Other neonatal emergencies: Tracheoesophageal fistula and omphalocele

Published on 07/02/2015 by admin

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Other neonatal emergencies: Tracheoesophageal fistula and omphalocele

Robert J. Friedhoff, MD

Tracheoesophageal fistula

Tracheoesophageal fistula (TEF) occurs as the result of failure of the tracheal bud to develop normally from the primitive foregut. TEF occurs in several forms (Figure 203-1); type C—esophageal atresia (more correctly agenesis because the proximal part of the primitive foregut develops primarily into a trachea rather than an esophagus) with a distal TEF—is the most common form (accounts for 90% of all TEFs). Maternal polyhydramnios may indicate the presence of the lesion before birth. Diagnosis is suspected at birth when the neonate has excessive drooling, cyanotic episodes, or coughing relieved by suctioning or the clinician is unable to pass a soft catheter into the infant’s stomach. TEF can be confirmed by radiography by showing a curled catheter in the upper esophageal pouch with an air bubble in the stomach. Contrast medium is unnecessary and contraindicated because the neonate may aspirate the medium. Associated conditions include prematurity (20%-25%), congenital heart disease (20%-25%), and other midline defects.

Figure 203-1 Types of congenital abnormalities of the esophagus. A, Esophageal atresia, no esophageal communication with the trachea. B, Esophageal atresia, the upper segment communicating with the trachea. C, Esophageal atresia, the lower segment communicating with the back of the trachea. More than 90% of all esophageal malformations fall into this group. D, Esophageal atresia, both segments communicating with trachea. E, Esophagus has no disruption of its continuity but has a tracheoesophageal fistula. F, Esophageal stenosis. (Modified from Gross RE. The Surgery of Infancy and Childhood. Philadelphia: WB Saunders; 1953.)

Preoperative management

Preoperative assessment is directed at detecting associated congenital lesions and assessing the patient’s pulmonary status. The infant should be fed in the semiupright position, and continuous suction should be applied to the upper esophageal pouch to prevent aspiration. Respiratory support with humidified O₂ should be provided. Routine newborn preoperative laboratory studies (i.e., hemoglobin, electrolytes, glucose, and calcium concentration with or without arterial blood gases) and echocardiography to detect cardiac anomalies, including a right aortic arch (5% of neonates with TEF), should be performed. Pulmonary complications of TEF will not resolve until the fistula is ligated. A preliminary gastrostomy is often performed under local anesthesia.

Intraoperative management

Induction techniques for repair of a TEF include the use of inhalation agents with a rapid sequence or awake intubation. The use of N₂O, which will add to gastric distention, should be avoided. Care must be taken to avoid intubating the fistula. A tracheal tube with the Murphy eye facing anteriorly should be inserted into the right main bronchus while listening for unilateral breath sounds; the tracheal tube is then pulled back until bilateral breath sounds are heard. Some clinicians prefer to cut the distal end of the tracheal tube, eliminating the Murphy eye. Use of a cuffed tracheal tube to both ventilate and occlude the fistula has been reported. Placement of a Fogarty catheter to identify and occlude the fistula using a pediatric bronchoscope can be attempted. Spontaneous ventilation, to avoid gastric distention until the fistula has been ligated, should be performed, and then controlled ventilation can be used.

Thoracoscopic repair of the fistula will avoid a thoracotomy and its sequelae. Use of a Fogarty catheter placed in the right main bronchus with the aid of a bronchoscope will facilitate one-lung ventilation. An alternative technique is to manipulate the tracheal tube to the left main bronchus with a bronchoscope. Surgical insufflation of CO₂ (5-6 mm Hg) into the right hemithorax will cause right lung collapse and possible hypercapnia and hypoxemia. Time to extubation and discharge from the neonatal intensive care unit are decreased with thoracoscopic repair.

A precordial stethoscope should be placed under the dependent lung. Routine intraoperative monitors and an arterial catheter are typically used. Regional anesthesia can be added as an adjuvant.

Postoperative care

Respiratory status in the intensive care unit can be optimized with the use of tracheal intubation and mechanical ventilation. Damage to the esophageal anastomosis can be avoided by marking a suction catheter so that it is not inadvertently extended past the anastomosis during nasopharyngeal suctioning.

Postoperative complications

Tracheal compression secondary to tracheomalacia may occur. Infants with TEF typically have abnormal swallowing; 68% have gastroesophageal reflux, leading to possible aspiration. Esophageal stricture is common. A tracheal diverticulum may persist, causing problems with subsequent intubations.

Omphalocele

Anesthetic management for omphalocele and gastroschisis are essentially the same, but knowledge of the associated anomalies will influence anesthetic decisions. Omphalocele and gastroschisis are congenital defects of the anterior abdominal wall, permitting external herniation of abdominal viscera. Gastroschisis is not midline (usually occurs on the right), has a normally situated umbilical cord (not covered with a hernia sac), and is rarely associated with other congenital anomalies but is associated with an increased incidence of prematurity.

Omphalocele has a 75% incidence of other congenital defects, including cardiac anomalies (ventricular septal defects most common), trisomy 21, and Beckwith-Wiedemann syndrome (omphalocele, organomegaly, macroglossia, and hypoglycemia). Epigastric omphaloceles are associated with cardiac and lung anomalies. Hypogastric omphaloceles are associated with exstrophy of the bladder and other genitourinary anomalies.

Preoperative care

The exposed viscera must be covered with a sterile plastic bag or film to limit evaporative heat loss from exposed bowel. Deficits of fluid and electrolytes (often excessive) need to be replaced prior to operative repair. Hypoglycemia should be corrected slowly with a glucose infusion (6-8 mg·kg⁻¹·min⁻¹). Severe rebound hypoglycemia may occur after bolus doses of glucose. The stomach should be decompressed using a nasogastric tube.

Intraoperative management

General tracheal anesthesia, using a combination of an inhaled anesthetic agent (N₂O should be avoided) and a parenteral opioid, along with controlled ventilation is required. Preoxygenation followed by awake or rapid sequence intubation is preferred.

Routine monitors, along with an arterial catheter and central venous line for measurement of intravascular pressures, are recommended. Elevated intra abdominal pressures, high ventilatory pressures, and inferior vena cava compression, which can result in circulatory stasis in the lower limbs, should be avoided.

Postoperative management

Problems seen intraoperatively with ventilation, elevated intra abdominal pressure causing compression of the inferior vena cava and impaired visceral blood flow, prolonged ileus, and decreased hepatic clearance of drugs can continue postoperatively. Urine output should be monitored closely.

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