DUSTIN R. HAFERBECKER
HISTORY OF PRESENT ILLNESS
A 3-year-old boy was referred to the emergency department for evaluation of wheezing, cough, and increased work of breathing. He had been well until 3 days prior to admission, when he developed rhinorrhea and cough without fever. Nebulized albuterol was prescribed for wheezing and retractions, with little improvement. On the day of admission, the child’s respiratory distress had continued and his cough had worsened and was accompanied by mild sternal discomfort exacerbated by coughing. He had received nebulized albuterol every 4 hours during the day of admission without significant relief. There was no vomiting or diarrhea. The onset of wheezing was not accompanied by an episode of choking or gagging. There was no history of trauma.
The boy’s medical history was unremarkable. There were no previous episodes of wheezing. He was born at 39 weeks gestational age without perinatal complications. There was no family history of atopic dermatitis or asthma.
T 37.7°C; RR 52/min; HR 130 bpm; BP 108/70 mmHg; SpO2 95% in room air
Weight 50th percentile
Physical examination revealed a fair-haired Caucasian boy in mild respiratory distress. On examination, there was no conjunctival injection or chemosis. Clear rhinorrhea was present. He had mild intercostal and subcostal retractions. His lung examination revealed dullness to percussion, diminished breath sounds, and prominent wheezing at the left base. There was good aeration without wheezing, rales, or rhonchi in the remainder of the left lung and throughout the right side. An I/VI vibratory systolic ejection murmur was present at the left sternal border. His abdomen was thin and soft with active bowel sounds and no organomegaly or palpable mass. The remainder of the physical examination was normal.
Laboratory analysis revealed 15 100 white blood cells/mm3 with 0% band forms, 52% segmented neutrophils, 33% lymphocytes, and 5% eosinophils. Hemoglobin, platelet count, electrolytes, blood urea nitrogen, and creatinine were normal.
COURSE OF ILLNESS
The patient’s lung examination did not change with the administration of nebulized albuterol. A chest radiograph revealed the diagnosis as indicated in Figure 1-3.
FIGURE 1-3. Chest radiograph. A. Antero-posterior view. B. Lateral view.
DISCUSSION CASE 1-2
The most likely cause of a first episode of wheezing in a 3-year-old boy, particularly in the context of an upper respiratory infection, is asthma. Foreign body aspiration should also be strongly suspected in this age group, especially if there are asymmetries on lung examination. Less common causes in this age group include anaphylaxis, which is typically associated with urticaria or other features of a systemic allergic response, and airway compression due to mediastinal tumors, lymph nodes, or other structures. In the immunocompromised host, Pneumocystis jiroveci (formerly P. carinii) pneumonia often presents with tachypnea, wheezing, and respiratory distress in the absence of fever. Children with cystic fibrosis usually have poor weight gain, pancreatic insufficiency, and recurrent respiratory symptoms. The characteristics of this case that prompted additional evaluation included hypoxemia, progressive respiratory distress that was unresponsive to beta-agonist therapy, and the presence of focal wheezing evident on lung examination.
The chest radiograph (Figure 1-3) revealed a heterogeneous opacity overlying the lower half of the left lung consistent with the appearance of both small and large bowel in the thorax. The mediastinal structures are displaced rightward. The diagnosis is postero-lateral congenital diaphragmatic (Bochdalek) hernia with delayed presentation.
INCIDENCE AND EPIDEMIOLOGY
Congenital diaphragmatic hernia (CDH) is a simple anatomic defect in which a hole in the diaphragm allows abdominal viscera to herniate into the thorax. CDH defects are usually left-sided (80%). The incidence of CDH is estimated to be 1 per 2000 to 5000 births. While most cases of CDH are diagnosed prenatally or during the neonatal period, approximately 10%-20% have delayed presentation (age >1 month). They are thought to occur most often as a sporadic developmental anomaly, although familial cases have been reported. The recurrence risk in a first-degree relative is approximately 2%. Approximately 40% of liveborn patients who have CDH have one or more associated anomalies including cardiac (60%), genitourinary (23%), gastrointestinal (17%), central nervous system (14%), and chromosomal (10%) (Table 1-3). Infants with isolated CDH are more likely to be premature, macrosomic, and male.
TABLE 1-3. The prevalence of associated anomalies detected in 40% of patients with congenital diaphragmatic hernia.
Population-based studies of CDH among live-born, stillborn, and spontaneously aborted fetuses suggest that approximately 30% of fetuses who have CDH will die before birth, usually from chromosomal or lethal nonpulmonary malformations. Among fetuses with prenatally diagnosed CDH and without major associated anomalies, early term delivery (i.e., 37 weeks compared with 39-41 weeks gestational age) may confer a survival advantage. In CDH, the location of the defect may also affect postnatal survival and the development of chronic lung disease. In one study, more neonates with left-sided CDH died of severe pulmonary hypertension despite extracorporeal membrane oxygenation. Fewer neonates with right-sided CDH died, yet higher degrees of pulmonary hypoplasia and oxygen requirement were observed despite extracorporeal membrane oxygenation.
Congenital diaphragmatic hernias may vary in size and occur in various portions of the diaphragm. Types of CDH include postero-lateral (Bochdalek) (59.5%), antero-medial (Morgagni) (2.6%), hiatal (23.3%), and eventration (14.6%). Postero-lateral diaphragmatic hernias result from an absence or defective fusion of the septum transversum dorsally and pleuroperitoneal membrane postero-laterally. There appear to be two groups of patients with delayed presentations of postero-lateral CDH. In the first group, the defect is long-standing, but the viscera are confined by a hernia sac or obturated by a solid organ. Presentation occurs when the sac ruptures or the intraabdominal pressure is raised, causing the viscera to herniate. A previously normal chest radiograph is supportive. The second group also has a congenital defect but only present when a complication of the herniated contents such as volvulus, strangulation, or acute or recurrent respiratory distress develops.
Many patients with CDH are diagnosed antena-tally by ultrasound. In such instances, other congenital anomalies, particularly those affecting the cardiovascular and central nervous systems, should be sought. The presentation of CDH in the neonatal period is determined primarily by the severity of the pulmonary hypoplasia and pulmonary hypertension. The most severely affected infants show obvious respiratory signs within the first 24 hours of life. Classically, these infants are born with a scaphoid abdomen and develop progressive respiratory distress as swallowed air causes intestinal distension followed by worsening lung compression and mediastinal shift. These infants may have cyanosis, increased work of breathing, and respiratory failure.
In contrast, the presentation of diaphragmatic hernia outside the neonatal period is extremely varied, and may be associated with misleading clinical and radiologic assessments. Children who have CDH with delayed presentation may have recurrent respiratory distress, chronic pulmonary infection, or acute gastrointestinal symptoms caused by gastric volvulus or intestinal obstruction.
Prenatal ultrasound. CDH may be diagnosed by ultrasound during routine obstetric screening or during investigation of polyhydramnios, which may complicate up to 80% of pregnancies in which CDH occurs. The accuracy of prenatal diagnosis varies, depending on the site of the lesion and the presence of corroborating criteria, such as mediastinal shift and abnormal fetal abdominal anatomy. The diagnosis is suggested strongly by the presence of a fluid-filled stomach or intestine at the level of the four-chamber view of the heart.
Fetal MRI. In cases where CDH is expected based on ultrasound but remains unclear, fetal MRI has the potential to assist in the diagnosis. The additional information provided by MRI may also be helpful in counseling the family regarding potential value of prenatal and postnatal interventions.
Associated studies. Once the diagnosis of CDH in a neonate has been confirmed, a careful search for associated anomalies should be performed. Additional studies to consider include renal and cranial ultrasonography, echocardiography, and karyotyping.
Chest radiograph. The diagnosis is confirmed by a chest radiograph that demonstrates loops of intestine within the chest. The location of the gastric bubble should also be noted, and its position can be confirmed by placement of a nasogastric tube. Occasionally, a large multicystic lung lesion such as congenital cystic adenomatoid malformation will have the appearance of a CDH on plain radiography. In these instances, ultrasonographic visualization of an intact diaphragm or computed tomographic scan of the chest may be necessary. In an older child, the radiographic appearance of CDH may be misinterpreted pneumothorax, pneumatocele, or lobar consolidation.
Upper gastrointestinal barium series. Confirmative barium studies represent an unnecessary delay in appropriate therapy for the neonate. However, in the older child they serve to confirm the diagnosis. Additionally, up to 30% of children with delayed presentation of CDH have associated abnormalities of bowel fixation or rotation requiring repair.
Prenatal care. Antenatal diagnosis of CDH has allowed optimal immediate care of affected infants. Birth at a tertiary care center that has pediatric surgery and neonatology services as well as advanced strategies for managing respiratory failure, including extracorporeal membrane oxygenation (ECMO), usually is most appropriate. A spontaneous vaginal delivery should be anticipated unless obstetric issues dictate otherwise.
Fetal therapy. The role of in utero surgery for CDH remains controversial. Fetal intervention is currently focused on temporary occlusion of the fetal trachea for those fetuses who have CDH and liver herniation above the diaphragm in an attempt to correct the severe pulmonary hypoplasia often associated with CDH. Normally, fetal lungs produce a continuous flow of fluid that exits the trachea into the amniotic space. In the presence of tracheal obstruction, the lungs grow, and there is gradual reduction of herniated viscera back into the abdomen. Following a period of intrauterine tracheal occlusion sufficient to cause a reversal of pulmonary hypoplasia, the fetus is delivered and maintained on placental support until the tracheal obstruction is relieved and an adequate neonatal airway is established. Other forms of antenatal therapy include the development of pharmacologic strategies that target pulmonary growth and development.
Delivery room and intensive care. Immediate resuscitation includes prompt endotracheal intubation, avoidance of bag-mask ventilation, placement of a nasogastric tube to provide intestinal decompression, and ongoing care in an intensive care nursery by individuals experienced in the management of the newborn who has CDH.
Surgical repair in the neonate. Historically, neonates who had CDH were rushed to the operating room under the mistaken belief that decompression of the lungs by reduction of the abdominal viscera offered the greatest chance of survival. This disorder is no longer thought to require immediate surgery because the primary problem after birth is not herniation of abdominal viscera into the chest but severe pulmonary hypoplasia and associated pulmonary hypertension. Average time to surgery now ranges from 3 to 15 days after birth. New treatments including ECMO and permissive hypercapnia with gentle ventilation to minimize barotrauma have led to incremental increases in survival rates which now range from 78% to 94%. Other treatments such as partial liquid ventilation, inhaled nitric oxide, surfactant-replacement therapy, and maternal corticosteroid therapy prior to birth require additional study in patients with CDH.
Surgical repair in the child with delayed presentation. The timing of repair in patients who present with CDH beyond the neonatal period typically occurs within days of presentation, or earlier if symptoms are acute. The prognosis in late-presenting CDH is good. It does not depend on lung hypoplasia as in neonatal CDH, but relates to accurate diagnosis of the condition and immediate operative correction in symptomatic cases. Complications of delayed repair in the symptomatic patient include incarceration or strangulation of herniated bowel and cardio-respiratory arrest due to mediastinal compression by the herniated viscera.
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