urgencias en neonatos.pdf

PEDIATRIC EMERGENCIES 0889-8537/01 $15.00 + .OO
NEONATAL SURGICAL
EMERGENCIES
Letty M. P. Liu, MD, and Leila Mei Pang, MD
Advances in perinatology and neonatology over the last 2 decades
have improved the survival of premature, especially extremely prema-
ture (< 1500 g) and critically ill, newborn babies. Most of the disorders
that were considered neonatal surgical emergenciesin the past no longer
require immediate surgery because of new technology and new methods
of treating sick neonates. This article describes the more common neona-
tal disorders that require semi-elective or emergency surgery, and fo-
cuses on factors that affect the anesthetic management of patients with
these disorders.
PYLORIC STENOSIS
Pyloric stenosis is the most common gastrointestinal obstructive
anomaly in neonates. It occurs in approximately 1in 500 live births, and
is found more frequently in males. Symptoms are usually not apparent
until the second to sixth week of life, and are caused by hypertrophy of
the muscular layer of the pylorus. The affected area feels like an olive-
shaped mass. It is palpated most easily when the stomach is empty, and
is located slightly to the right of the midline in the epigastric area. A
barium swallow roentgenogram or ultrasonogram can confirm the le-
ion.^^
When an infant is suspected of having pyloric stenosis, oral feedings
From the Department of Anesthesiology, University of Medicine and Dentistry of New
Jersey-New Jersey Medical School, Newark, New Jersey; Department of Anesthesiol-
ogy and Pediatrics, Columbia University, College of Physicians and Surgeons of
Columbia University; and New York-Presbyterian Hospital, Columbia-Presbyterian
Medical Center, New York, New York
ANESTHESIOLOGYCLINICS OF NORTH AMERICA
VOLUME 19 NUMBER 2 * JUNE 2001 265

266 LIU&PANG
should be discontinued.Metabolic derangements associated with pyloric
stenosis result from persistent vomiting, with loss of water, hydrogen,
chloride, sodium, and potassium. As hydrogen ions are lost, the kidneys
initially secrete potassium in exchange for hydrogen to maintain a nor-
mal serum pH. When sodium depletion becomes more severe, the kid-
neys secrete potassium and hydrogen in exchange for sodium, which
results in a patient who is hypokalemic, hypochloremic, and alkalotic.'03
If electrolyte loss continues, the kidneys secrete an acid urine (i.e.,
paradoxic acidosis), and metabolic alkalosis becomes more profound.
Eventually, metabolic acidosis from dehydration and hypoperfusion
occurs.
Anesthetic Management
' Surgical correction of pyloric stenosis, pyloromyotomy, is not a
procedure that should be performed emergently if the patient is dehy-
drated or is depleted of electrolytes. Fluid, electrolyte, and acid-base
balance should be re-established before anesthetizing a neonate with
pyloric stenosis, so that perianestheticcomplicationscan be avoided. For
example, if a patient is still alkalotic postoperatively, hypoxia can occur
as the baby attempts to correct the alkalotic state by hypoventilating.
Mild-to-moderate fluid and electrolyte problems (chloride > 90 mEq/L
and urine specific gravity < 1.020) can be corrected with 5%dextrose in
0.45% sodium chloride and 20 to 40 mEq/L of potassium, infused at a
rate of 10mL/kg per hour. Severe dehydration and electrolyte imbalance
(chloride < 90 mEq/t, sodium < 120 mEq/L, and no urine output)
requires volume expansionwith isotonic sodium chloride or colloid and
blood until urinary output is re-established. Potassium chloride then can
be added to the infusion.In severe cases of dehydration, restoring fluid,
acid-base, and electrolytebalance may take several days.
Immediately before the induction of anesthesia, standard monitor-
ing (e.g., blood pressure cuff, ECG leads, pulse oximeter probe, and
precordial stethoscope) should be started, and a large-bore orogastric
tube should be passed into the stomach several times until the amount
of fluid aspirated is minimal. Endotracheal intubation after preoxygen-
ation and a rapid-sequence induction is the method many anesthesiolo-
gists prefer for inducing anesthesia in these babies. Induction agents and
doses for these patients are found in Table 1.If difficulty with intubation
is anticipated, an endotracheal tube should be placed to secure the
airway before anesthesia is induced. An inhalation induction of anesthe-
sia should be avoided in these patients because they have an increased
risk for vomiting and aspirating gastric contents. Even after multiple
attempts to remove gastric contents by suction, a considerable amount
of residual material still may be present. Anesthesia may be maintained
with inhalation anesthetics or in combination with intravenous drugs.
Any volatile anesthetic drug may be used for anesthesia; however, the
same inspired concentration of volatile anesthetic generally causes a

NEONATAL SURGICAL EMERGENCIES 267
Table 1. DRUGS AND INTRAVENOUS DOSE
Drugs Dose
Anticholinergic drugs
Atropine 0.01-0.02 mg/kg
Glycopyrrolate 0.005-0.01 mg/kg
Thiopental 6-7 mg/kg
Propofol 2.5-3 mg/kg
Etomidate 0.3 mg/kg
Muscle relaxants
Depolarizing
Nondepolarizing
Anesthetic induction drugs
Succinylcholine 1-2 mg/kg
Cisatracurium 0.2 mg/kg
Rocuronium O.&l mg/kg
Vecuronium 0.1 mg/kg
Pressors
Catecholamines
Dopamine 3-5 kg/kg/min
higher incidence of cardiovascular instability in infants, compared with
older patients. This effect can be attributed to several factors, including
faster equilibration, rapid myocardial and brain uptake, increased anes-
thetic requirements, and sensitivity of the immature myocardium to
volatile agents (especially halothane). These factors, the decrease in
myocardial contractile mass, and less magnitude and velocity of fiber
shortening produce the adverse cardiovascular effects. Volatile agents
also depress the baroreceptor reflexes in a concentration-dependent man-
ner in the younger compared with the older patient.76,
77, Io8
Before terminating anesthesia, measures to minimize postoperative
pain should be instituted. These include rectal acetaminophen, (3040
mg/kg),15 caudal analgesia, and infiltration of the surgical incision with
a local anesthetic (e.g., 0.25% bupivacaine) before abdominal closure.
After the patient is awake and ventilating adequately, the endotracheal
tube can be removed.
Postoperatively, the child may exhibit signs of drowsiness or leth-
argy. Respiratory depression (e.g., apnea) also may be pre~ent.~
If total
body potassium is decreased (which may occur despite a normal serum
potassium), there may be altered electrical forces across cell membranes.
This causes an unpredictable response (i.e., potentiation) to nondepolar-
izing neuromuscular blocking agents and weakening of the muscles,
including the muscles of respiration, creating a need for postoperative
mechanical ventilation. If hypokalemia is severe, rhabdomyolysis and
impairment of smooth muscle function can occur. Bladder dysfunction,
ileus formation from lack of peristalsis, poor peripheral vascular tone
with orthostatic hypotension, and a poor pressor response to catechola-
mines are possible. Cardiac dysrhythmias also may be present because

268 LIU&PANG
hypokalemia enhances the intrinsic automaticity, sustains dysrhythmias,
and alters cond~ctivity.~~
CONGENITAL DIAPHRAGMATIC HERNIA
Approximately 1in 2500 babies is born with a congenital diaphrag-
matic hernia.85
The disorder is characterizedby failure of the pleural and
peritoneal canal to close at approximately the eighth week of gestation,
resulting in herniation of the abdominal viscera into the thoracic cavity
and pulmonary hypoplasia from compression by the viscera on the
developing lungs. Hernias through the posterolateral portions of the
diaphragm (Foramen of Bochdalek) account for approximately 80% of
diaphragmatic hernias; herniation on the left side is five times more
common than on the right side. These Bochdalek hernias are the largest
diaphragmatic hernias, and pulmonary hypoplasia is more extensive in
these patients. Hernias through the anterior part of the diaphragm
(Foramenof Morgandi)account for only 2% of all diaphragmatic hernias;
esophageal hiatus hernias account for 18%.
The prevalence of posterolateralhernias may be related to the devel-
opment of the diaphragm. During the second month of gestation, a
pleuroperitoneal membrane is formed. This membrane eventually di-
vides the common pleuroperitoneal cavity into two compartments, the
pleural cavity and the peritoneal cavity. The last areas of the membrane
to develop are the posterolateral portions, with the right side closing
before the left. At approximately the ninth gestational week, the gut,
which was in the yoke sac, migrates to the peritoneal cavity. If this
migration occurs before the pleuroperitoneal membrane closes off the
pleural cavity, the stomach, spleen, liver, and bowel can migrate into the
pleural cavity and compress the developing lungs. Compression of the
lungs affects their growth. Although the lung on the side of the hernia
is more severely affected, the lung on the contralateral side is also
hypoplastic. Severe pulmonary hypoplasia with arrest of bronchial and
bronchiolar development occurs if a large volume of vicera is present in
the pleural cavity before the 12th week of gestation.66Compression of
the lungs, especially when airways are dividing and pulmonary arteries
are forming, causes a decrease in lung volume, number of bronchi and
alveoli, and cross-sectional area of pulmonary arterial branches.66The
pulmonary artery is smaller, arterial branching is diminished, and the
arteries are more muscular. Although significant lung growth at the
alveolar level and remodeling of the vasculature (i.e., in larger, less
muscular arteries) occurs after birth, the time this takes exceeds the
current limitation of supportive measures, such as extracorporeal mem-
brane oxygenation.1°Severe impairment of normal pulmonary develop-
ment often results in a critically ill neonate. Persistent pulmonary hyper-
tension with increased vascula; resistance frequently occurs; in many
cases, these conditions lead to hypoxemia, acidosis, and death.39,
45, 66
The results of recent animal models have challenged current think-

ing regarding the cause of congenital diaphragmatic hernia. When the
drug nitrofen (2,2dichloro-phenyl-p-nitrophenylether)was used, the left
lung failed to develop, leading to a left diaphragmatic hernia. Congenital
diaphragmatic hernia may be secondary to the failure of normal lung
development rather than being the cause of
With the increased use of prenatal ultrasonography, prenatal diagno-
sis of congenital diaphragmatic hernia has become more common.', 47, 56
Neonates with congenital diaphragmatic hernias usually have scaphoid
abdomens and barrel chests. Children who are in respiratory failure
within the first 6 hours of life have the highest mortality, whereas those
diagnosed later generally have a good prognosis.s6,1
1
1 Approximately
one third of the babies who are symptomatic in the first 6 hours of life
have an associated anomaly, with cardiac lesions pred~minating.~~,
40
The babies with associated anomalies, especially those with cardiac
anomalies, have significantly lower APGAR scores. Their best postductal
Poz before extracorporeal membrane oxygenation or surgery is lower
than that in those children with hernia with no other anomalies.40The
literature indicates that a sustained alveolar-to-arterial oxygen tension
gradient of greater than 600 mm Hg and an oxygenation index over 40
for 8 to 12 hours still are associated with mortality.99Some clinicians
suggest that the persistence of a postductal Pao2below 100mm Hg and
of a Paco2 above 40 mm Hg despite optimal conventional therapy
indicates poor prognosis.
Data extrapolated from Boix-Ochoals and Bohn16,l7 indicate that
some babies who have a persistently low postductal Pao2should have
their preductal Paozmeasured because it is a directly measured physio-
logic value. An infant with congenital diaphragmatic hernia with a
persistent Paoz below or who cannot generate a preductal Pao2of
at least 100mm Hg at some point has pulmonary hypoplasia to a degree
incompatible with life despite extracorporeal life support (ECM0).99
Before Ladd and Gross's series in 1940 of long-term survivors,
operative repair of neonates with congenital diaphragmatic hernia was
considered impossible.68For years later, the survival rate of these pa-
tients remained at approximately 50%.50,
75, 9
1 Despite improvements in
the clinical management of neonates, diagnostic tools, and surgical tech-
niques, the multicenter Congenital Diaphragmatic Hernia Study Group
reported, in 1998, a survival rate of only 63Y0.*~
In the past, babies with congenital diaphragmatic hernia were
rushed to the operating room immediately after birth, without taking
time for stabilization. The change in practice to delay surgery until the
respiratory problems are stabilized reflects the present belief that surgery
cannot correct respiratory insufficiency. The primary problem in these
babies is not respiratory failure from lung compression by the herniated
viscera but respiratory failure from severe pulmonary hypoplasia and
pulmonary hypertension.*Currently,neonates with congenital diaphrag-
matic hernia are managed medically until their respiratory and cardio-
*References6, 13, 17, 19, 28, 54, 59, 72, 93, and 107.

270 LIU&PANG
vascular statuses are ~tabilized.4~.
51, 88, 96, lo4,lo9 Only after they are
optimized are they scheduled for semi-electivesurgery.
Because pulmonary hypoplasia and associated anomalies are the
leading causes of death in neonates with congenital diaphragmatic her-
nia, treatments now are directed at correcting problems caused by these
conditions, with concurrent improvement in outcome. Lung rupture
from barotrauma easily can occur at any time during the perioperative
period. Ventilatory strategies that minimize airway pressure and reduce
barotrauma to the severely hypoplastic lungs improve survival. Gentle
ventilation that allows arterial CO, to be slightly higher than normal
(i.e.,permissivehypercapnia)and marginal postductal oxygen saturation
are associated with a higher survival rate than conventional ventilation
with or without extracorporealmembrane
High-frequency ventilation has been advocated to reduce baro-
trauma and to produce alkalosis to improve pulmonary blood flow. This
artificial ventilation method can be used before, during, and after surgi-
cal repair.20,
35, 74, 96 The major disadvantage of using high-frequency
ventilation during anesthesiais that end-tidal CO, is difficult to monitor.
Frequent monitoring of end-tidal CO, and O2 saturation and arterial
blood gas determinations are essential to ensure effectivealveolar venti-
lation and oxygenation. If CO, tension is allowed to rise too high,
pulmonary vascular resistance,which is generally high, increases further.
A pneumothorax should be consideredif sudden unexplained hypo-
tension or desaturation occurs. A pneumothorax that is not treated
promptly can lead to significant hypotension and hypoxia. A pneumo-
thorax on the contralateral side can affect ventilation more significantly
than one on the same side as the hernia, because the lung on the
contralateral side is generally the better developed.'15 In patients with
chest tubes, an increase in lung compliance and abdominal distension
may be caused by a pneumoperitoneum. If the air leak into the chest is
large and the chest tube cannot evacuate the gas from the thorax ade-
quately,gas could flow through the diaphragmatic defect into the perito-
neal cavity. Significant abdominal distension can result, causing dimin-
ished lung expansion and hypoxia. In this case, decompressing the
abdomen with a large-bore needle allows the gas to escape so the lungs
can expand.
New modes of therapy have led to some improvement in the sur-
vival rate of neonates with congenital diaphragmatic hernia. Extracor-
poreal membrane oxygenation is one treatment, that has improved
the survival rate of infants who originally had a predicted mortal-
ity of 80%.'01 Inhaled nitric oxide, a selective pulmonary vasodilator,
does not improve survival of neonates with congenital diaphragmatic
hernia.lo1The efficacy of surfactant replacement therapy in these pa-
tients is currently unclear.96 Further discussion of these treatment
modalities is beyond the scope of this article, but can be found in the
Surgical repair of congenital diaphragmatic hernia in neonates can
be performed through an abdominal incision, but some surgeons prefer
4
1
,
60, 74
literature.21,23,43,69-71,82. 83

a thoracoabdominal approach. Small defects are closed by suturing
existing diaphragmatic tissue together. With large defects, an artificial
diaphragm is constructed. If the artificial diaphragm material is not
permeable to gases, abdominal distension from a pneumothorax is mini-
mized and the need for a peritoneal drain is reduced.37Occasionally,
abdominal closure may not be possible without compromising ventila-
tion. In these cases, an abdominal silo is created to house the viscera
until the abdominal wall stretches enough to allow abdominal closure
at a later stage.
The anesthetic management of neonates with congenital diaphrag-
matic hernia involves a thorough assessment of the child. Management
of these patients depends on their physiologic condition and anatomic
pathology. A review of laboratory, radiographic, and physical findings
and optimization of any anomalies should be completed before anesthe-
sia is administered. Listening to breath sounds beforehand and knowing
whether the hernia is on the left or right side are important. For example,
a decrease in breath sounds over the right chest in a child with a right-
sided hernia may not be caused by the intubation of the left main stem
bronchus.
In the past, babies with congenital diaphragmatic hernia were oper-
ated on immediately after birth. Surgery now is delayed until the pa-
tients are medically stabilized.8,
l l ~
112Consequently, many babies already
are intubated, and have indwelling intravenous and arterial lines in
place by the time they arrive at the operating room. Children who are
not intubated and mechanically ventilated before arriving at the op-
erating room generally fare best if they are nursed in a semirecumbent
position with their affected side down. An orogastric or nasogastric tube
often is inserted to decrease and prevent distension of the stomach and
intestines.Neonates who are not intubated before arrival at the operating
room generally are intubated awake or after a rapid-sequence induction
(see Table 1).An anticholinergic drug, such as atropine, 0.02 mg/kg
administered intravenously, is often the only drug used for premedica-
tion. This drug is administered immediately before the induction of
anesthesia to prevent bradycardia and a drop in cardiac output during
induction. If the baby is stable and an awake intubation is planned,
analgesics may be administered to decrease the stress of airway instru-
mentation. Although an inhalation induction of anesthesia in a spontane-
ously breathing child is possible, assisted or controlled ventilation gener-
ally is required to ventilate the child adequately before a satisfactory
level of anesthesia is achieved for laryngoscopy and intubation. If the
stomach is i
h the chest, mask ventilation with high inflation pressures
should be avoided to prevent gastric distension. High inflation pressures
also should be avoided because many of these children develop lower

272 LIU&PANG
esophageal sphincter incompetence and are at risk for reflux and aspira-
tion of gastric content.80
The choice of drugs for anesthesia should be determined by the
patient's general condition. In infants and children with small veins,
pentothal is preferred to propofol because of the high incidence of pain
when propofol is administered into small veins. High doses of narcotics
(e.g., fentanyl, 15-25 p,g/kg) can be used if hemodynamically tolerated.
Nitrous oxide should be avoided because it defuses into the bowel
lumen, causing further bowel expansion, and may compromise lung
expansion, especially if the intestines are in the chest. The risk and
benefitsof the various inhalation anestheticsshould be consideredbefore
deciding on their use. Compared with other volatile anesthetics, halo-
thane produces a greater decrease in inotropy and chronotropy of the
heart at equipotent doses.
Vigilant monitoring is mandatory in neonates with congenital dia-
phragmatic hernias. Monitoring blood pressure, ECG, pulse oximetry,
capnography, temperature, and heart rate is essential during anesthesia
for all babies with congenital diaphragmatic hernias. Following preduc-
tal and postductal oxygen saturation with pulse oximeter and probes on
the right upper extremity and on a lower extremity allows early detec-
tion of right-to-left shunting. Although invasive monitoring is not neces-
sary in all patients, it may be indicated in those who are in respiratory
distress. Cannulation of the right radial artery will allow measurement
of preductal blood gases. In addition to providing continuous blood
pressure readings, preductal blood gases can be measured. Conditions
that can cause pulmonary vasoconstriction, such as hypoxia, acidosis,
and hypothermia, should be avoided. If possible, oxygen saturation
should be kept above 80 mm Hg, and CO, should be kept within normal
or only slightly above the normal range (i.e., permissive hypercapnia).
Metabolic acidosis should be treated immediately, and any significant
blood loss should be replaced.
Familiarity with the different therapeutic modalities that may be
needed during anesthesia is essential to provide optimal anesthetic care.
Understanding the principles of high-frequency ventilation and ECMO
is essential. Occasionally, the hernia is repaired while a child is still on
ECMO, despite hemodynamic and pulmonary in~tability.~~
For these
patients, an opioid and a nondepolarizing muscle relaxant may cause
less hemodynamic instability than an inhalation anesthetic. A volatile
anesthetic agent, such as isoflurane, can be used for these patients by
administering it through the EMCO circuit (Fig. l).7
For children on
ECMO, drugs may be administered directly to them, or into the ECMO
circuit.Because patients on ECMO are heparinized, intraoperative bleed-
ing can be problematic because hemostasis is abnormal.1o6
ESOPHAGEAL ATRESIA AND
TRACHEOESOPHAGEAL FISTULA
Approximately 1 in 4000 babies are born with esophageal atresia,
and 90% of them have an associated tracheoesophageal fistula (i.e.,

h)
v
w
Figure
1.
lsoflurane
during
extracorporeal
membrane
oxygenation.

274 LIU&PANG
cardiac, gastrointestinal, genitourinary, musculoskeletal, or craniofacial
anomalies) are present in 30% to 50% of newborns with esophageal
atresia and tracheoesophageal fistulas.87,
89, 92, Io2 One form of the associ-
ated anomalies is the VATER (i.e., vertebral and vascular anomalies,
imperforate unus, tracheoesophageal fistula, radial aplasia, and renal
abnormalities) or VACTERL (i.e., vertebral anomalies, imperforate unus,
cardiac anomalies, tracheoesophagealfistula, renal abnormalities, radial
limb aplasia) association.
The diagnosis of esophageal atresia is usually made when a tube
cannot be passed into the newborn’s stomach after delivery, after the
first feeding when coughing and choking occurs, or after recurrent
pneumonia associated with feedings. Prenatally, the diagnosis should be
considered if polyhydramnios is present. After birth, the diagnosis is
confirmed by the inability to pass an orogastric tube into the stomach.
Location of the atretic segment is confirmed by a radiograph showing
the tip of a radiopaque catheter that is passed into the esophagus until
it stops. Air in the stomach and intestines usually is seen in abdominal
radiographs of neonates with tracheoesophageal fistula. The absence of
air usually indicates esophageal atresia without a fistula. Occasionally,
the diagnosis of a tracheoesophageal fistula is not made until later in
the child’s life.
Although Thomas Gibson first described esophageal atresia in 1697,
no baby survived until Dr. Logan Levin performed the first successful
staged repair in 1939.79
Four years later, the first primary repair was
performed. Because of subsequent advances in neonatal and periopera-
tive care, nearly all babies survive. The exceptions are those who are
very premature (< 1500 g) and those who have severe cardiac or chro-
The most common form of esophageal atresia and tracheoesopha-
geal fistula (80%-90% of patients) is an upper esophagus ending in a
blind pouch and the distal esophagus forming a tracheoesophageal
fistula.38,
67 In most cases, anastomosis of the two ends of the esophagus
is possible. The challenge occurs when a long segment of atresia is
present. A staged repair with traction, myotomies, or multiple esopha-
gotomies on the segments is possible in some cases.34, In others, a
portion of the colon or jejunum or a tube made from the stomach was
interposed.2,
3, 32, Gastric interposition is another procedure.s4Although
survival is improved with these interposition procedures, the mortality
rate in these patients is high.
Morbidity and mortality in neonates with esophageal atresia and
tracheoesophageal fistula generally are related to pulmonary complica-
t i o n ~ . ~ ~ ,
26, 33, 90, 97 The goal of preoperative management should be to
minimize these complications. Once the disorder is diagnosed, attempts
should be made to prevent aspiration pneumonitis. Oral feedings should
not be given, and the baby should be nursed in the semirecumbent
position to minimize the possibility of aspiration of gastric and nasopha-
ryngeal contents. A tube should be passed into the esophagus and
suctioned frequently to minimize the accumulation of nasopharyngeal
mosomal anomalies.4,11, 12. 24.26. 92.98

secretions in the blind pouch. For an extremely premature or critically
ill infant, a staged approach should be considered. After the diagnosis
is made, a gastrostomy is placed to prevent excess gastric distension
from impairing diaphragmatic excursion, and definitive repair is post-
poned until the baby is more stable.4,
52
Atropine generally is the only drug used for premedication of
infants with esophageal atresia and tracheoesophageal fistula. It is given
to decrease the incidence of bradycardia from vagal stimulation during
intubation and to maintain cardiac output during the induction of anes-
thesia. Monitors should include devices to measure blood pressure, ECG,
heart rate, temperature, pulse oximetry, and capnography. A precordial
stethoscope placed on the left chest under the axilla allows monitoring
of heart and breath sounds.
If a difficult intubation is anticipated, if gastric distension is present,
or if the baby is vomiting, endotracheal intubation should be performed
while the child is still awake. Otherwise, intubation usually is performed
after a rapid-sequence induction of anesthesia (see Table 1).If an inhala-
tion induction of anesthesia is chosen before the endotracheal tube is
placed distension of the stomach will be minimized if the child is
allowed to breathe spontaneously. To prevent gas from transiting
through the fistula and distending the stomach when ventilation is
assisted or controlled before the endotracheal tube is inserted airway
pressure should be minimized. Because a tracheoesophageal fistula gen-
erally is located on the posterior aspect of the trachea and just proximal
to the carina, placing the endotracheal tube into a bronchus and with-
drawing it until breath sounds are equal may prevent ventilation of the
fistula.94
Rotating the endotracheal tube during intubation so the bevel
faces posteriorly may prevent intubation of the fistula. After the endotra-
cheal tube is placed, positive-pressure ventilation should be instituted,
and the size of the stomach should be assessed before administering a
muscle relaxant. If gastric distension becomes a problem, it may be
necessaryto allow the child to breathe spontaneously until a gastrostomy
tube is placed or until the surgeon can obstruct the fistula manually.
After a gastrostomy, ventilating the patient adequately may be difficult
if the volume of gas flowing through the fistula is high. In these cases,
a balloon Fogarty catheter placed in the fistula through a bronchoscope
or insertion of this catheter under fluoroscopic guidance through the
gastrostomy into the fistula will occlude the fistula and allow for easier
ventilation of the 58
In most cases, the esophagus is anastomosed primarily, and the
fistula is ligated through a right thoracotomy. During surgery, airway
obstruction can occur if the trachea is compressed, secretions become
inspisated or a blood clot forms in the airway. The surgeon must be

276 LIU&PANG
informed of the problem so that he or she can correct the situation or
help change the endotracheal tube.
At the end of the surgical procedure, most infants are extubated if
they are awake and are not at risk for postoperative respiratory prob-
lems. Those who are at risk for respiratory problems (e.g., postanesthetic
apnea3',73, ]lo) should remain intubated until they demonstrate that they
can sustain adequate ventilation postoperatively. Premature extubation
also may be dangerous in these babies because the recently closed fistula
may be ruptured by the endotracheal tube if it needs to be reinserted.
Neonates with a tracheoesophageal fistula frequently have a reduc-
tion in tracheal cartilage (i.e., tra~heomalacia).3~,
48, Io5 In babies with tra-
cheomalacia, ventilation may be adequate immediately after extubation.
In some patients, ventilatory problems may not be apparent until later in
the postoperative period. Dynamic collapse of the trachea during inspira-
tion, map be magnified as the child's respiratory efforts increase. Tra-
cheopexy may be necessary, or a tracheotomy may be required.22,
30, 65, m
OMPHALOCELE AND GASTROSCHISIS
Omphalocele and gastroschisis are abdominal wall defects that can
be diagnosedby fetal ultrasound in the first trime~ter.~,~~
Salient features
of these conditions are shown in Table 2. Omphalocele occurs in 1 in
6000 births, and is caused by a failure of the gut to migrate from
the yolk sac to the abdomen during gestation.36,
62 Neonates with an
omphalocele have a high incidence of other anomalies, and frequently
are premature at birth. Associated anomaliesinclude-cardiac,gastrointes-
tinal (e.g., malrotation, Meckel's diverticulum, intestinal atresia), geni-
tourinary (e.g., extrophy of the bladder), metabolic (e.g., Beckwith-
Wiedemann syndrome: macroglossia, hypoglycemia, organomegaly,
gigantism), and chromosomal abnormalities. Cardiac and thoracic de-
fects are more frequent in neonates with epigastric omphaloceles,
whereas cloaca1anomalies and extrophy of the bladder more frequently
are associated with hypogastric omphaloceles.
Gastroschisis results from occlusion of the omphalomesenteric ar-
tery during gestation, and involves herniation of the viscera through the
lateral abdominal wall defect.53
Gastroschisis occurs in 1in 15,000births,
and is associated with a low incidence of other anomalies. Intestinal
Table 2. COMPARISON OF OMPHALOCELE WITH GASTROSCHISIS
Omphalocele Gastroschisis
Incidence 1:6000 1:15,000
Gestation Premature Term
Peritoneal covering Present Absent
Incidence of other anomalies High Low

atresia, however, is higher in neonates with gastroschisis, compared with
omphaloceles.
Preoperative management of neonates with gastroschisis and om-
phalocele is similar, and is directed at preventing infection and minimiz-
ing fluid and heat loss. Covering the exposed viscera or membranous
sac with sterile saline-soaked dressings and wrapping these dressings
with plastic wrap decreases evaporative fluid and heat loss.
Although surgical correction of an omphalocele or gastroschisis is
urgent, surgery usually is delayed until the patient is properly prepared
for anesthesia. Preoperative preparation involves a thorough evaluation
because many of these babies have associated anomalies. Preoperative
management should be individualized. Fluid and electrolyte abnormali-
ties should be corrected preoperatively.
Anesthetic management involves volume resuscitation and the pre-
vention of hypothermia. Even when the abdomen is relaxed by muscle
relaxants and the viscera are not distended, primary closure may not
always be possible without markedly increasing intra-abdominal pres-
sure. Stretchingthe abdominal wall and pushing bowel contents toward
the stomach and rectum may help decrease intra-abdominal pressure.
Ventilatory compromise and decreased organ perfusion are the major
problems that result when intra-abdominal pressure is increased mark-
edly. Other problems include bowel edema, anuria, and hypotension. A
pulse oximeter probe on the lower extremity will detect a decrease in
oxygen saturation that could be caused by congestion of the lower
extremities due to obstruction of venous return. Measurement of intra-
gastric pressure, central venous pressure, or cardiac index can aid in
determining whether primary closure is appropriate.ll3r114 If primary
closure is not reasonable, a staged repair can be done. This involves
leaving the bowel extraperitoneally encased in a synthetic mesh (silon
chimney) or plastic pouch, that is reduced in stages over several days
until the abdominal cavity can accommodate the viscera without com-
promising organ perfusion or ventilation. Most neonates do not require
anesthesia for the daily reduction in size of the chimney, but they do
need anesthesia for the final stage of repair, which involves removing the
synthetic material and closing the abdomen. Postoperative management
depends on the type of repair and whether or not the child has associ-
ated anomalies. Fluid resuscitation should continue postoperatively be-
cause fluid loss through the viscera continues, especially in a staged
repair, where the viscera are left extraperitoneally.
NECROTIZING ENTEROCOLITIS
Necrotizing enterocolitis is a condition that results from hypoper-
fusion of the gut. It occurs predominantly in premature infants with a

278 LIU&I’ANG
gestational age of less than 32 weeks and with a weight of less than
1500 g. The pathogenesis of this condition is elusive. Immaturity of the
gastrointestinal mucosal barrier and the immune system and premature
oral feeding are conditions frequently implicated in causing this condi-
95 Early signs of necrotizing enterocolitis include feeding problems,
lethargy, hyperglycemia, bloody stools, and fever. The abdomen may be
distended and tender. Radiographic studies that may initially suggest
an ileus with edematous bowel show free air in the abdomen if intestinal
perforation occurs.
Necrotizing enterocolitis frequently is treated medically if the diag-
nosis is made early. Enteral feedings are discontinued, the abdomen is
decompressed with a nasogastric or orogastric tube that is attached to
intermittentlow-pressuresuction, and blood volume is replenished with
intravenous fluids. Broad-spectrum antibioticsusually are administered,
althoughno specificorganismhas been implicated in causing necrotizing
enterocolitis. Dopamine is given to improve renal and intestinal perfu-
sion and cardiac output.
Indications for surgery are usually refractory sepsis or intestinal
perforation. As a result, babies with necrotizing enterocolitis are usually
severely ill when they are scheduled for surgery. They may be hypoten-
sive, anemic, thrombocytopenic, and coagulopathic, and have prerenal
azotemia and a metabolic acidosis.
Patients with necrotizing enterocolitis frequently arrive in the op-
erating room with an endotracheal tube in place. If they are not intu-
bated, a rapid-sequence or awake intubation is performed after the
standard monitors are placed. Drugs used for anesthesia depend on the
patient’s condition.A narcotic (e.g., fentanyl, 1-5 kg/kg) and a relaxant
(e.g., cisatracurium, 0.1-0.2 mg/kg) frequently are the only drugs used
for anesthesia,because potent inhalation anestheticsmay decreaseblood
pressure below acceptable levels. Nitrous oxide generally is avoided to
prevent further intestinal distension. Other drugs may be required to
treat cardiovascular instability or electrolyte abnormalities. Dopamine
may be indicated if renal perfusion and cardiac output are low; bicarbo-
nate may be indicated if the base deficit is significant.
Volume resuscitation is crucial when managing neonates with necro-
tizing enterocolitis. Third-space fluid loss is high, and multiple blood
volumes of lactated Ringer’s solution or albumin may be needed to
replenish intravascularvolume. Blood, fresh frozen plasma, and platelets
also may be needed to improve oxygen-carrying capacity or to treat
factor deficiencies.
After surgery, babies are transported with their endotracheal tube
in place to the ICU, and are placed on a ventilator until extubation
criteria are met. Fluid and drug resuscitation may need to be continued
until vital signs are stable.

INTESTINAL OBSTRUCTION
Intestinal obstruction is a surgical emergency in the newborn that
requires swift intervention. Delays in diagnosis and treatment may lead
to intestinal perforation, bowel necrosis, and septicemia.
DUODENAL OBSTRUCTION
The incidence of duodenal obstruction in the neonate is 1in 10,000
to 40,000 births. It frequently is associated with other congenital anoma-
lies, such as Down syndrome, cystic fibrosis, renal anomalies, intestinal
malrotation, and midline defects, such as esophageal atresia and imper-
forate anus.63,78
Obstruction of the duodenum can be due to an intralumi-
nal diaphragm or membranous web. Infants with obstructions may or
may not pass meconium in the first day of life, depending on whether
the obstruction is partial or complete. The infant presents with vomiting
of bile or bile-stained gastric contents and minimal abdominal disten-
sion.
JEJUNOILEAL ATRESIA
Jejunoileal atresia causes complete intestinal obstruction. The inci-
dence is 1 in 5000 live births. This lesion, in contrast to duodenal
obstruction, rarely is associated with other congenital an~malies.~~
Fifty
percent of infants with this lesion are premature. Jejunoileal atresia is
believed to be secondary to an intrauterine vascular accident.
MECONIUM ILEUS
Meconium ileus is an intraluminal obstruction of the distal small
bowel caused by abnormal meconium. This entity is found exclusively
in patients with cystic fibrosis.Approximately 10% to 20% of the patients
with cystic fibrosis are born with meconium ileus. In some patients, the
obstruction is managed medically; in others, surgical intervention is
necessary. During surgery the obstruction is located, and the meconium
is massaged into the colon. Occasionally, the meconium may need to be
softened by agents such as acetylcysteine before it can be massaged into
the colon. If the meconium cannot be pushed into the colon, an enteros-
tomy is performed, and the meconium obstruction is evacuated from
the bowel.
MALROTATION AND VOLVULUS
The true incidence of malrotation and volvulus of the intestines is
not known because many patients are undiagnosed, and is believed to

280 LIU&PANG
occur because of abnormalities or arrests in the rotation of the bowel.
Areas of ischemia and atresia develop, resulting in bowel strangulation,
bloody stools, peritonitis, and hypovolemic shock. Malrotation fre-
quently is associated with major cardiac, esophageal, urinary, and anal
anomalies,congenital diaphragmatic hernia, and abdominal wall defects.
Malrotation is two times more common in male infants, and frequently
presents in the neonatal period. This problem also can present in adult-
hood.
IMPERFORATE ANUS
The incidence of anal atresia is 1in 5000 live births. The presence
of this entity is usually obvious at birth, and can range from a mild
stknosis to a complex syndrome with other associated congenitalanoma-
lies. In general, the higher the location of the anomaly, the greater the
incidence of associated anomalies. In male infants, an operative proce-
dure to relieve the obstruction may be required soon after birth. In
female infants, the usual presence of a rectovaginalfistula in association
with the imperforateanus prevents the development of distension; oper-
ative intervention may be postponed for several weeks.
Anesthetic considerations for patients with intestinal obstruction
include airway management, fluid and electrolyte replacement, treat-
ment of sepsis, and postoperative pain management.
Complete intestinal obstruction increases the risk for aspiration of
gastric or intestinal contents. Diaphragmatic excursion is impeded by
abdominal distension and may cause respiratory distress. To prevent
further abdominal distension in a patient with a suspected difficult
airway, the patient should be intubated while awake; a rapid-sequence
induction with cricoid pressure might be considered in a patient with
no apparent airway problems.
Patients with intestinal obstructionmay be volume depleted second-
ary to dyes used in diagnostic tests and to peritonitis, ileus, bowel
manipulation, and sepsis. Volume resuscitation with at least 10 mL/kg
per hour of normal saline or colloid may need to be given before
anesthesia can be induced. The quality of heart tones, urine output,
blood pressure, skin color, and turgor will aid in fluid management. In
some cases invasive monitoring with arterial and central venous pres-
sures are necessary.
The choice of anesthetic agents depends on the patient’s condition.
Nitrous oxide should be avoided to prevent further distension of the
bowel. Regardless of the anesthetic drugs used, an adequate circulating
blood volume must be maintained to ensure perfusion of vital organs.

SUMMARY
Improvements in the diagnosis and treatment of congenital disor-
ders have resulted in a change in surgical practice. Many conditions that
formerly required corrective surgery immediately after birth are no
longer surgical emergencies.Most babies with congenital anomalies that
can be corrected by surgery are now stabilized and optimized before the
procedure. This article focused on the more common conditions that
require semi-elective or urgent surgery in the neonatal period. Salient
features of each of these disorders were described. Factors unique to
each of these conditions that can affect the anesthetic course of these
children were discussed. Methods and techniques that may aid in the
anesthetic management of these children were delineated.
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Address reprint requests to
Letty M. P. Liu, MD
Department of Anesthesiology
University of Medicine and
Dentistry of New Jersey-
New Jersey Medical School
185South Orange Avenue, MSB E-538
Newark, NJ 07103

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