NEONATAL EMERGENCIES-* OMPHALOCELE* GASTROSCHISIS

Speaker: Dr Bhagirath.S.N

Moderator: Dr Sarika

Omphalocele (Exomphalos) Incidence: 1 in 5000 live births

• Gut contents are normally extruded out in the 5th week of fetal life

• During this time the pleuro peritoneal cavities which are in unison get divided into thoracic and abdominal cavities by the newly formed diaphragm (around 7th week)

• around 9th week, the extruded gut contents come back into the abdominal cavity. • If there is failure on part of the gut contents to come back into the abdominal cavity in entirety, then a part of the gut remains outside.

• This mass of tissue is ensheathed by a membrane called amnion

• this membrane affords protection against both infection and loss of extracellular fluid.

• typically the umbilical cord is at the apex of the mass.

GastroschisisIncidence: 1 in 5000 live births

• Gut contents are normally extruded out in the 5th week of fetal life

• During this time the pleuro peritoneal cavities which are in unison get divided into thoracic and abdominal cavities by the newly formed diaphragm (7th week)

• around 9th week, the extruded gut contents come back into the abdominal cavity. • unlike an omphalocele, gut contents enter back in entirety at 9th week.

•owing to a disruption in blood supply from the omphalomesenteric

artery, there is ischemia and atrophy of several layers of abdominal wall

at base of the umbilical cord.

• This leads to an area of weakness in the abdominal wall.

Gastroschisis

•It is through this weakness that gut

contents pouch out later in foetal life.

There is no membrane covering the

mass and therefore no protection is

afforded against infection or loss of

extra cellular fluid.

• As the gut lies exposed (without a

membrane) it tends to irritate the

uterine lining increasing the chances

of premature delivery.

• typically the umbilical cord is at one

side of the mass

Associated congenital anomalies

•Are more with omphalocele than Gastroschisis

1. Bowel atresia

2. Imperforate anus

3. Congenital heart disease (20%)

4. Bladder exostrophy

5. Beckwith Weidman syndrome: Mental retardation, hypoglycemia,

congenital heart disease, large tongue and omphalocele

6. Other defects predominantly involving the gut such as malrotation.

Antenatal diagnosis

•Involves assessment of α fetoprotein levels which are high in

abdominal wall defects.

• Maternal Serum α fetoprotein level is also assessed but is less sensitive

than α fetoprotein from amniotic fluid.

• Levels of these markers are high in omphalocele.

• USG helps in definitive diagnosis

• USG additionally helps in picking up coexistent congenital anomalies.

Preoperative care

•Obtain I.V. access

• Assess for associated congenital anomalies

• Manage respiratory insufficiency.

• Aspirate from the nasogastric tube.

Perioperative care

1. Anticipate difficulty airway in a neonate with large tongue as in

Beckwith Wiedemann syndrome

2. IV or inhalational induction may be preferred. Rapid sequence

induction is also found to be useful.

3. Endotracheal intubation (nasal tube) and IPPV are required.

4. Maintenance with volatile anesthetic with oxygen and air.

5. If extubation is not planned for at the end of surgery then judicious

use of opoids is accepted.

6. A caudal epidural confers good post operative analgesia.

7. An arterial line is helpful in monitoring blood pressure and arterial

blood gases.

8. Since a large volume of tissue is exposed to room air, the amount of

loss in terms of fluids can be substantial and need to be replenished. 9. To this end, organ perfusion needs to be maintained at optimal levels,

especially so when the abdominal contents are compressing the inferior vena cava and compromising cardiac output.

Perioperative care

11.During surgery intra-abdominal pressure increases, lung compliance

falls, and ventilation usually becomes more difficult. Ventilatory rate

and pressure along with the FIO2 usually need to be increased. A slight

degree of head up may be helpful.

12.To summarise, the chief concerns in these surgeries are fluid loss

replacement and maintaining ventilation.

13.Fluid loss must be minimised by covering the gut contents outside the

abdominal cavity with a sterile bag containing saline.

Perioperative care

14.Fluid loss replacement is best done with balanced salt solution with

5% albumin.

15.It is best to avoid N2O to prevent further abdominal distension.

16.Adequate muscle relaxation is important to facilitate better closure of

abdominal wall, but if the defect is large then a forceful closure may

hamper circulation to bowel, Kidneys and lower limb. In fact use of

pulse oximetry to assess perfusion in the lower limb is avidly

advocated.

When to attempt a primary closure in a single sittingas opposed to multiple sittings…?

• Intragastric pressure is measured.

• If it is below 20 mm of Hg then a primary closure is done in a single

sitting.

• If it is above 20 mm of Hg then a delayed closure technique is

adopted. If closure is difficult through conventional approaches…?• A wide silo is incorporated into the abdominal wall covering the

viscera.

• Every 2-3 days the silo is reduced either bedside or on the OT table

with or without Ketamine.

• A hurried reduction impedes circulation and compromises oxygenation

• After several stages of such reduction final solution is to achieve

complete closure under general anesthesia with muscle relaxation.

• Surgery may not be an immediate solution, but probably remains the

only effective one.

Post operative care

• Coexistent pulmonary hypoplasia (especially in Omphalocele) requires

careful consideration during ventilation

Too little risks inadequate oxygenation Too much results in

barotrauma

• Better not to extubate

• Postoperative complications include

Post operative hypertension

Edema of extremities

Post operative care

• Post operative hypertension

Increased intra abdominal pressure

Decreased renal perfusion

Increased renin secretion

Activation of renin-angiotensin-aldosterone system

Hypertension

References….

Clinical Anesthesia by Paul.G.Barash6th editionP1222-1225

Miller’s Anesthesia 7th Edition, Vol 2

P1178, 1180

References….

Paediatric anaesthesiaEdited by Edward DoyleUnits 11 & 12

Smith’s Anesthesia for Infants & Children

Motoyama & DavisP 1098, 99