Chapter 86

1464 PART 5 ■ Anesthetic, Surgical, and Interventional Procedures: Considerations
inhaled nitric oxide 199 or extra corporeal membrane oxygenation
(ECMO). 200
Improved outcome has been reported following preoperative
stabilization of the patient and treatment of pulmonary hyperten -
sion. 201 An interesting phenomenon with the pulmonary hyper -
tension experienced by CDH patients (and some other neonatal
disorders as well, e.g., meconium aspiration syndrome and
idiopathic persistent pulmonary hypertension of the newborn) is
that the tendency to react with severe vasospasm appears to be
time limited and once the patient is through this period pulmo -
nary hypertension will not reappear for the rest of the patient’s life.
However, some patients with pronounced pulmonary hypoplasia
will never come through this period and will develop chronic
pulmonary hypertension as a result. Before this period has passed
the patient can respond with vasospasm to almost any kind of
stressful stimulus and it is readily apparent that emergency surgery
with the release of cytokines and other neuroendocrine stress
factors is not helpful. If on the other hand the patient is stabilized
and has been so for “a hundred hours” without signs of deterio -
ration or episodes of pulmonary vasospasm surgery can be
performed without a stormy intra- and postoperative period. 201
Most patients will eventually fulfill these modern criteria but a
small subsegment will not and will have to be operated on despite
the lack of full stabilization. Such patients are often on advanced
adjuvant treatments (e.g., high-frequency oscillatory ventilation,
inhaled nitric oxide or ECMO), which put very specific demands
on the surgical and anesthetic teams.
One key issue in the treatment of CDH patients is to try to
predict which patients have enough lung tissue to survive with
maximum medical treatment and which patients have pulmonary
hypoplasia of such severity that extrauterine life is not possible.
No specific tests or observations can yet define this with
satisfactory sensitivity and specificity but some indications can be
achieved from the immediate postpartum situation and also
examination of the patient’s red blood cells. If the baby presents
with immediate symptoms and has never shown an acceptable
blood-gas analysis as an indicator of sufficient amount of lung
tissue to sustain gas exchange (lack of “honeymoon period”), this
is a strong indicator of poor prognosis. In severe cases of intrau -
terine herniation, cardiac output will be compromised, leading to
a compensatory erythropoesis. This will cause the occurrence of
significant amounts of immature nucleated erythrocytes at birth.
If the CDH patient displays ≥2.0 10 9 /L of nucleated red blood
cells in the blood stream, this is an significant indicator of a poor
prognosis, and if ≥0.5 10 9 /L ECMO is frequently needed. 202 The
main steps of anesthetic management are listed in Table 86–20.
Omphalocele
The incidence of the malformation is 1/5000. This abdominal wall
defect can range from minute to very significant with herniation of
parts of the intestine, spleen and the liver. Contrary to gas troschisis,
the herniated viscera will be covered by a hernia sac or mem -
brane. 203 If this membrane has ruptured, the situation might look
very similar to gastroschisis, but a closer inspection of the abdo -
minal wall will disclose the true nature of the condition. Although
they present similar appearances, omphalocele is quite different
from gastroschisis from an embryologic standpoint. Omphalocele
is also much more often associated with other malformations
(mainly cardiac) than gastroschisis, which only represents a
midline fusion failure. Small omphaloceles can be closed without
any problems, whereas larger herniation can cause significant
problems. This is mainly due to the increase in intra-abdominal
pressure resulting from forcing the herniated viscera into an abdo -
minal cavity which is too small. This increase in intra-abdominal
pressure will cause a cephalad shift of the diaphragm, interfering
with ventilation, and will also affect organ blood flow. 204,205 In this
situation, both renal and hepatic function will be impaired. Due to
a reduction in renal perfusion transient oliguria or even anuria tend
to occur and reductions in liver blood flow will reduce the capacity
for hepatic drug clearance. In this situation the terminal half-life
of both renal and hepatic dependent drugs can be significantly
prolonged (e.g., fentanyl, local anesthetics). Forceful closure of the
abdominal defect will also cause significant tension of the skin and
the abdominal wall and necrosis with secondary infection are
frequent complications. To avoid the above the surgeons on
occasion will opt to create a “tent” by artificial material and suspend
this contraption in order to allow gravity to reduce the herniated
viscera gradually by distending the abdominal cavity over a period
of 4 to 7 days. During this period, the tent will be reduced slowly
in the same manner as rolling the end of a tube of tooth paste. The
omphalocele can then usually be closed without any major pro -
blems. Drawbacks with this approach are the risk for infection and
the risk of suture disruption at the wound edges.
Although not an absolute emergency, surgery should be per -
formed as soon as convenient. Proper preoperative stabilization
and investigation must take precedence, but surgery should not
be postponed until the next working day due to the risk of
infection and fluid balance problems. To avoid fluid loss and
evaporative heat loss, the omphalocele should be covered by wet
sponges and a plastic wrap during the preoperative period. Despite
this, close attention has to be paid to preserving body temperature
and an optimal volume and electrolyte status. The main steps of
anesthetic management are summarized in Table 86–21.
Gastroschisis
The incidence of gastroschisis is 1/10,000. In this condition, the
abdominal wall defect is located in the midline between the
umbilicus and the xiphoid process. Most parts of the gut will
usually be herniated and not covered by any membrane. The gut
does not appear entirely normal but will instead be edematous and
partly covered by fibrin. This malformation is rarely associated
with any other congenital birth defects but a routine search for
mainly cardiac malformations should nevertheless be undertaken.
The diagnosis of this condition is obvious from inspecting the
patient. An intact umbilicus, the location of the herniation and
the lack of any covering membrane/hernia sac distinguishes this
lesion from omphalocele. Clinical handling of this condition will
not in any major way differ from the handling of patients with
more pronounced forms of omphalocele. Thus, for guidelines
please see Table 86–21.
Intestinal Obstruction
The gastrointestinal tract can be affected by mechanical obstruc -
tion at any location between the pylorus and the anus. The
handling of the more frequent of these disorders will be discussed.
Pyloric Stenosis
This lesion is caused by pathologic hypertrophy of the pyloric
smooth muscle. Neonates rarely display any symptoms of this
condition since the very characteristic forceful projectile type of
vomiting will usually not occur until 4 to 6 weeks of age. 206