the preductal Pao2. Using pre- and postductal pulse oximetry may serve the same purpose.
A discrepancy between upper and lower limb blood pressures or reduced femoral pulses may suggest coarctation of the aorta. Babies with coarctation of the aorta often develop new-onset tachypnea and absent femoral pulses later in the first day of life or into the second day of life. Femoral pulses are palpable at birth but disappear after the ductus arteriosus has closed with coarctation of the aorta.
Patients with hypoplastic left heart syndrome may present with poor pulses in all four limbs, poor perfusion, and tachypnea after the immediate newborn period once the ductus arteriosus has closed (see chapter 126, "Congenital and Acquired Pediatric Heart Disease").
Stepped Evaluation and Treatment
TABLE 108-7Steps to Evaluate and Treat Neonatal Central Cyanosis ||Download (.pdf) TABLE 108-7 Steps to Evaluate and Treat Neonatal Central Cyanosis
Identify breathing pattern to characterize infant into airway obstruction, cardiac pulmonary, or CNS/metabolic pattern.
Obtain peripheral oxygen saturation pre- and postductal, check pulses in all 4 extremities, and obtain ABG.
Perform hyperoxia test. Deliver 100% oxygen for 5–10 min. Congenital cyanotic heart disease cannot increase oxygen saturation >20% or raise Pao2 to 100 mm Hg.
Obtain stat chest x-ray to identify pneumothorax, congenital diaphragmatic hernia, or pulmonary infiltrates, and assess cardiac size and shape and pulmonary vasculature for clues to congenital heart disease.
Establish vascular access in umbilical or peripheral vein, obtain POC glucose, CBC, and metabolic panel. Treat hypoglycemia (glucose <25 milligrams/dL [1.38 mmol/L]) with 10% dextrose in water, 2 mL/kg IV bolus, or 3.3 mL/kg/h (see "Hypoglycemia" section below).
Institute continuous positive airway pressure or intubate and ventilate if O2 saturation does not improve with standard methods for oxygen delivery.
If oxygenation still does not improve, treat as presumptive congenital cardiac disease with prostaglandin E1 starting at 0.05 microgram/kg/min and titrate to the minimum effective dose.
The hyperoxia test is a quick method to help differentiate a cardiac from a noncardiac cause for cyanosis. Place the newborn in a 100% hood for 5 to 10 minutes. Cyanotic newborns with a pulmonary disorder can increase their oxygen saturation >20% and their Pao2 to >100 mm Hg. Those with a fixed shunt secondary to congenital cyanotic heart disease or the right-to-left shunting of persistent pulmonary hypertension of the newborn cannot do so.
Obtain a chest x-ray to identify pulmonary disease, abnormalities of pulmonary blood flow, and abnormalities of heart size. If physical examination and chest x-ray have not pointed to a particular diagnosis, an echocardiogram will be needed later on. An echocardiogram is not necessary in the ED during the initial resuscitation.
Although oxygen therapy is the mainstay of treatment for cyanosis, treat the underlying cause. Provide positive-pressure ventilation (continuous positive airway pressure or endotracheal intubation and mechanical ventilation) to the cyanotic newborn with significant respiratory symptoms. Monitor blood gas and pulse oximetry. Establish vascular access, and initiate 10% dextrose in water at 3.3 mL/kg/h (80 mL/kg/24 h) if in the first 24 hours of life. Check serum glucose every 30 to 60 minutes until stable (see "Hypoglycemia" below). Administer empiric antibiotics for sepsis while obtaining appropriate labs (CBC with differential count and platelets, blood culture, chest x-ray, and, possibly, urine culture and C-reactive protein).
If, after initial examination and testing, cyanotic heart disease cannot be ruled out, begin an infusion of prostaglandin E1 starting at 0.05 microgram/kg/min, and titrate to the lowest effective dose to maintain ductal patency.
Pulmonary air leaks are seen more commonly in newborns with respiratory distress syndrome, meconium aspiration syndrome, pneumonia, pulmonary hypoplasia, and congenital diaphragmatic hernia. Pneumothoraces may occur in the otherwise normal newborn in the first few minutes after birth due to increased intrathoracic pressure created with the onset of respiration in the fluid-filled newborn lungs. Air can also dissect into the pulmonary interstitium, mediastinum, pericardium, peritoneum, and subcutaneous space. Pneumothoraces may also be iatrogenic secondary to overexuberant bagging during resuscitation, especially with already compromised lungs. Unfortunately, the disorders that most commonly lead to pneumothoraces are also associated with respiratory distress and cyanosis, which may delay the suspicion and diagnosis of the pneumothorax.
Clinical Features and Diagnosis
Tension pneumothorax requires rapid treatment to avoid severe respiratory compromise, cardiovascular collapse from impaired venous return to the heart, and, possibly, death. In the preterm newborn, tension pneumothoraces are also highly related to subsequent intracranial hemorrhage, presumably secondary to venous backup into the cerebral circulation.
Tachycardia, tachypnea, and retractions are noted. On auscultation, breath sounds are decreased on the side of the pneumothorax. If there is a tension pneumothorax, heart sounds and point of maximum impulse may be displaced in the direction away from the pneumothorax. Transillumination of the chest with a bright light is another method to help rapidly establish pneumothorax, by "lighting up" the pleural air. Bedside US can also identify pneumothorax. Chest x-ray will confirm the diagnosis.
The management of a pneumothorax depends on pneumothorax size and the tension it creates in the pulmonary space. A small, nontension pneumothorax can be observed without evacuation. In a term or near-term newborn, the nitrogen washout technique, placing the baby in a 100% oxygen hood for 6 to 12 hours, will usually accelerate clearance of the air leak. This technique is contraindicated in preterm newborns due to concerns of oxygen toxicity to the lungs and retinas.
Emergency evacuation of a tension pneumothorax may be performed with an 18- or 20-gauge 1-inch percutaneous catheter. Instill local anesthetic at the insertion site before the procedure if the patient is not in extremis. After elevating the neonate's affected side with towels under the back, insert the catheter into the fourth intercostal space at the anterior axillary line, which should correlate with the nipple line. Once the pleural space is penetrated, withdraw the needle, and attach the catheter to a three-way stopcock connected to a 10- or 20-mL syringe. Open the stopcock to the syringe, and aspirate the pleural air. More than one syringe of air may be evacuated if a large pneumothorax is present. Clinical improvement should occur after removal of the pleural air. A 10F or 12F chest tube or an 8.5F pigtail catheter can then be placed.
In the first four hours after birth, asymptomatic hypoglycemia requiring IV therapy is defined as <25 milligrams/dL. Levels of 25 to 44 milligrams/dL (1.38 to 2.4 mmol/L) require feeding and repeat evaluation in 1 hour. After 4 hours of age, serum glucose levels should be ≥45 milligrams/dL (2.4 mmol/L), with levels of 35 to 44 milligrams/dL (1.94 to 2.4 mmol/L) requiring feeding and 1-hour postprandial glucose checks. Risk factors for hypoglycemia in the newborn include prematurity, low birth weight (<2.5 kg), small for gestational age, large for gestational age (>4 kg), infant of a diabetic mother, hypothermia, sepsis, and intrapartum stress.
Symptoms of hypoglycemia are quite varied and include tremors, irritability, lethargy, hypotonia, apnea, tachypnea, tachycardia, cyanosis, high-pitched cry, and seizures. Hypoglycemic newborns may be asymptomatic despite very low glucose levels.
Treat mild hypoglycemia (25 to 44 milligrams/dL [1.38 to 2.4 mmol/L]) in an otherwise well newborn by feeding. Treat significant hypoglycemia (<25 milligrams/dL [1.38 mmol/L]) immediately with a bolus of dextrose (10% dextrose in water, 2 mL/kg IV/IO), and then administer continuous IV therapy with 10% dextrose in water at 100 mL/kg/24 h and adjust based on serum glucose levels every 30 to 60 minutes until stable and ≥45 milligrams/dL (2.4 mmol/L).
CONGENITAL DIAPHRAGMATIC HERNIA
Congenital diaphragmatic hernias are frequently diagnosed prenatally with US, which expedites proper initial newborn resuscitation.
Anatomically, congenital diaphragmatic hernia is a diaphragmatic defect, either posterolaterally through the foramen of Bochdalek or, less commonly, through the retrosternal foramen of Morgagni. Most are left-sided.16,17,18,19 The diaphragmatic defect allows intra-abdominal contents, including stomach, bowel, and, occasionally, liver, to enter the chest during the second trimester of gestation, leading to pulmonary hypoplasia.
The lung ipsilateral to the diaphragmatic defect is hypoplastic, although the degree of hypoplasia may vary. Ultimate morbidity and mortality are determined both by the extent of hypoplasia of the contralateral lung secondary to compression from the abdominal contents in the thoracic space and whether or not the liver is located in the thorax.17 Total lung volumes >45% of normal are predictive of survival.18 Significant associated malformations, especially cardiac defects, are seen in one fourth to one half of patients with congenital diaphragmatic hernia.
The clinical hallmark is persistent respiratory distress at birth, often with a characteristic "seesaw" side-to-side respiratory pattern due to the severely hypoplastic ipsilateral lung. A halting, gasping type of respiratory pattern along with persistent cyanosis is frequently noted. The abdomen appears scaphoid, because abdominal contents are partially situated in the thoracic space. Auscultation of bowel sounds in the chest strongly suggests the presence of congenital diaphragmatic hernia. Radiographic examination is confirmatory.
Rapid endotracheal intubation is the treatment of choice for respiratory distress. Bag-mask ventilation will inflate the GI contents in the chest and will further compromise ventilation. Endotracheal intubation followed by ventilation with a rate of 40 to 50 breaths/min and lowest peak inspiratory pressures that allow for normal chest rise will help avoid pneumothoraces due to barotrauma to the hypoplastic lungs. Gentle hyperventilation to a PCO2 between 30 and 35 mm Hg may help lower pulmonary vasculature resistance and allow for an easier stabilization phase before surgical correction of the diaphragmatic defect. Place a large-bore (10F) orogastric tube set to low continuous suction to minimize further lung compression from overaerated GI contents.
Obtain chest and abdominal x-rays and blood gas analysis to confirm the initial diagnosis and guide stabilization and management. After initial stabilization, emergent referral to a pediatric specialty center is essential.
Despite the advent of antenatal diagnosis, alternate ventilatory strategies (high-frequency oscillatory ventilation), a larger armamentarium to treat pulmonary hypertension (inhaled nitric oxide therapy, sildenafil, and extracorporeal membrane oxygenation), and changing surgical strategies (delayed repair to allow more time for resolution of pulmonary hypertension), mortality from congenital diaphragmatic hernia remains quite high at 30% to 60%.19,20,21
GASTROSCHISIS AND OMPHALOCELE
A gastroschisis is a defect located to the right of the umbilicus from which uncovered intestine is extruded. An omphalocele is a large, centrally located defect of the abdominal wall containing stomach, intestine, and, frequently, liver that is covered by the mesentery. The umbilical cord inserts directly into the omphalocele sac. Rarely, an omphalocele may be ruptured either before delivery or during delivery. Associated anomalies are seen in 10% to 21% of patients with gastroschisis and 40% to 75% of patients with omphalocele.22,23,24 Associated defects include cardiac defects (such as tetralogy of Fallot), syndromes (Beckwith-Wiedemann), and chromosomal abnormalities (trisomy 13, trisomy 18), in addition to associated intestinal atresias.
The initial management of gastroschisis and omphalocele is similar: handle the covered sac and free intestine with care. Place the newborn on a radiant warmer to help prevent hypothermia due to increased heat loss from the exposed abdominal contents. The ABCs of stabilization should be performed as needed.
If an omphalocele is present, note its size and contents. Cover the sac with warmed saline gauze wrapped gently around the baby with Kerlix, and then place an additional cover with plastic wrap to help minimize evaporative losses. Start IV 10% dextrose in water at 1.5× maintenance (i.e., 5 to 6 mL/kg/h or 120 to 150 mL/kg/24 h) to compensate for the additional insensible water loss. Monitor urine output and electrolytes closely to determine ongoing fluid needs.
If a gastroschisis is present, immediately check for dusky or cyanotic intestine, which indicates reduced flow to the affected bowel due to torsion and vascular occlusion. Gently rotate the bowel to relieve torsion if necessary to prevent bowel infarction. Emergency pediatric surgical consultation is essential. If the intestine appears pink, cover with warmed saline gauze, wrap with Kerlix, and further cover with plastic wrap. Be careful not to compress the intestine, which could result in obstruction of blood flow to the bowel. Insensible water loss is much greater in the newborn with gastroschisis due to the open defect with large amounts of extruded bowel. Therefore, IV 10% dextrose in water should be started at 6 to 7 mL/kg/h (at least 150 mL/kg/24 h).
Check glucose periodically. Antibiotics, usually ampicillin, 50 to 100 milligrams/kg IV, and gentamicin, 4 to 5 milligrams/kg IV, should be given.
Immediate consultation with a neonatologist and pediatric surgeon is necessary. The overall outcome for gastroschisis is quite good, with survival exceeding 90%.25,26 Survival with omphalocele is somewhat less at 73% to 88%, depending largely on the presence of associated anomalies.25
Tracheoesophageal fistula develops secondary to a failure of separation of the developing foregut structures, the trachea and esophagus, during the embryologic stage of development. There are five types of tracheoesophageal fistula: (1) esophageal atresia with a distal tracheoesophageal fistula (88% of cases), (2) isolated esophageal atresia without tracheoesophageal fistula (7%), (3) esophageal atresia with proximal tracheoesophageal fistula (1%), (4) esophageal atresia with proximal and distal tracheoesophageal fistulas (1%), and (5) H-type fistula without esophageal atresia (3%). Tracheoesophageal fistula is highly associated with several other malformations, designated as the acronyms VATER or VACTERL association: vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, radial anomaly/renal anomalies, and limb anomalies.
The diagnosis of tracheoesophageal fistula can be missed during prenatal US examination. When esophageal atresia is present, polyhydramnios is usually noted before or at delivery. Newborns with tracheoesophageal fistula/esophageal atresia will usually have excessive oral secretions noted shortly after birth. When attempting to pass a nasogastric tube, the tube coils in the esophageal pouch and often comes back out of the mouth. No air passage will be heard when a 5-mL air bolus is injected into the nasogastric tube. A chest x-ray with a nasogastric tube in place will demonstrate the esophageal pouch. Confirmatory contrast studies are not indicated and may actually be contraindicated because the esophageal contents can be aspirated into the lungs.
Management of tracheoesophageal fistula includes placing the child in head-up (reverse Trendelenburg) positioning to help prevent passage of gastric contents through the tracheoesophageal fistula into the lungs, placing the nasogastric tube into the esophageal pouch on low intermittent suction to prevent buildup and possible aspiration of oral secretions, and giving the newborn nothing by mouth. Initially, standard 10% dextrose in water IV fluids are best. Immediate referral to a center with neonatologists and pediatric surgeons is essential.