Tuesday, February 21, 2017

Neonatal emergencies are not uncommon problems. They appear either at the time of birth, during the in-hospital post-birth period, or at home within several weeks of discharge. In all instances they present significant diagnostic and treatment challenges to the clinician, and must be taken seriously.

A classic pneumonic used by Neonatologists and Pediatric Emergency Physicians is "THE MISFITS." A brief discussion of each of these conditions follows.

T-Trauma (non-accidental and accidental)H-Heart disease/Hypovolemia/HypoxiaE-Endocrine (congenital adrenal hyperplasia, thyrotoxicosis)M-Metabolic (electrolyte imbalance)I-Inborn errors of metabolism (metabolic emergencies)S-Sepsis (meningitis, pneumonia, urinary tract infection)F-Formula mishaps (under or over-dilution)I-Intestinal conditions (volvulus, intussusception, necrotizing enterocolitis)T-Toxins/PoisonsS-

Emergency evaluation of neonates with head trauma may be a difficult process. An infant with nonaccidental head trauma may only have subtle historical findings and no physical exam findings. Because of this evaluation of neonates with a suspected injury should always include neuroimaging, which may include a computed tomography (CT) scan, ultrasound, or magnetic resonance imaging (MRI). Skull x-rays are not always helpful because infants can have a significant intracranial injury without a skull fracture.ED management will depend on presenting symptoms but should include evaluation and stabilization of the ABC's (airway, breathing, circulation), a bedside blood glucose evaluation, and appropriate temperature regulation. If there is bruising or a known intracranial bleed, then the laboratory evaluation should include a complete blood count (CBC), platelet count, prothrombin time (PT), and a partial thromboplastin time (PTT). Neuroimaging should be completed after stabilization. A skeletal survey and ophthalmologic exam should be part of the hospital evaluation.
Heart Disease and Hypoxic Findings:
Cyanosis is a pathologic process that requires immediate attention and evaluation. Although the differential diagnosis of cyanosis includes respiratory causes, infectious causes, central nervous system abnormalities and toxins, there is always the possibility of a cyanotic heart defect and so it should always be considered. Cyanotic congenital heart conditions include the 5 T's: Tetralogy of Fallot, Tricuspid Atresia, Transposition of the Great Vessels, Total Anomalous Pulmonary Venous Return, and Truncus Arteriosis.Cyanotic heart defects may not be detected in the newborn nursery because there is still adequate oxygenated blood to the systemic circulation through a patent ductus arteriosus (PDA). Although the PDA typically functionally closes in the first 10-14 hours of life, several factors can delay its closure, including prematurity, respiratory distress, acidosis, and hypoxia. The PDA is anatomically closed by 2 weeks of age, contributing to the possibility of a relatively delayed detection of cyanotic heart defects.
Providing 100% oxygen is helpful in differentiating between cardiac and noncardiac causes of cyanosis. After providing oxygen, a noncardiac disease should have at least a 10% increase in the pulse oximetry value, whereas cyanotic heart disease will have minimal change in the oxygen saturation. During stabilization the physical exam should include blood pressures in all 4 extremities and a careful cardiac exam. Although a murmur may be audible, the absence does not exclude a cardiac defect. A chest radiograph (CXR) and electrocardiogram (ECG) should be included in the evaluation, but an echocardiogram is diagnostic.

Acyanotic Heart Disease:
Acyanotic heart disease typically presents with symptoms of congestive heart failure. There is usually a more gradual clinical decompensation when compared with the cyanotic heart defects and it may not present until after the first 2-3 weeks of age. Causes include ventricular septal defect, atrial septal defect, coarctation of the aorta, and patent ductus arteriosis. Other causes of congestive heart failure in neonates includes: severe anemia, trauma, sepsis, supraventricular tachycardia, metabolic abnormalities, lupus, and thyrotoxicosis.The classic symptoms for congestive heart failure include tachypnea, tachycardia, and hepatomegaly. The history may include poor or slow feeding, sweating or color change with feeding, and poor weight gain. Initial management will include stabilization of the ABC's, a CXR, ECG, and laboratory evaluation including a CBC and serum electrolytes. An echocardiogram will be diagnostic of the heart defect and management usually includes furosemide (1.0 mg/kg IV), plus dopamine or dobutamine for cardiovascular support. Careful attention is necessary to not fluid-overload these patients.
Supraventricular tachycardia (SVT) is the most common neonatal dysrhythmia. Presenting complaints may range from tachycardia to poor feeding, irritability, heart failure, and shock. This is not usually a difficult diagnosis because the heart rate is sustained at ≥ 220 beats per minute with a QRS < 0.08 seconds. There are a host of medications that can be used to treat the condition.

Bronchiolitis is a viral lower-airway disease that is caused by respiratory syncytial virus (RSV) 80% of the time, but other etiologies include adenovirus, influenza, or parainfluenza. In addition, RSV is responsible for 50% to 90% of bronchiolitis hospital admissions. Bronchiolitis is more common in the winter and spring seasons, but may present anytime. These patients may present with more classic symptoms that include rhinorrhea, cough, congestion, or significant respiratory distress and wheezing. Apnea also may be the only initial symptom in an infant with no other respiratory symptoms. Infants with severe, prolonged apnea accompanied by bradycardia and who are unresponsive to oxygen therapy and stimulation may require intubation. More commonly, the decision will need to be made of whether to treat with nebulized racemic epinephrine or a beta-agonist. Nebulized racemic epinephrine has demonstrated better results on respiratory distress than a beta-agonist. The adjunct use of corticosteroids has not been shown to improve the symptoms of bronchiolitis. However, infants who have an underlying reactive airway component to their illness and respond to beta-agonists, or have severe bronchiolitis, are potential candidates for corticosteroid therapy.
Endocrine Emergencies:
Congenital adrenal hyperplasia: Although these patients are often diagnosed at birth by routine newborn screening, occasionally the diagnosis is missed because of an inadequate blood sample, laboratory error, or inability to contact the family. In this instance, the patient may present in the first few weeks of life with symptoms of vomiting, hypoglycemia, or even shock. The most common cause of congenital adrenal hyperplasia (CAH) is a deficiency in the 21- hydroxylase enzyme.Thyrotoxicosis: Neonatal thyrotoxicosis may develop in infants born to mothers with Graves disease. It is caused by transmission of maternal thyroid-stimulating immunoglobulin. The presentation is often delayed and may present with symptoms such as poor feeding, failure to thrive, tachycardia, irritability, hyperthermia, vomiting, diarrhea, jaundice, thrombocytopenia, respiratory distress, heart failure and shock. Initial diagnosis may be difficult without a clear history of Graves disease from the mother. Evaluation should include thyroid functions tests.

 Metabolic Emergencies:
Inborn errors of metabolism (IEM) often have a delayed diagnosis and symptoms may be unrecognized because they are uncommon and require a high level of suspicion for diagnosis. State-mandated newborn screening may be helpful for recognizing some of the IEM, but there are over 400 causes that have been identified and it is not possible to routinely screen for all of them. Presenting symptoms may be subtle and an IEM should be considered in any neonate who does not have another obvious cause for symptoms. Nonspecific symptoms include poor feeding, vomiting, failure to thrive, tachycardia, tachypnea, or irritability. Occasionally the diagnosis may be more apparent and include symptoms of seizures, lethargy, hypoglycemia, apnea, temperature instability, and acidosis. Physical exam findings are usually normal.Initial management should include stabilization of the ABC's and a bedside blood glucose evaluation. Laboratory evaluation should include a CBC, serum electrolytes, pH, lactate, ammonia, liver function tests, and urinalysis for reducing substances and ketones. The complete evaluation should also include blood and urine for organic and amino acids.

It is standard of care to complete a full sepsis evaluation (CBC, blood culture, urinalysis, urine culture, cerebral spinal fluid [CSF] culture and analysis, and CXR) in any neonate with a rectal temperature of ≥ 100.4° F. Although the evaluation of a febrile neonate is well supported, it is the recognition of sepsis and the initiation of a work-up in neonates with a less specific presentation that is a more difficult challenge. The symptoms and historical facts that should prompt the consideration of a full sepsis evaluation include poor feeding, irritability, apnea, hypothermia, jaundice, rashes, increased sleeping, seizures, or vomiting. A neonate may have sepsis or other serious bacterial infection and may have only minor complaints. It is standard of care to administer broad-spectrum antibiotics to all neonates who undergo a sepsis evaluation or present with life-threatening symptoms that do not have another readily apparent cause.Neonatal herpes deserves specific mention because the symptoms may be subtle and there may be no maternal history in 60% to 80% of women with an unrecognized infection.Early recognition and treatment with acyclovir 20 mg/kg IV may significantly decrease the mortality from over 90% to approximately 30%. Initiation of treatment should be considered in any neonate with high fever, CSF with a lymphocytosis or numerous red blood cells in an atraumatic spinal tap, seizures, or a known maternal history of herpes infection. The CSF analysis should include a herpes polymerase chain reaction (PCR) and herpes culture. There may be an elevation on liver function tests and a CXR may demonstrate pneumonitis.

Intestinal Emergencies:
Vomiting in the neonatal period should always prompt the consideration of a pathologic process. It may be difficult to differentiate a life-threatening cause from a mild viral gastroenteritis or even severe gastroesophageal reflux. The initial symptoms may be nonspecific and the history may not be helpful in a neonate who has not developed a normal pattern. Bilious emesis is always concerning and should always initiate a pediatric surgery consultation.Malrotation is caused by an abnormal rotation of bowel in utero that results in an unfixed portion of bowel that may later twist on itself, resulting in volvulus and bowel ischemia or death. Malrotation occurs in 1 out of 5000 live births and is usually diagnosed in the first month of life. The presenting symptoms include bilious emesis and poor feeding, or lethargy and shock in more advanced presentations. Initial management includes stabilization of the ABC's, fluid resuscitation, a nasogastric tube placement, and pediatric surgical consultation. Abdominal radiographs may be normal, have signs of small bowel obstruction, or the classic "double bubble" sign may be present. An upper gastrointestinal (GI) study with contrast is the gold standard for diagnosis, but an abdominal ultrasound may also be helpful in an experienced technician's hands. Confirmation radiographic studies should never delay surgical consultation or transfer to an appropriate pediatric facility.
Toxic megacolon or enterocolitis is a life-threatening presentation of a patient with Hirschsprung disease. Hirschsprung disease occurs in 1 out of 5000 live births and may often go unrecognized because constipation is common and usually benign. The history of constipation, especially with the additional history of failure to pass meconium in the first 24 hours of life, should increase suspicion of Hirschsprung disease. Presenting symptoms may include poor feeding, vomiting, irritability, abdominal distention, and hematochezia and shock as the condition progresses to enterocolitis. Initial management should include stabilization of the ABC's, fluid resuscitation, and administration of broad-spectrum antibiotics. An abdominal radiograph may reveal an enlarged or dilated section of colon.
Although necrotizing enterocolitis (NEC) is classically a disease of premature neonates that is diagnosed in the neonatal intensive care unit, it may occasionally occur in the term neonate after discharge from the newborn nursery. These neonates may present with symptoms similar to those with Hirschsprung enterocolitis. Management also includes stabilization of ABC's, fluid resuscitation, and nasogastric tube placement. An abdominal radiograph that demonstrates pneumatosis intestinalis or portal air is diagnostic of NEC. Administration of broad-spectrum antibiotics, pediatric surgical consultation, and critical care management is required.
Infants who present with projectile vomiting should be evaluated for hypertrophic pyloric stenosis (HPS). This disease is common and occurs in 1 out of 250 live births with a male:female ratio of 4:1. This disease is more common in the firstborn male. The classic electrolyte disturbance of hypochloremic, hypokalemic metabolic alkalosis is now an uncommon finding because HPS is often diagnosed before these electrolyte abnormalities develop. The history supporting nonbilious emesis immediately after a vigorous feeding is often present. An increased incidence of HPS has been shown in neonates who have had an early exposure to oral erythromycin. Increased awareness of HPS and ease of ultrasound evaluation for the definitive diagnosis usually results in an early diagnosis. The classic physical exam findings of a palpable "olive" structure in the right upper quadrant and visible peristaltic waves may be present. Diagnosis is confirmed with an ultrasound that reveals a thickened and lengthened pylorus. If an upper GI study is performed, a "string sign" will be visible. Although surgical management is the standard, reports of pharmacologic management with IV atropine followed by oral atropine show satisfactory results.
Jaundice is a physical finding in the neonate that may represent a normal process in a healthy baby or a more severe or life-threatening illness. Because jaundice is a common complaint, it may be difficult to recognize which neonates require more attention. Initial evaluation will be dependent on the clinical presentation but should include laboratory evaluation for conjugated (direct) and unconjugated (indirect) bilirubin, hematocrit, reticulocyte count, and Coombs test. Direct hyperbilirubinemia is always pathologic and the more common causes include biliary atresia, alpha-1 anti-trypsin deficiency, and hepatitis. Indirect hyperbilirubinemia is usually due to breastfeeding or normal physiologic causes, but the more concerning causes include ABO incompatibility, sepsis, glucose-6-phosphate deficiency, spherocytosis, Gilbert's disease, or Crigler-Najjar syndrome.

Toxic ingestions are uncommon in this age group, but occasionally result from a maternal ingestion in a breastfeeding mother, homeopathic remedies, or overuse of accepted medications.Although teething does not occur in the first month of life, colic is a common concern at this point and results in lost sleep and frustration. Teething gels may be used as an attempt to relieve distress for both parents and neonates. Note that teething gels often contain benzocaine which may cause methemoglobinemia with overuse.

Neonates with suspected seizure activity may be difficult to diagnose in the ED setting. The history may only include a concern by the family that their newborn is not acting right or is more somnolent. Neonates have immature cortical development, and seizure activity may not be generalized or tonic-clonic. Symptoms that should be taken seriously include lip- smacking, abnormal eye or tongue movements, pedaling, or apnea. The most common causes of neonatal seizures include: sepsis, trauma, inborn errors of metabolism, hypoglycemia, hypocalcemia, hypo and hypernatremia, drugs, infections, congenital anomalies, intracranial hemorrhage, and hypertension.Initial management includes stabilization of the ABC's, bedside blood glucose level, and serum electrolytes. Immediate correction of hypoglycemia (< 40 mg/dL) with 2-4 cc/kg or a 10% dextrose solution may be necessary. If hypoglycemia was the cause of the seizure and the symptoms resolve with glucose replacement, then bedside blood glucose tests should be repeated and the neonate should be placed on a maintenance dextrose IV solution to prevent further hypoglycemic episodes. Other laboratory tests should include a CBC, blood culture, and liver function tests. Because 5% to 10% of all neonatal seizures are of infectious etiology, a full sepsis evaluation should be completed when patient stability permits.The first-line pharmacologic management is lorazepam 0.1 mg/kg IV. This may be repeated 2 or 3 times before moving to the second-line treatment, phenobarbital. The third-line treatment would be phenytoin or fosphenytoin IV. Table 8 provides the step-wise pharmacologic treatment and doses for neonatal seizures.

Medical/Legal Considerations:
The evaluation of a sick neonate is complex and fraught with incorrect diagnoses. Yet, a correct diagnosis and timely initiation of treatment can obviate catastrophic outcomes. Often, it is better to over diagnosis rather than under diagnose. This way the neonate will be admitted and closely observed. In all instances, consultants should be called liberally. In all instances, presumptive and empiric treatment can often make the difference between life and death.