Inguinal Herniorrhaphy and Umbilical Herniorrhaphy

During the seventh month of gestation, the testicle descends from the abdomen through the inguinal wall into the scrotum. The processus vaginalis, a peritoneal covering, encloses the testicles during their descent. In term infants, the processus vaginalis is usually closed at birth, but it remains patent in 15% to 37% of people. In premature infants, the incidence of closure is much higher, depending on the gestational age at the time of birth. The continued patency of the processus vaginalis is the principal factor in the development of congenital hernias and hydroceles.

Inguinal hernia repair is the most frequent general surgical procedure performed by pediatric surgeons. Males are more frequently affected than females, and the incidence of inguinal hernia is highest in the first year of life. Right-sided hernias (60%) occur more frequently than left-sided (30%) and bilateral (10%) hernias. Other risk factors associated with inguinal hernias are prematurity, chronic respiratory illness, and excessive intraperitoneal fluid (ventriculoperitoneal shunts, ascites, peritoneal dialysis).

The surgical technique for this procedure is well described (Rowe and Lloyd, 1986). Laparoscopic techniques have also been described (Lobe and Schropp, 1992; Lee and Liang, 2002; Schier et al., 2002), as well as needleoscopic techniques (Prasad et al., 2003). The overall complication rate after an elective hernia repair is about 2%, and it increases to 14% after operations for incarcerated hernia. A major surgical issue in patients with a unilateral inguinal hernia is whether the contralateral side should be explored, thereby subjecting the patient to possible unnecessary damage to the contralateral vas deferens and spermatic cord. In a number of studies, a patent contralateral processus vaginalis occurs about 60% of the time. However, this patency appears to be age related, with the highest rate occurring in infants (63%), and with the incidence decreasing until 2 years of age, when it appears to plateau at 41% (Rowe and Lloyd, 1986). Despite the high incidence of patent processus vaginalis, the incidence of contralateral hernias is about 15%. The development of a contralateral hernia is also age dependent. If the initial hernia developed in the first year of life, there is a fourfold greater chance that a contralateral hernia will develop compared with children whose initial hernia manifested after 1 year of age. In girls with unilateral inguinal hernias, the incidence of positive explorations for contralateral hernias is 60%. Consequently, girls almost always undergo contralateral exploration. Laparoscopy without a separate incision has been advocated to examine the contralateral side for a patent process vaginalis when the ipsilateral hernia sac is of sufficient width to allow passage of a laparoscope (Yerkes et al., 1998) (Fig. 23-3).

FIGURE 23-3 Laparoscopic hernia repair with patent process vaginalis.

Herniorrhaphies are commonly performed as an elective procedure; however, in children with incarceration and signs of bowel obstruction, a rapid-sequence induction with application of cricoid pressure is needed.

The following discussion pertains to elective, uncomplicated hernias. Anesthesia can be induced by mask inhalation of volatile agents or by IV or rectal technique. Endotracheal intubation is usually unnecessary for herniorrhaphy, except in infants younger than 1 year, in whom it may be difficult to maintain an adequate airway with bag and mask ventilation without distending the stomach. However, the use of the LMA in these patients may make tracheal intubation unnecessary. The patient must be well anesthetized when the spermatic cord is being manipulated. Inadequate depth of anesthesia at this stage can result in laryngospasm or bradycardia. Caudal epidural anesthesia or ilioinguinal/iliohypogastric nerve block can be quite effective, both in providing postoperative pain relief and in diminishing the intraoperative anesthetic requirements (Markham et al., 1986). Premature infants have a particularly high incidence of inguinal hernias. In these infants, for whom an inhalation anesthetic may have increased risks, spinal anesthesia (Harnik et al., 1986) and caudal epidural (Spear et al., 1988) anesthesia have been used successfully to avoid general anesthesia and endotracheal intubation (Williams et al., 2006).

Orchiopexy

Cryptorchidism affects approximately 0.8% of 1-year-old boys. The undescended testicle may lie within the abdomen, the inguinal canal, or the external ring just proximal to the scrotum. Although the undescended testicle is usually associated with a hernia, the most significant medical risk for the patient is the chance of developing a malignancy, which is 10-fold greater than in a normally descended one.

The objectives of repair for undescended testicles are to alter the course of the spermatic artery from the renal pedicle to the internal ring to the external ring, and to create in its place a direct line from the renal pedicle to the scrotum. However, the surgical approach to patients with undescended testes is not uniform (Hinman, 1987; Heiss and Shandling, 1992). The general approach to patients with a nonpalpable testis is inguinal exploration. If neither the testis nor proof of its absence is found, the lower posterolateral surface of the peritoneal cavity is explored. When the testis is found, it is either removed or surgically placed in the scrotum. This can be accomplished by a staged orchiopexy, autotransplantation of the testis, or Fowler-Stephens procedure. The Fowler-Stephens approach takes advantage of the vascular arcades between the deferential and spermatic arteries in the cord. Because of this collateral blood flow, high ligation of the testicular vessels can preserve the testicular blood supply and provide the surgeon with mobility in bringing the testicle down into the scrotum. The Fowler-Stephens approach has undergone modification and is now generally done in two stages. The first stage involves clipping the spermatic vessel, whereas the second stage, performed months later, involves the formal orchiopexy. With the advent of laparoscopic surgery, both stages of the Fowler-Stephens approach can be done with the aid of a laparoscope (Atlas and Stone, 1992; Bogaert et al., 1993).

The anesthetic considerations are similar to those for inguinal hernia repair. Because of the traction and manipulation of the spermatic cord and testicle, the incidence of intraoperative bradycardia and laryngospasm is somewhat increased. Consequently, a deeper level of anesthesia is required. However, the need for a deeper plane of anesthesia and the risk for bradycardia and laryngospasm can be lessened by the use of intraoperative nerve blocks or regional anesthesia. If an intraabdominal exploration or the use of laparoscopy is anticipated, the trachea is generally intubated. Because the incidence of postoperative nausea and pain is significant, caudal nerve blocks and prophylactic antiemetics, such as ondansetron (0.1 mg/kg) are recommended.

Surgery for Pyloric Stenosis

Pyloric stenosis is one of the most common gastrointestinal abnormalities appearing in the first 6 months of life. This disorder has a polygenic mode of inheritance and occurs four times more commonly in males and more frequently in white infants. The frequency of this disorder ranges from 1.4 to 8.8 per 1000 live births (Zeidan et al., 1988; Dubé et al., 1990; Saunders and Williams, 1990; Bissonnette and Sullivan, 1991; Murtagh et al., 1992). Some controversy exists regarding the associated risk for pyloric stenosis with the maternal postnatal exposure to macrolides (Louik et al., 2002; Sorensen et al., 2003). Pyloric stenosis has been associated with cleft palate and esophageal reflux.

The cardinal features of pyloric stenosis are projectile vomiting, visible peristalsis, and a hypochloremic, hypokalemic, metabolic alkalosis. Although hypokalemia is a frequent finding, Schwartz and colleagues (2003) reported in a retrospective chart review that 36% of patients with pyloric stenosis were noted to have hyperkalemia. Nonbilious vomiting is the classic presenting symptom and generally occurs between 2 and 8 weeks of age. Jaundice occurs in less than 5% of patients and is thought to be associated with caloric deprivation and hepatic glucuronyl transferase deficiency. The jaundice resolves after successful treatment. Diagnosis is made by palpation of an olive-sized mass in the upper abdomen and is frequently confirmed by radiographic studies. Although false-positive studies are rare, false-negative findings can occur in up to 19% of the ultrasound examinations and in 10% of the contrast studies. Preoperative ultrasound measurements of the pylorus correlate well with intraoperative surgical measurements (Muramori et al., 2007).

The pathologic condition involves gross thickening of the circular muscles of the pylorus, resulting in a gradual obstruction of the gastric outlets. Vanderwinden and coworkers (1992) noted a deficiency of nitric oxide synthetase in the muscle layers of infants with pyloric stenosis. The pathophysiology of pyloric stenosis frequently leads to hypovolemia and a hypochloremic metabolic alkalosis.

Winters (1973) outlined the pathophysiology that leads to hypochloremic, hypokalemic, metabolic alkalosis. In pyloric stenosis, persistent vomiting results in a loss of gastric juices rich in hydrogen and chloride ions and, to a lesser extent, sodium and potassium ions. Because the obstruction is at the level of the pylorus, the vomitus does not contain the usual alkaline secretions of the small intestine; the patient develops a metabolic alkalosis. As an increased bicarbonate load is presented to the kidneys, the resorptive capacity of the proximal tubule is overwhelmed, and an increased amount of NaHCO₃ and water is delivered to the distal tubule. Because NaHCO₃ cannot be reabsorbed in the distal tubule, aldosterone secretion occurs. Increased aldosterone increases sodium reabsorption and kaliuresis. Potassium loss is further exacerbated by potassium being exchanged in the tubule for hydrogen in an effort to maintain normal plasma pH.

With persistent vomiting and intravascular volume depletion, the renal response shifts to maintain the patient’s intravascular volume, and sodium conservation occurs. Increased secretion of aldosterone promotes sodium conservation and potassium excretion. In the distal tubule, sodium is also conserved in exchange for hydrogen ions. This may result in a paradoxical aciduria and worsening metabolic alkalosis.

Surgical pyloromyotomy, a relatively simple procedure in the hands of skilled pediatric surgeons, is curative (Fig. 23-4). The operative mortality rates of 10% has declined to less than 0.5%. The surgery can be performed either as an open procedure or laparoscopically. In a comparative study, Campbell and colleagues (2002) noted that laparoscopic pyloromyotomy has become the dominant approach.See related video online at www.expertconsult.com Hall and coworkers (2009) have shown that laparoscopically performed procedures have shorter times for patients to achieve full enteral feeds and faster hospital discharge times than patients having open pyloromyotomy. However, laparoscopic pyloromyotomy is associated with an increased rate of complications, higher hospital charges, and a reduction in the general surgical resident’s operating experience (Campbell et al., 2002). Pyloromyotomy for pyloric stenosis is not a medical emergency that requires immediate surgical intervention. The major anesthetic considerations are recognizing and treating dehydration and acid-base abnormalities before beginning anesthesia. In addition, the patient is at risk for aspirating gastric contents.

FIGURE 23-4 Pyloric stenosis. Operative technique of pyloromyotomy: A, Incision made on anterosuperior surface through avascular area. B, Cross-section of hypertrophied pylorus after operation has been completed. C, Circular muscle is separated, allowing submucosa to bulge. Laparoscopic view of pyloromyotomy: D, Hypertrophied pyloris. E, Incision. F and G, Spreading the incision to the mucosae. H, Upper GI study demonstrates the antral “teat:” shouldering (black arrows), and the elongated, narrowed, double-tracked pyloric channel (white arrows).

(A to C, From Benson CO: Infantile hypertrophic pyloric stenosis. In Welch KJ, et al., editors: Pediatric surgery, ed 4, Chicago, 1986, Year Book Medical; H from Blickman JG, Parker R, Barnes PD: Pediatric radiology, St Louis, 2009, Mosby.)

The initial therapeutic approach is aimed at repletion of intravascular volume and correction of electrolyte and acid-base abnormalities (e.g., 5% dextrose in 0.45% NaCl with 40 mmol/L of potassium infused at 3 L/m² per 24 hours). Most children respond to therapy within 12 to 48 hours, after which surgical correction can proceed in a nonemergent manner. The use of cimetidine has also been shown to rapidly normalize the metabolic alkalosis in patients with hypertrophic pyloric stenosis (Banieghbal, 2009).

Once the child is satisfactorily hydrated and after the appropriate monitors (precordial stethoscope, electrocardiogram, pulse oximeter, and blood pressure cuff) are placed, the infant is ready for induction of anesthesia. The obstructed pylorus and associated vomiting increase the possibility of aspirating gastric contents during induction of anesthesia. A thorough evacuation of stomach contents through a nasogastric or orogastric tube, with proper preoxygenation and monitoring, greatly reduces the chance of regurgitation during induction, although it does not completely eliminate the possibility of aspiration (Cook-Sather et al., 1997). Infants with pyloric stenosis are thus considered by some anesthesiologists to have a status equivalent to that of infants with a full stomach; therefore, a rapid-sequence induction is preferred to secure the airway and minimize the risks of aspiration (Dierdorf and Krishna, 1981; Battersby et al., 1984). On the other hand, mask inhalation induction preceded by careful emptying of the stomach has been used safely in several pediatric centers (MacDonald et al., 1987). In a prospective nonrandomized observational study of 76 infants with pyloric stenosis, Cook-Sather and colleagues (1998) compared three techniques: awake intubation, rapid-sequence intubation, and modified rapid-sequence intubation (ventilation through cricoid pressure). In this study, awake intubation was not superior to anesthetized, paralyzed intubations. Awake intubation prevented neither bradycardia nor oxygen desaturations.

After induction and intubation of the trachea, a nasogastric or an orogastric tube is reinserted and left in place during the operative procedure. This allows the surgeon to test the integrity of the pyloric mucosa after pyloromyotomy. A small volume of air is injected down the nasogastric tube, and the surgeon manipulates the air bubble into the duodenum and occludes the bowel lumen both proximal and distal to the incision. Mucosal perforation is indicated if there is air leakage. After the operation, which usually requires less than 30 minutes, the effects of any nondepolarizing muscle relaxant are reversed. The infant can then be safely extubated when fully awake and with intact protective airway reflexes. Some believe that opioid analgesia is seldom necessary (Battersby et al., 1984) and may predispose patients to a prolonged emergence from anesthesia (MacDonald et al., 1987). It is not unusual to encounter lethargy or drowsiness in these infants in the immediate postoperative period. Respiratory depression has been noted to occur postoperatively and is possibly related to cerebrospinal fluid pH and hyperventilation (Andropoulos et al., 1994). Rare occurrences of hypoglycemia, apnea, convulsions, and cardiac arrest in the early postoperative period have also been cited. These events have been ascribed to the cessation of IV glucose infusions and the depletion of liver glycogen (Shumake, 1975). Infants usually begin oral feedings 8 hours after the procedure. The choice of maintenance anesthetic agent for infants with pyloric stenosis has been studied (Wolf et al., 1996; Chipps et al., 1999; Davis et al., 2001; Galinkin et al., 2001).

Wolf and coworkers (1996) found that clinical postoperative apnea occurred in 3 of 11 infants anesthetized with isoflurane, and in none of the nine infants anesthetized with desflurane. In a multicenter study comparing halothane and remifentanil, where both drugs were administered to similar clinical endpoints, remifentanil was not associated with postoperative respiratory depression. In this study, all infants received both preoperative and postoperative pneumograms, and remifentanil (as opposed to halothane) was not associated with new pneumogram abnormalities in the postoperative period (Davis et al., 2001; Galinkin et al., 2001).

Wilms Tumor Procedures

Wilms tumor is the most common childhood abdominal malignancy, occurring with an incidence, consistent throughout the world, of 5.0 to 7.8 per 1 million children less than 15 years of age. Wilms tumor accounts for about 6% of all malignancies in childhood. The incidence is equal in the two genders. The peak age at diagnosis is between 1 and 3 years. Wilms tumor occurs bilaterally in 5% of patients. Patients with Wilms tumor frequently have associated anomalies (aniridia, 1%; hemihypertrophy, 2%; genitourinary abnormalities, 5%; ectopic and solitary kidneys [horseshoe kidneys, ureteral duplications, hypospadias]). Other associated conditions include Beckwith-Wiedemann syndrome and neurofibromatosis. The signs and symptoms associated with Wilms tumor are variable. The most frequent finding is an increasing abdominal girth with a palpable abdominal mass (85%). Hypertension occurs in 60% of patients, and hematuria is present in 10% to 25%. Acquired von Willebrand’s syndrome with Wilms tumor occurs infrequently (Baxter et al., 2009).

Wilms tumor is generally located in the upper or lower renal pole. It may involve the renal vein (10% of cases) and extend up the vena cava to the right atrium (5% of cases) (Fig. 23-5). Prognosis for patients with the disease is related to its staging (Table 23-1). Patients with favorable staging have an 80% to 90% chance of cure, whereas patients with metastasis have a 50% chance of long-term survival. Risk factors for local recurrence of Wilms tumor include an advanced local stage (involvement of the paraaortic lymph nodes), unfavorable histology, and spillage of tumor at the time of resection (Shamberger et al., 1999). Overexpression of HER2, an oncoprotein, has been shown to be a good predictor of overall survival and longer recurrence-free survival (Ragab et al., 2010). Therapy for Wilms tumor includes surgery, chemotherapy, and radiotherapy. Depending on the size of the tumor and the staging, chemotherapy may be started either before or after surgery. Chemotherapy generally involves vincristine, actinomycin, and anthracycline (doxorubicin).

FIGURE 23-5 Wilms tumor. A, Tumor extension into renal vein and inferior vena cava (IVC). B, Inferior vena cavagram showing IVC displacement and possible invastion of tumor. C, Renal arteriogram feeding vessels into tumor thrombus in IVC. D, CT scan of intraluminal thrombus in the IVC.

(A, From Ehrlich PF: Wilms tumor: progress and considerations for the surgeon, Surg Oncol 16:157, 2007. B, C, and D from Marks WM, Korobkin M, Callen PW, et al: CT diagnosis of tumor thrombosis of the renal vein and inferior vena cava, Am J Roentgenol 131:843, 1978.)

TABLE 23-1 Wilms Tumor Staging

Preoperative evaluation of the patient is related to the presence of metastases and the patient’s cardiopulmonary function. If the patient has had prior chemotherapy with Adriamycin, cardiac function should be assessed by echocardiography (see Chapter 4, Cardiovascular Physiology, and Chapter 36, Systemic Disorders). Serum electrolyte levels should be assessed if there is a history of vomiting. Renal dysfunction is unusual even in patients with bilateral Wilms tumor. Although the surgical approach is generally an open incision, laparoscopic nephrectomy has been reported for the unilateral removal of tumor (Barber et al., 2009; Duarte et al., 2009). Anesthetic considerations revolve around the issue of abdominal distention with delayed gastric emptying and potentially large intraoperative blood losses. Abdominal distention may place the patient at risk for aspiration of gastric contents, so full-stomach precautions should be taken at the induction of anesthesia. Intraoperative blood loss can be a significant factor because of the tumor’s location and possible involvement of the renal vein and vena cava (Cristofani et al., 2007). Two large-bore IV catheters are recommended. Because of the possibility that the vena cava may be cross-clamped (either to be explored for extension of tumor or to control hemorrhage), the large-bore catheters should be inserted above the diaphragm.

Pulmonary function may be compromised because of metastasis, tumor embolization, abdominal distention, or surgical traction. Monitoring of the patient should include pulse oximetry and capnography, as well as the standard monitors of electrocardiography, blood pressure, and esophageal stethoscope. Arterial catheters are generally reserved for patients with large tumors, patients with previous intraabdominal surgery (increased number of adhesions), and patients with significant cardiorespiratory depression.

After induction, anesthesia is maintained with potent inhalation anesthetic agents. Nitrous oxide is avoided because of bowel distention, and opioids are administered to reduce the anesthetic requirements. An alternative approach that provides excellent operative conditions and postoperative pain control is the use of combined general anesthesia with either a continuous epidural infusion or paravertebral catheters.

Neuroblastoma Procedures

Neuroblastoma, the most common extracranial solid tumor of childhood, involves the postganglionic sympathetic nervous system. Fifty percent of tumors arise in the adrenals, 30% occur below the diaphragm, and 20% occur in cervical or thoracic sites. Neuroblastoma accounts for 8% to 10% of pediatric cancer malignancies. The median age at presentation is 22 months, with 37% of patients presenting at less than 1 year of age, and 51% of new patients being less than 4 years of age. Clinical presentation may be related to the primary tumor, to its metastasis, or to the associated paraneoplastic syndromes (Table 23-2). Metastases from neuroblastoma occur in lymph nodes, liver, cortical bone, bone marrow, orbits, and skin. The paraneoplastic syndromes can exhibit hypertension secondary to catecholamine release, or kidney displacement with renal artery stretching and renin-angiotensin stimulus. The gastrointestinal symptoms (diarrhea, flushing, abdominal distention) are attributed to vasoactive intestinal peptides (VIPs), whereas the etiology of opsoclonus and ataxia is unclear.

TABLE 23-2 Presenting Signs and Symptoms of Neuroblastoma

Tumor prognosis has been related to age at presentation, extent of disease (staging), degree of tumor differentiation, amount of catecholamine metabolites, serum ferritin level, lactate dehydrogenase level, neuron-specific enolase level, serum lymphocyte count, ganglioside presence, N-myc amplification, deletion of chromosome 1p, additional copies of chromosome 17q, and TRKA expression (Smith et al., 1989; Hiyama et al., 1991; Berthold et al., 1992; Eckschlager, 1992; Murakami et al., 1992; Qualman et al., 1992; Shuster et al., 1992; Haase et al., 1999). However, patient age and tumor stage are the two most important independent variables (Fig. 23-6). The Evans staging system uses tumor location, lymph node involvement, and presence of metastases, whereas the Pediatric Oncology Group system emphasizes tumor resectability and identification of residual disease to predict survival and treatment.

FIGURE 23-6 Prognoses for patients with neuroblastoma as related to age and staging. A, Children less than 1 year of age. B, Children older than 1 year. Staging is according to the Pediatric Oncology Group (POG) system. Stage A: Complete gross resection of primary tumor, with or without microscopic residua. Intracavitary lymph nodes that are not adhered to and removed with primary (nodes adhered to or within tumor resection may be positive for tumor without upstaging patient to stage C) are histologically free of tumor. If primary is in abdomen or pelvis, liver is histologically free of tumor. Stage B: Grossly unresected primary tumor. Nodes and liver are the same as for stage A. Stage C: Complete or incomplete resection of primary. Intracavitary nodes not adhered to primary histologically are positive for tumor. Liver as in stage A. Stage D: Any dissemination of disease beyond intracavitary nodes: extracavitary nodes, liver, skin, bone marrow, bone. Stage D(S): Would be Evans stage I or II except for metastatic tumor in the liver, bone marrow, or skin. Evans stage I: Tumor confined to the organ of structure of origin. Evans stage II: Tumor extending in continuity beyond the organ or structure of origin but not crossing the midline. Regional lymph nodes on the ipsilateral side may be involved.

(Data courtesy Dr. Jonathan J. Shuster and the Pediatric Oncology Group. From Brodeur GM: Neuroblastoma and other peripheral neuroectodermal tumors. In Fernbach DJ, Viett TJ, editors: Clinical pediatric oncology, St Louis, 1991, Mosby.)

Treatment involves surgical resection and chemotherapy. Although neuroblastoma is radiosensitive, 45% of patients present with metastasis, so the use of radiation is sometimes limited in primary therapy. In a series of adrenal neuroblastomas less than 6 cm not associated with adjacent vessel or organ involvement, DeLagausie and colleagues (2003) reported successful tumor removal with laparoscopic techniques. The anesthetic considerations depend on the planned surgical procedure, the location and size of the tumor, and the metabolic effects of the tumor. Electrolyte imbalance may result from vomiting and diarrhea caused by excessive production of VIP. Despite the production of catecholamines, significant hypertension has been reported in 9% to 30% of patients (Weinblatt et al., 1983; Haberkern et al., 1992).

Intraoperatively, blood loss and third-space fluid losses can accompany the resection of tumor. Haberkern and coworkers (1992) noted in a retrospective review that 45% of patients had hypotension after the tumor excision, whereas fewer than 3% of the patients had cardiovascular signs of increased catecholamine release during tumor resection. Although in patients with mediastinal neuroblastoma, airway complications are rare because of the tumor’s location in the posterior mediastinum, airway compromise can occur, and evidence of airway compression by the tumor should be evaluated before starting the anesthetic induction. IV or inhalational inductions may be performed. Both volatile agents and opioids have been safely used along with combined regional and general anesthetic techniques (Haberkern et al., 1992).

Anti-Gastroesophageal Reflux Procedures

Gastroesophageal reflux (GER) involves a dysfunction of the esophageal sphincter mechanism that allows gastric contents to return into the esophagus. Thus, GER may place an anesthetized patient at risk for aspiration. The clinical spectrum of GER can range from patients who are completely asymptomatic to patients with severe esophagitis, esophageal bleeding, esophageal stricture, malnutrition, and respiratory compromise. In the pediatric population, GER can be physiologic, secondary to immature maturation of the lower esophageal sphincter mechanism; however, this aspect of GER generally resolves by 15 months of age. GER is also seen in children who are neurologically compromised, as well as in patients who have survived diaphragmatic hernias, tracheoesophageal fistula, and esophageal atresia repairs (Barry and Auldist, 1974). GER has also been noted in about 10% of patients who have undergone successful treatment of pyloric stenosis.

In normal children, reflux of gastric contents is prevented by the gastroesophageal junction. This junction is composed of a lower esophageal sphincter (LES). The LES is a high-pressure zone in the distal esophagus that lies in both the mediastinum and the abdomen and becomes functionally mature by 6 weeks of postnatal age. Factors that affect the valve mechanism of the LES include the cardioesophageal angle of His, the esophageal hiatus (a sling of muscle that is part of the diaphragm), and the phrenoesophageal ligament. The degree of reflux, the duration of acid exposure in the esophagus, the ability of the esophagus to clear its contents, and the extent of mucosal damage are the primary factors that determine the degree of esophagitis and consequently its clinical and pathologic significance.

In pediatric patients, the complications of GER include respiratory compromise (bronchospasm, chronic aspiration with pneumonitis, reactive airways disease, and apnea) and esophagitis (esophageal metaplasia, Barrett’s esophagus, stricture, dysphagia). Diagnostic evaluation includes an upper gastrointestinal series, a nuclear scan, an upper endoscopy, and an esophageal pH probe.

Treatment of GER may involve both medical and surgical therapies. Medical therapy consists of both conservative and pharmacologic interventions (thickened feedings, avoidance of overfeeding, postcibal position therapy). The use of medication is aimed at blocking acid secretions using histamine (H₂)-blocker agents (e.g., ranitidine) and improving gastroesophageal motility and gastric emptying (e.g., metoclopramide, bethanechol). Cisapride, a dopamine antagonist, is also used as a motility drug. Its mode of action is postulated to increase the release of acetylcholine from the myenteric plexus and to increase receptor sensitivity to acetylcholine.

Surgical procedures are aimed at establishing an intraabdominal segment of esophagus and creating a physiologic angle of His (Fig. 23-7). The two common procedures are the 360-degree fundoplication of Nissen and the partial wrap of Thal-Nissen. To avoid the gas bloat syndrome (aerophagia, gastric distention, inability to belch or vomit) associated with Nissen fundoplications, the Thal-Nissen partial wrap is frequently used.

FIGURE 23-7 A, Salient features of Nissen fundoplication in infants. Crural sutures to reduce hiatus (A). Generous loose, adequate tissue in the wrap (B). Sutures placed through seromuscular depth of both gastric and esophageal walls (C). Sutures to fix the fundus to the diaphragm (D). Appropriately sized mercury-filled dilator to ensure adequate lumen (E). Gastrostomy in all infants and whenever there is any question of gastric outlet problems (F). B, The Thal fundoplication. A partial wrap of the fundus is performed anteriorly around the lower esophageal segment. C, Laparoscopic view of completed Nissen fundoplication

(A, From Randolph JG: Experience with the Nissen fundoplication for correction of gastroesophageal reflux in infants, Ann Surg 198:579, 1983; illustrated by Peter Stone. B, from Ashcraft KW: Thal fundoplication. In Ashcraft KW, Holder TM, editors: Pediatric esophageal surgery, Orlando, 1986, Grune & Stratton.)

The surgical procedure can be performed as either an open or a laparoscopic procedure (Randolph, 1983; Georgeson, 1993; Rothenberg, 1998; Bourne et al., 2003; Esposito et al., 2003; Steyaert et al., 2003). See related video online at www.expertconsult.com. The failure rates of the surgical approaches appear to be similar (Lopez et al., 2008), and laparoscopic fundoplications can be performed in children who have had previous open procedures (Barsness et al., 2009). In children undergoing laparoscopic antireflux procedures, the physiologic perturbations of pneumoperitoneum, increased intraabdominal pressure, and the associated absorption of carbon dioxide need to be considered.

Surgical success rates approach 95% in pediatric patients with normal neurologic development, but in children who are neurologically impaired, morbidity and mortality remain high. It is important to determine if the underlying symptoms of these patients result from GER as opposed to nasopharyngeal incoordination or esophageal or antral dysmotility; (Martinez et al., 1992; Smith et al., 1992). The presence of GER places the patient at risk for aspiration during induction of anesthesia. Preoperative preparation with H₂-blockers and motility drugs should be continued. A rapid-sequence induction should be used if a difficult airway is not anticipated. At least one large-bore IV catheter should be placed, although fluid and blood losses are minimal. However, pneumothorax, lacerated spleen, puncture, or compression of the vena cava or aorta, and lacerated hepatic veins can occur.

Other anesthesia concerns in patients with GER are the degree of neurologic and respiratory compromise of the patient. Because these children frequently have seizure disorders, preoperative concern should be directed at proper anticonvulsant therapy. Oral anticonvulsants generally cannot be administered for 48 to 72 hours in the postoperative period. Consequently, patients requiring carbamazepine and valproic acid need alternative medicines so that breakthrough seizures do not occur. In addition, a significant number of patients with neurocompromise may also have ventricular-peritoneal shunts. However, the Nissen fundoplication does not appear to increase the risk for shunt infection to more than the risk of placing a shunt (Bui et al., 2007).

For children with severe respiratory compromise or neuromuscular disease, postoperative ventilatory support may be necessary. In children without significant preoperative pulmonary compromise, extubation may be delayed after surgery and supplemental oxygen given as needed. After surgery, the use of antireflux medication decreased. Within 1 year of surgery, 75% were reported on antireflux medication (Lee et al., 2008).

Surgery For Biliary Atresia

Biliary atresia, characterized by a lack of gross patency of the extrahepatic bile duct, occurs in 1:15,000 live births (Shim et al., 1974). In 10% to 15% of patients, other abnormalities associated with embryologic development are seen, including absent inferior vena cava, intestinal malrotation, polysplenia, and preduodenal portal vein (Lilly and Chandra, 1974). Although biliary atresia is often considered a congenital lesion, it has dynamic properties as well. In microscopic studies of the biliary anatomy obtained from patients at 2 and 4 months of age, the histologic results suggest that biliary structures gradually disappear and are replaced by fibrous tissue. In addition, the success rate for the palliative surgical procedure has been reported as 50% in infants operated on before 4 months of age and 80% in those undergoing surgery before 2 months of age (Ohi et al., 1985). In a study by Serinet and colleagues (2009), among 695 patients who underwent the Kasai procedure, the 2-, 5-, 10-, and 15-year survival rates were 57.1, 32.9, 32.4, and 28.5%, respectively. Increased age at the time of Kasai procedure has been associated with decreased survival rates (Serinet et al., 2009).

Kasai and coworkers (1989), in a review of 245 patients undergoing corrective procedures over a 35-year period, noted that 10-year survival was 74% in infants operated on before 60 days of life. However, Tan and colleagues (1994) have questioned whether earlier corrective surgery is associated with ductal patency. In a series of 205 patients, they noted that survival may be more closely related to the severity of intrahepatic biliary cholangiopathy.

In a 27-year review of 81 patients with biliary atresia, Wildhaber and coworkers (2003) noted that direct bilirubin of less than 2.0, the absence of bridging liver fibrosis, and the number of cholangitis episodes were predictive factors in the success of the Kasai portoenterostomy. Popovic and colleagues (2003) noted that cholinesterase levels can be a useful index of liver function (protein synthesis) early after the Kasai procedure and is independent of albumin synthesis.

Clinically, biliary atresia presents in infants from 1 to 6 weeks of age. About 50% are anicteric until the second or third week of life. The diagnosis of biliary atresia is confirmed either by liver biopsy or by exploratory laparotomy. Surgical palliation for biliary atresia involves hepatic portoenterostomy (Kasai procedure) (Fig. 23-8).

FIGURE 23-8 The Kasai procedure and its various modifications. A, Original Kasai. B, Kasai H-double-barreled vent. C, Bishop-Koop vent. D, Gallbladder Kasai.

(From Filston HC, Izant RJ Jr: The surgical neonate, evaluation, and care, Norwalk, Conn, 1985, Appleton-Century-Crofts.)

Complications of the surgical repair and from the underlying disease state include cholangitis, portal hypertension, and fat-soluble vitamin deficiency (Kasai et al., 1975). For the anesthesiologist, these complications take on greater significance in patients who return to the operating room for further surgical revision of biliary drainage, treatment of intraabdominal sepsis, or relief of an intestinal obstruction. Because these complications occur frequently and because end-stage liver disease can follow the Kasai procedure, the role of liver transplantation as a primary treatment of biliary atresia has been raised. Kasai and coworkers (1989) suggested that liver transplantation as a primary form of treatment may be indicated for patients older than 3 months with an enlarged, hard liver. Laurent and colleagues (1990) noted that although Kasai’s operation does improve the prognosis of biliary atresia, it is not a definitive cure, and 80% of these patients become candidates for liver transplantation.

Anesthetic management for a Kasai procedure (Kasai, 1974) in patients with biliary atresia follows the basic principles of pediatric anesthesia. In infants in whom venous access is already present, induction is achieved with a hypnotic agent, such as propofol (2 to 3 mg/kg), and a muscle relaxant (cisatracurium, 0.2 mg/kg). In infants without an IV catheter in place, inhalation induction is performed with oxygen, nitrous oxide, and sevoflurane. Once the child is adequately anesthetized, an IV catheter is inserted and a muscle relaxant is administered to facilitate endotracheal intubation and to decrease the concentration of potent inhalation anesthetic. After induction, anesthesia is maintained with an oxygen-air-isoflurane mixture along with IV opioids. Because of bowel distention, nitrous oxide is avoided.

Gelman and coworkers (1984) have shown that hepatic blood flow and oxygen supply are better maintained during isoflurane than during halothane anesthesia. Consequently, isoflurane in an oxygen and air mixture is most commonly administered to patients undergoing surgery for biliary atresia.

Anesthesia monitoring for the patient undergoing a Kasai procedure is similar to that used for other pediatric surgical procedures. Arterial cannulation and central venous pressure monitors are rarely used and are generally reserved for patients with coexisting problems, such as sepsis, pneumonia, cholangitis, and severe cirrhosis. In general, hemodynamic stability is well maintained and the need for intraoperative vasoactive agents is rare. Sometimes the surgical approach involves dividing the triangular and coronary ligaments and displacing the whole liver anteriorly. Although this technique may facilitate exposure, it may compress the inferior vena cava and thereby result in hypotension by decreasing venous return. Ventilation is controlled and end-tidal gases are monitored for carbon dioxide, oxygen, and volatile anesthetic agents. Adequacy of oxygenation is monitored by the pulse oximeter.

The operative procedures generally last 3 to 4 hours, and major blood loss does not occur. Perioperative fluid therapy involves replacement of maintenance and deficit fluids as well as provision for the calculated third-space losses. Third-space losses may vary from 6 to 10 mL/kg per hour. Generally, lactated Ringer’s solution is used to restore third-space losses.

Prevention of hypothermia is a major concern for the anesthesiologist. The large surface-to-volume ratio of infants, their relative lack of insulation tissue, coupled with the cold operating room, exposure of body cavities to low environmental temperatures, infusions of cold fluid, and ventilation with dry gases, all increase the potential for hypothermia during surgery. Consequently, great effort must be applied both before and during surgery to protect against heat loss. Methods of preventing heat loss are discussed in Chapter 6, Thermoregulation: Physiology and Perioperative Disturbances.

The pharmacology of anesthetic agents in infants and children with hepatic disease has not been fully evaluated. Although the liver is the major site of drug biotransformation, the effects of hepatic dysfunction on drug elimination and disposition are inconsistent. The degree of liver dysfunction and the drug’s ability to bind to plasma proteins are important variables in determining drug kinetics in patients with liver disease.

In general, liver function is fairly well preserved in the first few months of life in children with biliary atresia. As the children get older and ductal fibrosis begins, liver dysfunction ensues. Consequently, in children who return for repeat surgical procedures, the pharmacology of IV anesthetic agents and adjuncts may be altered.

In infants with biliary atresia undergoing the Kasai procedure, if major fluid shifts have not occurred, blood loss has been minimal, and the patient has remained warm, all efforts are made to reverse the muscle relaxation and extubate the trachea at the end of the procedure. In children with other organ system failures (specifically sepsis, cholangitis, or pneumonia), those who are cold at the end of the procedure (<35° C), or those who have undergone transfusion of more than one blood volume, extubation is delayed until warmth and hemodynamic stability are restored. In these children, postoperative recovery and monitoring are carried out in an intensive care setting. The long-term (5-, 10-, and 20-year) survival rates for 80 children after a Kasai procedure, without transplantation, were 63%, 54%, and 44%, respectively. By age 20, almost half had cirrhosis and its sequelae (Shinkai et al., 2009).

Liver Tumor Procedures

Liver tumors in children are uncommon, but 72% of pediatric primary hepatic tumors and 1.1% of all childhood tumors are malignant. Of these malignant tumors, hepatoblastoma and hepatocarcinoma are the predominant tissue types (Table 23-3). Hepatoblastoma commonly affects white boys less than 2 years of age. An abdominal mass that has increased in size is usually the presenting symptom. Anemia, jaundice, and ascites are infrequent findings. Liver function test results are frequently normal. From 2% to 3% of patients may have an associated hemihypertrophy (Geiser et al., 1970). Hepatoblastoma has also been associated with isosexual precocity as a result of the liver’s ectopic gonadotropic production and the Beckwith-Wiedemann syndrome (Sotelo-Avita et al., 1976), polyposis coli, Wilms tumor, and fetal alcohol syndrome. An increased incidence of hepatoblastoma has been associated with low birth weight (Ikeda et al 1997; Feusner et al., 1998) (Box 23-4). Between 1973 and 1997, the rate of hepatoblastoma increased. This is in contrast to the decreased incidence observed for hepatocarcinoma (Darbari et al., 2003).

TABLE 23-3 Malignant Hepatic Tumors

From Exelby PR, Filler RM, Grosfeld JL: Liver tumors in children in the particular reference to hepatoblastoma and hepatocellular carcinoma: American Academy of Pediatrics Surgical Section Survey—1974, J Pediatr Surg 10:329, 1975.

Hepatoblastomas are derived from primitive epithelial parenchyma and are classified by the predominant epithelial component. Among the variants are fetal, embryonal, macrotrabecular, and anaplastic. Survival is related to the histology and completeness of the surgical resection (Table 23-4). Fetal histology has a greater than 90% survival rate, compared with a 50% survival rate for embryonal histology. A few survivors have anaplastic histology. Patients with resectable stages I and II hepatoblastomas have better survival (95%) than patients with unresectable stage III (69%) or metastatic disease (37%). For patients with resectable disease, a 5-year survival rate is 83%, as opposed to 41% for those who had residual tumor after surgery (Finegold et al., 2008) (see Box 23-4). Complete surgical resection offers the only chance for cure in patients with hepatocellular carcinoma, because the tumor is chemoresistant. In patients requiring a liver transplant, the 1-, 5-, and 10-year survival rates are 86%, 67%, and 58%, respectively (Fig. 23-9).

TABLE 23-4 Children’s Oncology Group Staging for Hepatoblastoma

From Finegold MJ, Egler RA, Goss JA, et al: Liver tumors: pediatric population, Liver Transpl 14:1545, 2008.

FIGURE 23-9 One-year patient survival: United Network for Organ Sharing (UNOS) standard transplant and research file 1989–2007. A total of 8047 patients (age, <18 years) who underwent orthotopic liver transplant between 1989 and 2007 were analyzed from the UNOS database. Of these patients, 237 underwent transplantation for hepatoblastoma, 58 for hepatocellular carcinoma, 35 for hemangioendothelioma, and 36 for other tumors. HB, Hepatoblastoma; HCC, hepatocellular carcinoma; HEH, hemangioendothelioma.

(From Finegold MJ, Egler RA, Goss JA, et al: Liver tumors: pediatric population, Liver Transpl 14:1545, 2008 [fig. 6].)

Liver transplantation has been used as both a primary surgical therapy and a rescue for incomplete resection or recurrence of disease. Patients who were rescued had a 30% disease-free survival compared with 82% in the primary treatment group (Otte et al., 2004).

Hepatocellular carcinoma appears to have two age peaks: one at less than 4 years of age and the other between 12 and 15 years of age (Leventhal, 1987). As in adults with hepatocellular carcinoma, the prognosis of survival in children with the disease is 5% to 10%. Typically, patients with hepatocellular carcinoma have the systemic symptoms of weight loss, jaundice, fever, and lethargy. As opposed to adults with this tumor, only about 5% of children have associated cirrhosis (Jones, 1960). Other associated diseases include von Gierke’s disease, type I glycogenesis, cystinosis, extrahepatic biliary atresia, α₁-antitrypsin deficiency, hypoplasia of intrahepatic bile ducts, Wilson’s disease, giant cell hepatitis, and Solo’s syndrome (Zangeneh et al., 1969; Palmer and Wolfe, 1976; Weinberg et al., 1976; Dehner, 1978) (see Box 23-4). Complete surgical resection offers the only chance for a cure for patients with hepatocellular carcinoma, because the tumor is chemoresistant. In patients requiring a liver transplant, the 1-, 5-, and 10-year patient survival rates are 86%, 67%, and 58%, respectively (see Fig. 23-9).

Anesthetic management for pediatric patients undergoing hepatic lobe resection or tumor resection involves the same principles as for patients with biliary atresia. Efforts at maintaining adequate alveolar ventilation, temperature homeostasis, cardiovascular stability, and fluid management have been described. Some patients receive adjunct chemotherapy before surgery. The chemotherapeutic protocol must be reviewed. Frequently, Adriamycin, an anthracycline, is a major component of hepatic cancer chemotherapy and has been associated with a dosage-dependent irreversible cardiomyopathy. All patients receiving anthracycline chemotherapy should be studied by history, physical examination, electrocardiography, chest radiography, and echocardiography to further evaluate signs and symptoms of cardiac toxicity and cardiac reserve (see Chapters 4 and 36, Cardiovascular Physiology and Systemic Disorders).

Because the potential for massive blood loss exists in patients undergoing hepatic resection, adequate venous access and invasive monitoring are essential to patient management. Two or three large-bore peripheral IV catheters are inserted, and a central venous pressure catheter is placed to monitor cardiac filling pressures. Either the radial or the femoral artery is cannulated, not only to monitor blood pressure but also to determine blood gas levels, chemistry, and coagulation profile. Because of the potential for large fluid shifts, a Foley catheter is placed to measure urine output and assist in assessing the adequacy of fluid resuscitation.

Massive blood volume replacement is a frequent component of the anesthetic resuscitation in children undergoing hepatic resection. Massive blood volume replacement may create physiologic derangements that have anesthetic and surgical consequences. These physiologic alterations include disorders of coagulation, acid-base imbalance, electrolyte imbalance, hypothermia, and decreased tissue oxygen delivery.

Many children undergoing tumor resection require postoperative ventilatory support. The anesthetic plan should permit early tracheal extubation in the operating room. However, in the event that intraoperative findings reveal unresectable tumor, postoperative care should include observation in the pediatric intensive care unit and attention to changes in intravascular volume and blood pressure. Continued bleeding may require transfusion of blood or fresh frozen plasma, or even return to the operating room for surgical control.

Hirschsprung’s Disease Procedures

The basic pathology underlying congenital megacolon, or Hirschsprung’s disease, is aganglionosis, or total absence of ganglion cells, in the intrinsic nerve supply of the bowel. The aganglionic area extends proximally from the anal sphincter and involves varying lengths of colon. The normal nerve supply, consisting of Auerbach’s plexuses and Meissner’s plexuses, which together form the myenteric nerve complex of the bowel, usually becomes an increasingly diffuse network in the descending and terminal portions of the bowel. Absence of the ganglion cells, which occurs in approximately 1 in 10,000 infants, causes a condition resembling spasm in the area without ganglion cells, and the normal bowel proximal to the spastic portion undergoes tremendous distention, with retention of feces and intestinal obstruction or, in less serious cases, prolonged bouts of constipation. Although the cause of Hirschsprung’s disease is unknown, defects in nonadrenergic, noncholinergic innervations may prevent relaxation of the aganglionic segment. Bealer and colleagues (1994) demonstrated that nitric oxide synthetase is deficient in the aganglionic colon of patients with Hirschsprung’s disease, and that this deficiency may prevent smooth muscle relaxation of the aganglionic segment. On a molecular level, mutations in the RET protooncogene have been found (Sancandi et al., 2000).

In 10% to 20% of patients with Hirschsprung’s disease, it is clinically present at birth. Symptomatic infants have delayed passage of meconium, irritability, failure to thrive, and abdominal distention. Older children may present with constipation, fecal soiling, and diarrhea. The major complication from Hirschsprung’s disease is acute enterocolitis, a potentially life-threatening event. Diagnosis of Hirschsprung’s disease is made by radiographic examination and confirmed by suction biopsy specimens from the rectum. Surgery is usually a two-stage procedure, with the initial procedure being a colostomy. The definitive surgical procedure is generally performed when the child is older (>1 year). The surgical approaches are varied and over time have undergone modifications (Fig. 23-10). Attention has focused on the use of a one-stage transanal endorectal pull-through approach (Elhalaby et al., 2004). Each surgical technique has its own associated intraoperative and perioperative complications, but enterocolitis, wound dehiscence, anastomotic leakage, intestinal obstruction, and fecal soiling are common to all. All of these surgical procedures aim either to excise or to bypass the aganglionic portion of the bowel and to free and advance the remaining normal portion of bowel toward the rectum. These procedures are often long (6 to 8 hours) and involve surgical explorations through the perineum and abdomen.

FIGURE 23-10 Lateral views of the three major operative procedures for Hirschsprung’s disease. Evolution of each occurs from left to right. Unshaded native rectum is aganglionic. Shaded, pulled-through bowel contains ganglion cells. A, State’s procedure was a prototypical anterior resection of dilated rectosigmoid. Lengthy aganglionic segment remained. In Swenson’s procedure, an oblique anastomosis resulted in ganglion cells within 1 cm of the verge posteriorly. B, In the original Duhamel’s operation, the oversewn native rectum enlarged as a blind loop, which resulted in a fecaloma that caused partial obstruction. In Martin’s modification, the blind loop is obviated by complete division of the septum and anastomosis of the anterior walls of the native rectum and pulled-through colon. Bowel that contains ganglion cells reaches within 1 cm of the anal verge posteriorly. C, In the original Soave’s procedure, full-thickness colon that contained ganglion cells was advanced through the demucosalized native rectal sleeve. Excess colon extended from the anus for several weeks before transection and delayed anastomosis. In the Boley modification, a primary anastomosis is done 1 cm above the verge. Ganglion cells are present circumferentially at that level.

(From Philappart AI: Hirschsprung’s disease. In Ashcraft KW, Holder TM: Pediatric surgery, ed 2, Philadelphia, 1993, Saunders.)

Laparoscopic surgery has also been used in the treatment of Hirschsprung’s disease (Jona et al., 1998; Wulkan and Georgeson, 1998; Georgeson et al., 1999). The minimally invasive assisted pull-through technique is generally used for patients when the aganglionic segment is confined to the rectum sigmoid or proximal left colon (Georgeson, 2002). Anesthetic concerns for patients with Hirschsprung’s disease are similar to those for any child having surgery. Maintaining body temperature and providing appropriate fluid therapy (for replacement of large third-space losses) are the major challenges for the anesthesiologist.

Anesthesia induction can be either by inhalation or IV means. Because of the surgical bowel manipulation and the relatively obstructive nature of the underlying disease, nitrous oxide is discontinued after induction, and anesthesia is maintained with a mixture of air, oxygen, and potent inhalation agent. Long-term follow-up of patients with Hirschsprung’s disease suggests that 25% of patients will require reoperation, and that 19% to 25% of patients will develop enterocolitis (Fortuna et al., 1996).

Surgery For Appendicitis

Acute appendicitis is a common condition in children. Although the mortality from acute appendicitis is rare (case-fatality ratio, 0.3%) (Addiss et al., 1990), morbidity (peritonitis, abscess formation, wound infection) is related to the state of the appendix at the time of the operation. The highest incidence of appendicitis is found in patients aged 10 to 19 years. The incidence of perforation of the appendix in children appears to be about 30% to 45%, but in preschool children and infants it can be as high as 80%. The incidence of appendicitis appears to be affected by race and gender. The incidence of appendicitis is 1.4 to 1.6 times greater in whites than nonwhites, whereas the perforation rate for nonwhites is 22% compared with 18% for whites (Addiss et al., 1990).

The signs and symptoms of appendicitis are variable. The incidence of negative appendectomy (surgery performed without positive appendicitis) is significant. In males, the negative appendectomy rate is about 9%, whereas in females it is about 22%. In females, diagnostic accuracy decreases during childbearing years, whereas in males, diagnostic accuracy does not appear to be affected by age. Classically, the patient presents with periumbilical pain that eventually localizes to the right lower quadrant. Anorexia, nausea, and vomiting are frequent, as is a low-grade fever. Continued progression of the inflammatory course results in increased tenderness in the right lower quadrant as well as pain referred to the right lower quadrant on palpation of other areas of the abdomen. With advanced disease, gangrene and perforation of the appendix occur, with ensuing peritonitis and possible abscess formation. Both ultrasound and computed tomographic (CT) imaging have been used to evaluate appendicitis in children. The advantages of ultrasound include cost, lack of exposure to radiation, and its ability to assess ovarian pathology, but CT affords a higher diagnostic accuracy and better delineation of extent of disease where the appendix is perforated.

The pathophysiology of appendicitis is thought to be related to an obstruction of the lumen of the appendix, with subsequent bacterial overgrowth and distention of the appendix (Fig. 23-11). In untreated cases, distention and overgrowth lead to gangrene and rupture. Although there is some urgency in making the diagnosis and surgically removing the appendix, the operation is never so urgent that a proper review of the patient’s medical history and physical assessment cannot be performed.

FIGURE 23-11 Laparoscopic acute appendicitis.

Preoperative anesthetic management of the child with diagnosed appendicitis includes concerns regarding fluid and electrolyte disorders. Because these children may have been vomiting and may be febrile, signs and symptoms of dehydration should be assessed and any fluid or electrolyte deficits corrected.

Once the child has been adequately volume-resuscitated and a normal airway is anticipated, an IV rapid-sequence induction with cricoid pressure is performed. Anesthetic technique (inhalation agents versus opioid-based techniques) may depend on the surgical technique used to remove the appendix. Although frequently the appendix is removed by laparotomy, the role of laparoscopy (especially in female patients) in both diagnosis and management is increasing (Gilchrist et al., 1992; Kuster and Gilroy, 1992; Olsen et al., 1993). See related video online at www.expertconsult.com In a study by McAnena and coworkers (1992), the median postoperative hospitalization stay was one half and the rate of wound infection one third in patients undergoing laparoscopic appendectomy compared with patients undergoing open appendectomy. In a study involving 30 pediatric hospitals, Newman and colleagues (2003) noted significant variability in practice and resource utilization among the institutions. In addition, the length of stay did not differ between those patients who underwent an open or a laparoscopic appendectomy.

Regardless of surgical technique, monitoring of the patient includes electrocardiogram, pulse oximeter, temperature probe, blood pressure cuff, precordial stethoscope, and end-tidal gas measurements. Depending on the patient’s body temperature, active cooling techniques (cooling blanket, rectal acetaminophen suppositories, cool IV fluids, and cool intraabdominal irrigations) may be needed to help lower the patient’s temperature. The addition of inhalational anesthetics may also augment cooling by promoting cutaneous vasodilation with subsequent increased heat loss.

Intussusception Repair

Intussusception is the invagination or telescoping of one portion of the intestine into another (Fig. 23-12). It tends to occur more frequently in males than females. Over 50% of cases occur in children less than 1 year of age, and less than 10% of cases occur in children older than 5 years. Ninety percent of cases have idiopathic causes—frequently seen in children less than 1 year of age. Older children are more likely to have Meckel’s diverticulum, intestinal polyps, lymphoma, adhesions, trauma, hemolytic uremic syndrome, or ectopic pancreatic nodule as an etiology. Intussusception has also been reported postoperatively and after blunt abdominal trauma (Komadina and Smrkolj, 1998; Linke et al., 1998). In addition, an association between rotavirus vaccine and intussusception has been reported (Zanardi et al., 2001).

FIGURE 23-12 A, Intussusception. B, Laparoscopic view of intussusception, C, Laparoscopic view of reduced intussusception with hypertrophid Peyer’s patch at the lead point. D, Diagnostic enema encounters the intussusceptum in the mid-transverse colon (M). E, The coiled-spring appearance of an ileocolic intussusception: the contrast material has interdigitated between the intussusceptum and the intussuscipiens

(A, From deLorimier AA, Harrison MR: Pediatric surgery. In Dunphy JE, Way LW: Current surgical diagnosis and treatment, Los Altos, Calif, 1979, Lange Medical. D and E, From Blickman JG, Parker R, Barnes PD: Pediatric radiology, St Louis, 2009, Mosby, p 73.)

The clinical presentation of acute intussusception involves sudden paroxysms of abdominal pain, bloody stools, and an abdominal mass, although in one series of patients, 18% of the children had painless intussusception (Hutchison et al., 1980). In a review of 14 published reports, Losek (1993) noted that bloody stools were present in 42% of patients. Occult blood was noted in 43% and abdominal masses were present in 62% of patients. Intussusception can also manifest with neurologic findings (lethargy, apnea, seizures, hypotonia, opisthotonus) similar to a picture of septic encephalopathy (Conway, 1993). Other symptoms and signs may include diarrhea, vomiting, fever, and dehydration. In other children, intussusception can be a chronic entity that may mimic gastroenteritis (Shekhawat et al., 1992), whereas in neonates, intussusception may mimic necrotizing enterocolitis (Price et al., 1993).

About 90% of intussusceptions are ileocolic, and the remainder are ileoileal and colocolic. Treatment for intussusception involves the administration of appropriate fluids to combat dehydration, and radiologic or surgical attempts to reduce the invaginated bowel. Hydrostatic enemas with barium or air have been reported to be successful in 80% of patients. However, enemas are contraindicated in patients with evidence of peritonitis, shock, and intestinal perforation. Surgical laparotomy with manual reduction or resection (or both) as well as laparoscopic approaches have been described for surgical management in patients with unsuccessful radiologic reduction and in patients with signs of intestinal perforation, peritonitis, and shock (Hay et al., 1999).

Anesthetic considerations include restoring electrolyte and fluid deficits. Shock should be treated before commencing anesthesia. The intravascular deficits may be further exacerbated by the presence of barium in the gastrointestinal tract. The child with an intussusception should also be considered at risk for aspiration, and because of the intestinal obstruction, nitrous oxide should be avoided. Anesthesia should be induced with IV agents. If hemodynamic instability is a concern, ketamine or etomidate should be used as the hypnotic agent for induction.

Thoracoscopy

During the past decade, the use of video-assisted thoracoscopic surgery has dramatically increased in both adults and children (see Video Endoscopy, p. 745). As with laparoscopy, reported advantages of thoracoscopy include smaller chest incisions, reduced postoperative pain, and more rapid postoperative recovery compared with thoracotomy (Weatherford et al., 1995; Angelillo Mackinlay et al., 1996 Mouroux et al., 1997).

Thoracoscopic surgery is being used extensively for pleural débridement in patients with empyema, lung biopsy, and wedge resections for interstitial lung disease, mediastinal masses, and metastatic lesions. More extensive pulmonary resections, including segmentectomy and lobectomy, have been performed for lung abscess, bullous disease, sequestrations, lobar emphysema, CCAM, and neoplasms. Thoracoscopic procedures used in infants and children are listed in Box 23-6.

Thoracoscopy can be performed while both lungs are being ventilated using CO₂ insufflation and a retractor to displace lung tissue in the operative field. However, SLV is extremely desirable during thoracoscopy, because lung deflation improves visualization of thoracic contents and may reduce lung injury caused by the retractors (Benumof, 1995).

Surgery for Chest Wall Deformities

Pectus excavatum (funnel chest) (Fig. 23-13) and the less common pectus carinatum (pigeon breast) deformities are congenital abnormalities of the sternum, ribs, and costal cartilages. These deformities are usually minimal at birth but progress with age. A higher incidence of both deformities occurs in children with Marfan syndrome or congenital heart disease, and in families in which other children have the defect (Shamberger and Welch, 1987; Robicsek and Lobato, 2000). These children often appear asymptomatic but occasionally have cardiac or pulmonary abnormalities related to the deformity (Malek et al., 2003). Patients with pectus excavatum generally present with normal or modestly reduced forced vital capacity and total lung capacity and, in severe cases, V/Q mismatch. The heart is displaced to the left and compressed, lending to arrhythmias, right-axis deviation on electrocardiogram, a functional murmur, and reduced stroke volume—most noticeable in the standing position and during exercise, explaining the mild exercise intolerance experienced by some patients. The cardiac and pulmonary abnormalities are in most instances benign and may worsen as the child ages but may be improved by surgical repair. There also is an increased incidence of mitral valve prolapse in patients with pectus deformities (Shamberger et al., 1987).

FIGURE 23-13 Pectus excavatum deformity becomes most obvious when the child is in the sitting position.

Preoperative assessment focuses on exercise tolerance and other signs of cardiopulmonary compromise, such as lung infections. Laboratory evaluation includes a chest radiograph; pulmonary function tests, arterial blood gases, and electrocardiogram are added only if there is clinical evidence of significant underlying disease. Echocardiography is now commonly performed to detect the presence of mitral valve prolapse, and, if the child has it, prophylaxis for subacute bacterial endocarditis is administered. Patients are often emotionally distressed by the appearance of a chest deformity and may benefit from preoperative counseling and, if needed, premedication.

Classic operative repair involves extrapleural excision of the sternocostal cartilages and mobilization of the sternum and ribs. The most common complications of operative repair are pneumothorax, flail chest, and postoperative atelectasis; blood loss is usually minimal to moderate. Intraoperative monitoring includes temperature, blood pressure, pulse, heart and breath sounds, airway pressure, and oxygen saturation or tension. Capnography is also useful, but arterial catheterization is needed only if there is a specific indication. General anesthesia with controlled ventilation is the method of choice, with no agents specifically indicated or contraindicated because of the operation itself. Oxygen by face mask is administered in the recovery room, but it is usually not needed after the child fully awakens. Although patient-controlled analgesia is commonly used for postoperative analgesia, both intercostal nerve blocks and thoracic epidural analgesia have become increasingly popular for children undergoing pectus repair (Robicsek, 2000).

A thoracic epidural catheter provides more reliable analgesia to the operative area than a lumbar epidural that has been threaded a great distance. However, thoracic epidural catheters are not as easy to insert as lumbar catheters, and many practitioners are not comfortable with their routine use. Although a technique using electrocardiographic guidance and insertion from the caudal space has been described, it is not widely used (Tsui et al., 2002). An additional issue with the thoracic catheters is the safety of their insertion under general anesthesia (Horlocker, 2003). Although some children allow insertion before induction (McBride et al., 1996), many younger children are not likely to remain cooperative for the procedure, mandating insertion after induction (Hammer, 2002; Birmingham et al., 2003). Moreover, several centers have actively and successfully used thoracic epidural techniques in anesthetized children for thoracic and cardiac procedures without complications related to insertion after induction (Cassady, 2000; Birmingham, 2003). Solutions of both bupivacaine with fentanyl and fentanyl alone have been used successfully, including in the patient-controlled mode for appropriately mature children (Caudle et al., 1993; Birmingham et al., 2003) (see Chapter 16, Regional Anesthesia).

Another approach is to use a minimally invasive technique in which the costal cartilages are preserved and the sternum is elevated with a bar. Under direct vision and through a thorascope, a transmediastinal tunnel is created and a prebent bar is passed behind the sternum with the convex side down. The bar is then rotated 180 degrees to elevate the sternum (Fig. 23-14) (Nuss et al., 1998; Nuss, 2002). Borowitz and coworkers (2003) have shown that static pulmonary function and ventilatory response to exercise was normal both before and after surgery, thereby suggesting that placement of the bar does not result in an increased chest wall restriction. In addition, Lawson and colleagues (2003) noted that the surgical repair of the pectus excavatum after the Nuss procedure had a positive impact on the patient’s physical and emotional well-being. Complications of this minimally invasive approach include atelectasis, subcutaneous emphysema, pericardial and pleural effusions, myocardial perforation, diaphragmatic perforation, and dislocation of the stabilizing bar (Willekes et al., 1999; Hebra et al., 2000; Molik et al., 2001; Moss, 2001; Hosie et al., 2002; Uemura et al., 2003). Postoperative pain after the Nuss procedure is significant. Thoracic epidural analgesia for 2 to 3 days, followed by oral opioid and nonsteroidal antiinflammatory drug therapy, is appropriate.

FIGURE 23-14 CT scan of a patient undergoing Nuss procedure (A). AP (B) and lateral (C) radiographs of a patient with a Nuss bar in place.

Thoracotomy, Lobectomy, and Pneumonectomy

Thoracotomy in the infant or child may be indicated for congenital abnormalities (cysts), tumors (mediastinal teratomas), trauma (gunshot wounds), or infective lesions (bronchiectasis). Subsegmental resection is used for biopsy and removal of metastatic tumors, whereas lobectomy is most commonly used for removal of congenital anomalies and extensive tumor metastasis. Pneumonectomy in children is done for various tumors, congenital abnormalities, and inflammatory lesions such as bronchiectasis. Perioperative management differs dramatically depending on the indication for surgery.

Anesthesia

General endotracheal anesthesia presents various challenges to the anesthesiologist. A quiet, smooth inhalation induction is often used in infants and smaller children, whereas an IV induction is used in the older child. If there is concern about spillage of lung contents, rapid securing of the airway with IV induction is preferred to minimize coughing. The choice of appropriate anesthetic agents depends on both the patient’s status and the surgical lesion. Nitrous oxide can accumulate in cysts with air-fluid levels and should be avoided in these patients or in patients requiring a high fraction of inspired oxygen (Fio₂). Volatile agents are especially useful in patients with bronchospastic disorders. The rate of rise of inhalational anesthetics may be slowed in the presence of intrapulmonary shunting. Precipitous hypotension is another potential problem with volatile agents in patients with low cardiac reserve. Muscle relaxants are routinely used along with controlled ventilation employing humidified gases. Although mechanical ventilators are usually acceptable, manual ventilation provides useful information to the anesthesiologist about changes in compliance or airway resistance, especially in infants or in procedures where there is recurrent obstruction of the airway.

Single-Lung Ventilation Techniques

Single-Lung Ventilation Using a Single-Lumen Endotracheal Tube

The simplest means of providing SLV is to intentionally intubate the ipsilateral main stem bronchus with a conventional single-lumen ETT (Baraka, 1987; Kubota et al., 1987; Rowe et al., 1994). See related video online at www.expertconsult.com. When the left bronchus is to be intubated, the bevel of the ETT is rotated 180 degrees and the patient’s head is turned to the right (Bloch, 1986; Kubota et al., 1987). The ETT is advanced into the bronchus until breath sounds on the operative side disappear. A fiberoptic bronchoscope (FOB) may be passed through or alongside the ETT to confirm or guide placement (Watson et al., 1982). When a cuffed ETT is used, the distance from the tip of the tube to the distal cuff must be shorter than the length of the bronchus so that the ETT does not occlude the upper lobe bronchus (Lammers et al., 1997) (Fig. 23-15). This technique is simple and requires no special equipment other than a FOB. This may be the preferred technique of SLV in emergency situations such as airway hemorrhage or contralateral tension pneumothorax.

FIGURE 23-15 Obstruction of the left upper lobe bronchus with a cuffed endotracheal tube used for left-sided, single-lung ventilation.

Problems can occur when using a single-lumen ETT for SLV. If a smaller, uncuffed ETT is used, it may be difficult to provide an adequate seal of the intended bronchus. This may prevent the operative lung from adequately collapsing, or it may fail to protect the healthy, ventilated lung from contamination by purulent material from the contralateral lung. The operative lung cannot be suctioned using this technique. Hypoxemia may occur because of obstruction of the upper lobe bronchus, especially when the short right main stem bronchus is intubated.

Single-Lung Ventilation Using a Balloon-Tipped Bronchial Blocker

A Fogarty embolectomy catheter or an end-hole, balloon-wedge catheter may be used for bronchial blockade to provide SLV (Fig. 23-16) (Ginsberg, 1981; Lin and Hackel, 1994; Hammer et al., 1996; Turner et al., 1997). Placement of a Fogarty catheter is facilitated by bending the tip of its stylet toward the bronchus on the operative side. A FOB is used to reposition the catheter and confirm appropriate placement. When an end-hole catheter is placed outside the ETT, the bronchus on the operative side is initially intubated with an ETT. A guidewire is then advanced into that bronchus through the ETT. The ETT is removed and the blocker is advanced over the guidewire into the bronchus. An ETT is then reinserted into the trachea alongside the blocker catheter. The catheter balloon is positioned in the proximal main stem bronchus under fiberoptic visual guidance. With an inflated blocker balloon, the airway is completely sealed, providing more-predictable lung collapse and better operating conditions than with an ETT in the contralateral bronchus.

FIGURE 23-16 Balloon-tipped catheters used as bronchial blockers for single-lung ventilation. A, Fogarty catheter. B, Balloon wedge catheter. C, Cook endobronchial blocker.

(From Hammer GB: Pediatric thoracic anesthesia, Anesthesiol Clin North Am 20:153–180, 2002.)

A potential problem with this technique is dislodgment of the blocker balloon into the trachea. The inflated balloon then blocks ventilation to both lungs or prevents collapse of the operated lung, or both. The balloons of most catheters currently used for bronchial blockade have low-volume, high-pressure properties, and overdistention can damage or even rupture the airway (Borchardt et al., 1998). One study, however, reported that bronchial blocker cuffs produced lower cuff-to-tracheal pressures than double-lumen tubes (Guyton et al., 1997). When closed-tip bronchial blockers are used, the operative lung cannot be suctioned, and continuous positive airway pressure (CPAP) cannot be provided to the operative lung if needed.

When a bronchial blocker is placed outside the ETT, care must be taken to avoid injury caused by compression and resultant ischemia of the tracheal mucosa. The sum of the catheter diameter and the outer diameter of the ETT should not exceed the tracheal diameter. Diameters for pediatric ETTs are shown in Table 23-5.

TABLE 23-5 Diameters of Pediatric Endotracheal Tubes

Inner Diameter (mm)	Outer Diameter* (mm)
3.0	4.3
3.5	4.9
4.0	5.5
4.5	6.2
5.0	6.8
5.5	7.5
6.0	8.2
6.5	8.9
7.0	9.6

* Cuffed tubes add approximately 0.5 mm to the outer diameter.

From Sheridan Tracheal Tubes, Kendall Healthcare, Mansfield, Mass.

Adapters have been used that facilitate ventilation during placement of a bronchial blocker through an indwelling ETT (Arndt et al., 1999; Takahashi et al., 2000). For use in children, a 5-F endobronchial blocker designed with a multiport adapter and FOB has been described (Cook Critical Care, Bloomington, IN) (Hammer, 2001; Hammer et al., 2002). The balloon is elliptical, so it conforms to the bronchial lumen when inflated. The blocker catheter has a maximal outer diameter of 2.5 mm (including the deflated balloon), a central lumen with a diameter of 0.7 mm, and a distal balloon with a capacity of 3 mL. The balloon has a length of 1.0 cm, corresponding to the length of the right main stem bronchus in children approximately 2 years of age (Scammon, 1923). The blocker is placed coaxially through a dedicated port in the adapter, which also has a port for passage of an FOB and ports for connection to the anesthesia breathing circuit and ETT (Fig. 23-17). The FOB port has a plastic sealing cap, whereas the blocker port has a Tuohy-Borst connector, which locks the catheter in place and maintains an airtight seal. Because oxygen can be administered during passage of the blocker and FOB, the risk for hypoxemia during blocker placement is diminished, and repositioning of the blocker may be performed with fiberoptic guidance during surgery (Bird et al., 2007).

FIGURE 23-17 The Cook 5-F endobronchial catheter is shown inserted in the multiport adapter (Cook Critical Care, Bloomington, IN). The adapter has four ports for connection to (clockwise from bottom) the breathing circuit, fiberoptic bronchoscope (FOB), endobronchial catheter, and endotracheal tube (A). After the FOB and endobronchial catheter have been inserted through the multiport adaptor, the FOB is placed through the monofilament loop at the distal end of the catheter (arrow). The multiport adaptor is then attached to the indwelling endotracheal tube (B) and the breathing circuit (C). The FOB is directed into the main stem bronchus on the operative side. The catheter is then advanced until the monofilament loop slides off the end of the FOB into the bronchus.

(From Hammer GB: Selective bronchial blockade in small infants, Anesth Analg 93(6):1624–1625, 2001.)

When placement of a bronchial blocker inside the ETT is guided by an FOB, both the blocker catheter and the FOB must pass through the indwelling ETT. The inner diameter of the ETT through which the catheter and FOB are to be placed must be larger than the sum of the outer diameters of the catheter and the FOB. The 5-F blocker catheter and an FOB with a 2.2-mm diameter, for example, may be inserted through an ETT as small as 5.0 mm in inner diameter. For children with an indwelling ETT smaller than 5.0 mm in inner diameter, a blocker catheter can be positioned under fluoroscopy (Fig. 23-18).

FIGURE 23-18 Positioning a bronchial blocker under fluoroscopy. A, The catheter has been advanced into a segmental bronchus on the left. B, The catheter has been pulled back so that the balloon is in the left main stem bronchus.

Single-Lung Ventilation Using a Univent Tube

The Univent tube (Fuji Systems Corporation, Tokyo, Japan) is a single-lumen ETT with a second lumen containing a small blocker catheter that can be advanced into a bronchus (Fig. 23-19) (Kamaya and Krishna, 1985; Kawande, 1987; Gayes, 1993). A balloon located at the distal end of this small tube serves as a blocker. Univent tubes require a FOB for successful placement. Univent tubes are now available in sizes as small as 3.5- and 4.5-mm inner diameter for use in children older than 6 years (Table 23-6) (Hammer et al., 1998). Because the blocker tube is firmly attached to the main ETT, displacement of the Univent blocker balloon is less likely than when other blocker techniques are used. The blocker of the 4.5-mm Univent tube has a small lumen, which allows egress of gas and can be used to insufflate oxygen or to suction the operated lung.

FIGURE 23-19 The Univent tube is a single-lumen endotracheal tube with a second lumen containing a small blocker catheter.

TABLE 23-6 Univent Tube Diameters

Inner Diameter (mm)	Outer Diameter* (mm)
3.5	7.5/8.0
4.5	8.5/9.0
6.0	10.0/11.0
6.5	10.5/11.5
7.0	11.0/12.0
7.5	11.5/12.5
8.0	12.0/13.0
8.5	12.5/13.5
9.0	13.0/14.0

* Sagittal/transverse.

A disadvantage of the Univent tube is the large amount of cross-sectional area occupied by the blocker channel, especially in the smaller-sized tubes. Smaller Univent tubes have a disproportionately high resistance to gas flow (Slinger and Lesiuk, 1998). The Univent tube’s blocker balloon has low-volume, high-pressure characteristics, so mucosal injury can occur during normal inflation (Benumof et al., 1992; Kelley et al., 1992).

Single-Lung Ventilation Using a Double-Lumen Tube

All double-lumen tubes (DLTs) are essentially two tracheal tubes of unequal length, molded longitudinally together. The shorter tube ends in the trachea, and the longer tube, in the bronchus. Marraro (1994) described a bilumen tube for infants (Pawar and Marraro, 2005). DLTs for older children and adults have cuffs located on the tracheal and bronchial lumens. The tracheal cuff, when inflated, allows positive pressure ventilation. The inflated bronchial cuff allows ventilation to be diverted to either or both lungs and protects each lung from contamination from the contralateral side.

Conventional plastic DLTs, once available only in adult sizes (35-F, 37-F, 39-F, and 41-F), are now available in smaller sizes (Table 23-7). The smallest cuffed DLT is 26-F (Rusch, Duluth, GA) and may be used in children as young as 8 years. DLTs are also available in sizes 28-F and 32-F (Mallinckrodt Medical, St. Louis, MO), suitable for children 10 years of age and older.

TABLE 23-7 Tube Selection for Single-Lung Ventilation in Children

DLTs are inserted in children using the same technique used in adults (Brodsky and Mark, 1983). The tip of the tube is inserted just past the vocal cords and the stylet is withdrawn. The DLT is rotated 90 degrees to the appropriate side and then advanced into the bronchus. In the adult population, the depth of insertion is directly related to the height of the patient (Brodsky et al., 1996). No equivalent measurements are yet available in children. If fiberoptic bronchoscopy is to be used to confirm tube placement, an FOB with a small diameter and sufficient length must be available (Slinger, 1989).

A DLT offers the advantage of ease of insertion and the ability to suction and oxygenate the operative lung with CPAP. Left DLTs are preferred to right DLTs because of the shorter length of the right main bronchus (Benumof et al., 1987). Right DLTs are more difficult to accurately position because of the greater risk for right upper lobe obstruction. DLTs are safe and easy to use. There are very few reports of airway damage from DLTs in adults, and none in children. Their high-volume, low-pressure cuffs should not damage the airway if they are not overinflated with air or distended with nitrous oxide while in place. Guidelines for selecting appropriate tubes (or catheters) for SLV in children are shown in Table 23–7. There is significant variability in overall size and airway dimensions among children, particularly among teenagers, and these recommendations are based on average values for airway dimensions. Larger DLTs may be safely used in adult-size teenagers.