Oesophageal Atresia And Tracheo-Oesophageal Fistula - CEACCP

Oesophageal Atresia And Tracheo-Oesophageal Fistula O. Al-Rawi MB ChB FRCA PD Booker MBBS FRCA MD

Oesophageal atresia (OA) is a congenital complete interruption of the oesophageal lumen. Approximately 92% of patients with OA have a tracheo-oesophageal fistula (TOF), which is a congenital fistulous connection between the oesophagus and the trachea or a main bronchus. Approximately 4% of patients with TOF do not have OA. The incidence of OS/TOF is 1 in 3500 live births.1

Classifications A number of surgical classifications have been described as surgical corrections evolved. In addition, there are anatomical classifications based on the frequency of each type of anomaly (Fig. 1), and prognostic classifications that can be used to predict morbidity and mortality rates (Table 1).2

Aetiology The aetiology of OA/TOF is poorly understood. The birth of an infant with OA/TOF in a family without a previous history of the condition is associated with a recurrence risk of about 1%.1 The twin concordance rate for OA/ TOF is about 2.5%. These data suggest that genetic factors do not play a major role in the pathogenesis of OA/TOF. However, there are specific chromosomal anomalies that predispose to this condition, such as trisomy 18 and 21. Three separate genes associated with OA/ TOF in humans have recently been identified.1 Analysis of anomalous tracheo-oesophageal development in adriamycin-exposed rat embryos suggests that defective sonic hedgehog (Shh) gene expression, signalling, or both, leads to disruption of the normal development of the foregut.3 Animal models also suggest that the embryological origin of the upper oesophagus is different from that of the distal oesophagus. Human studies suggest that the fistula develops from a trifurcation of the embryonic lung bud.4

Associated anomalies

Key points

More than 50% of newborns presenting with OA/TOF have associated anomalies, many of them leading to considerable morbidity and mortality. Isolated OA shows the highest association with other anomalies compared with other forms of OA/TOF. The incidence of OA/TOF in pre-term infants is relatively high. Congenital heart disease is the most common co-morbidity and can be a major determinant of survival. In particular, anomalies of the aortic arch are associated with long-gap OA and TOF. A variety of phenotypic variants have been described in association with OA/TOF: a well-known acronym is the VACTERL association (vertebral, anorectal, cardiac, tracheoesophageal, renal, and limb abnormalities). Rarely, OA/TOF may be associated with the Holt–Oram syndrome, the DiGeorge syndrome, polysplenia, and the Pierre –Robin syndrome. Other commonly associated anomalies are listed in Table 2.1

The aetiology of oesophageal atresia with or without tracheo-oesophageal fistula is unclear, although 10% of patients have chromosomal abnormalities.

Most cases are diagnosed antenatally allowing delivery location to be optimized. Improvement in survival in high-risk cases is related to better postoperative care. Long-term follow-up is essential because of ongoing morbidity in the majority of patients.

Diagnosis Antenatal Antenatal diagnosis of OA/TOF, by ultrasound examination, should result in delivery close to a specialist centre where appropriate neonatal surgical facilities are available. Parents should receive counselling only after a careful search for associated anomalies has been made. Antenatal diagnosis helps prevent inadvertent feeding and pulmonary aspiration pneumonitis.

Postnatal OA and TOF should be suspected if a newborn is noted to have difficulty in clearing saliva, repeated episodes of coughing and choking, or transient cyanosis shortly after birth. Alternatively, infants may present with a sudden onset of respiratory distress following attempts at feeding. Failure to pass a nasogastric tube with the feeling of distal resistance at the blind end of the upper oesophageal pouch

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Fifty per cent of newborns with these conditions have associated congenital anomalies; congenital heart disease is the most common.

O. Al-Rawi MB ChB FRCA Research Fellow in Anaesthesia Cardiothoracic Centre, Liverpool Thomas Drive Liverpool L14 3PE UK PD Booker MBBS FRCA MD Consultant Paediatric Anaesthetist Royal Liverpool Children’s Hospital Eaton Road Liverpool, L12 2AP UK Tel: þ440151 252 5223 Fax: þ440151 252 5460 E-mail: [email protected] (for correspondence)

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Oesophageal atresia and tracheo-oesophageal fistula

Figure 1. (A) Oesophageal atresia (OA) with distal tracheo-oesophageal fistula (TOF). (B) Isolated OA. (C) Isolated TOF. (D) OA with proximal TOF. (E ) OA with double TOF.

can confirm the diagnosis. A plain X-ray that includes the chest and abdomen may demonstrate the nasogastric tube coiled in the upper pouch (Fig. 2). If OA is associated with a TOF, gas-filled intestine and stomach below the diaphragm will be shown on the radiograph film. Occasionally, a fine nasogastric tube can coil in an otherwise normal proximal oesophagus. Hence, gentle downward pressure on a relatively large Replogle (sump suction) tube under radiographic examination may be required to confirm the diagnosis. In isolated OA, a gasless abdominal X-ray is observed. An expectant search for associated anomalies is paramount; the cardiovascular system, in particular, should be carefully examined to exclude congenital heart defects whose treatment may take priority over correction of OA/TOF.

infants. Delay in surgical correction increases the risk of aspiration of saliva as a result of accumulation in the upper oesophageal pouch. Furthermore, reflux of gastric acid through the lower pouch and a TOF can cause pneumonitis. Echocardiographic examination should be obtained before surgical correction to demonstrate any cardiac or vascular abnormality that could affect anaesthetic management or surgical approach. The presence of a cardiac defect may significantly affect prognosis and determine the operative approach, as thoracotomy is usually performed opposite to the side of the aortic arch. Confirmation of reasonably normal haematological and biochemical profiles should be sought, and blood sent for type grouping and serum saved, before the baby is brought to the theatre.

Preoperative preparation

Anaesthetic management

After confirming the diagnosis, i.v. fluids should be given to prevent dehydration and hypoglycaemia. Prophylactic antibiotics help to reduce the risk of perioperative respiratory infection. The upper oesophageal pouch should be cleared by continuous suction applied to a Replogle tube or repeated suctioning of the upper pouch and oropharynx. Infants should be nursed supine or in a lateral position. Arrangement for transfer to the nearest neonatal surgical unit should be made as soon as possible, as surgery should be performed within the first 24 h in otherwise healthy

Anaesthesia for neonates is often induced in the operating theatre rather than the anaesthetic room, so it is important to check that all necessary equipment is readily available. A forced air warming device should be used to help maintain the infant’s core

Table 1. The Spitz classification Group

Features

Survival (%)

I II III

Birth weight .1500 g, no major cardiac anomaly Birth weight ,1500 g or major cardiac anomaly Birth weight ,1500 g and major cardiac anomaly

98.5 82 50

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Table 2. Congenital anomalies associated with OA and TOF (Liverpool series 1953 –97) Type

581 cases, n(%)

Cardiac Urogenital Skeletal Vertebral Anorectal Gastrointestinal Palatal/laryngotracheal VACTERL

154 (27%) 105 (18%) 71 (12%) 64 (11%) 67 (12%) 53 (9%) 44 (8%) 25 (19%)

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Figure 2. Loop of nasogastric tube seen in upper oesophageal pouch just below the heads of the clavicles. Gastric air-bubble confirms presence of TOF.

temperature, as its use makes it unnecessary to increase environmental temperature above the normal range. Before induction of anaesthesia, the baby should have an oximeter probe taped on the right hand. The upper pouch tube is aspirated and then removed. Inhalational induction using sevoflurane in oxygen is performed; when respiratory movements decrease, a 3.0- or 3.5-mm tracheal tube is inserted. Ventilation with a bag and mask should be avoided as this may cause problematic gastric inflation. Once the correct size of tracheal tube has been determined and spontaneous respiration re-established, a rigid ventilating (Storz) bronchoscope (usually 3.0 mm) can be introduced. A bronchoscopic examination of the trachea and main bronchi will confirm the diagnosis and position of the TOF(s). A T-piece and open-tailed bag is attached to the 15 mm side port of the bronchoscope, allowing spontaneous ventilation by the baby throughout the procedure. Following the bronchoscopic examination, the tracheal tube is reinserted and positioned such that it occludes the TOF (usually just proximal to the carina). Rotation of the tracheal tube, such that the bevel faces away from the fistula, usually allows ventilation of

both lungs while occluding the fistula. Correct positioning of the tracheal tube may be problematic and requires the use of a small, flexible bronchoscope introduced through the tracheal tube. Occasionally, when the TOF is at the carina or more distally, it is necessary to perform bronchial intubation and one lung ventilation until the TOF is ligated. The use of bronchial blockers or a Fogarty catheter to block the TOF has also been described. Once the tracheal tube has been correctly positioned so that the fistula is occluded, the baby may be given a muscle relaxant and ventilated gently by hand. Airway pressures are kept to a minimum (and hypercapnia allowed) until after the fistula is divided. Once the neonate is anaesthetized and stable, insertion of an arterial line for continuous monitoring of blood pressure is advisable, as haemodynamic instability during surgical manipulation may occur (see below). Moreover, the cannula will allow repeated sampling for blood gases during the perioperative period. Central venous access is helpful for monitoring filling pressures and as a secure route for drug administration. Usually, the infant is positioned for a right thoracotomy in a lateral position, with the right

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arm raised across the head. Use of appropriate padding, tapes, and gel blocks should ensure secure and safe positioning of the patient.

Intraoperative considerations The extrapleural approach to the posterior mediastinum is used whenever possible, though occasionally the pleura is breached. The azygos vein is often divided to facilitate access to the TOF. Rarely, the inferior vena cava drains into the right atrium via the azygos vein; therefore, before division, it is important that the surgeon performs a test occlusion. Only after confirmation that this manoeuvre does not affect blood pressure can the azygos vein be ligated and divided as it enters the superior vena cava. The integrity of the TOF repair is evaluated by instilling saline into the thoracic cavity and confirming that application of positive airway pressure to the airway does not cause bubbles to leak from the suture line. A well-labelled nasogastric tube is inserted by the anaesthetist and placed by the surgeon into the stomach before the oesophageal anastomosis is complete.

Postoperative care Patients should be managed in a paediatric intensive care unit. I.v. fluids and broad-spectrum antibiotics are continued. Analgesia and sedation, which can be provided using morphine 10–20 mg kg21h21 and midazolam 50–100 mg kg21h21, should be carefully monitored. If the anastomotic repair appears satisfactory and there is no other indication for artificial ventilation, the trachea should be extubated as soon as possible. There is no evidence to suggest that prolonged paralysis and artificial ventilation affects anastomotic healing.5 H2-antagonists such as ranitidine are commonly used to reduce the effects of gastrooesophageal reflux (GOR). Trans-anastomotic tube feeding is usually started by 48 h after surgery.

Complications Early Even after surgical repair, most patients will have structural and functional abnormalities of the trachea and oesophagus as a result of defective embryological development. Typically, the trachea retains a wide membranous section compared with a normal ‘C’-shape with a relatively narrow membranous portion. This abnormality can lead to tracheomalacia of varying severity. Abnormal tracheal epithelium and loss of goblet cells, especially around the area of the original fistula, can result in susceptibility to repeated chest infections; it is, however, unclear whether these problems are caused by developmental anomalies or repeated aspiration. Anastomotic leak occurs in 11 –21% of patients and about 50% of these develop an oesophageal stricture. Major disruption is rare and is usually manifest by an early pneumothorax and salivary drainage from the chest drain. The majority of leaks are small and resolve spontaneously with or without pleural drainage. When

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conservative management fails, a cervical gastrostomy may have to be performed, delaying oesophageal replacement until after recovery.6 The presence of OA/TOF affects the development of the mesenteric plexus, leading to abnormal peristalsis and impaired lower oesophageal sphincter tone. Patients with OA/TOF have reduced neuronal tissue in Aurbach’s plexus in the lower oesophagus and gastric plexus.7 GOR occurs in 35–58% of patients and is probably the result of intrinsic oesophageal dysfunction. Management is initially conservative and includes antacids, proton pump inhibitors, and prokinetic agents. Fundoplication surgery is performed in 6–45% of patients; surgical management varies widely between different institutions.

Late Respiratory complications occur in up to 46% of patients with repaired OA/TOF, 19% have recurrent pneumonia and 23% have repeated episodes of aspiration. These respiratory complications are secondary to GOR (74%), tracheomalacia (13%), recurrent TOF (13%), or oesophageal stricture (10%).8 Anastomotic stricture is relatively common after repair of an oesophageal gap of 2.5 cm or more. In these instances, the anastomosis is frequently under tension, which increases the incidence of strictures. TOF recurs in about 9% of cases, typically 2 –12 months after surgical repair. Recurrence is more likely after excessive oesophageal mobilization during surgery, anastomotic leak, and oesophageal stenosis.

Prognosis There have been many different outcome-based classification systems. The Spitz system, based on birth weight and the presence or absence of major congenital heart disease, is one of the most commonly employed tools in current practice (Table 1).2 Generally, the mortality rate for OA/TOF remains on the decline and is currently ,1.5% for patients without major cardiac anomalies and with a birth weight of .1500 g.

References 1. Shaw-Smith C. Oesophageal atresia, tracheo-oesophageal fistula, and the VACTERL association: review of genetics and epidemiology. J Med Genet 2006; 43: 545–54 2. Lopez PJ, Keys C, Pierro A et al. Oesophageal atresia: improved outcome in high-risk groups? J Pediatr Surg 2006; 41: 331 –4 3. Arsic D, Cameron V, Ellmers L et al. Adriamycin disruption of the Shh-Gli pathway is associated with abnormalities of foregut development. J Pediatr Surg 2004; 39: 1747– 53 4. Crowley AR, Mehta SS, Hembree MJ et al. Bone morphogenetic protein expression patterns in human esophageal atresia with tracheoesophageal fistula. Pediatr Surg Int 2006; 22: 154– 7 5. Beasley SW. Does postoperative ventilation have an effect on the integrity of the anastomosis in repaired oesophageal atresia? J Paediatr Child Health 1999; 35: 120–2

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6. Tsai JY, Berkery L, Wesson DE et al. Esophageal atresia and tracheoesophageal fistula: surgical experience over two decades. Ann Thorac Surg 1997; 64: 778–84

8. Kovesi T, Rubin S. Long-term complications of congenital esophageal atresia and/or tracheoesophageal fistula. Chest 2004; 126: 915–25

7. Nakazato Y, Landing BH, Wells TR. Abnormal Auerbach plexus in the esophagus and stomach of patients with esophageal atresia and tracheoesophageal fistula. J Pediatr Surg 1986; 21: 831– 7

Please see multiple choice questions 12 –16

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