NEONATOLOGY: MANAGEMENT, PROCEDURES, ON-CALL PROBLEMS, DISEASES, AND DRUGS - part 9 ppt

with or without the complication of midgut volvulus. V. Diagnosis. The exact cause of the obstruction may not be known until a laparotomy is performed. A. Abdominal x-ray study. In complete duodenal obstruction, the pathognomonic x-ray finding is a "double bubble." Two large gas collections, one in the stomach and the other in the first portion of duodenum, are the only lucencies in the GI tract. B. Radiologic contrast studies 1. Partial obstructions will probably require an upper GI series to identify the site of difficulty. 2. Malrotation. It is important to eliminate malrotation as a possibility because its complication, midgut volvulus, is a true surgical emergency. This is best done by an upper GI series, identifying a transverse portion of the duodenum leading to a fixed ligament of Treitz, or by barium enema, localizing the cecum to its normal, right lower quadrant position. VI. Management A. Duodenal atresia or annular pancreas. In cases of atresia or annular pancreas, gastric suction will control vomiting and allow "elective" surgical correction. B. Malrotation mandates immediate surgical intervention because the viability of the intestine from the duodenum to the transverse colon may be at risk from midgut volvulus. Proximal Intestinal Obstruction I. Definition. Proximal intestinal obstruction is obstruction of the jejunum. II. Pathophysiology. Jejunal obstruction typically results from atresia of that segment of the bowel, usually caused by a vascular accident in utero. III. Clinical presentation. Infants with jejunal obstruction usually have bilious vomiting associated with minimal abdominal distention, because few loops of intestine are involved in the obstructive process. IV. Diagnosis. A plain abdominal x-ray study reveals only a few dilated small bowel loops with no gas distally. V. Management. Surgical correction is required. Distal Intestinal Obstruction I. Definition. The term distal intestinal obstruction denotes partial or complete obstruction of the distal portion of the GI tract. It may be either small bowel (ileum) or large bowel obstruction. The list of causes includes the following: A. Ileal atresia. B. Meconium ileus 1. Uncomplicated (simple) obstruction of the terminal ileum by pellets of inspissated meconium. 2. Complicated meconium ileus, implying compromise of bowel viability either prenatally or postnatally. C. Colonic atresia. D. Meconium plug-hypoplastic left colon syndrome. E. Hirschsprung's disease (congenital aganglionic megacolon). II. Clinical presentation. Infants with obstructing lesions in the distal intestine have similar signs and symptoms. They typically have distended abdomens, fail to pass meconium, and vomit bilious material. III. Diagnosis A. Abdominal x-ray studies show multiple dilated loops of intestine; the site of obstruction (distal small bowel vs colon) cannot be determined on plain x-ray films. B. Contrast radiologic studies. The preferred diagnostic test is contrast enema. It may identify colonic atresia, outline microcolon (which may signify complete distal small bowel obstruction), or suggest a transition zone (which may signify Hirschsprung's disease). The procedure can identify and treat meconium plug-hypoplastic left colon syndrome. If the test is normal, ileal atresia, meconium ileus, and Hirschsprung's disease are possibilities. C. Sweat test. A sweat test may be needed to document cystic fibrosis in cases of meconium ileus (unlikely to be helpful in the first few weeks of life). D. Mucosal rectal biopsy for histologic detection of ganglion cells is the safest and most widely available screening test for Hirschsprung's disease. However, laparotomy is often necessary to determine the exact nature of the problem in infants with normal results of barium enema. IV. Management A. Nonoperative management is "curative" in cases of meconium plug and hypoplastic left colon. 1. Passage of time and colonic stimulation by digital examination and rectal enemas promote return of effective peristalsis. 2. In infants who achieve apparently normal bowel function, one must rule out Hirschsprung's disease by mucosal rectal biopsy; a small percentage of patients with meconium plug will prove to have aganglionosis. 3. Interestingly, uncomplicated meconium ileus, if identified, can often be treated by nonoperative means. Repeated enemas with Hypaque or acetylcysteine (Mucomyst) may disimpact the inspissated meconium in the terminal ileum and relieve the obstruction. B. Surgical therapy. Surgical intervention is required for atresia of the ileum or colon, for complicated meconium ileus, and when the diagnosis is in doubt. Hirschsprung's disease is usually treated in the neonatal period by colostomy through ganglionic bowel. Some surgeons are performing "one-stage" pull-through procedures, without preliminary colostomy. Imperforate Anus I. Definition. Imperforate anus is the lack of an anal opening of proper location or size. There are two types: high and low. A. High imperforate anus. The rectum ends above the puborectalis sling, the main muscle responsible for maintaining fecal continence. There is never an associated fistula to the perineum. In males, there may be a rectourinary fistula, and in females, a rectovaginal fistula. B. Low imperforate anus. The rectum has traversed the puborectalis sling in the correct position. Variants include anal stenosis, imperforate anus with perineal fistula, and imperforate anus without fistula. II. Diagnosis is by inspection and calibration of any perineal opening. All patients with imperforate anus should have x-ray studies of the lumbosacral spine and urinary tract because there is a high incidence of dysmorphism in these areas. III. Management. Surgical therapy in the neonate consists of colostomy for high anomalies and perineal anoplasty or dilation of fistula for low lesions. If the level is not known, colostomy is preferable to blind exploration of the perineum. If colostomy is done, a contrast x-ray study of the distal limb should be performed to ascertain the level at which the rectum ends and to determine the presence or absence of an associated fistula. CAUSES OF RESPIRATORY DISTRESS Choanal Atresia I. Definition. Choanal atresia is a congenital blockage of the posterior nares caused by persistence of a bony septum (90%) or a soft tissue membrane (10%). II. Pathophysiology. Unilateral or bilateral obstruction at the posterior nares may be secondary to soft tissue or bone. Choanal atresia, which is complete and bilateral, is one of the causes of respiratory distress immediately after delivery. The effects of upper airway obstruction are compounded because neonates are obligate nose-breathers and will not "think" to breathe through the mouth. III. Clinical presentation. Respiratory distress resulting from partial or total upper airway obstruction is the mode of presentation. IV. Diagnosis is based on an inability to pass a catheter into the nasopharynx via either side of the nose. V. Management. Simply making the infant cry and thereby breathe through the mouth will temporarily improve breathing. Insertion of an oral airway will maintain the ability to breathe until the atresia is surgically corrected. Pierre Robin Syndrome I. Definition. This anomaly consists of mandibular hypoplasia in association with cleft palate. II. Pathophysiology. Airway obstruction is produced by posterior displacement of the tongue associated with the small size of the mandible. III. Clinical presentation. Severity of symptoms varies, but most infants manifest a high degree of partial upper airway obstruction. IV. Management A. Infants with mild involvement can be cared for in the prone position and fed through a special Breck nipple. Adjustment to the airway compromise will occur over days or weeks. B. More severe cases require nasopharyngeal tubes or surgical procedures to hold the tongue in an anterior position. Tracheostomy is generally a last resort. Vascular Ring Airway compromise is rarely severe and usually presents as stridor. Laryngotracheal Esophageal Cleft I. Definition. Laryngotracheal esophageal cleft is a rare congenital anomaly in which there is incomplete separation of the larynx (and sometimes the trachea) from the esophagus, resulting in a common channel of esophagus and airway. This communication may be short or may extend almost the entire length of the trachea. II. Pathophysiology. The persistent communication between the larynx (and occasionally a significant portion of the trachea) and the esophagus results in recurring symptoms of aspiration and respiratory distress with feeding. III. Clinical presentation. Respiratory distress during feeding is the presenting symptom. IV. Diagnosis. Contrast swallow may suggest the anomaly, but endoscopy is essential in firmly establishing the diagnosis and delineating the extent of the defect. V. Management. Laryngotracheal esophageal cleft is treated by surgical correction, which is difficult and often unsuccessful. H-Type Tracheoesophageal Fistula I. Definition. This anomaly is the third most common type of TEF, making up 5% of cases. Esophageal continuity is intact, but there is a fistulous communication between the posterior trachea and the anterior esophagus. II. Pathophysiology. If the fistula is small, as is usually the case, "silent" aspiration occurs during feedings with resulting pneumonitis. If the fistula is unusually large, coughing and choking may accompany each feeding. III. Clinical presentation. Symptoms, as noted previously, depend on the size of the fistula. IV. Diagnosis. Barium swallow is the initial diagnostic study and may identify the fistula. The most accurate procedure, however, is bronchoscopy (perhaps combined with esophagoscopy); this should allow discovery and perhaps cannulation of the fistula. V. Management. Surgical correction is required. The approach (via the neck or chest) is determined by location of the fistula. Intrinsic Abnormalities of the Airway I. Definition. Abnormalities of, or within, the airway that cause partial obstruction fall into this category. Examples include laryngomalacia, paralyzed vocal cord, subglottic web, and hemangioma. II. Pathophysiology. These lesions result in partial obstruction of the airway and cause stridor and respiratory distress of varying severity. III. Clinical presentation. See section II: Pathophysiology. IV. Diagnosis. The diagnosis is established by endoscopy of the airway. V. Management is individualized. Some problems, such as laryngomalacia, will be outgrown if the child can be supported through the period of acute symptoms. Other lesions, such as subglottic webs, may be amenable to endoscopic resection or laser therapy. Congenital Lobar Emphysema I. Definition. Lobar emphysema is a term used to denote hyperexpansion of the air spaces of a segment or lobe of the lung. II. Pathophysiology. Inspired air is trapped in an enclosed space. As the cyst of entrapped air enlarges, the normal lung is increasingly compressed. Cystic problems are more common in the upper lobes. III. Clinical presentation. Small cysts may cause few or no symptoms and are readily seen on x-ray film. Giant cysts may cause significant respiratory distress, with mediastinal shift and compromise of the contralateral lung. IV. Diagnosis. Usually, the cysts are easily seen on plain chest x-ray films. However, the radiologic findings may be confused with those of tension pneumothorax. V. Management. Therapeutic options include observation for small asymptomatic cysts, repositioning of the endotracheal tube to selectively ventilate the uninvolved lung for 6-12 h, bronchoscopy for endobronchial lavage, and operative resection of the cyst with or without the segment or lobe from which it arises. Cystic Adenomatoid Malformation I. Definition. The term cystic adenomatoid malformation encompasses a spectrum of congenital pulmonary malformation involving varying degrees of adenomatosis and cyst formation. II. Pathophysiology. Severity of symptoms is related to the amount of lung involved and particularly to the degree to which the normal ipsilateral and contralateral lung is compressed. III. Clinical presentation. Signs of respiratory insufficiency such as tachypnea and cyanosis are modes of presentation. IV. Diagnosis. The characteristic pattern on chest x-ray film is multiple discrete air bubbles, occasionally with air-fluid levels, involving a region of the lung. The radiographic appearance can mimic that of congenital diaphragmatic hernia (CDH). V. Management. Treatment is surgical resection of the involved lung, allowing reexpansion of compressed normal pulmonary tissue. Congenital Diaphragmatic Hernia I. Definition. A patent pleuroperitoneal canal through the foramen of Bochdalek is the essential defect in CDH. II. Pathophysiology A. Prenatal. The abnormal communication between the peritoneal and pleural cavities allows herniation of intestine into the pleural space as the developing GI tract returns from its extracoelomic phase at 10-12 weeks' gestation. Depending on the degree of pulmonary compression by herniated intestine, there may be marked diminution of bronchial branching, limited multiplication of alveoli, and persistence of muscular hypertrophy in pulmonary arterioles. These anatomic abnormalities are most notable on the side of the CDH (usually the left); they are also present to some degree in the contralateral lung. B. Postnatal. After delivery, the anatomic anomaly may contribute to the development of either or both of the following pathologic conditions: 1. Pulmonary parenchymal insufficiency. Infants with CDH have an abnormally small functional lung mass. Some have so few conducting air passages and developed alveolia condition known as pulmonary parenchymal insufficiencythat survival is unlikely. 2. Pulmonary hypertension. Infants with CDH are predisposed anatomically to pulmonary hypertension of the newborn (PHN), also known as persistent fetal circulation (PFC). In this condition, blood is shunted around the lungs through the foramen ovale and patent ductus arteriosus. Shunting promotes acidosis and hypoxia, both of which are potent stimuli to additional pulmonary vasoconstriction. Thus, a vicious cycle of clinical deterioration is established. III. Clinical presentation. Most infants with CDH exhibit significant respiratory distress within the first few hours of life. IV. Diagnosis. Prenatal diagnosis can reliably be made by ultrasonography. Delivery should occur in a neonatal center with extracorporeal membrane oxygenation (ECMO) capability. Afflicted infants tend to have scaphoid abdomens because there is a paucity of the GI tract located in the abdomen. Auscultation reveals diminished breath sounds on the affected side. Diagnosis is established by a chest x-ray film that reveals a bowel gas pattern in one hemithorax, with shift of mediastinal structures to the other side and compromise of the contralateral lung. V. Management A. Indwelling arterial catheter. Blood gas levels should be monitored by an indwelling arterial catheter. B. Supportive care. Appropriate respiratory and metabolic support should be provided. CDH lungs are surfactant deficient, and replacement therapy appears to be helpful. Avoidance of aggressive conventional hyperventilation, permissive hypercapnia, seems to improve survival and decrease complications. C. Nasogastric intubation should be performed to lessen gaseous distention of the stomach and intestine. For the same reason, any positive-pressure ventilation must be delivered by endotracheal tube, never by mask. D. Surgical correction is by reduction of intrathoracic intestine and closure of the diaphragmatic defect. Surgical intervention is obviously an essential element of treatment, but it is not the key to survival. Formerly, surgery was performed on an urgent or emergent basis. Current thinking favors a delayed approach, allowing the newborn to stabilize a hyperreactive pulmonary vascular bed and to improve pulmonary compliance. If indicated, ECMO can be instituted and repair performed while on support 1 or 2 days after decannulation. E. ECMO is used in the treatment of neonates with severe respiratory failure. Exposure of venous blood to the extracorporeal circuit allows correction of PO 2 and PCO 2 abnormalities as well as recovery of the lungs from the trauma associated with positive-pressure ventilation (see Chapter 11). VI. Prognosis. Mortality rates for infants with CDH are still in the range of 50%. This high rate has prompted a search for other modes of treatment in addition to the expensive, labor-intensive modality ECMO. A. Fetal surgery has been performed successfully on a limited basis, with the idea that in utero intervention will lessen the risk for development of pulmonary hypoplasia, which may be incompatible with life after delivery. Formal operative correction of CDH in the fetus has been abandoned, but several centers currently perform in utero tracheal occlusion in selected patients. This appears to result in increased lung fluid and to promote pulmonary growth. B. Medications. Another major area of research is the attempt to develop a pharmacologic agent to selectively decrease pulmonary vascular resistance. Such an agent would help solve the problem of PHN (PFC). ABDOMINAL MASSES Renal Masses In most clinical series, the majority of abdominal masses in neonates are renal in origin. They may be unilateral or bilateral, solid or cystic. After physical examination, evaluation begins with ultrasonography, which is simple and safe to perform. Ultrasonography should define the solid or cystic nature of the mass, determine the presence or absence of normal kidneys, and yield information on other intra-abdominal abnormalities. In selected instances, more involved procedures such as renal scan, computed tomography (CT) scan, retrograde pyelography, venography, and arteriography may be needed to define the problem and plan appropriate therapy. I. Multicystic kidney is a form of renal dysplasia and the most common renal cystic disease of the newborn. Fortunately, it is usually unilateral. Ultrasonography can define the nature of the disorder, and CT/nuclear renal scans are useful in assessing the remainder of the urinary system. Nephrectomy is appropriate treatment. II. Hydronephrosis. Urinary obstruction, depending on its location, can cause unilateral or bilateral flank and abdominal masses. Treatment is by correction of the obstructing lesion or decompression proximal to it. A kidney rendered nonfunctional by back pressure is usually best removed. Obstructive uropathy may be one category of lesion suitable for in utero intervention. Surgery on the developing fetus to decompress the obstructed urinary system may improve the postnatal status and increase survival. III. Infantile polycystic kidney disease. Inherited in an autosomal recessive fashion, this entity involves both kidneys and carries a grim prognosis. IV. Renal vein thrombosis. The typical presentation is one or more flank masses and hematuria, usually within the first 3 days of life. Risk factors are maternal diabetes and dehydration. In general, conservative nonoperative management is recommended. V. Wilms' tumor. See p 580. Ovarian Masses Simple ovarian cyst has been called the most frequently palpated abdominal mass in the female neonate. It presents as a relatively mobile, smooth-walled abdominal mass. It is not associated with cancer, and excision with preservation of any ovarian tissue is curative. Hepatic Masses The liver can be enlarged, often to grotesque proportions, by a variety of problems. When physical examination, ultrasonography, and other x-ray studies suggest hepatic origin, CT or angiography should be performed. These studies may be diagnostic and will aid in surgical planning. Lesions include the following: I. Hepatic cysts. II. Solid, benign tumors. III. Vascular tumors A. Hemangiomas of the liver may cause heart failure, thrombocytopenia, and anemia. Therapeutic options include digitalis, corticosteroid administration, embolization, hepatic artery ligation, and liver resection. B. Hemangioendothelioma. IV. Malignant tumors. Hepatoblastoma is by far the most common liver cancer in the neonate. Serum alpha-fetoprotein may be elevated. Although surgical resection remains the key to achieving cure, new chemotherapeutic protocols (cisplatin [Platinol] and doxorubicin [Adriamycin]) may significantly improve the formerly dismal prognosis for infants with this tumor. Gastrointestinal Masses Palpable abdominal masses that arise from the GI tract are unusual and tend to be cystic, smooth walled, and mobile (depending on the size). Causes include intestinal duplication and mesenteric cyst. RETROPERITONEAL TUMORS Neuroblastoma I. Definition. Neuroblastoma is a primitive malignant neoplasm that arises from neural crest tissue. It is probably the most common congenital tumor and is usually located in the adrenal gland. II. Clinical presentation. This tumor typically presents as a firm, fixed, irregular mass extending obliquely from the costal margin, occasionally across the midline and into the lower abdomen. III. Diagnosis A. Laboratory studies. A 24-h urine collection should be analyzed for vanillylmandelic acid and other metabolites. B. Radiologic studies. A plain abdominal x-ray film may reveal calcification within the tumor. Intravenous pyelogram (IVP) and CT scan typically show extrinsic compression and inferolateral displacement of the kidney. Search for possible metastatic deposits involves bone marrow aspiration and biopsy, bone scan, chest x-ray study, and chest CT scan. IV. Management. Planned therapy should take into account the well-recognized but poorly understood fact that neuroblastoma is notably less aggressive in the young infant than in the older child. Wilms' Tumor (Nephroblastoma) I. Definition. Wilms' tumor is an embryonal renal neoplasm in which blastemic, stromal, and epithelial cell types are present. Renal involvement is usually unilateral but may be bilateral (5% of cases). II. Clinical presentation. A palpable abdominal mass extending from beneath the costal margin is the usual mode of presentation. III. Risk factors include aniridia, hemihypertrophy, certain genitourinary anomalies, and a family history of nephroblastoma. IV. Diagnosis A. Laboratory studies. There is no tumor marker for Wilms' tumor. B. Radiologic studies. Ultrasonography is generally followed by CT scan, which reveals intrinsic distortion of the caliceal system of the involved kidney. The possibility of tumor thrombus in the renal vein and inferior vena cava should be evaluated by ultrasonography and venography, if necessary. V. Management A. Unilateral renal involvement. Nephrectomy is the first step in treatment. Surgical staging determines the administration of radiotherapy and chemotherapy; both are very effective. B. Bilateral renal involvement. Treatment of bilateral Wilms' tumor is highly individualized. Teratoma I. Definition. Teratoma is a neoplasm containing elements derived from all three germ cell layers: endoderm, mesoderm, and ectoderm. Teratomas in the neonate are primarily sacrococcygeal in location and are believed to represent a type of abortive caudal twinning. II. Clinical presentation. This tumor is usually grossly evident as a large external mass in the sacrococcygeal area. Occasionally, however, it may be presacral and retroperitoneal in location and may present as an abdominal mass. III. Diagnosis. See section II: Clinical Presentation. Digital rectal examination of the presacral space is important. IV. Management. Because the incidence of malignancy in these tumors increases with age, prompt surgical excision is required. ABDOMINAL WALL DEFECTS Gastroschisis I. Definition. Gastroschisis is a centrally located, full-thickness abdominal wall defect with two distinctive anatomic features. [...]... in congenital diaphragmatic hernia: the extracorporeal life support organization registry, 199 0- 199 9 J Pediatr Surg 2001;36:1 199 Greenholz SK: Congenital diaphragmatic hernia: an overview Semin Pediatr Surg 199 6;5:216 Langer JC: Gastroschisis and omphalocele Semin Pediatr Surg 199 6;5:124 Moss RL et al: A meta-analysis of peritoneal drainage versus laparotomy for perforated necrotizing enterocolitis... (eds): Neonatal-Perinatal MedicineDiseases of the Fetus and Infant, 7th ed Mosby-Year Book, 2002 Rovet J et al: Long-term sequelae of hearing impairment in congenital hypothyroidism J Pediatr 199 6;128:776 Skuza K et al: Prediction of neonatal hyperthyroidism in infants born to mothers with Graves' disease J Pediatr 199 6;128:264 Zimmerman D: Fetal and neonatal Hyperthyroidism Thyroid 199 9 ;9: 727 SECTION... function in premature infants The hypothyroxinemia of prematurity Clin Perinatol 199 8;25 :99 9 Hunter MK et al: Follow-up of newborns with low thyroxine and nonelevated thyroid-stimulating hormone-screening concentrations: results of the 20-year experience in the Northwest Regional Newborn Screening Program J Pediatr 199 8;132:70 Krude H et al: Molecular pathogenesis of neonatal hypothyroidism Horm Res... lung cysts Semin Pediatr Surg 199 4;3:233 O'Neill JA et al (eds): Pediatric Surgery, 5th ed Mosby-Year Book, 199 8 Pena A: Imperforate anus and other hindgut malformations Semin Pediatr Surg 199 7;6:165 Wong JT et al: Congenital diaphragmatic hernia: survival treated with very delayed surgery, spontaneous respiration and no chest tube J Pediatr Surg 199 5;30:406 CHAPTER 79 Thyroid Disorders INTRODUCTION... potassium conductance, and possibly indirect antiadrenergic effects SUPPLIED: Injection, 6 mg/2 mL ROUTE: IV DOSAGE: 0. 1-0 .2 mg/kg by rapid IV push over 1-2 s ADVERSE EFFECTS: Do not use in second- or third-degree AV block May produce a shortduration first-, second-, or third-degree heart block; hypotension; brief dyspnea; and facial flushing Half-life is . organization registry, 199 0- 199 9. J Pediatr Surg 2001;36:1 199 . Greenholz SK: Congenital diaphragmatic hernia: an overview. Semin Pediatr Surg 199 6;5:216. Langer JC: Gastroschisis and omphalocele Pediatr Surg 199 4;3:233. O'Neill JA et al (eds): Pediatric Surgery, 5th ed. Mosby-Year Book, 199 8. Pena A: Imperforate anus and other hindgut malformations. Semin Pediatr Surg 199 7;6:165 gestational age: newborn term infants, 2. 0-5 .3 ng/dL; preterm infants of 3 1-3 6 weeks' gestation, 1. 3- 4.7 ng/dL; and infants of 2 5-3 0 weeks' gestation, 0. 6-3 .3 ng/dL. C. TSH measurement