Special Neonatal Surgical Problems

Meningomyelocele

Meningomyelocele (hernial protrusion of a part of the meninges and spinal cord through a defect in the vertebral column) is a relatively common neonatal abnormality. The following should be considered in addition to the usual concerns for management of neonates: (1) special positioning for endotracheal intubation (defect on a "doughnut" and towels under the head), (2) the possibility of underestimating fluid and blood loss from the defect, (3) the high association of this condition with hydrocephalus, (4) the possibility of cranial nerve palsy resulting in inspiratory stridor, and (5) the potential for brain stem herniation. The anesthesiologist must establish adequate intravenous access and invasive monitoring if appropriate; replace all fluid deficits, including loss from the defect (usually with normal saline); and ensure that cross-matched blood is available. Latex allergy precautions should be used with these patients for their first and all subsequent anesthetics.^[331]

Pyloric Stenosis

Pyloric stenosis is normally manifested in the first 3 to 6 weeks of life. The following are major concerns for the

TABLE 60-10 -- Comparison of gastroschisis and omphalocele malformations

	Gastroschisis	Omphalocele
Pathophysiology	Occlusion of the omphalomesenteric artery	Failure of gut migration from the yolk sac into the abdomen
Incidence	≅1 in 15,000 births	≅1 in 6000 births
Incidence of associated anomalies	≅10%–15%	≅40%–60%
Location of defect	Periumbilical	Within the umbilical cord
Problems associated with the defect	Exposed gut inflammation, edema, dilated and foreshortened gut (chemical peritonitis)	Congenital heart disease (≅20%)
		Exstrophy of the bladder
		Beckwith-Wiedemann syndrome (macroglossia, visceromegaly, hypoglycemia, hyperviscosity)
Modified from Roberts JDJ, Cronin JH, Todres ID: Neonatal emergencies. In Coté CJ, Todres ID, Goudsouzian NG, et al (eds): A Practice of Anesthesia for Infants and Children, 3rd ed. Philadelphia, WB Saunders, 2001, pp 294–314.

anesthesiologist: (1) a full stomach, occasionally filled with barium sulfate; (2) metabolic alkalosis with hypochloremia and hypokalemia; and (3) severe dehydration.

This operation is never a surgical emergency. Patients should be carefully evaluated, and severe metabolic imbalance should be corrected before surgery. Even if the child arrives with a nasogastric tube in place and although the diagnosis is most commonly made by ultrasound rather than barium swallow, the stomach should still be suctioned with a wide-bore catheter in the supine, right, and left lateral positions immediately before induction of anesthesia and as much of the stomach contents as possible removed.^[332] Patients with pyloric stenosis can be managed with awake endotracheal intubation followed by low-dose rocuronium (0.3 mg/kg) or mivacurium (0.2 mg/kg) or rapid-sequence induction of anesthesia with cricoid pressure after atropine (0.02 mg/kg), propofol (3 mg/kg), and succinylcholine (2 mg/kg). Arguments can be made for either type of induction, and selection depends on the skill and familiarity of the anesthesiologist with that technique.^[333] Postoperative analgesia is generally provided by local infiltration of the skin incision with bupivacaine (maximum dose, 1 mL/kg of 0.25% bupivacaine) and rectal acetaminophen (a 40-mg/kg initial dose followed by 20 mg/kg every 6 hours rectally or 10 to 15 mg/kg by mouth every 4 to 6 hours for a total 24-hour dose of approximately 100 mg/kg). There have been conflicting reports of apnea events after pyloromyotomy.^{[334] [335]} One well-controlled clinical trial described 3 of 13 patients with new-onset apnea after halothane anesthesia.^[204] Until larger studies are carried out, it may be prudent to observe these patients with apnea monitors and pulse oximeter postoperatively.

Omphalocele and Gastroschisis

Omphalocele and gastroschisis are major defects in closure of the abdominal wall that result in exposure of viscera that are either covered (omphalocele) or not covered (gastroschisis) by peritoneum ( Table 60-10 ). The major problems with these defects include (1) severe dehydration and massive fluid loss, both from the exposed visceral surfaces (gastroschisis—chemical peritonitis) and from third-space losses caused by partial bowel obstruction; (2) heat loss; (3) the difficulty of surgical closure; and (4) the

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Patients with omphalocele or gastroschisis must be cared for expeditiously to reduce the potential for infection and compromise of bowel function and to minimize the loss of fluid and heat; optimizing fluid and electrolyte balance before surgery is recommended.^[336] Adequate intravenous access and invasive monitoring are usually necessary. The liberal use of muscle relaxants provides optimal surgical conditions for closure of the defect; hypotension secondary to tension on a major organ (liver) or vena cava compression is common. If the surgeon is unable to close the defect in one procedure, a staged procedure is planned. In either situation, postoperative ventilation will be necessary until the abdominal wall has had time to stretch to accommodate the viscera. Intravenous alimentation may also play a vital role in the rapid recovery of these patients. A small percentage of patients with omphalocele will also have Beckwith-Wiedemann syndrome, a condition characterized by profound hypoglycemia, hyperviscosity syndrome, and associated visceromegaly. It should be noted that increased abdominal pressure after a tight closure may compromise hepatic function and markedly alter drug metabolism.^{[179] [180]} Staged closure with a premade spring-loaded Silastic silo is being used with increasing frequency to minimize repeat trips to the operating room and the need for postreduction ventilation.^{[337] [338]}