Appendix II: Perioperative Pediatric Care
Summary: 9 "things" you need to remember about pediatric/neonatal surgery
All children (in particular though, the newborn and premature) are at risk for hypothermia before, during and after surgery. A large body surface area, minimal amount of insulating fat and lack of shivering thermogenesis all contribute to this increased susceptibility to hypothermia. As glycogen stores are depleted rapidly and brown fat stores are used up, energy needs must be met, primarily with infusions of glucose intravenously. Later on, during the course of the child's illness, total parenteral nutrition (TPN) may be required.
An assortment of congenital anomalies occurs in this area: cystic hygroma, thyroglossal duct cysts, and branchial cleft cysts and sinuses. Lymphadenopathy may be due to infection (pyogenic, tuberculous - typical or atypical) or neoplasia (lymphoma, Hodgkin's disease, metastases). Dermoid cysts may occur at the lateral corner of the eyebrow (external angle or dermoid) or on the scalp or midline of the neck.
Defects in the diaphragm (foramen of Bochdalek) result in herniation of the abdominal viscera into the chest (most often the left) in-utero. The resulting compression of the lung results in ipsilateral hypoplasia, and in severe cases, bilateral pulmonary hypoplasia. The hypoplasia in turn results in pulmonary hypertension and a right-to-left intra and extra cardiac shunt i.e., the unoxygenated blood from the right side of the heart completely bypasses the lungs - a condition known as P.F.C. (persistent fetal circulation). A large number of these children will die without specialized ventilation, nitric oxide (a selective pulmonary vasodilator) or E.C.M.O. (extracorporeal membrane oxygenation). Correction of hypoxaemia, hypercarbia and acidosis are far more important than the anatomic repair and always takes precedence over it. The diagnosis of C.D.H. can be suspected in the newborn who is dyspneic and has a scaphoid abdomen.
Umbilical hernias are extremely common and generally will resolve with time. Very rarely a loop of bowel may incarcerate resulting in a bowel obstruction. Repair of the hernia then becomes urgent. Elective repair is left until the child is 2-4 years of age.
Gastroschisis is a condition characterized by a full thickness abdominal wall defect occurring to the right of the midline through which most or all of the abdominal viscera herniate, without the benefit of a covering layer/membrane. Heat/fluid loss and infection are the major concerns initially; malnutrition from failure of gut function to return occurs late. These babies are frequently SGA (small for gestational age) or premature, but rarely have other life-threatening anomalies so if they are treated properly, survival is the norm.
Omphalocoele is a condition arising from a central abdominal wall defect, but where the viscera are covered with a membranous sac (peritoneum, chorion, etc.). These babies frequently have other potentially lethal abnormalities (including cardiac and chromosomal) so these need to be considered prior to, during and after surgery.
The most extreme examples of abdominal wall defects are the exstrophic anomalies: exstrophy of the bladder and exstrophy of the cloaca (vesicointestinal fissure).
Babies are continually swallowing and digesting amniotic fluid in-utero. The fluid is absorbed from the G.I. tract, enters the fetal circulation and is ultimately circulated to the mother by the placenta. If the fetus cannot swallow or digest and absorb the fluid, an excess of amniotic fluid develops - polyhydramnios. This is one of the cardinal features of esophageal atresia and proximal obstructions of the G.I. tract. Abdominal distention and failure of passage of meconium are two other cardinal features of obstruction. It is important to know that a baby may have an obstruction with one or more of the above features missing! Bilious vomiting virtually always occurs with a mechanical obstruction. Green vomit must be considered a SURGICAL EMERGENCY. Virtually all obstructions are treated by emergent/urgent surgery.
It is important to realize that if an anomaly occurs in one area, look for other anomalies: e.g., the VACTERR association (vertebral, anus, cardiac, tracheoesophageal, radius and renal).
Malrotation with mid-gut volvulus is the most lethal form of bowel obstruction occurring in the newborn period and not infrequently presents much later in childhood. A newborn infant who passes flatus or transitional stool, then develops signs of a bowel obstruction (i.e. bilious vomiting) has malrotation and a mid-gut volvulus 'til proven otherwise! Obstruction of the superior mesenteric artery and vein occurs as the bowel twists, and ischaemic necrosis and gangrene occur rapidly - within a few hours.
Contrast studies (barium upper g.i. or barium enema) are used selectively to diagnose the level of obstruction; upper g.i., if the suspected obstruction is proximal; barium enema if the obstruction is likely colonic or terminal ileum. Gastrograffin, because of its hyperosmolarity (1600 mosm/L) is NEVER given by mouth or N/G tube because of the risk of aspiration and subsequent pulmonary edema.
G.E.R.D. is a common condition in infants and older children, presenting with symptoms and signs varying from simple regurgitation to life-threatening respiratory problems secondary to aspiration (near-miss SIDS, reactive airway disease). Esophageal injury from prolonged exposure to gastric contents may result in esophagitis and its sequelae - stricture and more rarely, Barrett's esophagus ("columnar-lined esophagus").
Diagnosis is made on the basis of a clinical history along with imaging studies - barium swallow, radionucleotide gastroesophageal reflux scan, endoscopy and 24-hour pH monitor (the "gold standard" in cases difficult to diagnose).
Treatment is primarily medical with positional therapy, thickening of feeds, promotility agents (Cisapride) and either H2 receptor antagonists or Omeprazole. Surgery is reserved for those infants who fail medical therapy which would include virtually all infants with respiratory symptoms on the basis of G.E.R.D. The standard operative procedure is a Nissen fundoplication.
Meconium peritonitis refers to in-utero perforation of the bowel with scattered calcification in the peritoneal cavity seen on plain x-ray. The cause of the perforation may be an isolated vascular accident or meconium ileus - therefore cystic fibrosis must be excluded.
H.P.S. is a relatively common condition occurring between 2 and 8 weeks of life. It is NOT congenital. Projectile, NON-Bilious vomiting in an otherwise apparently healthy infant is classic. It is more common in first born males, but can be seen just as easily in female infants. A family history of H.P.S. may be present (particularly in the mother). Dehydration with a hypochloremic, hypokalemic, metabolic alkalosis will be seen in varying degrees dependent upon severity and duration. Treatment is rehydration and correction of the electrolyte abnormalities - followed by surgery (Ramstedt pyloromyotomy) when the baby is stable.
Appendicitis in the older child is usually a fairly straight-forward diagnosis but can present many traps for the unwary in the younger child - typically the toddler (18 mos. to 3 yrs. of age). The history may be atypical and the symptoms are frequently attributed to gastroenteritis. The incidence of rupture is higher in this group. The child with abdominal pain who is "uncooperative" can be sedated (with Demerol) and re-examination may be more informative/revealing. Never omit the rectal examination in a child/infant with abdominal pain.