OESOPHAGEAL ATRESIA

Oesophageal atresia is characterized by the congenital absence of a segment of the thoracic digestive tube, and is very often associated to a tracheo-oesophageal fistula (TOF). The obstruction of the oesophagus leads to laryngo-tracheal aspiration, but the aspiration of the gastric content through the TOF is the determining factor in the occurence of the lethal chemical pneumonitis.
The progress recorded elsewhere in neonatology has considerably reduced the mortality rates due to this malformation. Such is unfortunately not yet the case in our pediatric units where the hecatomb -mortality rates of 80%- comes for the most part as a result of the conditions under which perinatal care takes place.

1
The clinical aspect is evocative enough in the new-born whose mouth is encumbered by saliva, and who is likely to suffer from suffocation at each suckle. A soft catheter introduced through the nostril comes against the obstacle 10cms below. Often one might be under the impression that the catheter is going down freely when in fact it is curling up at the bottom of the oesophageal pouch; all the more since the aspiration process does not reveal any gastric liquid while an injection of air does not produce any audible gurgle at the level of the epigastrum.

Radiological tests confirm the atresia:
* A simple X-ray taken laterally and centered on the base of the neck shows a displacement or constriction of the trachea by the proximal segment of the pouch.


* An antero-posterior and lateral x-ray under opacification with Micropaque shows out the oesophageal pouch and specifies its position in relation to the vertebral column and the tracheal bifurcation. It is usually found at the level of T2 and above the carina. All the while one can observe the condition of the lungs are in, the morphology of the column, the cardiac shade, and the distribution of air in the digestive tube.

 

  Besides the degree of pulmonary resoundness and the of systemic state, the overall clinical statement is used to evaluate signs of associated anomalies such as anal imperforation, cardiopathy, chromosomic abberation, or Vater syndrome. Finally, one can also appreciate the degree of maturity
( weight, stage in pregnancy, hydramnios, and perinatal conditions ).

2
Anatomical data:
* The adopted classification is that of Ladd whose type III - the most frequent- is taken as an example in this study.
* The vascular impoverishment of the distal oesophagus and the extention of the atresic segment intervene as important factors  of post-surgical morbidity ( fistulization, leakage, stenosis... ).
* The approach to the thoracic oesophagus through the retropleural route is anatomically sounder and prevents the spread of   a mediastinal infection, but its execution is a delicate procedure. The transpleural route is on the other hand necessary for future interventions.

3
Therapeutic modes:
Caring oesophageal atresia is a laborious and complex process which comprises two stages each of which intervenes as a determining factor of success:

    *Caretaking in general which consists of preparing the new-born for major surgery by taking into  account the general condition of the baby and evaluating risk criteria. It is also important to ensure proper conditions physiological and nutritional comfort until all operative wounds have     healed. In this respect,the quality and availability of this primary care is dependent first and     foremost on discipline. Material means take a back seat to the competence of a motivated staff schooled in the respect of the rules of asepsy, the economy of gestures, routine hygiene, and the prevention of aggravating factors such as hypothermia, promiscuity, aggressive handling.

    *When considering surgery the assigned objective is of the prevention of a gastrointestinal reflux, and the establishment of anatomical continuity of the oesophagus. Both interventions gain to be performed concurently when physical and anatomical conditions are most conveniently exploitable. Barring these optimal conditions it is preferable to first stem the reflux by carrying out an oesophagoplasty when conditions are best suited for such an a procedure.

3-1
Pre-operative management ensures:

    *Repeated aspiration of the oesophagus, and avoiding aggressive maneuvers which could result in bleeding or irritate the child whose agitation could worsen the gastrotracheal reflux.
    *Prevention of hypothermia ( adequate covering). The best results are attained by using an incubator in which a humidified and heated atmosphere maintains the corporal temperature at 36C and the debit of oxygen at 40%.
    *The introduction of a central catheter through the saphenous or umbilical vein following the collection of the appropriate biological samples.
    *The collection of urine in an appropriate container.
    *The semi-seated position with arms a safe distance away from the various attached tubes.

3-2 The anaesthesia comprises a most delicate phase, that of intubation. Indeed, the anteposition of the larynx of the new-born renders the exposition of the glottis most difficult, and the risk of misrouting very real. The intubation of the proximal segment can tear the bottom of the pouch while the intubation of the oesotracheal fistula is a more serious procedure which can asphyxiate the child. The endotracheal tube without lateral eyelet hole is carefully slipped in the trachea. The auscultation of the pulmonary and epigastric areas allows for the positionning of its extremity midway between the orifice of the fistula and the carina.

3-3 The surgical stage aims to eliminate the oesophageal reflux. Immediately following another operation is performed to establish the continuity of the oesophagus but this can also be done at some later date.

4
Therapeutic indications:
Criteria of prognostical order established by Waterston some thirty years ago are used to distinguish between cases which can be treated during a single operative session ( group A: vigorous children with a birth weight superior to 2500 g and presenting no associated anomalies or pneumopathy) and those for whom it would be wise to schedule several ( group B: new-borns of borderline weight carriers of infections or presenting anomalies). In group C we find critically ill patients, immature babies or those suffering from a number of malformations and in an unstable physiological state. This last group needs to be treated with the utmost care: handled as little as possible, and without pretension.
In our environment however, the process of tracking and transfering new-borns at risk is inadequate, as a result one rarely gets to deal with cases belonging to the extreme groups ( A & C), but rather with those of the intermediary group where the majority of babies are presented to us several hours or several days late. At that stage atresia’s morbidity consequences have developped and any attempt to intervene in a radical manner is to be excluded for the near future.
Therefore we are of the opinion that there is a need to distinguish between the ideal case - where major surgical intervention is possible, be it a radical one- from the case where the concern remains the nutritional deficiency, the pulmonary infection, and the septic state deriving from it.

4-1
Priority is given to controlling the TOF which represents the main factor of distress.
The gastrostomia has to be performed on an emergency basis, notwithstanding the condition of the child, using local anaesthesia if necessary. Two catheters are to be used: one for feeding is to be introduced beyond the pylore, the other for decompression is to be connected to a half-full bottle containing an aseptic solution.

4-2 The ideal case is that of the new-born taken-in at birth who is mature and vigorous, and presenting no anomalies. Following a brief preparation in the operating room three procedures are performed: gastrostomia and the approach to the posterior mediastinum; ligature of the oesotracheal fistula; preparation of the oesophageal ends for a possible anastomosis.
At this point one is confronted by one of three possibilities:

    * The anastomosis can be performed : the ends are easily brought together, and the continuity can be achieved without tension.
    * The anastomosis can possibly be performed : the gap between the ends is reducible but at the cost of a certain tension.
Several tricks can be used to alleviate the stress placed on the sutures ( Haight " telescope" procedure, myotomy, paralysis of the proximal segment...) but one ought to keep in mind that the outcome could be perturbed by the development of a fistula, a leakage, or stricture.
    * The anastomosis cannot be performed: the ends are too far apart. The oesophagoplasty is postponed under cover of the two stomies, gastric and pharingeal.

4-3
During the critical stage the child is seen late; he is either at the septimic stage or exhibits congenital malformations. In this case the surgical act is limited to the exclusion of the TOF by a pharyngostomy and a gastrostomy. Decompressing the stomach and maintaining the child in
a semi-seated position considerably help reduce the reflux and attain the desired outcome and a stabilization of vital functions. At that point one can envisage a transmediastinal approach to the fistula and eventually atresia’s cure.

5 Complications:
The first ten days following surgery are critical, during that period a number of events can occur such as the failure of tracheal or oesophageal sutures. After the first month however complications are of a mechanical nature and related to the quality of the oesoplasty performed and its impact on the near organs. Eventhough the evolution can be less dramatic a laborious follow-up stretching over several months is called for in this situation.

5-1 The oesophageal anastomosis’ failure generally occurs between the third and sixth day and is revealed by the occurrence of respiratory distress followed by the lung’s collapse. The outcome is fatal if the situation is not rapidly attended to.
Radiological verification of the presence of a mediastinal effusion, associated to a pneumothorax or not, forces an urgent intervention which consists of:
    * Excluding the oesophagus through a double stomie, oesophageal and gastric, the latter to be accompanied by a feeding jejunostomy.
    * Draining the mediastinum and eventually the pleural cavity.
    * Medicating with wide spectrum antibiotics and corticosteroids.
     If the child overcomes these conditions an intervention on the oesophagus should be scheduled to take place several weeks later, this time using
     the transpleural route.

Preventing this fearsome complication requires:
    * Tremendous care while performing the surgical act.
    * Opting for the retropleural route which limits all risk of effusion to the mediastinum.
    * Renouncing to the performance of an anastomosis if the gap exceeds 2cm.
    * Using Haight’s procedure or any equivalent which calls for a two-layer anastomosis: muscular  and mucuous.
    * Reducing the tension exerted on the anastomosis by paralyzing the muscular structure of  the proximal segment, or alternatively by fixing the proximal pouch to the prevertebral fascia ( Swenson ).
    * Avoiding the tutering catheter which inflames the oedema, and not attempting dilatation before the end of the first month.

5-2 The fistulization is attributable to the same reason, but to a lesser degree, namely a leakage of the anastomosis. Other factors can precipitate it such as knots being too tight, use of traumatizing equipment But the occurrence of a localized infection is, and remains, the main risk factor to be monitored. The fistula can become extended and cause flooding of the mediastinum, respiratory distress, and an extensive growth of cellulitis. It can appear minuscule and is characterized by a low hum medistinal foyer. This condition can be confirmed radiologically following the child’s ingestion of an opaque solution, or revealed through endoscopy. Mediastinal flooding needs to be dealt with on an emergency basis, and one should assume that a complete failure has occured. As to the small fistules they should spontaneously dissipate after a few weeks.

5-3 The recurrence of the TOF is as serious an event as the failure of the anastomiosis; several causes have been found to account for this event:
    * The simple ligature of the fistula.
    * The development of abcess between the oesophagus and the trachea.
    * The contiguity of the oesophageal anastomosis to the tracheal implantation of the fistula of which the end would have been left in a diverticular shape.
    The signs of its presence include  sudden respiratory distress during breastfeeding, epigastric distention, and at times sudden death. Endoscopic visualization of the fistula is both difficult and laborious. It requires the oesophageal instillation of blue methylen while the distal end is kept obturated by a Foley-balloon.

Treatment is metted out on a case by case basis :
    * When no mediastinitis has developped and the overall state is deemed favorable, the fistula is accessed directly through a thoracotomy.
    * In the alternative case the tracheal orifice is blinded and the oesophagus excluded through a pharingostomy, mediastinal drainage, and feeding jejunostomy. The gastrotomy will be maintained to prevent any reflux.

5-4 The anastomotic stricture:
It can be detected in half the cases, and one ought to make a distinction between the stricture which occurs during the first month and the one which appears later.
    * Precocious stricture spreads vertically and results from the perioesophageal sclerosis of a necrotic area, or from a peptic oesophagitis induced by a gastroesophageal reflux,   ( the widening of the oesophageal hiatus is in this case attributable to an excessive  mobilization of the cardia ).


   * Late stricture is limited and presents no peripheral sclerosis. The anastomotic procedure and the multiplicity of layers seem to be responsible in this case.  Regardless of the particularsituation, the symptomatology is made manifest by a stridor during breast-feeding, dysphagia, tracheobronchial congestion, occlusion of foreign bodies, and a gradual progression toward anemia and hypotrophy.
The confirmation of this condition can again be obtained radiologically or endoscopically; the latter way allows for a better appreciation of the extent and the suppleness of the shrunken segment. The stricture is moderate when a 4mm oesophagoscope can be slipped through , and considered to be severe if it prevents the passage of a thread-like catheter.

 

    * The moderate and supple stenosis requires no therapeutic intervention.
    * The stenosis of less than 4mm in diameter necessitates biweekly bougirage until a bougie  #Ch 14 can easily be put through.
    * As to the peptic oesophagitis the appreciation of its evolution requires resting the oesophagus.
      The child is fed by gastro or jejunostomy. After several months the lesions have stabilized and it is then possible to offer palliative therapies (dilatation ) or  radical ones ( oesophagoplasty ) .