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''Originally from Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia''

Heidi Meyer
Karmen Kemp*
Red Cross War Memorial Children’s Hospital Rondebosch
Cape Town 7700 Western Cape
Cape Town
South Africa

*Correspondence Email: karmen.kemp@uct.ac.za

== INTRODUCTION ==
Neonates present a challenge to the anaesthetist. They have unique physiology as they transition from intrauterine to extrauterine life, limited physiological reserve and immature drug handling. The goals of anaesthesia are to provide stable conditions for surgery, minimise physiological disturbance, reduce pain, and support the neonate during the postoperative period. This article will describe general considerations for anaesthesia in term and preterm neonates, and anaesthesia for some specific neonatal conditions.

== REOPERATIVE ASSESSMENT OF THE NEONATE ==
As for any child undergoing anaesthesia, it is important to take a detailed history and examination, together with relevant investigations to assess the current physiological status and the impact of any associated congenital abnormalities, which may or may not be related to the surgical condition. This helps to plan when best to proceed with the surgery, and the level of postoperative support required.

=== History ===
The history should include the gestational age, birth history, current age and weight, and significant peri-natal events such as low APGAR scores, respiratory distress requiring respiratory support, hypoglycaemic episodes, NICU admissions, evidence of sepsis or any antenatal concerns such as maternal illness. The anaesthetist should check whether intramuscular vitamin K has been given to prevent haemorrhagic disease of the newborn. The fasting status should be established if the child is receiving feeds - ideally 2 hours for clear fluids, 4 hours for breast milk, 6 hours for formula feed.

<blockquote>'''DEFINITIONS'''

•Neonate is aged up to 28 days

•Term neonate is born between 37 to 40 weeks post conception

• Preterm neonate is born at <37 weeks post conception

•Extreme preterm neonate is born <28 weeks post conception

• Low birthweight <2.5kg

• Very low birthweight <1.5kg</blockquote>

=== Examination ===
Examine the child carefully. In particular, it is important to look for signs of respiratory distress (respiratory rate, nasal flare, subcostal recession), and cardiovascular compromise (check heart rate, blood pressure, peripheral perfusion and capillary refill). Check the oxygen saturation – low oxygen saturation may be associated with respiratory disease, or in some cases with cyanotic congenital heart disease.

=== Investigations ===
Relevant investigations will be guided by the clinical findings and the underlying condition, although resources may limit investigations that can be performed. They may include the following:

===== Laboratory investigations: =====

* Full blood count and haemtocrit 
* Blood glucose  Urea and electrolytes 
* Coagulation studies 
* Liver function tests and bilirubin 
* Capillary blood gas

===== Radiological investigations: =====

* CXR, AXR 
* Echocardiogram 
* Cranial/spinal/renal ultrasound

Finally, the anaesthetic plan, including risks, should be discussed with the parent(s) or guardian(s), and consent taken for anaesthesia including regional anaesthesia and blood transfusion if indicated.

== GENERAL PRINCIPLES OF ANAESTHESIA IN NEONATES ==


It is important to prepare and check all equipment that may be 
required, prior to the start of anaesthesia (see Figure 1).


FIGURE 1

=== Monitoring ===
Standard monitoring must be applied prior to induction of anaesthesia. This includes oxygen saturation, ideally pre-ductal (right hand) and post-ductal (other limbs). A low post-ductal 
oxygen saturation may be a sign of low pulmonary blood flow, for instance due to significant pulmonary hypertension in a septic neonate (see transitional circulation below).

ECG and non-invasive blood pressure measurement should be used. The lower limit of mean arterial blood pressure can be estimated to be equivalent to the gestational age in weeks; by about 6 weeks of age, the normal mean arterial pressure is 50-60 mmHg. Basic intra-operative monitoring should ideally also include a precordial or oesophageal stethoscope and, if available, capnography must be used.

=== Airway Equipment ===
Intubation and ventilation will be required unless it is an extremely short procedure. The size of the tracheal tube will depend on the weight of the neonate; most term babies require a size 3.5 tracheal tube (see Table 1). Make sure that strapping is available. Precut the tape to fix the tracheal tube firmly in  place immediately after intubation. An appropriately sized oral airway (preterm 000 – 00 and term neonate 0) and face mask 
should be available. Dead space within the apparatus is kept  to a minimum with the appropriate sized breathing circuit and filter.

=== Warming ===
Neonates are extremely vulnerable to heat loss and  hypothermia. Hypothermia (core temperature <36°C) is  associated with postoperative apnoeas, coagulopathy and  poor wound healing, and worsens outcomes. The theatre  environment should be warmed (or air conditioning turned  down) to at least 20-23°C and the baby kept covered as much  as possible. A forced air warmer and a radiant heater should be used if available. Warmed packs should be considered if other sources of warming are not available; take care not to place warmed packs directly in contact with the skin. Fluids and blood products should be warmed. The temperature of the  baby should be measured unless the procedure is very quick.

=== Preparation of drugs ===
The first thing to be drawn up is a saline flush so that the IV 
line can be flushed immediately after a drug is given. Calculate 
the correct dose of analgesics, muscle relaxants and antibiotics 
and draw these up. Double check dose calculations – it is easy 
to make 10-fold errors in neonatal practice.

Emergency drugs should be drawn up in the appropriate doses. These include atropine (20mcg.kg-1), suxamethonium (1-2mg.kg-1) and adrenaline (10mcg.kg-1 , i.e. 0.1ml.kg-1 1:10,000 adrenaline).

=== Induction of anaesthesia ===
Inhalational induction is ideally with sevoflurane although halothane can also be used. The MAC of volatile agents is lower in neonates than in older children, and the onset of anaesthesia is relatively fast due to the rapid respiratory rate and high cardiac output. However, the neonatal myocardium is extremely sensitive to the negative inotropic effects of volatile agents, so deep volatile anaesthesia must be avoided. Sevoflurane can cause apnoea at high concentrations and the induction concentration should not exceed 6%. The neonate might require assisted mask ventilation until an airway is secured as they may hypoventilate during induction; take care to turn the inspired concentration of volatile agent down if assisted ventilation is used, otherwise the child will become very deep, very quickly. Halothane is more likely to cause myocardial depression and the induction concentration should be kept less than 2%. Halothane can cause arrhythmias in high concentrations, especially if the CO2 is also high. Atropine (20mcg.kg
-1 IM or IV) should be considered prior to induction to reduce bradycardia, particularly if halothane is used. Alternatively, intravenous induction with ketamine (2mg.kg
-1) or thiopentone (2-4mg.kg-1) can be performed; induction of anaesthesia will be rapid (the anaesthetist must be confident they can manage the airway), and recovery may be delayed. Ketamine is particularly useful for the critically unwell neonate as cardiovascular depression is minimised. Use glycopyrrolate (10mcg.kg-1 IV) or atropine (20mcg.kg-1 IV or IM) to minimise the secretions caused by ketamine.

=== Maintenance of anaesthesia ===
Anaesthesia is maintained with volatile, oxygen and air or nitrous oxide. A ketamine infusion run at 2-4mg.kg.hr-1 is a useful alternative in unstable neonates. Attention must be paid when positioning the patient and pressure points must be protected. Whenever the child is moved, check the position of the tracheal tube as it is very easy to displace the tracheal tube in neonates, which could have potentially catastrophic consequences.

=== Pain management ===
It is important to consider pain management in all neonates. Pain pathways are fully developed before birth, and neonates display the physiologic, hormonal, and metabolic markers of the stress response.1  Preterm infants have been shown to have an increased sensitivity to pain and even non-painful stimuli may be perceived as painful.2  Long-term effects on pain responses have been documented in neonatal boys who were circumcised without analgesia.3 However, immature metabolic pathways for drugs and immature respiratory control mean that neonates are more sensitive to the side effects of analgesics commonly used during surgery. Multimodal analgesia should be used for all neonates. Options include paracetamol (7.5mg.kg-1 IV, or 20mg.kg-1 PR), opioids such as fentanyl or morphine titrated to effect (fentanyl 1mcg.kg-1 IV, morphine 10-20mcg.kg-1 IV). Regional anaesthesia or infiltration of local anaesthetics should be used where possible. Non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided because of the immature renal system. Non nutritive sucking, sucrose and breast milk have also been shown to be safe and effective for reducing pain associated with procedures such as cannulation.4,5

=== Invasive monitoring ===
Invasive monitoring (intra-arterial and central venous pressure) may be indicated depending on the type of surgery and the physiological status of the patient. Invasive monitoring is mandatory in circumstances such as cardiac surgery where there is the potential for rapid changes in blood pressure, use of inotropes or potential for large volume blood loss. In other circumstances, for instance neonatal laparotomy, the risks/benefits should be considered. Invasive monitoring is time consuming to insert, associated with complications and may delay the start of surgery. If the surgery is sufficiently urgent it may be necessary to proceed without. 24G or 22G catheters may be inserted into radial or femoral arteries for arterial monitoring, but distal limb perfusion must be checked. 4Fr or 5Fr central lines may be inserted into the femoral or internal jugular vein, ideally with ultrasound guidance. Near infrared spectroscopy (NIRS) can be used, if available, as a non-invasive monitor of tissue perfusion.6

=== Oxygen ===
Unmonitored oxygen therapy leading to hyperoxia in neonates is associated with retinopathy of prematurity, bronchopulmonary dysplasia and damage to the developing brain. Neonatal exposure to 100% oxygen is rarely necessary, and should be avoided except prior to interventions such as intubation. Hypoxia is also harmful, so targeting oxygen saturation levels between 91% and 95% is probably the safest practice.7-9 In low income countries where it may not be possible to deliver a variety of inspired oxygen mixtures, an air/oxygen mix should be used if possible and oxygen saturations should be monitored before, during and after anaesthesia.

=== Postoperative apnoea ===
Apnoea can be defined as a pause in breathing of more than 20 seconds or cessation of respiration of any duration accompanied by bradycardia or oxygen desaturation. Preterm infants are particularly at risk apnoeas due to an immature respiratory control centre. This effect is potentiated by general anaesthetic agents, and all term neonates <44 weeks post-conceptual age (PCA) and pre-term neonates (<60 weeks PCA) are at risk of postoperative apnoea. Infants with multiple congenital abnormalities, a history of apnoea and bradycardia, chronic lung disease and anaemia (Hb <10g.dl-1) are at particular risk for postoperative apnoeas.10

Prophylactic caffeine (10mg.kg
-1 
orally) can be given to prevent post-operative apnoea in premature neonates.11 Intravenous aminophylline (5mg.kg-1) is an alternative although it has more side effects including tachycardia, jitteriness, irritability, feed intolerance, vomiting and hyperglycaemia.It is important to allow sufficient time for neonates to wake up at the end of the operation, and they should be closely monitored in recovery until the anaesthetist is happy that they have returned to their normal awake state. All neonates <44 
weeks post-conceptual age (PCA), ex-preterm infants up to 60 weeks PCA and any patients with whom there is any concern regarding the possibility of post-operative apnoeas should have post-operative apnoea and oxygen saturation monitoring for 24 hours.

=== Hypoglycaemia and hyperglycaemia ===
Persistent, recurrent or severe hypoglycaemia (blood glucose 
<2.5mmol.l
-1
) may lead to irreversible neurological injury in 
neonates. Preterm infants and those with intrauterine growth 
retardation (IUGR) are at particular risk of hypoglycaemia. 
Fasting	times	should	be	minimized,	blood	glucose	should	be	
monitored and glucose containing maintenance fluids should 
be continued if they have been required prior to surgery.
Treat hypoglycaemia with a bolus of 2ml.kg
-1 
of 10% 
dextrose. Hyperglycaemia (blood glucose >10mmol.l
-1
) is also 
detrimental and is associated with increased mortality and 
sepsis in extremely low birth weight infants, so do not use 
boluses of 50% glucose.
12
perioperative fluids
Assessment of the fluid status of the neonate will help to guide 
peri-operative fluid replacement. It is helpful to consider 
preoperative maintenance fluids, intraoperative fluids and 
postoperative maintenance.
preoperative maintenance fluids
A neonate may require preoperative maintenance fluids if 
they are unable to take fluids by mouth before surgery. In 
the first few days of life, the sodium requirement is not high, 
and typically 10% dextrose is recommended. After the post- 
natal diuresis has occurred at around day 3 of life, an isotonic 
fluid containing 5% dextrose and sodium should be used, and 
electrolytes and plasma glucose monitored (Table 2).

intraoperative fluids
During surgery, isotonic fluids such as Hartmann’s or Ringer’s 
lactate must be used for resuscitation, replacement and 
maintenance to maintain intravascular fluid volume, replace 
fluid deficits and avoid hyponatraemia. Blood glucose should 
be monitored.
The decision whether to order or administer blood or blood 
products will depend on the cardiovascular status of the 
neonate, presence of haemorrhage, type of surgery, the most 
recent blood results and the normal expected values (Table 
3). Once the decision to transfuse has been taken it may 
be worth transfusing to higher haemoglobin levels to avoid 
exposure to further donors. Ideally, the haematocrit should 
be measured during surgery using near-patient testing device 
such as a HemoCue
®
 or a blood gas machine. The British 
Committee for Standards in Haematology (BCSH) has a 
suggested transfusion ‘trigger’ for neonatal top-up transfusion 
(Transfusion Guidelines for Neonates and Older Children 
(http://www.bcshguidelines.com) (see Table 4). Suggested 
transfusion doses for blood and blood products are described 
in Table 5.
transitional circulation
In utero, the pulmonary vascular resistance is high and there 
is very little blood flow to the lungs as the placenta is the 
source of gas exchange. After birth as the neonate takes the 
first few breaths, a chain of events is set in place that results 
in the transition from the foetal circulation to the neonatal 
circulation with closure of the foetal shunts (foramen ovale, 
ductus venosus and ductus arteriosus). During the first few 
weeks of life the pulmonary vasculature is highly reactive; an 
increase in pulmonary vascular resistance can lead to reopening 
of the foetal shunts, in particular the arterial duct between the 
pulmonary artery and the aorta. As a result there is right-to- 
left shunting from the pulmonary artery (deoxygenated blood) 
to the aorta, causing profound hypoxia. The oxygen saturation 
measured in the right hand may be normal (‘pre-ductal’); the 
oxygen saturation in the other limbs (‘post-ductal’) will be low.
During the perioperative period it is important to prevent 
factors that increase pulmonary vascular resistance such as 
sepsis, hypoxia, acidosis, hypercapnoea, pain and hypothermia. 
When post-ductal oxygen saturations drop in relation to 
preductal oxygen saturations it may indicate a return to a 
foetal circulation.

neurodevelopmental effects of anaesthetics in 
neonates
Inadequate anaesthesia and analgesia have been shown to 
be detrimental to neonates, and associated with increased 
mortality. However, many animal model studies have been 
published recently that have demonstrated accelerated 
neuronal cell death (‘apoptosis’) and long-term behavioural 
changes after animals are exposed to anaesthetic agents in the 
neonatal period. The situation in humans remains unclear.
13 
The risks and benefits of surgery in neonates should be 
considered carefully, and non-essential elective surgery should 
be avoided in the neonatal period where possible.
transfer of neonates
Neonatal surgery should ideally be undertaken in an 
environment where the facilities and expertise are available for 
definitive treatment and on-going care. In certain situations, 
if the baby is unstable and not suitable for transfer to theatre, 
it may be necessary to undertake surgery on the NICU itself. 
In certain situations the baby may need to be transferred to a 
specialist centre. In low-income countries this may not be an
option and treatment may not always be possible.
Prior to transfer the appropriate personnel, equipment, drugs 
and fluids should be prepared and checked using a transfer 
checklist (Table 6). The neonate should be carefully assessed 
for stability for transfer or if necessary transfer may need to be 
delayed for further resuscitation and optimisation. Check that 
the monitoring is functional and the patient is adequately fluid 
resuscitated. Take time to ensure that the neonate is stable 
prior to transfer on the current drug infusions and mode of 
ventilation.
Careful monitoring during transfer is extremely important and 
will highlight clinical trends. A detailed handover is essential 
for good continuity of care.
SpeciFic neonatal patholoGieS
inguinal hernia repair
Inguinal hernia is common in premature neonates. The 
timing of surgery depends on the risk of incarceration, 
bowel strangulation or testicular atrophy versus the risk of
postoperative apnoea and the potential harm to 
neurodevelopment. The major anaesthetic risk is post- 
operative apnoea, which has been shown to vary from 4.7% to 
49% of patients.
10,14
Some units prefer spinal anaesthesia for inguinal hernia 
repair, others use a balanced anaesthetic technique using 
general anaesthesia with intubation, supplemented with a 
regional technique. There is currently not enough evidence to 
show whether the incidence of apnoea is lower using spinal 
anaesthesia, and the choice is usually determined by local 
preference of the surgeon and anaesthetist.
15

Editors’ note: As this edition of Update goes to press, the editors are 
aware that the GAS study is reporting its preliminary findings on 
apnoea comparing GA and spinal in >700 neonates, publication of 
full results is expected late 2018.

Caudal anaesthesia using 0.25% bupivacaine 0.75ml.kg
-1 
provides excellent supplementary analgesia for inguinal hernia 
repair under general anaesthesia. Alternatively, an ilioinguinal 
block can be performed with 0.5-1.0ml.kg
-1 
0.25% 
bupivacaine. These patients may require post-operative apnoea 
monitoring dependent on their PCA, as discussed earlier, and 
some premature infants will require post-operative ventilation 
or CPAP for treatment of apnoea. Paracetamol (7.5mg.kg
-1 
IV or 20mg.kg
-1 
rectal suppository) provides adequate post- 
operative analgesia

anorectal malformations
Anorectal malformations (ARM) occur in approximately 
1:5000 live births. They represent a wide spectrum of disease, 
from a simple membrane involving the distal rectum and anus 
to more complex anomalies involving the genital and urinary 
tract. Spinal anomalies are frequently found in these patients. 
These include spinal dysraphism, low lying cord (LLC) and 
tethered cord.
16 
Plain spinal Xrays and spinal ultrasound are 
used to screen for these abnormalities although they may 
be normal in occult dysraphism. Caudal anaesthesia may be 
beneficial and can be used in ARM if there is certainty that 
anomalies of the spine and spinal cord have been excluded.
17 
ARM may be associated with other anomalies including 
Vertebral, Anorectal, Cardiac, Tracheoesophageal, Renal and 
Limb abnormalities, collectively known as the VACTERL 
association.
Primary surgical repair can be undertaken in the neonatal 
period although more commonly a colostomy is performed 
and a definitive repair is carried out at a later date.
If caudal anaesthesia is contraindicated an opioid-based 
technique is used (fentanyl 1-2mcg.kg
-1 
or morphine 
20-50mcg.kg
-1 
[0.02-0.05mg.kg
-1
], with infiltration with 
local anaesthetic. Rectal suppositories cannot be used but

intravenous paracetamol is a useful adjunct if available. 
Standard monitoring is usually all that is required. Opioids 
should be carefully titrated as the usual aim is to extubate at 
the end of surgery.
The patient may be positioned supine or prone depending 
on the surgical technique. Prone positioning is associated 
with increased risk to pressure areas, abdominal compression 
resulting in difficulty with ventilation, endobronchial 
intubation or tracheal tube displacement. Long-term outcome 
is variable depending on the complexity of the anorectal 
malformation. These patients usually require serial anal 
dilatations following repair.

intestinal malrotation
Malrotation occurs in approximately 1:500 live births. Normal 
intestinal rotation around the superior mesenteric artery 
(SMA) and fixation during foetal development is interrupted. 
It may also be associated with congenital diaphragmatic hernia, 
exomphalos and gastroschisis.
Nearly 50% of cases will present in the first week of life most 
commonly with bilious vomiting secondary to duodenal 
obstruction.
18 
This may be due to a midgut volvulus, or 
physical compression secondary to peritoneal tissue bands 
or abnormal locations of the duodenum and its surrounding 
structures. If the condition is diagnosed early the neonate 
may be relatively well with only subtle abdominal signs. The 
neonate may present late with frank sepsis and peritonitis 
secondary to perforated or necrotic bowel. The gold standard 
radiological investigation is an upper GI contrast series. Plain 
X-rays are useful if there is concern of another diagnosis or to 
exclude visceral perforation.
These patients require adequate volume resuscitation and 
electrolyte replacement for ongoing fluid losses and should be 
taken to theatre as soon as is feasible. A nasogastric tube is 
inserted to suction the stomach. Prophylactic antibiotics such as 
co-amoxiclav	or	benzylpenicllin,	gentamicin	and	metronidazole	
are required. Ideally invasive monitoring is inserted although it 
should not delay surgery in the sick neonate. If the gut has been 
compromised, inotropes may be needed and any coagulopathy 
will require correction. A central venous line may be required 
for ongoing total parenteral nutrition in the septic neonate. 
An opioid based technique can be used although a caudal may 
be considered if the patient is haemodynamically stable, there 
are no other contra-indications and extubation is anticipated. 
Post-operative NICU care and ventilation is often necessary.
Long-term outcomes depend on the extent of the necrotic 
bowel. Some patients will develop short bowel syndrome and 
if there is extensive bowel necrosis the mortality is 100%.

necrotising enterocolitis (nec)
Necrotising enterocolitis occurs in approximately 0.5 – 5:1000 
live births. More than 90% of infants diagnosed with NEC are 
preterm.
19 
Morbidity and mortality are inversely proportional 
to the infant’s post-conceptual age (PCA) and birth weight.
The aetiology of NEC is multifactorial. Risk factors 
include vascular compromise of the gastrointestinal tract, 
commencement of enteral feeding, immature gastrointestinal 
immunity and sepsis. Hypoxia or ischaemia combined with 
reduced splanchnic blood flow can occur with patent ductus 
arteriosus (PDA), cyanotic heart disease, respiratory distress 
syndrome, shock, asphyxia and with the use of umbilical 
catheters.
NEC may present with subtle gastrointestinal signs including 
abdominal distension, intolerance of feeds, abdominal 
tenderness, blood in the stool and bilious vomiting or may 
present with perforation and peritonitis with systemic 
signs including shock, temperature instability, acidosis and 
disseminated intravascular coagulopathy. Supine and decubitus 
plain Xrays may show the presence of hepatic venous gas, free 
intraperitoneal air, dilated bowel loops, ascites and asymmetric 
bowel gas patterns along with pneumatosis intestinalis.
Initial management includes discontinuation of enteral feeds, 
insertion of a nasogastric tube and commencement of broad- 
spectrum	antibiotics	such	as	benzylpenicillin,	gentamicin	and	
metronidazole.	Ongoing	fluid	and	electrolyte	management	
with parenteral nutrition will be required. Frequent clinical 
monitoring of systemic and abdominal signs together with 
radiographic examination, monitoring of laboratory values 
and acid-base status guides further management. The only 
absolute indication for surgery is bowel perforation although 
the decision to proceed to surgery may be made if there is a 
clinical deterioration.
The preoperative assessment should evaluate and optimise any 
cardiovascular instability, metabolic acidosis, coagulopathy 
and respiratory compromise. If the patient is too unstable it 
may be necessary to carry out surgery on the NICU.
These patients are often already intubated and ventilated. A 
high dose fentanyl technique (10-20mcg.kg
-1
) may be used 
to promote cardiovascular stability and reduce the systemic 
stress response.
20 
Nitrous oxide should be avoided because 
of the risk of bowel distension. Low cardiac output state, 
organ hypoperfusion and acidosis secondary to large fluid 
shifts is common, and large volumes of intravenous fluids are 
frequently required. Invasive monitoring is useful to guide 
fluid management and allow frequent arterial blood gas 
sampling although this must be balanced against the risk of 
limb ischaemia in the preterm neonate. Insertion of an arterial

or a central line should not delay the start of surgery in the sick 
infant. There is a significant risk of coagulopathy and significant 
blood loss, and inotropes are often required. Packed red cells 
should	be	available	and	fresh	frozen	plasma	and	platelets	are	
often indicated based on laboratory results or clinical evidence 
of bleeding. Hypothermia and glucose instability are common 
and should be managed appropriately.
Mortality remains significant and long term complications 
include short bowel syndrome and neurodevelopmental delay.
oesophageal atresia and tracheoesophageal fistula 
Congenital tracheoesophageal fistula (TOF) occurs in 
approximately 1:3,000 live births. It arises during foetal 
development as a result of incomplete separation of the 
oesophagus from the laryngotracheal tube. It is classified based 
on the site and presence of the fistula and whether there is 
oesophageal atresia (Figure 2). There may be other associated 
VACTERL anomalies.

Neonates with TOF classically present within a few hours of 
birth with frothy sputum as they are unable to swallow oral 
secretions; delayed diagnosis is associated with episodes of 
coughing and choking associated with cyanosis, particularly if 
feeding is attempted. There may be copious oral secretions and 
abdominal distension due to gastric insufflation via the fistula. 
Left untreated the neonate will develop aspiration pneumonia. 
The diagnosis of oesophageal atresia is confirmed if it is not 
possible to pass a nasogastric tube and the chest Xray will 
show the nasogastric tube coiled in the proximal blind-ending

oesophagus (Figure 3). There may be an absent gastric bubble 
in isolated oesophageal atresia without a tracheoesophageal 
fistula.

The goals of pre-operative management are to stabilise the 
child, minimise respiratory embarrassment and assess for 
timing of surgery. A nasogastric tube is inserted into the 
upper oesophageal pouch to drain secretions. The patient 
must be nursed head up or on the side to minimise the risk 
of aspiration. Intravenous fluids and prophylactic antibiotics 
should be commenced. This allows time for investigations such 
as an echocardiogram to exclude other associated congenital 
abnormalities.
Our preferred technique is to induce anaesthesia after pre- 
oxygenation and to maintain spontaneous ventilation initially 
with volatile or intravenous anaesthesia. Prior to repair the 
surgeons may perform flexible or rigid bronchoscopy to assess 
the level of the fistula and to see if there is a second or proximal 
fistula. Take note of the distance measured from the cords 
to the fistula to guide tracheal tube placement; the fistula is 
mid-tracheal in two thirds of cases, and located at level of the 
carina in one third of cases. Muscle relaxants and gentle mask 
ventilation may be given prior to intubation. If possible the 
tracheal tube is placed distal to the fistula, with the bevel of the 
tracheal tube facing anteriorly.
A right thoracotomy is performed with the patient on the 
side with a roll under the chest. The tube position must be 
checked and effective ventilation confirmed after the change 
of position. The lung is then retracted which often results in 
difficulty with ventilation, hypercapnoea and acidosis. Periods
of manual ventilation may be required. If gastric distension 
occurs prior to ligation of the fistula, the tracheal tube should 
be disconnected intermittently to decompress the stomach via 
the airway. An arterial line is useful to facilitate arterial blood 
gas measurement as end tidal CO
2 
measurement is unreliable. 
Alternatively, transcutaneous CO
2 
monitoring can be used. 
Hypercapnoea and acidosis is of particular importance in 
the presence of certain cardiac anomalies as the increased 
pulmonary vascular resistance can lead to right-to-left shunting 
and severe hypoxia. Other pitfalls include ligation of the 
wrong structure, intubation of the fistula and endobronchial 
intubation.
A balanced anaesthetic should be given, with bolus fentanyl 
analgesia as required (1-2mcg.kg
-1
). Blood loss should be 
minimal and Ringer’s lactate 10-20ml.kg
-1 
is usually all 
that is required. The wound should be infiltrated with local 
anaesthetic at the end of surgery. Some term infants born in 
good condition and with normal preoperative pulmonary 
function may be extubated at the end of surgery; most are 
likely to require post-operative ventilation and they should be 
transferred to a facility able to provide this level of care for 
their surgery. Many patients will require serial dilatation of the 
oesophagus during infancy.
congenital diaphragmatic hernia
Congenital diaphragmatic hernia (CDH) occurs in 
approximately 1:3000 live births. In most cases the aetiology 
remains unknown. A defect in the diaphragm, usually on the 
left side, results in herniation of midgut structures into the 
thoracic cavity. Pulmonary vascular structure and reactivity 
are abnormal and there is a varying degree of lung hypoplasia. 
Diagnosis is made on antenatal ultrasound or on plain Xray 
postnatally when the abnormal bowel loops can be seen within 
the thoracic cavity.
Morbidity and mortality is related to the degree of pulmonary 
hypertension, right ventricular dysfunction and lung 
hypoplasia.
21 
A pre-operative echo is performed as a significant 
proportion of CDH have associated cardiac anomalies. 
Mortality still remains high in patients with significant co- 
existing congenital cardiac disease.
22 
It is generally accepted 
that delaying surgery, usually for 24-48 hours, allows a period 
of stabilisation. The reduction in pulmonary artery pressures 
and improvement in right ventricular dysfunction may 
improve outcome.
There has been a significant improvement in survival over the 
past 20 years due to the introduction of ‘gentle ventilation’ 
strategies.
23 
These include permissive hypercapnoea (PaCO
2 
<70mmHg), limiting inflation pressures (avoid PIP>25cm 
H
2
O and PEEP > 5 cm H
2
O) and accepting relative hypoxaemia

(aim for pre-ductal SpO
2 
90-95%). Surgery may need to be 
performed whilst the neonate is on high-frequency oscillation 
ventilation or extra-corporeal membrane oxygenation.
24
Preoperative assessment must pay particular attention to the 
presence of significant pulmonary hypertension, ventilation 
requirements, and associated cardiac anomalies. If the infant 
is not already intubated, anaesthesia is induced with care to 
avoid gastric insufflation with bag valve mask ventilation and 
further lung compression. A nasogastric tube is inserted to 
decompress the stomach. Invasive monitoring is required to 
allow serial blood gas measurement. There is a risk of blood loss 
and a unit of packed red cells should be available. In patients 
with significant pulmonary hypertension, having nitric oxide 
available in theatre may be critical for treatment of pulmonary 
hypertensive crises.
A subcostal or transverse abdominal incision is made and 
the herniated viscera are reduced into the abdomen. The 
diaphragmatic defect is then either closed primarily or with 
a prosthetic patch if the defect is large. Thoracoscopic repair 
is being undertaken in some centres. Following abdominal 
closure, raised intra-abdominal pressures may lead to 
difficulty with ventilation and a risk of developing abdominal 
compartment syndrome, and delayed closure may be necessary. 
Lung compliance decreases post-operatively and post-operative 
ventilation is usually necessary. These patients often suffer from 
chronic respiratory disease, gastro-oesophageal reflux disease 
and neurodevelopmental delay.

Gastroschisis and exomphalos (omphalocele) 
Gastroschisis and exomphalos are both ventral wall defects 
resulting in herniation of abdominal viscera. Diagnosis is 
ideally made on antenatal ultrasound scan.
Gastroschisis occurs in approximately 1:3000 live births. The 
herniated viscera are not covered by a sac. It is thought to 
occur secondary to an ischaemic insult during abdominal 
wall development or due to early rupture of the hernia of 
the umbilical cord. A relatively small percentage (10-20%) 
are associated with other congenital abnormalities and these 
predominantly involve the gastrointestinal tract.
25
Exomphalos occurs in approximately 1:5000 live births. Failure 
of normal embryological development results in the bowel 
remaining within the umbilical cord and not returning to the 
abdomen. The herniated viscera is covered by a sac. There is a 
high incidence of associated congenital abnormalities including 
cardiac anomalies. Specific chromosomal associations include 
trisomies 13, 15, 18 and 21 and it can be associated with 
Beckwith-Wiedemann syndrome.
To avoid bowel injury the baby is delivered by caesarean 
section. The operating theatre should be warmed, the baby
dried, any exposed bowel covered with plastic and a nasogastric 
tube is inserted to decompress the stomach. Fluid resuscitation 
is commenced, a urinary catheter inserted and broad spectrum 
antibiotics started. Co-existing congenital abnormalities, 
especially cardiac, should be assessed. A renal or cranial 
ultrasound may also be indicated.
Surgery is more urgent in gastroschisis due to the ongoing fluid 
losses and electrolyte and metabolic derangement. If primary 
closure is not possible then a ‘silo’ is placed over the exposed 
bowel, which may require a general anaesthetic if the defect 
needs extending to fit the device. The silo is suspended above 
the patient postoperatively, and the bowel is gradually reduced 
into the abdominal cavity under gravity over the ensuing few 
days in the NICU. When the patient is stable and spontaneous 
reduction of the bowel has reached a plateau, then surgery 
for reduction and closure of hernia is performed. Surgery for 
exomphalos is less urgent, unless the sac has ruptured. If the 
patient is stable and the defect is small a primary repair can 
usually be done. In large defects, if the sac has not ruptured, 
it	may	be	treated	with	topical	silver	sulfadizine	to	allow	
epithelisation with definitive surgery at a later stage.
The neonate will require intubation and ventilation for surgery. 
Expect significant ongoing fluid and heat losses due to the 
exposed viscera. Peripheral intravenous access may be all that 
is required, but central venous pressure monitoring and an 
arterial line are useful to help guide fluid administration. Avoid 
the femoral vessels as there is a risk of decreased perfusion with 
the increased abdominal pressures. Placing the post-ductal 
oxygen saturation probe on either lower limb helps to give an 
indication if there is poor perfusion. Muscle relaxants will assist 
the surgeons in reducing the abdominal contents. Reduction 
of the bowel may cause abdominal compartment syndrome, 
diaphragmatic splinting and high ventilation pressures. If the 
intra gastric pressures are >20mmHg or the peak inspiratory 
pressures exceed 30cm H
2
O then a staged repair is indicated.
26
Unless there is a very small defect the infant will require post- 
operative ventilation and a generous opioid-based anaesthetic 
technique can be used (fentanyl 10-20mcg.kg
-1
). These patients 
often require parenteral nutrition and a significant proportion 
present for further abdominal surgery.
conclUSion
Improving outcomes in neonatal anaesthesia is dependent 
on a thorough understanding of the unique anaesthetic 
requirements of the neonate and a detailed knowledge of 
the different pathologies that present during this period. 
Unnecessary surgery should be avoided during the neonatal 
period as anaesthesia and surgical stress may have detrimental 
effects on the very immature child.


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