SURGICAL EMERGENCIES IN THE NEWBORN

Transcription

1 Br.J. Anaesth. (1977), 49, 43 SURGICAL EMERGENCIES IN THE NEWBORN J. LISTER Although paediatric surgery has long been recognized as a branch of surgery requiring special techniques and the demands of the child patient have been accepted as differing from those of the adult, there were very few surgeons in the United Kingdom who confined their practice to children until after the Second World War. Surgery of children was carried out largely by general surgeons who perhaps took a special interest in children and, particularly in Scotland, by young surgeons whose first staff appointments were to the Children's Hospitals, but who usually proceeded to adult appointments later in their careers. Neonatal surgery is an emergency service; the application of highly specialized techniques in a very expensive environment would not be justified for surgery that could be conveniently delayed. Indeed, the majority of neonatal surgery is life-saving in nature. In the 1950's, however, with advancing knowledge of anaesthesia and the control of shock, a few centres throughout the world began to demonstrate that the newborn child could safely be submitted to major operative procedures both in the abdomen and the chest: a number of conditions incompatible with life were shown to be eminently suitable for surgery and in others corrective surgery could be started much earlier in life. Neonatal surgery emerged as a specialty which could not be easily undertaken by a general surgeon, and which demanded an expensive back-up service of doctors, nurses and ancillary staff as well as expensive equipment. It became clear that each Hospital Region in the United Kingdom required a specialist centre for neonatal surgery; such units would be in the regional children's centre, either in a separate children's hospital or in a large children's department in a general hospital, and would be associated with a medical school. The surgeons in such centres would provide a regional service for neonatal problems, with continuing care of those patients into childhood and of other less common surgical conditions in older children; they would also JAMES LISTER, M.D., F.R.C.S., Department of Paediatric Surgery, The University of Liverpool, Alder Hey Children's Hospital, Eaton Road, Liverpool L12 2AP. provide a complete surgical service for all children in the immediate district of the centre. It is thus to the demands of neonatal surgery that paediatric surgery in the United Kingdom owes its very rapid expansion from fewer than 10 surgeons in 1950 to something more than 40 in Neonatal surgical centres are extremely expensive, making heavy demands on medical and nursing staff and requiring not only specialist surgeons, but also a highly specialized service of anaesthesia, radiology, morbid anatomy and biochemistry, in addition to the close relationship with paediatricians. The requirements for such centres were studied by the Department of Health in 1968 (Ministry of Health, 1968) and an estimate, based on neonatal surgical demands, was approximately one paediatric surgeon per million population; a paediatric surgeon could not efficiently work single-handed and therefore paediatric centres with neonatal surgical services would not normally be established to serve a population of fewer than two million. Therefore it seemed reasonable to expect that a major centre would be established in each of the old regional hospital board areas. The stimulus for the establishment of such centres was certainly the increasing awareness amongst obstetricians and paediatricians of the availability of corrective surgery for life-threatening congenital abnormalities; but the development of an aggressive treatment in myelomeningocele which involved the early closure of the back lesion played a major part in increasing the demands for a neonatal surgical service. In the past 10 years there has been a gradual reduction in the number of newborn children referred for surgery (Lister, 1974), caused partly by the 25% reduction in the birth rate and partly by the change in the climate of opinion with regard to the treatment of severe myelomeningocele. These two factors have reduced annual admissions by approximately 40% in the past 5 years; for example the neonatal surgical unit in Alder Hey Hospital, Liverpool, had 265 admissions in 1970 and 165 in This decrease, however, is not expected to continue. The decrease in the birth rate is important, but changes in the fertility rate possibly more so; fertility rates for women over 35 have decreased a

2 44 BRITISH JOURNAL OF ANAESTHESIA great deal more than the fertility rates in younger women and it is in the older women that certain congenital abnormalities occur more frequently. An increase in the number of children born is expected in the 1980's when the grandchildren of the postwar bulge reach childbearing age. In addition, the decreasing admissions to the neonatal units, particularly in myelomeningoceles, has been partly offset by an increase in certain other conditions; for instance, in many parts of the world it appears there has been an increase in the number of cases of exomphalos. Neonatal necrotizing enterocolitis in North America, at least, a condition almost entirely confined to the low birth-weight baby with respiratory distress syndrome, has in a number of centres become an increasingly frequent surgical problem possibly because of an increase in the number of RDS survivors at risk. Steady improvements in the results of cardiac surgery with cardiopulmonary bypass in the early weeks of life make it likely that an increasing number of babies with cardiac anomalies will be submitted to surgery. Thus, while further centres are not obviously required, there remains ample justification for the maintenance of existing ones. These centres demand a co-operative effort of many medical specialists and others, but excellent standards of surgery and associated medical care can achieve nothing without constant nursing supervision at the highest levels of intensive care. The ideal situation of one trained nurse for each patient would require something in the region of 80 trained nurses for a 20-cot unit, an impossible level of staffing; for economic purposes the unit must be designed to allow constant supervision by a smaller number of nurses, but it must never be forgotten that newly born babies undergoing surgery will require the same level of nursing care throughout the 24 hours and the demands of the neonatal surgical unit will be extremely heavy compared with other areas in the hospital. GENERAL MANAGEMENT OF THE NEWBORN Depending on the density of population of a region, the neonate requiring surgery may have to be transported for considerable distances; provided a number of basic precautions are taken the patient will travel well and the few hours taken over the journey will not influence the outcome of surgery. Maintenance of airway Aspiration of vomitus remains a common cause of death in the newborn and it is essential that the stomach be kept empty during transport, especially in cases suspected of having intestinal obstruction. A soft nasogastric catheter should be strapped in place and left on open drainage; it should also be aspirated every 15 minutes or so to confirm that it has not become blocked. In addition, the child should be lying on his side so that any secretions can dribble out of his mouth. In certain conditions, notably a diaphragmatic hernia, and possibly some cases of oesophageal atresia, endotracheal intubation may be necessary to provide adequate ventilation and to protect the lungs from the development of pneumonia. Maintenance of body temperature The newborn child, with a relatively larger surface area than the adult, less insulating subcutaneous fat and a relatively small cell mass suspended in the relatively large volume of extracellular fluid, is to a certain extent at the mercy of his environment. It is important that the surface body temperature should be maintained at 36 C, which can best be achieved by nursing the baby in an incubator (a portable one for transportation) or well wrapped in a cellular blanket with the addition of aluminium foil to preserve heat. The newborn infant, even a premature one, is able to respond to cooling by increasing metabolism in order to increase heat production; but he remains at a physical disadvantage from heat loss and if exposure to cold is prolonged he may not be able to provide the extra oxygen required to maintain the high rate of metabolism. To the depletion of energy stores, hyperkalaemia and hypoglycaemia will then be added all the dangers of hypoxia and respiratory acidosis. Maintenance of circulating blood volume The circulating blood volume of the newborn child resembles very closely that of an adult being approximately 10% of his body weight and he is able to lose up to 10% of that circulating volume in an acute haemorrhage; this means that a 2.5-kg baby can only lose 25 ml of blood and therefore any surgical procedure demands that blood should be available for transfusion. The Blood Transfusion Service will require the mother's blood for cross-matching as well as blood from the baby and therefore a specimen of this should go with the child, when he is transported, to a neonatal surgical unit. It is relatively rare for the newborn referred for surgery to be in a state of dehydration or electrolyte imbalance. The fluid requirements in the first 2 or 3 days of life are

3 SURGICAL EMERGENCIES IN THE NEWBORN 45 low and unless there have been excessive abnormal losses the main requirements will be blood replacement at operation. Hypoglycaemia, however, with blood sugar concentrations of less than 20 mg% is not uncommon, especially in premature babies, and i.v. infusions of 10% glucose may be indicated to control this. Maintenance of acid-base balance The kidney of the newborn infant is often described as being immature and certainly its capacity to concentrate or dilute urine is limited as is its control of acid-base balance. However, under normal circumstances, the kidney of the newborn is remarkably efficient at maintaining serum electrolyte concentrations within an accurate range similar to that maintained in adult life and it is only when there are abnormal fluid losses such as in diarrhoea or intestinal obstruction that the precarious acid-base balance may be demonstrated; similarly, it is very easy to overload the kidneys with both salt and fluid by overgenerous i.v. therapy. Particularly in the premature infant, such overloading can be produced merely by "keeping the vein open" with an infusion during operation. RESPIRATORY DISTRESS There is no dispute that the major emergency in any hospital is the respiratory emergency and the newborn, who is suddenly thrust from a temperaturecontrolled environment, where his gaseous exchange continues without muscular effort across the placenta, into a cold world where he has to expand and ventilate his own lungs to obtain his oxygen, is particularly at risk. The establishment of effective ventilation in the newborn infant is a major factor in the reduction of perinatal morbidity and mortality and although it is true to say that a surgical cause of respiratory distress in the newborn is relatively uncommon, such conditions do demand some of the most urgent surgical treatment in the newborn period. Partial upper respiratory obstruction The newborn child is almost an obligatory nose breather and, consequently, naso-pharyngeal obstruction may cause extreme hypoxia. Choanal atresia is one example of such an obstruction and the Pierre Robin syndrome is another. In this latter condition there is micrognathia, the tongue being displaced backwards and consequently obstructing the upper airway, often in association with a high or even a cleft palate. These two conditions can be managed immediately by establishing an oral airway by fixing an airway tube into position and tube-feeding the baby. In severe cases of the Pierre Robin syndrome it is necessary to nurse the child in a prone position usually in a special frame with the neck held in the extended position either by cap-suspension or by an appropriate support. Oesophageal atresia Oesophageal atresia is one of those conditions in which the urgency is in making the diagnosis, not in the surgical treatment; the danger to life is not from the oesophageal atresia, but from the associated tracheo-oesophageal fistula which is present in 90% of cases. Once the diagnosis has been made, appropriate management can protect the lung from pneumonia which is the most likely cause of death. A delay of several hours before operation with appropriate antibiotic therapy and physiotherapy is justified and even positively indicated when there has already been aspiration of gastric content into the bronchial tree before the diagnosis has been made. Diagnosis is suspected when there has been polyhydramnios and when a child has excessive drooling of saliva. It can easily be excluded by the passing of a No. 10 catheter down the oesophagus and aspirating acid gastric juice. For x-ray confirmation of the position of any hold-up a radio-opaque catheter is all that is needed; the use of contrast medium is to be condemned because of the risk of overflow compounding the pneumonia (fig. 1). It is to be hoped that in a situation where the possibility of this abnormality is always borne in mind no patient will be fed before the diagnosis has been excluded. Once the diagnosis has been made the upper pouch is kept empty by intermittent suction and gastrooesophageal reflux discouraged by the position of the patient. The upright position discourages reflux, but encourages the collection of mucus in the upper pouch and nursing in the prone flat position probably hits the right balance between the two requirements. As in the management before surgery the aim of operation is to protect the lung from the aspiration of gastro-oesophageal content. This means that the primary object of the operation is division and ligation of the fistula between the lower oesophagus and the bronchial tree; if the oesophageal ends are close together then end-to-end anastomosis of the upper and lower pouches can conveniently be done at the same time and most surgeons now perform this operation through an extra-pleural approach.

4 BRITISH JOURNAL OF ANAESTHESIA m. FIG. 1. A: Oesophageal atresia; catheter arrested in upper pouch. Air below diaphragm indicates presence of fistula between trachea and lower pouch. Note right upper lobe consolidation, B: Oesophageal atresia; lack of gas below diaphragm indicates absence of trachec oesophageal fistula. Note not uncommon association of hemivertebra. If an end-to-end anastomosis of the oesophagus is likely to be technically difficult, or if the general condition of the child because of his low birth weight or because of severe associated anomalies or because of pneumonia makes an extensive procedure unduly hazardous, then a staged procedure can be undertaken, dividing the tracheo-oesophageal fistula and making a gastrostomy for feeding only, and returning at a later stage to complete the end-to-end anastomosis. It has to be remembered that at least half the children with oesophageal atresia have severe associated abnormalities, often muliple, involving the alimentary tract, the skeletal system, the kidneys and the heart. Diaphragmatic hernia Congenital diaphragmatic hernia is the most dramatic emergency in the newborn period; it most commonly occurs through a postero-lateral defect

5 SURGICAL EMERGENCIES IN THE NEWBORN of the left side of the diaphragm at the foramen of Bochdalek. The hernia usually consists of the whole of the midgut loop, often with the stomach and a large part of the descending colon. The left kidney, the spleen and left lobe of the liver are frequently involved and the filling of the midgut loop with air when the baby first cries, or, more commonly, when he first feeds, causes a large filling defect in the left pleural cavity with shift of the mediastinum to the right side. The result of this displacement is an interference with the ventilation of the right lung and severe hypoxia. Clinically there is "dextrocardia" and x-ray shows gross mediastinal shift (fig. 2). The hypoxia demands urgent treatment in the form of endotracheal intubation and ventilation, in addition to deflation of the gut by aspiration of a naso-gastric 47 tube. Two great dangers are present in artificial respiration for the child with diaphragmatic hernia; the use of a face mask is potentially lethal, since much of the air insufflated will go into the stomach and small bowel, increasing the "space-occupying lesion" in the left pleural cavity and shifting the mediastinum so as further to embarrass the right lung and even cause cardiac arrest by obstruction of the great veins and reduction of venous return. Endotracheal intubation is mandatory, but even with this there remains the danger of alveolar rupture and pneumothorax often on the good side so that the possibility of drainage of the pleural cavity must always be borne in mind. Traditionally, it has been taught that urgent operation and reduction of the hernia were essential if survival rates were to improve. It was shown 10 years ago (Butler and Claireaux, 1962) that almost one-third of children dying of congenital diaphragmatic hernia were considered stillbirths and another one-third died within the first 24 hours of life. But awareness of the urgency of the situation has not improved the survival rate; indeed, in the experience of most paediatric surgeons the survival rates have diminished. Many of those children dying had major associated malformations and many of the children have bilateral pulmonary hypoplasia which is incompatible with hie. Those patients with bilateral pulmonary hypoplasia will die whether they are operated on or not. In those patients with at least one good lung it should be possible to correct the respiratory acidosis before operation by adequate positive pressure mechanical ventilation. The urgency of the operation should not be quite as acute as was previously thought and a short time should be spent in an attempt to improve the acid-base balance before operation. Neonatal lobar emphysema An over-distension of one or more lobes of the lung, most commonly the left upper lobe, may produce respiratory distress with displacement of the mediastinum and acute cyanosis and dyspnoea, very similar to that found in diaphragmatic hernia (fig. 3). This condition is frequently accompanied by cardiac abnormalities, but emergency thoracotomy and lobectomy is usually necessary to relieve the respiratory distress. Congenital cystic disease of the lung FIG. 2. Congenital diaphragmatic hernia left, posterolateral. A hamartomatous malformation of the lung with multiple cysts may resemble diaphragmatic hernia

6 BRITISH JOURNAL OF ANAESTHESIA of ganglion cells in Hirschsprung's disease, immature ganglion cells in small premature babies, starved ganglion cells in hypoglycaemia and poisoned ganglion cells in septicaemia; and in a third group of children there is ischaemic enterocolitis, either as a result of umbilical vein infusion and interference with the haemodynamics of the portal system or as a result of reduced bowel perfusion in shock. In general, intestinal obstruction presents with delay in the passage of meconium, bile-stained vomiting and abdominal distension. Confirmation of diagnosis is obtained by straight x-ray of the abdomen in the upright position and the presence of distended loops of bowel and fluid levels in this x-ray are an indication for urgent laparotomy with removal or bypassing of the obstructing pathological entity. Should the x-ray show distended loops of bowel, but no fluid levels, then the presumption must be that the obstruction is not complete and the next diagnostic step will be contrast studies, probably in the form of a gastrografin enema. It is this contrast enema which will help to distinguish the difficult FIG. 3. Left upper lobar emphysema. both in the clinical presentation of cyanosis and dyspnoea and in the radiological evidence when multiple cysts may closely resemble air in the small bowel (fig. 4). Thoracotomy and resection of the affected lobe is indicated. Staphylococcal pneumonia Staphylococcal pneumonia may mimic congenital pulmonary cysts or diaphragmatic hernia, but the condition is usually bilateral and the child will present other evidence of the staphylococcal septicaemia. INTESTINAL OBSTRUCTION Oesophageal atresia and anorectal malformations account for approximately 10% each of the total admissions to the neonatal surgical unit. Other intestinal obstructions account for between 25% and 30% and of these only half are caused by straightforward mechanical obstructions such as atresia, hernia, volvulus and other extraluminal mechanical factors. More than half are obstructions of a much less positive nature, including intraluminal obstructions by a meconium plug or abnormal meconium in fibrocystic disease or by a milk bolus; a group of functional obstructions may result from various abnormalities in the myenteric plexus, absence FIG. 4. Cystic hamartomatous disease of left lung with gross mediastinal shift. Relatively large amount of bowel below diaphragm suggests diaphragmatic hernia is an unlikely diagnosis.

7 SURGICAL EMERGENCIES IN THE NEWBORN 49 group of children with intraluminal and functional obstructions and, indeed, in meconium ileus associated with fibrocystic disease and also in milk curd obstruction the gastrografin, by its hygroscopic effect, may frequently have a therapeutic effect and encourage the passage of the abnormal meconium or inspissated milk. The management of intestinal obstruction varies according to the cause, but is designed to remove or bypass the lesion. It must be remembered that, particularly in volvulus and intestinal atresias, massive resection of the small bowel may be indicated and, indeed, possibly some of the small bowel has been lost in the pathological catastrophe which caused the atresia. In many of these children, therefore, malabsorption problems will arise in the phase following surgery. The use of i.v. feeding has played a significant part in improved results. ABNORMALITIES OF THE TRUNK Exomphalos and gastroschisis Exomphalos is a large congenital.hernia into the base of the umbilical cord and gastroschisis is a defect of the abdominal wall close to, and on the right side of, the base of the umbilicus. The exomphalos sac may be intact, or may rupture before, during or after birth, so that there is prolapsed abdominal contents coming through it. The gastroschisis always is ruptured in utero and has no covering membrane. Both conditions demand surgical management. Exomphalos causes problems usually by its size: in the large exomphalos when the sac contains a large part of the liver, the abdominal cavity is so small that reduction of the contents of the sac and repair of the anterior abdominal wall is not possible without interfering with respiration and, indeed, with venous return through the inferior vena cava; gastroschisis also raises problems from the point of view of closure, because the extruded bowel is thickened and foreshortened because of its exposure to amniotic fluid and it is often difficult to reduce this completely. Treatment is preferably by excision of the sac (when present) and repair of the anterior abdominal wall. When this is likely to be impossible, because of the size of the contents, then the sac of the large exomphalos may be treated by painting with a desiccating solution of 2% tincture of mercurochrome. When the sac is ruptured or absent a patch or pouch of silastic sheeting may be used as a temporary closure of the abdominal wall. In exomphalos, the use of positive pressure ventilation has made possible the primary closure of some of the larger sacs and this, together with the use of i.v. feeding, has considerably improved the survival rate in this condition. Myelomeningocele Until a method of controlling hydrocephalus was available, myelomeningocele was not regarded as an emergency in the newborn period, since treatment of the back lesion was likely to be of no avail because the child would die of his advancing hydrocephalus. The development of a successful valved ventriculoatrial shunt, however (Nulsen and Spitz, 1952), led to a new look and a more aggressive approach to the back lesion (Sharrard et al., 1963). Sharrard and colleagues suggested that urgent closure of the back lesion resulted in a marked improvement in the neurological status of the infant and, in many centres, closure of the myelomeningocele became one of the most urgent of the neonatal emergencies. The urgency of operation excluded any possibility of discussion of the situation with the parents since it was felt that closure of the back should be completed within as short a time as possible of the birth of the child. The large number of handicapped survivors led to some re-thinking (Lorber, 1971) and to a change in the climate of opinion as to the treatment of these children. In many centres now an effort is made to recognize at birth those children who will have severe handicaps and possibly a poor quality of life, and those whose handicap will be minimal; and to select for treatment those children in whom a reasonably successful result can be anticipated, the intention being that those not treated will die. The dangerous assumption from this policy is that "operation" means survival and non-operation means death; neither of these assumptions is true and, indeed, the closure of the back can hardly be regarded as playing any significant part in the survival of the child. In general, the child who appears moribund on admission, usually from intracranial haemorrhage caused by birth injury associated with the severe hydrocephalus, or the child with lethal associated abnormalities, is not a child who should be submitted to operation since he is almost certain to die. At the other end of the scale, there are children with good movement in the lower limbs in whom closure within 24 hours of birth is indicated in order to prevent infection and desiccation, to preserve such movement of the lower limbs as is present. For a large number of children between these two extremes in whom there is very little movement below the hip flexors, operative closure of the back will not improve

8 50 BRITISH JOURNAL OF ANAESTHESIA function as suggested by Sharrard and colleagues (1963). There may be other indications for operation, however; for instance, whilst in some cases with severe kyphosis, attempted and failed operative closure would result in a worse back lesion than the original one, in many cases closure of the back will allow an earlier discharge home of a child with a healed back than if the lesion were allowed to epithelialize. From a psychological point of view there is no doubt that operative interference is regarded by most parents as evidence of a positive interest in caring for the child whilst non-operative treatment tends to be regarded as rejection by the surgeon. The increasing number of children with unclosed backs who do not die and develop severe hydrocephalus at the age of 3 or 4 months has made some paediatricians less anxious to refrain from referring these children to the surgeon in the neonatal period. Closure of the open myelomeningocele is not a life-saving procedure, but a function-saving one or one designed to make general management of the child easier; it is therefore not an acute emergency but a procedure which should be undertaken within the first hours of life. If left longer the chances of wound infection and meningitis increase. The measurement of alpha-foetoprotein concentrations in the amniotic fluid of "at risk" mothers has already made possible the recognition of severe neural tube anomalies and termination of pregnancies. It is probable that the development of techniques for measuring these concentrations in maternal serum and urine will make available a method of mass screening; open myelomeningocele could be a rarely seen abnormality if such a screening method and subsequent termination of affected pregnancies were universally accepted. CONCLUSION Apart from the probable increase in operation for congenital heart disease in the neonatal period, it is unlikely that new surgical procedures will be designed for the correction of other congenital abnormalities. It is the experience of most specialist neonatal surgical units that children do not die of the abnormality with which they were referred, but they die of associated abnormalities, often uncorrectable, they die of severe prematurity and they die of respiratory complications. It is likely that any improvement in results will be achieved by ventilation management rather than by advances in surgical techniques. SUMMARY Paediatric surgery is a young specialty whose rapid growth in the United Kingdom has largely been as a result of the development of neonatal surgery in the past 20 years. A decreasing birth rate, and pre-natal diagnosis of some major congenital anomalies with the possibility of termination of pregnancy, are likely to prevent further increases to neonatal surgical units. Expansion of case material is likely to come from earlier attacks on congenital heart disease, and improvement in results is more likely to come from improved respiratory management than from the development of new surgical techniques. REFERENCES Butler, N., and Claireaux, A. E. (1962). Congenital diaphragmatic hernia as a cause of perinatal mortality. Lancet, 1, 659. Lister, J. (1974). Is there a decline in neonatal surgery? J. Pediatr. Surg., 9, 1. Lorber, J. (1971). Results of treatment of myelomeningocele. An analysis of 524 unselected cases with special reference to possible selection for treatment. Dev. Med. Child. Neurol., 13, 279. Ministry of Health (1968). Report of the Joint Committee on Surgery for the Newborn. London: H.M.S.O. Nulsen, F. E., and Spitz, E. B. (1952). Treatment of hydrocephalus by direct shunt from ventricle to jugular vein. Surg. Forum, 2, 399. Sharrard, W. J. W., Zachary, R. B., Lorber, J., and Bruce, A. M. (1963). A controlled trial of immediate and delayed closure of spina bifida cystica. Arch. Dis. Child., 38, 18.