Anesthesiology

Gastroschisis

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What the Anesthesiologist Should Know before the Operative Procedure

Gastroschisis is a congenital defect of the abdominal wall which occurs in about 1:4,000 live births (Figure 1). The defect develops during the 10-14th week of gestation because of failure of the abdominal wall to close over the gut. The defect is usually apparent on prenatal ultrasound which may be obtained as part of routine prenatal care or because of increased maternal alpha fetoprotein. Gastroschisis is readily diagnosed at birth as a defect in the abdomen commonly off-midline to the right of the umbilicus. The herniated bowel is never covered by a membrane or sac and, therefore, is exposed to the atmosphere. Rarely, gastroschisis may be associated with other congenital anomalies.

Figure 1.

Gastroschisis (unrepaired) in the neonate (courtesy of S. Smith).

Gastroschisis is easily differentiated from omphalocele, which is a midline defect involving an overlying covering or hernia sac containing bowel and often liver.

The differences between gastroschisis and omphalocele are summarized in the Table 1.

Table 1.

Differentiating characteristics between gastroschisis and omphalocele
Characteristic Omphalocele Gastroschisis
Herniated viscera Bowel ± liver Bowel only
Sac Present Absent
Associated anomalies Common (50%) Uncommon (<10%)
Location of defect Umbilicus Right of umbilicus
Mode of delivery Vaginal/caesarean Vaginal
Incidence of prematurity birth 6% 28%
Surgical management Nonurgent Urgent
Prognostic factors Associated anomalies Condition of bowel

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

The gastroschisis is a surgical emergency requiring intervention in the first day of life. Because the abdominal contents and peritoneal cavity are exposed, delay in sugical intervention is associated with a significant risk of infection/sepsis, bowel dysfunction and direct injury to viscera, eventually may result in death of the infant.

Immediately after birth, management includes protection of the abdminal viscera. This can accomplished by wrapping the herniated abdominal contents in saline soaked gauze. The child should be positioned with the left side up or with the left hip elevated to prevent kinking of the mesentery and ischemia of the viscera.

Gastroschisis is usually not asscociated with other congenital anomalies. Because some cases may be confused with omphalocele, a rapid exam using echocardiography and abdominal ultrasound is warranted to rule out other anomalies, particularly intracardiac and renal defects.

2. Preoperative evaluation

Preoperative evaluation includes the same assessment which one should conduct for any neonate undergoing surgery. This involves assessment of the airway and respiratory system, the cardiovascular system and awareness of any other congenital anomalies. Preoperative hematocrit may indicate either hypervolemia/polycythemia because of placental transfusion or anemia if there has been unusual perinatal blood loss. Blood glucose may be low as a result of physiological stress in the neonate, and/or because intravenous fluids and dextrose supplementation are delayed while the healthcare team is distracted evaluating the child for other defects. The exposed bowel allows significant heat loss to occur. Therefore, the patient's temperature should be monitored preoperatively and care taken to avoid hypothermia. Intravenous access should be placed preferably in the upper extremities to provide intravenous (IV) fluids and medications.

Additional testing is usually not required.

3. What are the implications of co-existing disease on perioperative care?

Associated conditions or co-existing diseases rarely impact the care in immediate neonatal period. Infants who are born prematurely require special attention because of their immature respiratory system (treatment with surfactant, supplemental oxygen, and possibly mechanical ventilatory support). Other associated conditions may become symptomatic as the infant matures. These can include intestinal atresia, gastroesophageal reflux and cryptorchidism, as well as neurodevelopmental issues often seen with prematurity.

b. Cardiovascular system

N/A

c. Pulmonary

N/A

d. Renal-GI:

N/A

e. Neurologic:

N/A

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

Neonates who present for repair of gastroschisis will require antibiotics to prevent infection as discussed earlier. These must be given in a timely manner according to the dosing regimen. The patients usually do not require any medications specifically for this condition.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

N/A

i. What should be recommended with regard to continuation of medications taken chronically? not relevant

N/A

j. How To modify care for patients with known allergies - not relevant in the newborn period

N/A

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

Infants with gastroschisis are not at especially increased risk to develop latex allergies. However, as a general practice in pediatric anesthesia and surgery, latex-safe and latex-free environments are recommended; pediatric patients with congenital conditions may require multiple procedures and will be exposed repeatedly to latex.

l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]

Concerns about medication allergy are not usually relevant in neonatal period as infants have not had prior exposure to these medications.

m. Does the patient have a history of allergy to anesthesia? not relevant in neonatal period

Not relevant in the neonatal period.

5. What laboratory tests should be obtained and has everything been reviewed?

Laboratory tests should include hematocrit/hemoglobin and blood glucose. The anesthesiologist should be aware and be prepared to treat polycythemia or anemia, or hypoglycemia if present.

Expected normal values for hematocrit, hemoglobin, glucose or other laboratory tests are those expected in any neonate, and vary with the degree of prematurity and post-natal age of the patient.

See normal laboratory values according to postnatal age. Also, measure hemoglobin levels and blood glucose values.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Initial management in the delivery room consists of respiratory support as needed. The herniated bowel should be wrapped in saline soaked gauze to reduce heat and fluid loss and the chance of direct trauma. The goal of surgical treatment is primary replacement of the bowel into the abodminal cavity and closure of the abdminal wall defect, if possible. Therefore, the infant will need general anesthesia for the case and possibly, ventilatory support afterward.

Staged reduction

Increasingly, instead of emergent primary closure in the operating room, the surgeon will place a silastic silo over the defect after the neonate has been stabilized in the neonatal intensive care unit (Figure 2.) The silo is a pre-formed bag that can hold the herniated contents and may be sutured in place. The silo reduces evaporative fluid and heat loss, and protects the bowel. Use of the silo may make it possible to more quickly wean the infant from mechanical ventilation. Over several days, the herniated bowel is gradually replaced in the abdominal cavity by progressive reduction in the volume of the silo. Once the gut is easily accomodated in the abdominal cavity, the defect in the abdominal wall is closed surgically. This usually is a less stressful and less complicated procedure than emergent primary closure (Figure 3.)

Figure 2.

Gastroschisis: abdominal contents in silo (courtesy S. Smith).

Figure 3.

Gastroschisis:gradual reduction of silo with reinsertion of bowel into abdomen (courtesy of S. Smith).

Regional anesthesia

In experienced hands, an epidural catheter may be placed via the thoracic or high lumbar approach to provide intraoperative and postoperative analgesia. Adequate regional analgesia can reduce the amount of time the infant needs mechanical ventilation. Placement of the epidural catheter should be done by a pediatric anesthesiologist experienced in the technique.

General anesthesia

General endotracheal anesthesia is required for surgical closure of the gastroschisis defect. Standard American Society of Anesthesiologists (ASA) monitors should be used, including ETCO2 (end-tidal carbon dioxide in the expired air), SpO2 (blood oxygen saturation), ECG (electrocardiogram), non-invasive blood pressure cuff, thermometer, monitoring of airway pressures (peak inspiratory pressure, in particular). Two intravenous catheters should be placed to allow infusion of maintenance fluids and also blood products and medications as needed. A central venous catheter commonly is placed so that the neonate can receive total parenteral nutrition (TPN) while the post-operative bowel edema subsides and the abdomial viscera acclimates to the intra-abdominal environment. For the infant with respiratory distress or extreme prematurity, an arterial catheter will allow the anesthesiologist to closely monitor the blood pressure and obtain blood samples for hemoglobin and glucose testing during the procedure.

The general anesthetic technique commonly used is a balanced technique with fentanyl, neuromuscular blockade and low-dose volatile anesthetic like sevoflurane. Remifentanil infusion is an excellent alternative to fentanyl. The pharmacology of remifentanil has significant benefit for the neonate; the drug has a rapid onset, is easily titrated to achieve the depth of analgesia required for intraoperative care and has a rapid offset, allowing for more rapid extubation. For infants with a relatively small defect that is easily closed, it may be possible to extubate the patient soon after surgery.

If a regional anesthetic technique is not used and the child requires significant doses of opioid, the patient may need postoperative ventilatory support for several days.

Monitored anesthesia care

Monitored anesthesia care may be required for the premature child with gastroschisis who requires ventilatory support soon after delivery. The defect in these neonates is best managed by placement of a silo placed over the gut and abdominal content. If the infant is severely premature, the silo may be left in place for several weeks to allow the respiratory disease to improve. Similarly, if the abdominal cavity is too small to accommodate the viscera, the silo may be left in place while the patient grows and the abdominal volume increases. The child then is brought to the operating room for a formal surgical repair and closure of defect under general anesthesia.

6. What is the author's preferred method of anesthesia technique and why?

What prophylactic antibiotics should be administered?

Prophylactic antibiotics should be used; for neonatal surgery these often include ampicillin and gentamicin to prevent neonatal sepsis; alternatively, a broader spectrum antibiotic like ampicllin-sulbactam (Unasyn) may be preferred by the surgeon.

What do I need to know about the surgical technique to optimize my anesthetic care?

The primary challenges for the anesthesiologist include those seen with any neonatal surgery—adequate mechanical ventilation with the lowest peak inspiratory pressure (PIP) required; adequate supplemental oxygen sufficent to maintain SpO2 above 93%-95%, while too much oxygen may result in pulmonary and retinal damage; the primary goal of surgical treatment is to replace the gut back in the abdomen. However, the abdominal cavity may be too small to accomodate all of the content, and closure of the abdominal wall over the bowel may result in abdominal compartment syndrome and significant reduction in the lung volumes, particularly functional residual capacity (FRC). This can lead to the need for higher pressures to achieve adequate ventilation. In some case, venous return to the heart may be compromised, resulting in hypotension. Therefore, staged reduction may be a better treatment choice.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

Infants with gastroschisis will need general endotracheal anesthesia. The child may be extubated soon after surgery if the abdominal cavity easily accommodates the extra-abdominal contents. In cases where primary closure is possible but may be associated with compromised ventilation, the infant should be kept intubated and mechanical support continued. Several days may be required for postoperative edema of the bowel to subside and for the infant to be able to sustain adequate spontaneous ventilation. In this instance, the patient will need prolonged total parenteral nutrition until bowel function is adequate to accommodate gut feeds.

c. Postoperative management

Postoperatively these patients should be cared for in the neonatal intensive care for ongoing monitoring and support. Patients likely will need mechanical ventilatory support. They also may need prolonged parenteral nutritional support and care. They may exhibit temperature instability and require a thermoneutral environment provided by an infant warming bed.

These patients often require significant pain management for several days after surgery. Intravenous opioids using infusions (for example, 1-2 mcg/kg/h of fentanyl) are effective for the initial few days. Intermittent dosing of opioids in combination with acetaminophen may be sufficient afterward. Alternately, the infant may benefit from epidural analgesia provided via a thoracic, high-lumbar or caudal catheter which has been threaded rostrally. Placement and management of regional anesthesia in neonates and infants should be performed only by experienced pediatric anesthesiologists. Care of the epidural catheter and nursing care of these infants also requires a nursing team with sufficient knowledge and experience.

Infants receiving opioids or epidural analgesia should be closely monitored for respiratory depression.

Children with gastroschisis may return to the operating room for a variety of reasons. In the immediate postoperative period ileus of the bowel may occur because the abdminal cavity may be too small, compromising perfusion of the bowel; adhesions may produce bowel osbtruction; malrotation of the gut may result in volvulus. More commonly these infants may present for placement of central lines or percutaneously placed central cathethers (PICC). With proper support, most infants eventually can be discharged home to outpatient care.

What's the Evidence?

Baird, PA, MacDonald, EC. "An epidemiologic study of congenital malformations of the anterior abdominal wall in more than half a million consecutive live births". Am J Hum Genet. vol. 33. 1981. pp. 470-8.

(Excellent large study providing a good overview.)

Stoll, C, Alembik, Y, Dott, B, Roth, M-P. "Omphalocele and gastroschisis and associated malformations". Am J Med Genet. vol. A146A. 2008. pp. 1280-5.

(Update on the syndrome with an excellent discussion of embryology and prenatal aspects of care.)

Wilson, RD, Johnson, MP. "Congenital abdominal wall defects: an update". Fetal Diagn Ther. vol. 19. 2004. pp. 385-98.

(Updated summary of abdominal wall defects outlining some of the other issues/conditions the anesthesiologist may need to worry about in the perioperative period.)

Bianchi, A, Dickson, AP, Alizai, NK. "Elective delayed midgut reduction-no anesthesia for gastroschisis: selection and conversion criteria". J Pediatr Surg. vol. 37. 2002. pp. 1334-6.

(Very good discussion on the prevalent technique which can reduce perioperative risk and improve outcome.)

Ross, AK, Davis, PJ, Dear, G deL, Ginsberg, B, McGowan, FX, Stiller, RD, Henson, LG, Huffman, C, Muir, KT. "Pharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures". Anesth Analg. vol. 93. 2001. pp. 1393-401.

(Very good article on the use of remifentanil in the neonate and pediatric age group.)

Davis, PJ, Cladis, FP. "The use of ultra-short-acting opioids in paediatric anaesthesia". Clin Pharmacokinet. vol. 44. 2005. pp. 787-96.

(Review and good overview on the benefits and precautions involved with the perioperative use of ultra-short acting opioids including remifentanil.)

Brett, C, Davis, PJ, Davis, PJ, Cladis, FP, Motoyama, EK. "Anesthesia for general surgery in the neonate". Smith's Anesthesia for Infants and Children. Elsevier. 2011. pp. 554-88.

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