Congenital deformities of the anterior thorax can be divided into four groups: pectus excavatum, pectus carinatum, Poland's syndrome, and sternal clefts and defects, including ectopia cordis.

Pectus excavatum (funnel chest) appears as a depression of the sternum and lower costal cartilages. The first and second ribs and their costal cartilages, as well as the manubrium, are usually normal (Fig. 1) 2059. The sternal and cartilaginous deformity is variable in extent and is frequently asymmetrical: the right side is often more depressed than the left, with corresponding rotation of the sternum.

The aetiology of pectus excavatum is unknown, and there is little evidence to support the hypothesis that it arises from an abnormality of the diaphragm. The condition occurs once in every 300 to 400 live births, and is usually noted within the first year of life. In less than 5 per cent of cases the diagnosis is made at adolescence. A family history of anterior thoracic deformity is present in 37 per cent of patients, and scoliosis affects 26 per cent; 11 per cent of these have a family history of scoliosis. Pectus excavatum is common in patients with abdominal musculature deficiency syndrome (prune belly syndrome) and in patients with Marfan's syndrome, in whom it is often accompanied by scoliosis.

Pectus excavatum is well tolerated in infancy. Older children may complain of pain in the area of the deformed cartilage or of precordial pain during exercise. A few patients suffer from palpitations or syncope, presumably due to transient atrial arrhythmias: mitral valve prolapse may be identified in these patients. Since transient deformity of the chest wall commonly occurs in infants during vigorous breathing or crying, pectus excavatum should not be corrected before the age of 2 years.

Although some authors maintain that pectus excavatum causes no cardiovascular or pulmonary impairment, many patients seem to have increased stamina after surgical correction of the deformity. Abnormalities of pulmonary function are difficult to demonstrate, since ‘normal’ parameters vary widely and are heavily dependent on physical training and body habitus. Abnormalities suggested by several different studies of patients have included an increased work of breathing, abnormal ventilation to perfusion ratios, subnormal cardiac response to upright exercise, and cardiac compression. Exercise tolerance increases following surgery in many patients.

The earliest surgical repairs of pectus excavatum were reported by Meyer in 1911 and Sauerbruch in 1920. In 1949 Ravitch reported a technique that included excision of all deformed costal cartilages with the perichondrium, division of the xiphoid from the sternum, division of the intercostal bundles from the sternum, and a transverse sternal osteotomy overcorrecting the sternum anteriorly. Kirschner wire fixation was used in the first two patients, and silk suture fixation in later patients. There is no conclusive evidence that internal fixation with Kirschner wires or metallic struts provides better long-term results than those achieved in patients without metal fixation.

In 1958 Welch reported a technique that allowed safe and satisfactory correction of pectus excavatum. He emphasized total preservation of the perichondrial sheaths of the costal cartilage, preservation of the upper intercostal bundles, and anterior fixation of the sternum with silk sutures. This technique has been used at The Children's Hospital, Boston, to treat more than 700 patients in the past 30 years. Nevertheless, we use the struts devised by Rehbein to hold the sternum in an anterior position, in the belief that these provide stability and greater comfort with less chance of recurrence. The struts are removed 6 to 12 months after the initial repair. Metal internal fixation devices can cause serious complications, especially if placed behind the sternum next to the heart; however, we encountered no problems when Rehbein struts, inserted into the marrow cavity of the third or fourth ribs, are joined medially to create a metal arch anterior to the sternum. The sternum is then sewn to the arch to secure it in its new forward position.

Our operative technique is illustrated in Fig. 2 2060. In girls, particular attention is taken to place the incision within the inframammary fold, avoiding the complications of breast deformity and abnormal development. Skin flaps are mobilized primarily in the midline to the angle of Louis superiorly and to the xiphoid inferiorly. Bovie electrocautery minimizes blood loss. Starting medially, the chest wall muscles are detached and retracted to expose the depressed costal cartilages. The lateral extent of muscle elevation is the costochondral junction of the third to fifth ribs, and rarely the second. Particular care is taken to avoid injury to the intercostal bundles: this can result in major bleeding. The rectus muscles are detached from the lower sternum and xiphoid, allowing blunt dissection behind the sternum. The xiphoid often projects forward and should be removed. Subperichondrial resection of the costal cartilages is performed, removing the entire third, fourth, and fifth cartilages to the costochondral junctions. Longer segments of the sixth and seventh cartilages (5–6 cm) are resected to the point where they flatten to join the costal arch. Bridges joining the fifth and sixth costal cartilages are often present lateral to the sternum. Transverse osteotomy of the anterior table of the sternum is performed. The osteotomy must be large enough to allow the sternum to be brought forward after fracture. The osteotomy is then closed with heavy silk sutures while the sternum is held forward in a deliberately over-corrected position. Struts can be used to hold the sternum forward, and are especially helpful in patients with extensive sternal rotation or a severe depression. If required, the lowest one or two sets of intercostal bundles (sixth and seventh) can be divided from the sternum to allow it to be brought forward without excessive tension. The number of perichondrial bundles divided should be minimized to avoid an unsightly local depression just inferior to the tip of the sternum.

This technique allows precise resection of costal cartilages with preservation of perichondrial sheaths, without injury to mediastinal structures, and usually without pleural or pericardial entry. If the pleura is entered, the hole should be made large enough to prevent tension pneumothorax and the lungs should be ventilated with enough positive pressure to maintain inflation. Any pleural air is aspirated through a temporary catheter, which is withdrawn when the defect is covered by the pectoralis muscle closure. The wound is flooded with warm saline solution and cefazolin to remove clots. A single-limb medium Hemovac drain is brought through the inferior skin flap with the suction ports in a parasternal position to the level of the highest costal cartilage resection. The pectoralis muscle flaps are sutured to the sternum, advancing the muscles medially and inferiorly to cover the underlying sternum with muscle. The rectus muscles are then reattached to the lower sternum medially and to the pectoralis muscles laterally. A postoperative chest radiograph is obtained in the recovery room. Antibiotic prophylaxis consists of cefazolin, given once before surgery and for three doses afterwards. Blood loss is well below that at which transfusion is required. Safe and effective repair is possible at any age: we have experienced no deaths and few complications (4.4 per cent) in 704 patients.

Complications of pectus excavatum repair should be few and minor. Limited pneumothorax, which may or may not require aspiration, occurs in 2 per cent of patients. Tube thoracostomy was required in only four patients in our series. Wound infection is rare with the use of perioperative antibiotic coverage.

The most distressing complication following surgical correction of pectus excavatum is major recurrence years after the original repair (17 of 704 patients). It is difficult to predict which patients will be affected, but they often have an asthenic or ‘marfanoid’ habitus with poor muscle development and a narrow anterior/posterior chest wall diameter.

Pectus carinatum describes anterior protrusion deformities of the chest wall: these are less common than depression deformities (16.7 per cent of our series). The most common form of pectus carinatum consists of symmetrical anterior displacement of the sternum with concavity of the costal cartilages laterally: a chondrogladiolar defect (Fig. 3) 2061. Asymmetrical deformities, with anterior displacement of the costal cartilages on one side and normal cartilages on the contralateral side and a normally positioned or oblique sternum, are less common. ‘Mixed’ lesions are characterized by a carinate deformity on one side and a depression or excavatum deformity on the other. The upper or chondromanubrial deformities (‘pouter pigeon’ deformities), with protrusion of the manubrium and second and third costal cartilages with relative depression of the short body of the sternum are least common (Fig. 4) 2062.

The aetiology of pectus carinatum is no better understood than that of pectus excavatum. It appears as an overgrowth of the costal cartilages with forward buckling and anterior displacement of the sternum. A clear-cut familial tendency suggests a genetic basis for this deformity. In a recent review of 152 patients 26 per cent had a family history of chest wall deformity. A family history of scoliosis was obtained in 12 per cent of the patients. The condition is more common in boys than in girls. Scoliosis and other deformities of the spine are the most common associated musculoskeletal deformities.

Pectus carinatum usually appears in childhood; in almost half of our patients the deformity was not identified until at least 11 years of age. The deformity may appear in a mild form at birth and often progresses, particularly during the period of rapid growth at puberty. The chondromanubrial deformity is noted at birth and is associated with a short truncated sternum with absent sternal segmentation or premature obliteration of sternal studies. In a prospective review of 135 patients with sternal fusion anomalies, 18 per cent had documented congenital heart disease.

Surgical repair of carinate deformities was first reported by Ravitch in 1952. He resected multiple costal cartilages and performed a double sternal osteotomy to correct chondromanubrial deformity. In 1953 Lester reported two methods of repair for chondrogladiolar deformity. The first, involving resection of the anterior portion of the sternum, was abandoned because of excessive blood loss and unsatisfactory results. The second, although no less radical, used subperiosteal resection of the entire sternum. Chin advanced the transected xiphoid and attached rectus muscles to a higher site on the sternum (xyphosternopexy). This method produced posterior displacement of the sternum in younger patients with a flexible chest wall. Howard combined this method with subperichondrial costal cartilage resection and a sternal osteotomy. In 1973, Welch reported the approach which we use today.

As in the pectus excavatum repair, a transverse incision is made just below and within the nipples, with mobilization of the pectoral muscle flaps and subperichondrial resection of the deformed costal cartilages. A sternal osteotomy allows the sternum to be fractured and displaced posteriorly into an orthotopic position (Fig. 5(a)) 2063. A second osteotomy is occasionally required to enable the lower portion of the body of the sternum to be displaced posteriorly. For correction of the upper or chondromanubrial deformity, the costal cartilages must be resected from the second cartilage inferiorly. A generous wedge osteotomy is then performed at the point of maximal protrusion of the sternum. The superior segment of the sternum can then be displaced posteriorly as the osteotomy is closed, advancing the inferior segment anteriorly (Fig. 5(b)) 2063. This corrects both components of the deformity. Mixed pectus carinatum/excavatum deformities are managed with a transverse wedge-shaped osteotomy, allowing anterior displacement and rotation of the sternum (Fig. 5(c)) 2063. Closure and postoperative drainage are performed as in pectus excavatum.

Surgical correction of pectus carinatum is generally successful and postoperative recovery uneventful. Blood transfusions are rarely required and there is a 3.9 per cent complication rate. Complications include pneumothorax, wound infection, recurrence and postoperative pneumonitis. Rare patients require revision, usually in the form of resection of additional lower costal cartilages to correct for persistent unilateral malformation of the costal arch.

In 1841 Poland described congenital absence of the pectoralis major and minor muscles associated with syndactyly. The clinical manifestations of this condition cover a wide spectrum, often with chest wall and breast deformities. Thoracic deformity ranges from hypoplasia of the sternal head of the pectoralis major muscle and the pectoralis minor muscle with normal underlying ribs to severe hypoplasia of the ribs with complete absence of the anterior portions of the second to fourth ribs and cartilages (Fig. 6) 2064. There may be mild hypoplasia of the breast, or complete absence of the breast (amastia) and nipple (athelia). There is often minimal subcutaneous fat and no axillary hair on the involved side. Hand deformities include hypoplasia (brachydactyly), fused fingers (syndactyly), and mitten or claw deformity (ectromelia). There is no direct correlation between the extent of hand and thoracic deformities.

This condition is present from birth and has an estimated incidence of 1/30000 to 1/32000 live births. Breast abnormalities can be identified at birth by the absence of the underlying breast bud and hypoplasia or aplasia of the nipple, which is often superiorly displaced. The aetiology is unknown and cases are sporadic.

Assessment of the extent to which various musculoskeletal components are involved is critical for optimal thoracic reconstruction. If deformity is limited to the sternal component of the pectoralis major and minor muscles there is little functional deficit and repair is not necessary, although breast augmentation should be performed in females when growth is complete. If the underlying costal cartilages are depressed or absent, chest wall repair must be considered to minimize the concavity, eliminate the paradoxic motion of the chest wall, and to provide an optimal base for breast reconstruction in females. Ravitch reported correction of posteriorly displaced costal cartilages by unilateral resection of the cartilages, a wedge osteotomy of the sternum allowing rotation of the sternum, and fixation with Rehbein struts and Steinmann pins. Good results can often be achieved with bilateral costal cartilage resection and an oblique osteotomy. This method allows correction of the rotational deformity. The sternum is displaced anteriorly correcting the posterior displacement of the costal cartilages. An unappreciated carinate deformity is often present on the contralateral side, accentuating the ipsilateral concavity.

Absence of the medial portion of the ribs can be managed with split rib grafts taken from the contralateral side. These grafts must be secured to the sternum medially and to the hypoplastic rib ends laterally, and then can be covered with a prosthetic mesh if further support is needed. In these patients there is little tissue between the endothoracic fascia and the fascial remnants of the pectoral muscles. Augmentation of this area by transfer of a latissimus dorsi muscle flap is particularly helpful in girls, who will require breast augmentation. Latissimus transfer is seldom if ever required in boys and has the disadvantage of adding a second thoracic scar, as well as removing one of the major functional muscles of the shoulder and arm.

Deformities due to failure of ventral fusion of the thoracic wall can be divided into thoracic ectopia cordis, thoracoabdominal ectopia cordis, and cleft sternum without ectopia cordis.

Cleft sternum with an orthotopic heart is the simplest of these deformities. The cleft may be complete or incomplete and results from failure of ventral fusion of the sternal bars, which normally occurs at the eighth week of gestation. In cleft sternum the midline sternal separation is covered and the pericardium, pleura and diaphragm are intact; omphaloceles do not occur. Crying or a Valsalva manoeuvre produces a dramatic increase in the apparent severity of the deformity. Intrinsic congenital heart disease is rare.

Treatment is recommended in the newborn period, when the malformation can be closed primarily without prosthetic materials or cardiac compression. Primary closure in older patients produces excessive cardiac compression. Reconstruction of the anterior chest wall using multiple oblique chondrotomies lengthens the costal cartilages and decreases cardiac compression in older patients, who have a less flexible chest wall. Autologous grafts including costal cartilages, split ribs, and resection of the costal arch complex have been described, but repair undertaken in the newborn period is optimal and avoids the need for these methods.

While management of isolated cleft sternum is uniformly successful, few patients survive surgical treatment of thoracic ectopic cordis. These patients have a high incidence of associated intrinsic cardiac anomalies, in addition to the abnormal position of the heart and surrounding somatic structures. In thoracic ectopic cordis the heart is external to the thorax, protruding at the upper to mid-thoracic level. The apex of the heart points anteriorly. Attempts to return the heart to the thorax occlude the great vessels and are not tolerated.

The features of the Cantrell pentalogy are a cleft lower sternum, an anterior diaphragmatic defect due to failure of development of the septum transversum, absence of the parietal pericardium, an adjacent or completely separate omphalocele and, in most patients, a cardiac anomaly, frequently tetralogy of Fallot.

Immediate closure of the abdominal wall is required in neonates with an omphalocele and lower sternal cleft. An aggressive approach should be taken if survival rates are to be improved. Repair of the cardiac defect can be performed after somatic closure.

Tumours of the chest wall are occasionally seen in childhood. They include a spectrum of benign and malignant neoplasms which arise from bone, cartilage, muscle, and fibrous tissue. The appearance of an asymmetrical carinate protrusion during puberty can be confused with a neoplasm, but careful palpation will define the mass as the protruding costal cartilages of pectus carinatum. Any unexplained swelling of the chest wall must be biopsied. Malignant tumours are more common than benign tumours in children; there is a marked predominence of small round cell sarcomas, which are variably termed Ewing's sarcomas or Askin tumours. Rhabdomyosarcomas and chondrosarcomas are less common. Chest wall resection plays a major role in the treatment of these lesions, in conjunction with chemotherapy and radiotherapy. These are important adjuncts because of the high frequency of local recurrence and distant metastasis. Preoperative chemotherapy may allow complete resection, particularly of large tumours.

Children tolerate extensive resections of the chest wall. Malignant neoplasms arising within a rib (osteosarcoma, chondrosarcoma, and Ewing's sarcoma) need to be treated by resection of the entire rib, along with one normal rib above and below the tumour because of intramedullary spread of the tumour. Defects can be closed with Marlex mesh or Gore-Tex tissue patches. Incisions should be planned so that they will not lie directly over an anticipated defect. A muscle flap interposed between the prosthetic material and the skin closure maximizes chest wall stability and minimizes the likelihood of infection.

Congenital absence of a portion of the diaphragm results in herniation of the abdominal viscera into the thoracic cavity. Diaphragmatic defects occur about once in every 4000 live births and once in every 2200 births if stillbirths are included. Ninety per cent of these herniations are through the posterior part of the diaphragm, the foramen of Bochdalek.

Most patients suffer respiratory distress in the immediate neonatal period. This results from pulmonary hypoplasia and compression of the pulmonary parenchyma by abdominal viscera in the thoracic cavity. Despite significant advances in surgical and anaesthetic techniques, and in postoperative ventilatory management, the mortality rate is high, and treatment of congenital diaphragmatic hernia is one of the major unsolved problems in paediatric surgery.

Congenital diaphragmatic hernia is usually an isolated defect. However, cryptorchidism occurs in 30 per cent of boys, and 40 per cent of infants in one recent study had one or more severe malformations involving the heart, brain, genitourinary system, or craniofacial region. Survival of such patients is particularly poor.

The septum transversum grows posteriorly to meet the dorsal mesentery of the foregut, forming the central portion of the diaphragm during the fourth to eighth weeks of fetal life. The lateral folds of peritoneum and pleura develop simultaneously, completing the separation between the thorax and the abdomen. Disruption of this process results in a posterolateral defect in the diaphragm (foramen of Bochdalek). This closure of the pleuroperitoneal canal is completed on the right side before the left, which may explain why 90 per cent of the diaphragmatic defects present on the left side.

As the diaphragm is developing, the midgut undergoes elongation and development outside the coelom. The midgut normally returns to the abdominal cavity and undergoes rotation and fixation at about the tenth week of fetal life. If closure of the diaphragm is incomplete, the intestine herniates into the chest as it returns to the coelom, inhibiting development of the lung and preventing the normal process of intestinal rotation and fixation. The spleen, stomach, and left lobe of the liver as well as the bulk of the intestine often reside within the thoracic cavity.

Herniation of the abdominal viscera into the thoracic cavity seriously impairs development of the ipsilateral, and to some extent the contralateral, lung. This hypoplasia of the pulmonary parenchyma accounts for the major physiological problems encountered in these infants. Creation of a diaphragmatic hernia in fetal lambs results in a decrease in the total size of the lung, fewer vessels per unit area of lung, and increased muscularization of the pulmonary arterial tree. These findings are identical to those in the affected human infant. The degree of ‘pruning’ or hypoplasia of the pulmonary vessels correlates with the adequacy of ventilation. If the pulmonary parenchyma is inadequate, mechanical ventilation will not prevent severe hypoxia, hypercarbia, and acidosis in these infants. Those with CO&sub2; retention before surgery and 2 h afterwards despite maximal ventilatory manoeuvres have a 90 per cent mortality rate; 97 per cent of those in whom Paco&sub2; levels can be lowered survive. Occasionally, adequate ventilation can be achieved initially (the so-called honeymoon period), indicating that enough pulmonary parenchyma is present to sustain life. Later, arterial blood gas balance deteriorates, with the development of pulmonary hypertension and right to left shunting through the patent ductus arteriosus (persistent fetal circulation). In this situation a ‘reactive’ pulmonary circulation with progressive vasoconstriction and pulmonary hypertension decreases perfusion of the lung and results in clinical deterioration. Vasodilating agents do not alter this pattern of persistent fetal circulation. They dilate the systemic as well as the pulmonary circulation, causing systemic hypotension; this creates a need for additional fluid administration, which in turn results in further pulmonary oedema and deterioration. Recent studies suggest inhaled nitric oxide may provide selective pulmonary vasodilatation.

After birth air entering the gastrointestinal tract distends the herniated bowel, shifting the mediastinum toward the contralateral side and compressing the contralateral lung. This process can be largely prevented by sump catheter decompression of the stomach.

Most infants develop respiratory symptoms in the first 24 h after birth. Although a spectrum of respiratory distress exists, many children immediately become severely cyanotic. Physical examination discloses a scaphoid abdomen, displacement of the cardiac apex away from the side with the defect, and decreased or absent breath sounds on the affected side. Rarely, bowel sounds can be heard in the chest. The occasional infants who become symptomatic weeks to months after birth respond well to surgical treatment.

The diagnosis can almost always be established on an upright thoracic radiograph, which shows multiple loops of intestine in the thoracic cavity and no diaphragmatic outline. Differential diagnoses include cystic adenomatoid malformation, eventration of the diaphragm, pneumatoceles from staphylococcal pneumonia, and pulmonary agenesis or hypoplasia. The radiographic appearances of all of these entities include presence of the diaphragm and a normal intra-abdominal bowel gas pattern. As antenatal ultrasound is applied more widely a growing number of infants with congenital diaphragmatic hernia are being identified in utero. These infants have a poor prognosis: in a recent series of 94 cases there was an 80 per cent mortality rate. Many (76 per cent) have polyhydramnios and only 11 per cent of these survive. A recent single institution study of 38 infants with an in-utero diagnosis of congenital diaphragmatic hernia confirmed these findings: polyhydramnios occurred in 69 per cent of infants and only 18 per cent survived. All infants diagnosed before 24 weeks gestation died. A 16 per cent incidence of chromosomal abnormalities was encountered.

Initial resuscitation is mandatory if these infants are to survive. Intubation for respiratory distress is often required before a radiograph is available. A nasogastric tube should be inserted and placed on suction to prevent further distention of the intestine. Because the hypoplastic lungs are susceptible to barotrauma, ventilation with high pressure must be avoided. A tension pneumothorax on the contralateral side often proves fatal. Rapid ventilation (60–150 breaths/min) with short inspiratory times, low pressure (M45 cmH&sub2;O), and 100 per cent oxygen is most effective. Alkalosis, hypocarbia, and oxygenation all decrease pulmonary artery pressures and the right to left shunt seen in persistent fetal circulation. Goals of ventilation are a Pao&sub2; above 100 torr, Paco&sub2; below 30 mmHg, and pH above 7.4. Vacanti et al. have stressed the importance of sedating these infants preoperatively and postoperatively with fentanyl and pancuronium combined with rapid frequency ventilation and moderate fluid restriction. Sedation seems to benefit those with very reactive pulmonary vasculature, but it does not help those with inadequate pulmonary tissue, who develop early pulmonary hypertension and acidosis. The infant must be kept warm during transport to avoid peripheral vasoconstriction and acidosis: the latter can elevate pulmonary artery pressure.

Although surgical repair was traditionally performed urgently, recent studies have shown that ventilatory compliance decreases appreciably in infants after surgery, producing a decline in the arterial gases. The current practice is to stabilize these infants with ventilation, sedation, and intestinal decompression, deferring repair of the defect until 36 to 72 h after birth. Delay may avoid the development of pulmonary hypertension and persistent fetal circulation due to surgical stress.

High-frequency ventilatory support may improve oxygenation while minimizing barotrauma to the lung. Bohn et al. studied 58 infants with congenital diaphragmatic hernia presenting within the first 6 h of life. Infants with CO&sub2; retention and severe preductal shunting were unresponsive to hyperventilation and had a 90 per cent mortality rate. The second group of infants responded well to hyperventilation and had reversible ductal shunting: 97 per cent survived. High-frequency ventilation (375–1800 cycles/s) has been unsuccessful in infants with inadequate response to lower frequency ventilation.

Extracorporeal membrane oxygenation has been used in infants in whom all ventilatory efforts to achieve adequate oxygenation and alkalosis have failed. Criteria for the use of this technique include a preductal and postductal Pao&sub2; below 6.6 kPa and Paco&sub2; below 5.3 kPa, despite maximum ventilation as outlined above. Infants with any evidence of intracerebral haemorrhage on cranial ultrasound or gestational age under 37 weeks are excluded, since they are at increased risk of cerebral bleeding during heparinization. While extracorporeal membrane oxygenation has been successful in infants with persistent fetal circulation following meconium aspiration, neonatal respiratory distress syndrome, and sepsis, it has been much less successful in infants with congenital diaphragmatic hernia. In one study, extracorporeal membrane oxygenation produces a survival rate of 90 per cent among infants with medical causes of acute respiratory failure, but of only 38 per cent for those with congenital diaphragmatic hernia. Presumably this treatment cannot be maintained for long enough to allow lung growth in infants whose pulmonary hypoplasia is of a degree incompatible with life. It may be useful in infants with mild hypoplasia whose condition deteriorates after birth because of pulmonary artery hypertension and fetal circulation.

A transverse upper abdominal incision is created on the side of the diaphragmatic defect and the abdominal viscera are withdrawn from the chest by gentle traction. A retractor elevating the upper diaphragmatic leaf facilitates this manoeuvre by allowing air to enter the thorax as the intestines are withdrawn. The defect in the diaphragm is closed with interrupted mattress sutures of 3–0 or 4–0 silk or non-absorbable synthetic material. The posterior leaf of the diaphragm must be dissected free from the peritoneum and retroperitoneal tissues that tether it posteriorly The diaphragm is often better developed than is first thought. In the rare situation where no posterior leaf exists, sutures are placed around the tenth and eleventh ribs to provide solid fixation. If the diaphragm is inadequate for primary closure, a prosthetic patch of tissue Gore-Tex is used. Occasionally a sac will be present: this should be excised prior to closure of the diaphragm. In these cases the defect is not a congenital Bochdalek hernia, but rather a large eventration of the central diaphragm.

Although some surgeons prefer a thoracic incision for repair, the abdominal approach allows the intestines to be withdrawn from the abdominal cavity as the diaphragmatic defect is closed. It also allows placement of a gastrostomy tube for intestinal decompression and early feeding. Malrotation is generally present, and the duodenum should be inspected for obstructing Ladd's bands. The abdominal cavity may be small in babies in whom the bowel has resided in the thorax in utero; the abdominal wall can be stretched manually to facilitate closure. If primary closure produces excessive pressure, a ventral hernia can be created by closing only the skin or by the use of a silon pouch, but these techniques are rarely required. If a prosthetic closure is necessary, final closure of the abdominal wall can usually be achieved in several days. A chest tube is inserted into the pleural cavity prior to closure. It is placed on water seal and not to suction to avoid any excessive shift of the mediastinum, which may produce kinking of the mediastinal vessels. If the condition of the infant is unstable a chest tube on the contralateral side will prevent fatal tension pneumothorax. Extralobar pulmonary sequestration in association with congenital diaphragmatic hernia is rare: when present the sequestration should be removed.

Although the diaphragmatic hernia can usually be repaired, if both lungs are markedly hypoplastic, adequate oxygenation will never be achieved. Survival may be compromised in babies with relatively good lungs if pulmonary artery hypertension occurs. Extracorporeal membrane oxygenation can decrease the degree of pulmonary artery hypertension by producing adequate oxygenation, alkalosis, and hypocarbia. All three factors will lower pulmonary artery pressures, and this technique may save some infants who previously have succumbed to persistent fetal circulation.

Ventilatory support is nearly always needed following repair. It must be regulated to limit inspiratory pressures and minimize barotrauma to the lungs. The hypoplastic lung bud should not be distended artificially. Close monitoring of arterial blood gases is essential: deterioration often indicates rising pulmonary artery pressures and additional sedation with fentanyl should be instituted. Deliberate hyperventilation to produce alkalosis and hypocarbia will decrease pulmonary artery resistance and hence pressures. Comparisons of preductal (right radial artery) and postductal (umbilical artery or posterior tibial artery) gases will define the extent of shunting at the ductal level.

Acute deterioration may be due to a pneumothorax on the contralateral side: this should be confirmed radiographically and treated with intercostal tube drainage on 10 to 15 cmH&sub2;O suction.

Survival rates remain at about 50 per cent for patients symptomatic in the first hours of life. The apparent failure of results to improve can be attributed to the fact that severely affected babies who died before referral in the past are now surviving, due to antenatal diagnosis and rapid transport.

Late pulmonary function studies have shown no abnormality in total lung capacity, vital capacity, or diffusion, but have demonstrated reduced blood flow and a permanent reduction in pulmonary vessels in the ipsilateral lung.

Failure of fusion of the central and lateral portions of the diaphragm anteriorly results in a defect known as the foramen of Morgagni. This is far less common than the foramen of Bochdalek hernia (<2 per cent) and has less physiological significance. These retrosternal hernias usually have a true sac and cause few respiratory symptoms: intestinal obstruction is a more common mode of presentation.

The diagnosis is suggested by the presence of air or fluid levels in the retrosternal region on an upright thoracic radiograph (Fig. 10) 2069,2070. Barium contrast studies may demonstrate the presence of intestine in the sac, but are rarely necessary. The hernia is best repaired through a transabdominal approach, with excision of the sac and primary closure of the defect in the diaphragm. Because there is little compression of the lungs during fetal development, pulmonary hypoplasia or respiratory compromise after repair are rare.

Eventration of the diaphragm may be congenital, resulting from failure of normal ingrowth of muscle into the developing diaphragm or it may be acquired, resulting from phrenic nerve injury. Whatever the cause there is an abnormally redundant and attenuated diaphragm which has little or no ability to contract. Ninety per cent of these lesions are on the left side. Symptoms vary greatly: some patients suffer severe respiratory compromise, while in others it is an asymptomatic incidental finding. The diagnosis is best confirmed by fluoroscopy, which demonstrates paradoxical motion of the diaphragm. Flexibility of the mediastinum in infants permits transmission of the paradoxical motion of the diaphragm to the contralateral side.

The need for repair is determined primarily by the symptoms produced by the eventration, and not by the radiographic findings. A small eventration can be repaired easily through a limited, low thoracotomy, the defect being reefed up by plication with non-absorbable sutures until the diaphragm is taut. A large eventration has similar radiographical appearances to a Bochdalek hernia, the thorax being filled with abdominal viscera. This is best repaired through an abdominal incision.

Tracheal agenesis is a uniformly fatal lesion in which a segment of the trachea is absent or contains no lumen. Severe respiratory distress invariably occurs at delivery. Intubation via the larynx is unsuccessful, but satisfactory ventilation following oesophageal intubation when an oesophagotracheal fistula is present may allow the infant to survive for several hours. Diagnosis is confirmed by endoscopy. Associated complex cardiovascular anomalies are often present. Reconstruction has been attempted using the oesophagus as a trachea, with division of the oesophagus proximally to create a ‘spit fistula’ or by cervical oesophagoscopy and division of the stomach distally. There have been no survivors.

Tracheal stenosis is more amenable to surgical repair. If only a short segment of trachea is affected, dilatation of a membranous web or its resection may be successful. Extensive lesions involving a greater length of the trachea were first treated by a tracheoplasty with a costal cartilage graft in 1982; this has produced favourable results since then. Up to 50 per cent of these infants have associated cardiovascular malformations.

Infants with tracheomalacia have abnormal tracheal compliance due to increased pliability or hypoplasia of the tracheal cartilages. Stridor is usually present shortly after birth, but in most infants respiratory embarrassment is limited. Fluoroscopy demonstrates collapse of the trachea on vigorous breathing or crying. The normal trachea collapses if increased airway resistance is present. All of these infants must be evaluated endoscopically to exclude extrinsic obstructions. Bronchoscopy performed while the infant is breathing spontaneously will demonstrate tracheal collapse with inspiration. Tracheomalacia occurs most frequently in association with tracheo-oesophageal fistula. Compression of the trachea by the distended proximal oesophageal pouch in utero may produce this flexibility; alternatively, it may result from a diffuse abnormality of tracheal development. Abnormal separation of the oesophagus and trachea and hypoplasia of the tracheal rings are both components of development. Tracheomalacia may produce episodes of cyanosis following coughing spells or crying. In most infants the condition can be managed expectantly since the trachea becomes larger and the cartilage stiffens as the child grows.

Laryngotracheo-oesophageal cleft is a rare anomaly in which the posterior wall of the larynx and a variable length of trachea fail to separate from the oesophagus, resulting in a proximal communication between the airway and the oesophagus. It presents with recurrent episodes of aspiration and coughing on feeding. Diagnosis is often delayed. Contrast studies often have the appearance of contrast medium ‘spilling over’ from the oesophagus into the trachea. The cleft is best demonstrated endoscopically, with a catheter in the oesophagus and an endoscope in the trachea. Distension of the oesophagus with air blown into the catheter causes separation of the cleft beginning at the arytenoids and extending distally. Repair is performed through the neck, closing the trachea without narrowing it by using a small strip of oesophagus in the closure, interposing a strap muscle between the oesophageal and tracheal closures prevents recurrence. Extensive lesions involving much of the trachea are repaired through a combined cervical and thoracic approach and have only recently been successful.

An inhaled foreign body is commonly misdiagnosed. The sudden onset of coughing should suggest aspiration of a foreign body, even when a physical examination and chest radiograph are negative. Fluoroscopy and/or inspiratory and expiratory films increase the sensitivity of radiographic examinations, but normal results cannot entirely exclude the presence of a foreign body. Air trapping with hyperinflation of the lung, shift of the mediastinum, or decreased movement of the diaphragm support the presence of a retained foreign body. Most objects aspirated into the airway are not radio-opaque. In trained hands bronchoscopic examination carries little risk and should be performed in any infant with a history suggestive of a foreign body. The sudden onset of wheezing in an infant or child should also raise the question of foreign body aspiration. Pneumonia after an episode of coughing is an indication for bronchoscopy after initiation of antibiotic treatment.

Fibreoptic endoscopic equipment of suitable size for infants and children must be available, along with a set of foreign body instruments. Friable material, such as the frequently encountered peanut, can be removed with gentle foreign body forceps. The Fogarty arterial embolectomy catheter (3 or 4 French) can be used to remove an object that is likely to crumble if grasped by forceps. The catheter is inserted through the side port of the endoscope and it is passed beyond the object under direct vision. After inflation of the catheter balloon, the catheter and foreign body are withdrawn into the pharynx. Occasionally, if the endoscope is large enough, the foreign body can be pulled into the endoscope and extracted with it. Lobectomy may be required if successful extraction of the foreign body is not achieved and if the lung tissue distal to the foreign body has been destroyed by recurrent infection and bronchiectasis. Peanuts are especially troublesome, and exuberant granulation tissue develops around them.

Swallowed foreign bodies lodged in the oesophagus can cause respiratory symptoms as well as symptoms of oesophageal obstruction. They usually lodge just below the level of the cricopharyngeus, behind the larynx or at the level of the aortic arch. The history generally suggests ingestion and, as most objects swallowed are radio-opaque, a chest radiograph will usually confirm the diagnosis.

A patient with a foreign body in the oesophagus should be intubated to secure the airway before endoscopic removal of the foreign body is attempted. Coins, the foreign body most commonly lodged in the oesophagus, can be readily extracted with toothed foreign body forceps. Oesophagoscopy can be facilitated by gentle insufflation of oxygen through a catheter inserted through the side port of the oesophagoscope. Insufflation distends the oesophagus and allows better visualization. Retained secretions can also be aspirated through this catheter.

Respiratory symptoms may also occur if a foreign body perforates the oesophagus, producing an abscess and granulation tissue between the trachea and oesophagus. Management is generally limited to endoscopic extraction of the foreign body if possible. The inflammatory mass will resolve along with the respiratory symptoms and cervical or thoracic drainage is rarely required.

A variety of pulmonary lesions, ranging from agenesis of a lung to the more frequent cystic or hamartomatous malformations, result from abnormal parenchymal development. These malformations present primarily as space occupying lesions in an infant with decreased pulmonary function. Less often, recurrent pulmonary infections may be the mode of presentation.

In pulmonary agenesis the bronchus and pulmonary tissue are absent. The aetiology is unknown but agenesis frequently occurs in association with other complex anomalies, particularly of the heart and great vessels. Many affected children are asymptomatic, but tachypnoea may occur with crying or exercise. Pulmonary agenesis is associated with predisposition to recurrent pulmonary infections, although the mechanism for this is not understood. Death usually results from associated lesions: the combination of pulmonary agenesis and tracheo-oesophageal fistula has a particularly poor prognosis. Tracheal stenosis also occurs in association with agenesis of the lung. The diagnosis can be established on plain radiographs which demonstrate a shift of the mediastinum to the affected side, which is entirely opacified (Fig. 11) 2071,2072,2073. Distinction must be made between this lesion and a pleural effusion or empyema, which would shift the mediastinum to the contralateral side.

In pulmonary hypoplasia the mainstem bronchus and proximal divisions are normal, but the amount of parenchyma of one or both lungs is decreased. Pulmonary hypoplasia is most common in patients with congenital diaphragmatic hernia, in whom compression of the lung impairs normal development. The severity of symptoms correlates with the degree of hypoplasia.

The simplest pulmonary abnormality is an isolated pulmonary cyst. Historically, many of these were thought to be acquired lesions secondary to infection; this is not true in most cases. Lung cysts occur in young infants in the absence of infection and are lined with tall, ciliated columnar epithelium, appropriate for the respiratory tree. They generally communicate with the bronchial tree, can occur in either lung, and affect only in one lobe. Other pulmonary abnormalities may be present; the systemic arterial blood supply for the affected lobe may originate from the aorta rather than from the pulmonary artery. In some cases hamartomatous development is evident, and abnormal epithelium is present; the distinction between lung cyst, intralobar pulmonary sequestration, and cystic adenomatoid malformation is often blurred. Patients with cystic lesions may present with secondary infection. It can be difficult to distinguish between a lung abscess, resolving staphylococcal pneumonia with a pneumatocele, or a loculated empyema.An underlying anatomical abnormality must be suspected in a patient with ‘pneumonia’ that does not resolve completely or that recurs in the same anatomic location.

Congenital cystic adenomatoid malformation covers a broad spectrum of disease, with varying proportions of cysts and adenomata. Cystic adenomatoid malformations have been classified into three types: type I represents single or multiple large cysts (more than 2 cm in diameter) with prominent smooth muscle and elastic tissues in the wall; type II lesions are composed of multiple small cysts (less than 1 cm in diameter) lined by ciliated cuboidal to columnar epithelium. These are frequently associated with other congenital anomalies. The type III lesion is a large bulky non-cystic mass that often produces a mediastinal shift and which has a poor prognosis. The mass effect caused by these lesions in utero results in pulmonary hypoplasia, which may be severe.

Many infants present in the first month of life with respiratory distress; others present late, with cough and fever due to secondary infection of the lesion. Treatment requires resection of the abnormal pulmonary tissue. Prognosis is related directly to the presence of associated anomalies and the amount of normal pulmonary parenchyma. Antenatal diagnosis of cystic adenomatoid malformation is possible, and prognosis correlated with the type of lesion. Microcystic lesions are often associated with fetal hydrops and have a poor prognosis (80 per cent mortality), while the macrocystic lesions, which are rarely associated with hydrops, have a much better prognosis (29 per cent mortality). Early diagnosis allows delivery in a specialist unit and early surgical intervention. Rhabdomyosarcoma has been reported in a 32-month-old child with congenital cystic adenomatoid malformation.

Pulmonary sequestration is characterized by failure of the pulmonary tissue to communicate with the tracheobronchial tree, and the presence of an aberrant arterial supply to the pulmonary tissue. This often arises directly from the thoracic aorta (85–90 per cent of cases) and less frequently from the abdominal aorta. Multiple systemic arteries supply the sequestration in 15 per cent of patients. The venous drainage from a sequestration may be through systemic (azygos) or pulmonary veins.

An extralobar sequestration occurs when an isolated segment of pulmonary tissue is surrounded by pleura and is distinct from the normal lobes. It is not ventilated and is not susceptible to contamination by surrounding ventilated pulmonary tissue: such sequestrations rarely become infected. The systemic arterial supply to the segment can, however, result in high output cardiac failure from shunting through the sequestration (Fig. 14) 2077,2078,2079. Extralobar sequestration is most commonly present in the posterior mediastinum at the costophrenic sulcus, and is present on the left side in two-thirds of affected patients.

Intralobar sequestrations are more common (85 per cent of cases), and occur within a pulmonary lobe, usually a lower lobe that has a normal bronchial supply (Fig. 15) 2080,2081,2082. The intralobar sequestration lacks normal bronchial communication, but often has microscopic communications with the surrounding ventilated tissue, and can become secondarily infected. These lesions frequently present as recurring localized pulmonary infections. The arterial supply of the intralobar sequestrations generally arises from the aorta. Perfusion from both the pulmonary artery and aorta distinguishes sequestrations from other pulmonary lesions such as pulmonary cystic disease, localized bronchiectasis, or lung abscess.

Extralobar sequestration is treated by resection. The systemic arterial supply of these lesions is easily defined. Lobectomy is generally required for an intralobar lesion: both the pulmonary and systemic arterial supply must be identified before this can be undertaken safely.

Lobar emphysema (massive over-distension of one lobe) is an uncommon cause of respiratory distress in infancy. It produces compression and atelectasis of adjacent lobes, and can also shift the mediastinum, compressing the contralateral side. Respiratory symptoms appear early, and half of the patients present within the first 2 days of life. The left upper lobe is most frequently involved, followed by the right middle lobe; the lower lobes are rarely affected. Lobar emphysema is generally apparent on plain radiographs (Fig. 16) 2083,2084, and can be distinguished from pneumothorax, in which a rim of collapsed lung is visible. Placement of a chest tube following an incorrect diagnosis of a pneumothorax can injure the distended lung. Bronchovascular markings within the emphysematous lobe, although they are abnormally far apart, allow this condition to be distinguished from a distended pulmonary cyst. Bronchography can confirm the diagnosis, but is generally not undertaken as it may impair pulmonary function in an already stressed infant (Fig. 17) 2085. An anatomical cause of lobar emphysema is found in less than 50 per cent of resected specimens. Pathological findings include bronchial cartilaginous dysplasia and intrinsic obstruction of the bronchus. The polyalveolar lobe syndrome has recently been shown to be a cause of lobar emphysema. Patients with this condition have normal airways and arteries, but the resected lobe shows a three- to five-fold increase in the number of alveoli, representing a gigantic alveolar unit. If other congenital lesions are present, they usually involve the heart.

Treatment of lobar emphysema by resection of the affected lobe was first performed successfully by Robert Gross in 1945. The severity of respiratory distress determines the urgency of resection: profound respiratory distress improves immediately when the chest is opened and emergence of the distended lobe through the incision allows expansion of the atelectatic normal lobes.

Patients undergoing resection for lobar emphysema have no symptomatic impairment. One long-term follow-up study demonstrated normal total lung capacity in all 15 patients and normal vital capacity in 13 of 15 patients following lobectomy for congenital lobar emphysema. Radionuclide lung scans showed nearly equal lung volumes on both sides, and symmetrical pulmonary perfusion.

Major pulmonary infections have become less common since the introduction of antibiotics. Staphylococcal pneumonia still occurs, however, and its pulmonary and pleural complications must be identified. Chronic infection in a patient with cystic fibrosis produces progressive pulmonary damage and bronchiectasis. Although surgery is generally avoided, it may be required to control local areas of severe destruction and chronic infection.

Staphylococcus aureus is the most frequent organism associated with empyemas in childhood followed in frequency by Haemophilus influenzae and Streptococcus pneumoniae. Infants under 6 months of age are most commonly affected. A high fever is usually followed by respiratory symptoms. If pneumothorax occurs or if significant empyrema is present, an intercostal tube should be inserted immediately. This allows drainage of a large proportion of the infected material, with expansion of the lung. Drainage and appropriate antibiotics will control the infection in most cases and the mortality rate is low.

Pneumatoceles often form after staphylococcal infections, paradoxically at a time when the infant is improving clinically (Fig. 18) 2086,2087,2088. Rupture of a pneumatocele into the pleural space should be treated by chest tube drainage. Resection is not necessary: pneumatoceles invariably resolve. Pulmonary decortication is rarely needed when empyema is drained.

It can be difficult to determine whether a cystic lesion of the lung which is identified following a pulmonary infection is a congenital lung cyst or a pneumatocele. Differential diagnosis may be aided by the anatomical location of the lesion, a history of recurring localized infection, or a pre-existing radiographic abnormality. A known staphylococcal pneumonia is strongly suggestive of a pneumatocele. In most instances observation of the lesion is appropriate: pneumatocele will resolve progressively, albeit sometimes slowly, while a congenital cystic lesion will persist and should be resected.

Polymicrobial lung abscesses occur in children following aspiration. As in adults, the superior segment of the lower lobes and the posterior segment of the upper lobes are most commonly affected. An underlying immunodeficiency or neurological impairment is generally present in these patients. Primary treatment is with broad-spectrum antibiotics and chest physiotherapy.

Pneumothorax is the most common surgical complication of cystic fibrosis. Chest tube drainage is usually required, since pulmonary reserve is limited in these patients. Most adjunctive treatments aim to decrease the 80 per cent recurrence rate. Sclerosis induced with tetracycline, silver nitrate, quinacrine, and talc poudrage obliterates the pleural space and prevents recurrence. Pleurectomy or surgical pleural abrasion have a limited role in children who tolerate thoracotomy poorly, although these methods have the lowest rates of recurrence.

Pulmonary resection has limited indications in patients with cystic fibrosis. Haemorrhage from dilated bronchial vessels can produce massive haemoptysis. This can usually be controlled by angiographic embolization of the bleeding vessel, but if embolization fails resection of the affected segment may be required. Pulmonary resection is required more often for severe bronchiectasis and recurrent infection in a destroyed pulmonary lobe than for haemoptysis. Resection is reserved for lesions which fail to respond to medical treatment and which are a recurrent source of infection of the remainder of the lung. Radioisotope scans allow surgical resection to be planned such that loss of functional tissue is avoided. Aggressive postural drainage, chest physiotherapy, and treatment with broad-spectrum parenteral antibiotics should be undertaken before resection. Resection can then be employed safely in the patient with cystic fibrosis, but it should be limited to the severely destroyed pulmonary segment with little functional capacity.

Primary pulmonary neoplasms are rare in infancy and childhood, and the spectrum of tumours is different to that seen in adults. These lesions often present with cough, haemoptysis, wheezing or localized areas of pulmonary collapse. Respiratory failure is rare. One-third of these lesions are benign, primarily of inflammatory pseudotumours or hamartomas. Malignant lesions comprise the mis-named bronchial ‘adenomas’, which include carcinoids, mucoepidermoid carcinomas, adenoid cystic carcinomas, and mucous gland adenomas. All are capable of dissemination, except for the extremely rare mucous gland adenomas. Adenomas generally occur in a primary or secondary bronchus. These lesions can usually only be partially resected and attempts at surgery are often associated with heavy blood losses. Sleeve resection of the bronchus preserves pulmonary tissue and is currently used for the treatment of lesions that lend themselves to anatomical resection. Lobar resection should be performed if it is needed to remove the lesion entirely. Bronchiectasis may occur beyond an obstruction which has been present for many months: resection allows recurrent pulmonary infections to be avoided.

Bronchogenic carcinoma is the second most common malignant lesion after adenomas. Undifferentiated carcinoma and adenocarcinoma account for 80 per cent of these lesions; squamous cell tumours are less common in children (12 per cent) than in adults. Affected patients often have disseminated disease at presentation and the average survival is only 7 months. Pulmonary blastoma, a tumour which resembles fetal lung histologically, and other types of sarcomas account for the remainder of malignant primary lesions of the lung in infants and children.

Metastatic tumours are more common than primary pulmonary tumours in children. Most are metastatic sarcomas: these are the most frequent solid malignancies in infants and children, and carcinomas are rare. CT scanning aids in the identification of lesions, which would not be detected on routine chest radiographs. Treatment of the pulmonary metastasis is tumour specific, and may involve chemotherapy, radiotherapy, or resection of the primary lesion. Resection of isolated pulmonary metastases, especially osteogenic sarcoma, with adjunctive treatments may provide cure or long-term survival in patients previously thought to be ‘hopeless’. Pulmonary lesions which appear during treatment of a solid tumour must not be assumed to be metastatic; in one series of 37 children with known primary tumours, 33 per cent of pulmonary nodules were found to be benign lesions.

Chylothorax is a rare condition caused by the leakage of chyle from the thoracic duct or its tributaries. It may cause respiratory distress due to accumulation of lymph in the pleural space, most frequently the right side. In neonates spontaneous chylothorax is frequently related to an acute rise in venous pressure during delivery, which causes rupture of the thoracic duct. The most common cause of chylothorax is surgical trauma to the thoracic duct during mediastinal dissection for aortic arch anomalies and congenital heart disease. Its occurrence after repair of congenital diaphragmatic hernia results from injury to the thoracic duct by one of the sutures placed in the posterior diaphragmatic leaf. Chylothorax also occurs in premature infants with superior vena caval thrombosis.

The chest radiograph demonstrates opacification of one hemithorax with a shift of the mediastinal structures to the contralateral side (Fig. 20) 2092,2093. It must be distinguished from pulmonary agenesis, in which the mediastinum will be shifted toward the affected side.

Pleural drainage with a chest tube will allow many of these leaks to close. Limitation of fatty foods generally decreases lymphatic drainage. If high volume drainage persists, parenteral feeding will usually decrease lymphatic fluid production by the intestines, resulting in decreased drainage and closure. Parenteral nutrition also avoids the nutritional wasting that formerly resulted in an almost 50 per cent mortality rate in infants with chylothorax. When lymphatic drainage persists, surgical intervention is required. Identification of the site of the leak is facilitated by administration of a fat-laden meal prior to the surgery. This should be closed with non-absorbable sutures.

Malignant pleural effusions are rare in children. Obstruction of lymphatic drainage usually occurs in association with Hodgkin's disease or lymphoma: chemotherapy directed at the primary tumour allows the effusion to resolve.

Air in the pleural space, especially when under tension, causes severe respiratory compromise. It is most common in very premature neonates receiving treatment with high ventilatory pressure for hyaline membrane disease. It is particularly dangerous in infants with congenital diaphragmatic hernia, in whom ventilation is already marginal.

Pneumothorax is rare after the neonatal period until the teenage years, when it may occur in an otherwise healthy youngster, generally due to rupture of a small apical bleb. Pneumothorax may also be the first sign of pulmonary metastasis in patients with osteogenic sarcomas.

A pneumothorax can be confirmed by chest radiograph; differential diagnosis includes lobar emphysema and congenital cystic adenomatoid malformation. In a supine neonate air is often trapped anteriorly; this must not be overlooked. Treatment, which requires placement of a chest tube, is determined by the size of the pneumothorax and the degree of respiratory compromise. In the infant with a congenital diaphragmatic hernia and sudden respiratory decompensation, a chest tube should be placed on the contralateral side before chest radiography.

Spontaneous pneumothorax recurs in 50 per cent of teenage patients. If a pneumothorax recurs more than once, oversewing or resection of the blebs should be performed, in conjunction with abrasion of the parietal pleura with gauze sponges to promote adhesion of the lung to the chest wall. The intrathoracic exposure needed is not great: a vertical skin incision in the midaxillary line can be used, since it is not very noticeable, being hidden by the arm. A fourth interspace incision is created to enter the chest.

Mass lesions within the mediastinum can be divided into two broad categories; congenital cystic lesions and neoplastic tumours. Symptoms are related more to their size and location than to their cystic or neoplastic nature.

Cystic lesions occur throughout the mediastinum, and may present with respiratory symptoms including cough, wheezing, recurrent pneumonias, or stridor resulting from compression of the tracheobronchial tree. Infants may present in acute respiratory distress, and posterior mediastinal cysts occasionally causes oesophageal compression, resulting in dysphagia. Approximately one-third of these cystic lesions are identified on routine chest radiographs. CT scan performed with intravenous contrast can differentiate solid neoplastic lesions from cysts (Figs 22, 23) 2095,2096,2097,2098.

Most cysts are of bronchopulmonary origin, and they are found in close proximity to the tracheobronchial tree, often in a perihilar or subcarinal location where radiographic findings may be limited. Their presence is suggested by emphysema or air trapping of one lung due to incomplete bronchial obstruction. Partial collapse of one lung results from high grade bronchial obstruction.

Oesophageal duplications are found in the posterior mediastinum. They are generally in contact with the oesophagus but do not communicate with its lumen. A barium swallow may demonstrate extrinsic compression of the oesophagus. The lining of these duplication cysts is usually squamous epithelium, but respiratory epithelium also may occur; rarely they are lined with gastric mucosa and present with perforation or haemorrhage. Oesophageal duplications are generally isolated lesions, but they occasionally occur in patients with oesophageal atresia, vertebral anomalies, or intraspinal extensions (neuroenteric cysts). Back pain, sensory or motor deficits, or gait disturbances may be the first symptoms of a neurenteric cyst. All patients with vertebral anomalies or neurological symptoms and posterior cystic lesions should undergo preoperative myelography, or magnetic resonance imaging scanning as an intraspinal component of the cyst is often present.

Surgical resection is the treatment of choice, even when the lesion is asymptomatic. An untreated cyst may enlarge from accumulation of secretions, causing compression of the trachea or bronchus, or it may become infected. Malignant lesions can arise in these cysts, and if the cyst is lined with gastric mucosa, ulceration or perforation may occur. Oesophageal duplications share a common muscular wall with the oesophagus. Resection of only the mucosal portion of the cyst in the area of contact with the oesophagus avoids entry into the oesophageal lumen.

Cystic hygromas and thymic cysts occasionally arise in the mediastinum. Cystic hygromas are multilocular, thin-walled cysts of lymphatic origin which should be considered in infants with cervical or upper thoracic lesions. Their extent can be determined from routine chest radiographs. Occasionally a cystic hygroma is confined entirely to the mediastinum and causes severe respiratory distress, resulting from tracheobronchial compression. Surgical treatment is required, although complete resection is often impossible.

Cystic lesions of the thymus appear as an anterior mediastinal mass on chest radiographs. Their nature and origin will be best defined by CT scan with intravenous contrast. Major respiratory symptoms may be produced by large lesions: these are readily removed surgically.

Division of the mediastinum into anterior, middle, and posterior compartments will aid in the differential diagnosis of these lesions. Anterior mediastinal lesions consist of teratomas, thymomas, cystic hygromas, germ cell tumours, Hodgkin's disease, and non-Hodgkin's lymphoma. Middle mediastinal lesions are primarily lymphatic in origin and include lymphomas and Hodgkin's disease. Posterior mediastinal lesions located in the paravertebral sulcus are primarily neural in origin. They include neuroblastoma, ganglioneuroma, and neurofibroma. An extralobar sequestration can also present as a wedge-shaped, solid lesion in this area. Anterior mediastinal tumours may cause tracheal compression and respiratory symptoms. Posterior mediastinal lesions are more likely to present as asymptomatic masses, unless they are massive or produce neurological symptoms due to intraspinal extensions.

Tumours of neural crest origin generally arise from the sympathetic chain and are the most common masses affecting the mediastinum. The histological spectrum of neurogenic tumours ranges from benign ganglioneuromas to malignant neuroblastomas: neuroblastoma is the most common and occurs primarily in infants or young children.

Ganglioneuromas occur in older children and teenagers, are frequently asymptomatic, and are often discovered when spindle-shaped lesions are seen along the spine on chest radiographs obtained following trauma or for respiratory symptoms unrelated to the mediastinal mass. They can occur anywhere from the thoracic inlet to the diaphragm and may contain areas of calcification. Both ganglioneuromas and neuroblastomas may extend along the nerve roots into the spinal canal. Any child with neurological symptoms should undergo a myelogram, CT scan, or MRI. Surgical resection is the treatment of choice and is curative for benign lesions. Ganglioneuromas are encapsulated, firm, and generally readily resected. Histologically they contain ganglion cells and fibrous tissue.

Neuroblastoma in infants under 1 year of age is more benign than that affecting older children. In these infants, treatment comprises near total excision of the lesion and observation. No further treatment is required unless osseous metastases are present. Adjunctive chemotherapy and radiotherapy may be required in children over 1 year of age who have distant metastasis or residual tumour. The prognosis of intrathoracic neuroblastomas is more favourable than that of abdominal lesions of comparable stage.

Although variable, classical neuroblastoma consists of many small round cells (neuroblasts) which have a large nucleus and limited cytoplasm. Clustering of neuroblasts around a tangle of fine nerve fibres (rosette formation) is seen in tumours showing early differentiation. Ganglioneuroblastoma is a more differentiated tumour made up of mature ganglion cells, along with primitive neuroblasts in rosette patterns and other neural elements.

Plexiform neurofibroma in the mediastinum may be an isolated lesion or may be associated with neurofibromatosis (von Recklinghausen's disease). Resection of isolated lesions allows a histological diagnosis to be obtained. Resection is also required in patients with neurofibromatosis if the lesions become symptomatic. Rapid growth of these lesions follows their malignant degeneration to neurofibrosarcoma. Phaeochromocytoma can also occur along the sympathetic chain in the neck and mediastinum, producing symptoms of compression as well as flushing and hypertension.

Tumours in the anterior mediastinum may not produce symptoms until they become large. Cough, wheezing, dyspnoea on exertion, and orthopnoea are suggestive of important tracheal compression. CT is the best means of defining the extent of the lesion and the degree of tracheal compression. Lymphoma and Hodgkin's disease do not usually occur until adolescence.

Patients with Hodgkin's disease or non-Hodgkin's lymphoma require biopsy specimens before initiation of treatment. Resection should not be attempted. Disseminated disease is often present, but the tumour shows an excellent response to radiotherapy and chemotherapy. Tracheal compression by a large mass can produce cardiorespiratory collapse upon induction of anaesthesia. If the measured tracheal area on CT scan is less than 50 per cent of that expected for age, general anaesthesia must be avoided: a cervical biopsy can often be performed under local anaesthesia. Anterior thoracotomy can be performed under local anaesthesia, entering through the perichondrium of the resected second costal cartilage. Preliminary radiotherapy must spare an area of the tumour for biopsy confirmation of the diagnosis.

Mediastinal teratomas, the second most common tumour of the anterior mediastinum, are generally benign and may present at any age. They contain derivatives of all three germ cell layers and may be cystic. CT defines the extent of the lesion and any tracheal compression. Calcification and varying densities of the tissues in the mass suggest the diagnosis. Surgical resection is usually curative, although malignant elements in the tumour will require further therapy. Elements of choriocarcinoma carry the worst prognosis.

Thymomas are rare in infants and children. They are usually benign and arise in the upper anterior mediastinum or at the base of the neck. Although they may be massive, they generally compress adjacent structures rather than invade them. They are occasionally associated with myasthenia gravis. Surgical resection is required and recurrence is rare (2 per cent).

Malignant thymomas are epithelial in nature and invasive. Aggressive surgery is required: resection of lung, pleura, diaphragm, superior vena cava, and pericardium may be necessary to remove the lesion completely. Their response to chemotherapy and radiotherapy is limited.

The thymus may be the primary site of Hodgkin's disease. The diagnosis is established after resection of the mass, and additional chemotherapy or radiotherapy is required.

Seminomas, teratocarcinomas, embryonal carcinomas, choriocarcinomas, and endodermal sinus tumours can all arise within the anterior mediastinum. They present in the adolescent years or later with respiratory symptoms, and the correct diagnosis is rarely made before biopsy. Radiotherapy is required for the seminomas; the other lesions respond to chemotherapy.

Undifferentiated sarcoma and rhabdomyosarcoma may occur throughout the mediastinum. Complete resection is difficult: they tend to be extensive and to invade vital structures. Long-term survivors are rare, despite adjunctive therapy with radiation and chemotherapy.

The first successful primary repair of oesophageal atresia was performed in 1941. Today the vast majority of infants with oesophageal atresia survive and lead normal lives. In infants without a tracheo-oesophageal fistula the gap between the proximal and distal ends of the oesophagus is long, making primary repair difficult.

A fetus with oesophageal atresia is unable to swallow amniotic fluid in utero and polyhydramnios results. Prenatal ultrasound examination allows early identification of these infants. Polyhydramnios causes premature labour in one-third of these pregnancies. The most common associated anomalies are imperforate anus and congenital heart disease.

The diagnosis of oesophageal atresia should be considered in any infant producing excessive mucus or showing difficulty swallowing. It is confirmed by passing an 8 or 10 Fr catheter through the nose: the catheter will not reach the stomach, but meets a point of obstruction about 4 inches from the nostril. Air introduced through the catheter distends the pouch, defining its limits without the use of contrast agents, and a chest radiograph demonstrates the level of obstruction. If a radiocontrast agent is used, the study must be undertaken under fluoroscopic control, using a small volume of the agent and with the infant in the upright position to avoid aspiration. The contrast material should be removed immediately after the study, while the infant is held upright. Aspiration causes major pulmonary complications, and delays definitive surgery. Occasionally, the contrast material enters the trachea even when the proximal pouch is not overfilled, suggesting a proximal fistula. A fistula between the trachea and the distal oesophageal segment allows air to fill the stomach and intestine. If no air is seen in the stomach on an abdominal radiograph, a distal tracheo-oesophageal fistula is absent. In these infants the distal oesophageal segment is usually rudimentary, making primary repair difficult.

Infants in whom the diagnosis of oesophageal atresia is delayed develop severe pneumonitis due to aspiration of gastric secretions through a distal fistula. If pneumonitis occurs, primary repair should be delayed and a Stamm gastrostomy performed under local anaesthesia. The gastrostomy will vent air blown through the fistula into the stomach and prevent further reflux of gastric secretions. A sump suction catheter should be placed in the proximal pouch once the diagnosis is suspected, to prevent aspiration of saliva.

A right thoracotomy is performed through the fourth intercostal space. Although a transpleural approach can be used, a retropleural approach allows separation of the pleura from the chest wall and its reflection medially and anteriorly. This approach prevents complete collapse of the lung during operation, and if an anastomotic leak occurs drainage is confined to the limited extrapleural space. Empyema does not then develop in the pleural cavity.

The distance between the two ends of the oesophagus is variable, and is greatest in isolated oesophageal atresia. The oesophagus can be lengthened by mobilization of the proximal oesophageal pouch, which has an excellent blood supply in the submucosal layer. Application of pressure to the proximal pouch with either a rubber bougie or a Bâkes common-duct dilator facilitates the mobilization and removes the need to grasp the pouch, which may produce trauma.

The distal oesophageal pouch is ligated at its junction with the trachea and divided. The distal segment should not be mobilized: it has a tenuous segmental blood supply and ischaemia is easily produced. The two ends are anastomosed in a single-layer fashion. The two-layer anastomosis of Haight produces more strictures and does not prevent leaks. A segment of the azygous vein or mediastinal adventitia is interposed between the oesophageal anastomosis and the fistula closure to minimize recurrence. An extrapleural chest tube is left in close proximity to the anastomosis, sutured to the chest wall to prevent direct contact.

Undue tension often results in a leak or complete disruption of the anastomosis within 1 week of repair. If extensive mobilization of the proximal pouch does not allow anastomosis without undue tension, several techniques can be used to further increase oesophageal length. A circular myotomy through the muscular portion of the proximal pouch lengthens the proximal pouch but maintains a viable blood supply in the submucosa. A spiral myotomy has also been used to increase oesophageal length.

If all these methods fail, the distal oesophageal end should be closed and sewn to the chest wall to prevent its retraction. Following closure of the chest, a cervical oesophagostomy is placed anterior to the sternocleidomastoid muscle on the left. Oesophageal reconstruction is then performed at about 1 year of age, when the infant reaches 10 kg. Colonic replacement of the oesophagus can be performed retrosternally, although we prefer the left thoracic approach. (Fig. 30) 2114,2115. Others have used a tube created from the greater curvature of the stomach, rotated through the chest to bridge the gap. We believe, however, that this carries a risk of late peptic oesophagitis.

Successful repair is achieved in more than 95 per cent of infants with uncomplicated oesophageal atresia. Congenital heart disease or prematurity significantly worsens these results. In the past very small infants were treated with placement of an initial gastrostomy tube under local anaesthesia. If the infant's respiratory status was satisfactory, thoracotomy was performed several days later. The tracheo-oesophageal fistula was divided, closing the distal segment and tacking it to the chest wall to prevent retraction. Gastrostomy feedings were then given without risk of reflux into the tracheobronchial tree. A sump suction catheter was maintained in the upper pouch to prevent aspiration. Major problems can be encountered, however, ventilating very premature infants with hyaline membrane disease after gastrostomy tube placement. The distal fistula, stomach, and gastrostomy tube provide a low-pressure ‘vent’ that impairs adequate ventilation of the poorly compliant lungs. Some surgeons prefer initial ligation and division of the fistula, with delayed primary repair. Primary repair is now possible in many infants previously treated with the staged approach.

Special consideration must be given to infants with isolated oesophageal atresia in whom the oesophageal segments are too short to allow primary repair. Most of these infants have a rudimentary distal segment. The length of the segments can be defined radiographically, avoiding an unsuccessful thoracotomy. Most surgeons place a gastrostomy tube initially and begin feedings with the hope that reflux into the distal pouch will dilate this segment. Others use intermittent dilatation of the proximal pouch with Maloney dilatators, with variable success. Simultaneous electromagnetic stretching of both oesophageal ends elongates the oesophageal segments and allows delayed primary anastomosis. Difficulties with nursing these infants led to abandonment of this technique.

Swallowing is abnormal in children after repair of oesophageal atresia: fluoroscopic and manometric studies demonstrate a significant incidence of dyskinesia of the proximal and distal segments. Unco-ordinated peristaltic activity is common, and gastro-oesophageal reflux is seen in about 20 per cent of patients. Food reaches the stomach mainly by the effect of gravity in colonic and gastric conduits.

The anastomosis will leak if the repair is performed with excessive tension or if the distal oesophageal segment is mobilized. Small leaks are well tolerated if adequately drained, and most will close without intervention. If complete disruption of the anastomosis occurs, the chest must be explored and a cervical oesophagostomy (‘spit fistula’) created, with ligation of the distal oesophageal segment. Later oesophageal substitution will be required.

Strictures can occur after repair, with or without a preceding oesophageal leak. Most can be managed by dilatation, and injection of steroids into the scar prevents recurrence. The use of filiform and followers pulled through the gastrostomy is the safest method for dilatation. A refractory stricture may require resection and reanastomosis.

Recurrent tracheo-oesophageal fistula may be fatal: reoperation is always necessary. Closure of the fistula and reanastomosis of the oesophagus may be possible. It is important to place well-vascularized tissue over the tracheal closure (pericardium, pleura, or intercostal muscle), to prevent recurrence. If the oesophageal tissues are too inflamed only tracheal closure is possible.

Gastro-oesophageal reflux occurs in about 20 per cent of patients with repaired oesophageal atresia. The majority of symptomatic infants respond to non-surgical treatment. If reflux produces recurrent strictures a fundoplication is often required.

Tracheomalacia is occasionally seen in association with oesophageal atresia. In most instances the symptoms will improve with time, but in severe cases aortopexy is required.

Isolated tracheo-oesophageal fistula is uncommon, and its diagnosis requires a high index of suspicion in an infant with recurrent pneumonitis. The fistula runs in an oblique downward direction from the trachea to the oesophagus, and it can be missed if a barium swallow is not performed correctly. A small feeding tube should be placed in the cervical oesophagus. With the infant in a lateral position a small amount of contrast medium is injected under fluoroscopic control (Fig. 31) 2116,2117. If a suspected fistula is not seen on radiographic examination, endoscopy is performed under general anaesthesia using a 30° lens. If a fistula is seen a small Fogarty catheter can be passed through the endoscope and through the fistula into the oesophagus to facilitate its identification at surgical repair.

We approach an H-fistula through the right side of the neck taking special care to avoid injury to the recurrent laryngeal nerve. A strap muscle interposed between the trachea and oesophagus after the fistula is divided and ligated protects against recurrence.

Tracheobronchial remnants in the oesophageal wall produce oesophageal stricture. They may contain abnormal epithelial lining or respiratory ducts within the wall. This form of congenital oesophageal stricture does not respond well to dilatation: segmental resection with primary anastomosis or interposition of a short oesophageal substitute is generally required.

Gastro-oesophageal reflux occurs in children with or without hiatal hernia. It spontaneously disappears in the majority of patients as oesophageal sphincter tone, which is low at birth, increases with age. Infants with severe neurological disease uniformly fail to show such improvement: spasticity, abnormal pharyngeal function and gag reflex, aerophagia, and chronic supine position all exacerbate the oesophageal reflux.

Infants with gastro-oesophageal reflux present with a variety of symptoms, including vomiting, failure to thrive, recurrent pneumonia, and anaemia. Pneumonia is characterized by its migratory nature, lack of predominating organisms, and refractory nature. Apnoeic spells in infants may be dramatic and fatal. These spells typically occur when the infant is horizontal, usually after feeding and frequently during sleep. Reflux is often occult and unsuspected in the absence of vomiting. Older children and adolescents may develop symptomatic peptic oesophagitis, with retrosternal burning as the primary symptom. Less frequently dysphagia results from oesophagitis, spasm, or stricture.

Radiographic contrast studies often demonstrate reflux, but they do not provide an accurate assessment of its severity or significance. Radionuclide ‘milk scans’ can provide information about the rate of gastric emptying, the frequency of reflux, and the rate of oesophageal clearance of the isotope. Collection of isotope in the lungs documents aspiration. Radionuclide studies are also more sensitive than barium studies. Oesophageal pH probes allow assessment of the frequency of episodes of reflux as well as the length of time acid is present in the oesophagus.

Manometric studies of the oesophagus exclude primary oesophageal motility disorders as the cause of reflux. Surgical repair increases lower oesophageal sphincter pressure and can produce major obstructive problems in patients with oesophageal motility disorders. Oesophagoscopy with biopsy will also provide an accurate assessment of the severity of the oesophagitis, although the histology is more accurate than the gross findings at endoscopy unless ulceration or mucosal slough is present. Eosinophilic infiltration of the oesophageal wall is often seen in these patients with reflux.

Initial treatment of gastro-oesophageal reflux consists of administration of H&sub2;-receptor antagonists, which decrease the acidity of the stomach. Metoclopramide can increase the rate of gastric emptying as well as increase the pressure at the gastro-oesophageal junction. Thickening of foods with cereal and giving smaller and more frequent feedings can decrease the degree of reflux in infants. A sitting position has traditionally been employed to decrease reflux, although recent studies suggest that the prone position on a 30° incline is optimal.

Indications for surgical intervention include severe apnoeic episodes, failure to thrive, and recurrent pneumonia despite medical therapy. Emesis alone is rarely an indication. In older children the indications include persistent pain and active oesophagitis despite medical therapy, Barrett's oesophagus, and oesophageal stricture. Boix-Ochoa reported that only 4.2 per cent of 1525 patients under 14 months of age required surgical treatment. Surgery was required in 20 per cent of 475 patients over 14 months of age.

All surgical methods for correction of gastro-oesophageal reflux involve reducing the stomach and distal oesophagus into the abdominal cavity and increasing the pressure at the gastro-oesophageal junction (Fig. 32) 2118,2119. Most repairs also restore the acute angle of entry of the oesophagus into the stomach. Extensive oesophageal strictures due to chronic reflux fail to respond to simple dilatation and require an antireflux procedure combined with intraoperative and postoperative dilations. Oesophagectomy and substitution may be required if severe stricture is present because of neglected reflux.

Achalasia of the oesophagus is seen occasionally in children. It is characterized by failure of normal relaxation of the lower oesophageal sphincter, resulting in dysphagia, regurgitation of undigested food, retrosternal pain, weight loss, and pulmonary complications. Infants present with symptoms often attributed to gastro-oesophageal reflux, including choking, apnoea, pneumonia, and failure to thrive. The terminal oesophagus appears narrow on radiographs, ending in a ‘bird's beak,’ with dilatation above (Fig. 33) 2120. Manometric studies of the lower oesophageal sphincter demonstrate resting pressure two to three times normal, and absence of relaxation with swallowing. The pathology in the lower oesophagus is similar to that of Hirschsprung's disease of the rectum, with absence of intramural ganglion cells.

Treatment may include dilatation, oesophageal resection, and various plastic procedures. Dilatation generally provides only temporary symptomatic improvement, although it is often the initial treatment for adults. The modified Heller operation is satisfactory.

Although the incidence of ingestion of caustic agents has declined, it continues to occur. Alkalis, more frequently found in the household than strong acids, are the most commonly ingested. Most patients are about 2 years old, and generally under 5. Ingestions by adolescents are usually suicide attempts.

Strong acids primarily damage the stomach and duodenum and may produce perforation. They are less often the cause of serious oesophageal injury since they produce coagulation necrosis that limits the penetration of acid into the deeper tissues of the oesophagus. Strong alkalis, on the other hand, penetrate deeply into the muscle layers of the oesophagus by a process of liquefaction necrosis which continues until the alkali is neutralized. Serious injury to the stomach is uncommon. Ingestion of ammonia and household bleach (sodium hypochlorite) seldom causes severe oesophageal or gastric injury.

Clinical assessment of caustic damage to the oesophagus cannot be based reliably on the presence of burns in the mouth. Some children with obvious burns to the lips and mouth spit out the substance, avoiding oesophageal injury. Others have no evidence of oral burns, but have extensive oesophageal burns that, if left untreated, can result in severe stricture. Solid alkaline material causes severe burns of the mouth and/or pharynx but is expelled without being swallowed. Liquid agents are more rapidly swallowed, causing less tissue injury within the mouth and more injury to the oesophagus.

A barium swallow is not a sensitive means of identifying those children with early or limited oesophageal injury. Demonstration of an atonic dilated oesophagus has been related, however, to diffuse muscular necrosis and a high likelihood of a severe stricture. An atonic rigid oesophagus appearing as a narrow rigid tube with no peristaltic activity is also likely to develop a stricture.

Oesophagoscopy and laryngoscopy should be performed in all children with suspected caustic ingestion as signs and symptoms are poor predictors of injury. This procedure is usually performed within 48 h of admission, depending on the general condition of the child. A 24-h delay before endoscopy may allow a mild oesophageal injury to become apparent. No attempt should be made to pass the oesophagoscope beyond the most proximal site of injury because of the risk of perforation.

Various combinations of antibiotics, bougienage, oesophageal stents, and steroids have been used to treat experimentally produced burns of the oesophagus. A combination of these seems to be most effective, although a recent large prospective study failed to demonstrate benefit from the use of systemic steroids.

Oesophageal injury can be classified as a first-degree burn (mucosal hyperaemia, oedema, and superficial sloughing), a second-degree burn, involving all layers of the oesophagus (characterized by exudate, ulceration, and loss of mucosa) or third-degree burn, involving the entire oesophageal wall with erosion into the peri-oesophageal tissues. The last is rare, and requires an oesophagectomy. Treatment with steroids and antibiotics is continued for at least 2 to 3 weeks. Patients may begin taking liquids when they are able to swallow their saliva. Children with severe pharyngeal and/or laryngeal burns may require intubation or an emergency tracheostomy several hours after injury as airway oedema progresses. If vomiting and aspiration occur at the time of the initial injury, severe respiratory distress and pneumonitis can occur.

Oesophageal dilatation is often instituted once the acute injury has resolved and mucosal oedema has subsided (2 to 3 weeks after injury). Others await radiographic evidence of oesophageal narrowing before attempting dilatation. Extreme caution must be taken with the first dilatations performed to avoid the risk of perforating the friable oesophagus. Dilations performed daily as the mucosa regenerates prevents some strictures. Direct injection of steroids (triamcinolone diacetate) in conjunction with dilatation is helpful in preventing recurrence of some isolated strictures.

Oesophagectomy and replacement with colon is required in some patients with severe injuries or delayed treatment (Fig. 34) 2121. If a colonic replacement is required, it is best to remove the injured oesophagus which carries a long-term risk of carcinoma, estimated to be 1000-fold that in the normal population with a latency period of 20 to 40 years.

Vascular anomalies of the aorta that compress the trachea are among the surgically correctable causes of respiratory distress in infants and children. The aorta and its major branches develop from the six embryonic pairs of aortic arches corresponding to the branchial clefts. The third pair forms the carotid arteries, the fourth the aortic arch, the sixth the pulmonary artery and ductus arteriosus. The right side of the fourth arch generally disappears, producing the normal course of the aorta arching to the left and descending to the left of the spine. If the left fourth arch disappears and the right persists, the individual has a right aortic arch, a common anomaly. If both arches persist, they form a double arch or vascular ring encircling the trachea and oesophagus. Gross first described the operative correction of this problem in an infant.

Many anatomical variations exist (Table 5) 566: the most important and common are shown in Fig. 35 2122,2123,2124,2125,2126,2127. Some of the anomalies are asymptomatic; others may produce compression of the airway with severe respiratory symptoms from birth. Infants with a true vascular ring encircling the trachea and oesophagus have the most severe symptoms which are often aggravated by feedings. Other infants have a history of ‘noisy breathing’ but no actual distress until they develop an upper respiratory infection. These infants commonly lie in a hyperextended position which stretches the trachea taut, reducing the constricting effect of a compressing vessel. Flexing the head forward can totally occlude the airway. This contrasts with infants with laryngomalacia or other causes of upper airway stridor, in whom position of the head and neck does not affect the severity of the symptoms.

Diagnosis of a vascular anomaly is often established on plain chest radiographs, which demonstrate narrowing of the tracheal air column, and a barium swallow, showing oesophageal indentation. When the barium swallow is normal and the plain films are inconclusive, endoscopy should be performed to exclude tracheal and oesophageal compression. Ten per cent of patients with aortic anomalies requiring surgical treatment have associated cardiac lesions.

The sine qua non of surgical correction in these anomalies is accurate and complete identification of the vascular anatomy in the mediastinum before division of any vessels. We prefer a left thoracotomy through the third or fourth intercostal space. Most of the thymus is removed to expose the aortic arch and its branches. The most common of the vascular ring anomalies is shown in Fig. 35(a) 2122. The large arch lies posterior and the smaller anterior. The ring is divided at an appropriate point, usually between the left carotid and left subclavian artery. Division of the ligamentum arteriosum may further open the constricting ring. It is important to dissect the segment of trachea and oesophagus that had been constricted to make certain that they are completely free from compression.

Figure 35(b) 2123 shows a double arch in which the smaller limb lies behind the trachea and oesophagus. This limb is frequently very short and can slip away when divided, resulting in fatal haemorrhage. It is best to ligate the far end of this vessel securely, leaving an ample cuff beyond the ligature before it is divided. A clamp is used to control the end of the vessel nearer the operator, oversewing it flush with the descending aorta rather than relying on a ligature.

The right aortic arch (Fig. 35(c)) 2124 is a common variant. In association with a left ligamentum arteriosum or patent ductus arteriosus, it can entrap the trachea and oesophagus, producing clinical symptoms identical to those of a double arch.

Anomalous innominate artery is difficult to diagnose with certainty. The trachea is compressed by impingement in a crotch formed by the innominate and left common carotid artery (Fig. 35(d)) 2125. Several variations are possible: the innominate can be displaced far to the left and actually cross the tracheal wall, or the left carotid can originate more proximally on the arch than normal and can be the principal cause for compression.

The barium swallow is completely normal in infants with an anomalous innominate artery, in contrast to the true vascular ring anomalies. The plain chest radiograph may also be inconclusive. Bronchoscopy shows a pulsating vessel indenting the anterior wall of the trachea. One must be prepared to proceed to thoracotomy and repair following bronchoscopy, which may acutely aggravate the infant's respiratory distress. Repair is performed through a left thoracotomy. The thymus is subtotally removed and sutures are placed in the adventitia of the obstructing vessels to suspend them forward to the sternum (Fig. 35(d)) 2125. This procedure can produce dramatic results in some infants. Some infants with mild respiratory symptoms do not require surgery.

The aberrant subclavian artery (Fig. 35(e)) 2126 is common, being seen in about 1 per cent of subjects at postmortem examination. The right subclavian originates in an anomalous position from the aortic arch beyond the origin of the left subclavian artery. A pseudodiverticulum of the aorta is often present at its origin. The artery passes posteriorly, traversing the mediastinum posterior to the oesophagus in most instances. It may occasionally produce enough oesophageal compression to produce dysphagia. The symptoms are similar to those caused by an oesophageal stricture. Barium swallow studies show a characteristic oblique indentation of the barium column in the anteroposterior projection. The clinical symptoms are difficulty in swallowing, often with regurgitation and aspiration when the upper oesophagus fills and spills over into the trachea. Oesophagoscopy demonstrates narrowing of the lumen by a pulsating vessel compressing the posterior wall of the oesophagus.

Surgical correction, when required for symptoms, is performed through a left thoracotomy. The artery is divided at its origin from the aorta and the distal end is allowed to retract into the mediastinum releasing the compression of the oesophagus. The blood supply to the right arm is adequate with proximal division through collateral circulation at the shoulder.

Anomalous left pulmonary artery (vascular ‘sling,’ Fig. 35(f) 2127) is a rare but interesting cause of vascular compression of the trachea. The left pulmonary artery may cross anterior to the trachea, but can also be located between the trachea and the oesophagus. Angiography may be necessary to establish the diagnosis, although anterior indentation at the level of the pulmonary hilum is diagnostic if present. Surgical correction is accomplished by moving the origin of the left pulmonary artery to an appropriate location anterior to the trachea and dividing the ligamentum arteriosum. It may be associated with severe intrinsic stenosis of the distal trachea or right mainstem bronchus, which must also be treated. Cardiopulmonary bypass offers the safest approach to the repair of this anomaly.

Anaesthetic management of patients with these anomalies must allow for the constriction in the lower trachea. The endotracheal tube must pass beyond this point to maintain effective ventilation.

Residual symptoms may be present for a time after relief of obstruction due to persistent deformity of the softened cartilages of the previously compressed trachea. Ventilation may be required for several days after surgery. Oral feedings should not be attempted until the children are free from respiratory distress.

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