“The Full Stomach”: the Risk for Pulmonary Aspiration of Gastric Contents

A large number of abdominal surgeries are emergency procedures that require a rapid induction of anesthesia and protection of the airway to prevent regurgitation and aspiration. Children who present with these emergencies should be considered to be at risk for vomiting and/or regurgitation and aspiration during induction of and emergence from anesthesia. Adhering to fasting guidelines for elective surgery² does not ensure that the stomachs of children with acute abdomens are empty of liquids and solids. The only metric that has been associated with gastric emptying after an acute emergency in children is the time interval between the last food ingested and the occurrence of the pathologic event or trauma.² However, there is no firm fasting interval after a trauma that predicts a zero risk of regurgitation and aspiration. In a postal survey, 83% of anesthesiologists use a rapid-sequence induction (RSI) for children with a forearm fracture within 2 hours of feeding and after opioid administration, whereas fewer than 20% use an RSI for this fracture if the child had not eaten for 6 hours since the injury.³ The presence or absence of bowel sounds is also not predictive of gastric emptying or of the risk of regurgitation. Preoperatively, some children with acute abdomens are administered oral contrast agent before abdominal ultrasonography and/or computed tomography, in order to visualize the stomach contents and to estimate their volumes. However, these radiologic tools may not provide reliable estimates of the volume of the gastric contents.^4,5 Indeed, the absence of gastric contents in these scans does not eliminate the risk of vomiting and regurgitation. Consequently, there is no evidence that delaying the surgical procedure for the express purpose of emptying the stomach will reduce the risk of regurgitation; it cannot predict when the risk of regurgitation will be zero and may actually increase the risk of complications by delaying surgical attention to the acute abdomen.

Rapid-Sequence Induction

RSI is recommended for children with a full stomach, to quickly secure the airway. This approach is intended to minimize the risk of aspiration, although it is not evidence based. The strategy is to predetermine the drug doses and have all the required airway equipment ready to use. Predetermined drug doses are administered in a rapid sequence and when muscle relaxation is present, the trachea is intubated and the cuff (if used) inflated. Many clinicians include cricoid pressure to occlude the esophageal lumen during RSI, although no randomized studies have demonstrated that this combination prevents regurgitation and aspiration compared with an inhalational or slow IV induction. This lack of evidence, combined with both theoretical and actual complications associated with RSI and cricoid pressure in children, has generated skepticism regarding their role in preventing vomiting in children who are at risk.⁶ Only 74% of anesthesiologists in Northern Ireland perform RSI for children scheduled for appendectomy, 78% in the United States use it for pyloromyotomy and 83% in England use it for forearm fractures within 2 hours of eating and after recent opioid administration.^3,7,8 In two surveys, 16% and 28% of anesthesiologists in the United States and UK, respectively, reported that a number of children with full stomachs had experienced gastric regurgitation despite using RSI with cricoid pressure, and several of them had progressed to serious harm and even death.^7,9 Despite the lack of evidence that RSI is effective in children with full stomachs, we continue to recommend this approach for the majority of children at risk. Whether cricoid pressure contributes substantively to preventing regurgitation when RSI is performed remains unclear. Complications of RSI, for the most part, relate to improperly performed RSI (e.g., excessive cricoid pressure distorting the anatomy of the airway,¹⁰ causing difficulty in securing the airway) or poor selection of patients (those with a known difficult airway, where a more measured approach must take precedence over concerns for possible aspiration).

RSI in infants and children requires more planning than it does in older children and adults for several reasons. First, the induction drugs should be flushed into the child’s veins using a separate flush syringe, to ensure a rapid bolus administration of the drugs. Succinylcholine remains useful for rapid-sequence tracheal intubation for brief procedures. The introduction of intermediate-acting neuromuscular blocking drugs (NMBDs) with rapid onset, coupled with concerns about the risk of hyperkalemia after succinylcholine in children with undiagnosed neuromuscular diseases (especially males less than 8 years of age), have dramatically reduced the use of succinylcholine in elective surgery. With the shift from succinylcholine to nondepolarizing NMBDs for rapid paralysis in young children, inability to intubate and prolonged paralysis may present serious, possible life-threatening problems. Although sugammadex reverses some NMBDs, its effectiveness is limited to rocuronium and vecuronium and is not always available.^11–13 Second, preoxygenation is often difficult in infants and children because they commonly resist the tight application of the face mask needed to deliver high concentrations of oxygen. Failure to ventilate the lungs after induction and before tracheal intubation may result in desaturation more rapidly in young infants and children than older children, and in those with upper respiratory tract infections or other causes of a limited oxygen reserve.^14,15 During laryngoscopy and intubation, mask ventilation with 100% oxygen should begin when the saturation decreases to 95%, to attenuate the nadir in oxygen saturation that follows.¹⁴ Third, the force needed to occlude the esophagus when applying cricoid pressure to infants and children is poorly understood and poorly applied, can distort the view of the larynx during laryngoscopy, may not occlude the lumen of the esophagus, and may actually deform the lumen of the trachea if excessive force is applied.^6,10,16 Conversely, effective cricoid pressure that occludes the esophagus in children, may permit bag mask ventilation with up to 40 cm H₂O peak inspiratory pressure without gastric insufflation.¹⁷ This is known as a modified RSI. Thus, if the first attempt at tracheal intubation fails or the child desaturates during laryngoscopy, properly maintained cricoid pressure allows bag and mask ventilation of the lungs to restore oxygenation, without increasing the risk of regurgitation.

Indications for Preoperative Nasogastric Tube Placement

Although there are no published guidelines on this subject, it is reasonable to insert a nasogastric tube preoperatively to allow drainage of gastrointestinal fluids in cases of documented bowel obstruction (e.g., ileus, strangulated bowel, pyloric obstruction) or in other situations in which aspiration is judged to be a substantial risk. The child may experience discomfort while a nasogastric tube is inserted, but this must be balanced against the need to decompress the stomach and reduce the risk of regurgitation during induction of anesthesia. In the remaining cases, the placement of a nasogastric tube can wait until after tracheal intubation. It should be noted that placement of a nasogastric tube may decrease lower esophageal sphincter tone, increase the risk for reflux, and reduce the ability to clear refluxed gastric contents from the distal esophagus.^18,19 Thus the anesthesiologist is faced with the dilemma of whether or not to remove the nasogastric tube before induction. It is reasonable to apply suction to the nasogastric tube, evacuate all of the gastric contents before induction, and to remove the nasogastric tube before induction, because it is unclear if even properly applied cricoid pressure can prevent wicking of gastric contents along the path created by the nasogastric tube. It should be further noted that placing a nasogastric tube, although comforting, does not ensure an empty stomach.

Fluid Balance

Many acute abdominal emergencies are associated with pronounced shifts in fluid balance, mainly in the form of dehydration, electrolyte losses, third space fluid shifts, and hypovolemia. Adequate correction of these derangements is mandatory, in most instances, before proceeding with anesthesia and surgery. However, when a large fraction of the bowel becomes strangulated and ischemic, large volumes of fluid may be sequestered in the bowel. In these cases, hypovolemia should be suspected and resuscitation initiated as anesthesia is rapidly induced. In some elective cases (e.g., bowel resection because of inflammatory bowel disease), fluid and electrolyte resuscitation should routinely be a focus of special interest, because the child may not be fully compensated at the time of surgery.

To date, published studies indicate that resuscitation with crystalloid fluids yields similar results to that with colloids.²⁰ In most children, initial resuscitation is undertaken with balanced salt solutions. Although colloid therapy may result in less tissue edema and less volume infused, the added expense of colloids may not justify their routine use in children.

Potential for Strangulated or Ischemic Bowel

The need for anesthesia and surgery becomes more urgent when the bowel is suspected of being ischemic and/or necrotic. For example, if true volvulus is suspected, immediate action is necessary; otherwise the child is at risk for massive bowel resection with subsequent short bowel syndrome, a condition associated with serious lifelong medical problems. Even if the child is far from optimally resuscitated, anesthesia must be induced and maintained, preferably with anesthetics that do not depress the circulation excessively, while simultaneously correcting the dehydration (or hypovolemia) and electrolyte imbalance. The situation is somewhat less critical in the child with an incarcerated inguinal hernia, although delay of even this surgery should be minimized.

Translocation of bacteria from the intestinal tract and subsequent septicemia are possible with ischemic bowel. Ischemic bowel may release a host of mediators that can cause severe hemodynamic instability. Thus when a substantial segment of the bowel is becoming ischemic, the anesthesiologist must be prepared to maintain anesthesia without depressing the circulation excessively, acutely resuscitate the child with appropriate fluids, and administer inotropic and/or vasoactive medications as needed. It should be noted that hemodynamic instability might acutely worsen when reperfusion of the bowel is established or with simple opening of the abdomen. Close communication with the surgeon is paramount in these cases.

Presence of Concomitant Septicemia

Children with acute intraabdominal disease should always be regarded as being at risk for bacterial translocation with subsequent septicemia. Children with overt sepsis are usually easy to identify and may already be admitted to the pediatric intensive care unit. However, incipient or early sepsis may not exhibit overt signs, therefore signs of sepsis should be actively sought. If septicemia is present or suspected, appropriate intravenous (IV) antibiotics should be administered without delay, preferably before anesthesia and surgery. Septic or preseptic children can be extremely unstable; the possible need to administer inotropic and/or vasoactive drugs should be anticipated. Hemodynamic compromise may be dramatically revealed following anesthetic induction and loss of vascular sympathetic tone. Additionally, their lungs may be difficult to ventilate because of established or developing acute lung injury. Thus the anesthesiologist needs to be prepared to provide invasive monitoring (arterial and central venous pressures) and an anesthetic machine capable of providing positive end-expiratory pressure; in some situations an intensive care unit ventilator may be needed in the operating room.

Presence of Abdominal Compartment Syndrome

Acute intraabdominal disease processes may lead to a critically increased intraabdominal pressure (IAP).²¹ If the IAP increases above the capillary perfusion pressure of the intraabdominal organs, an abdominal compartment syndrome can develop. Organ perfusion will become compromised and ischemia and/or necrosis may develop. The most commonly affected organs in this situation are the bowels, kidneys, and liver. Abdominal compartment syndrome occurs less frequently in children than in adults.²² Causes of abdominal compartment syndrome include burns, extracorporeal membrane oxygenation,²³ closure of gastroschisis or omphalocoele,²⁴ abdominal trauma,^25,26 abdominal surgery,²⁷ and a variety of other intraabdominal pathologies, including necrotizing enterocolitis, Hirschsprung enterocolitis, perforated bowel, diaphragmatic hernia, and Wilms tumor.^23,28,29 Insufficient perfusion of the bowel may cause an ileus, translocation of bacteria, lactate accumulation, and production of mediators that cause hemodynamic instability. Increased IAP can reduce liver blood flow that will reduce hepatic function,³⁰ mainly manifested as an inability to metabolize lactate, a delay in drug metabolism,^30,31 and, in severe cases, impaired synthesis of coagulation factors. Because the pressure is also transmitted to the retroperitoneal space, renal function may become impaired, resulting in oliguria or anuria and reduced excretion of drugs.²⁸ In addition, cranial displacement of the abdominal contents and splinting of the diaphragm may seriously compromise ventilation.³²

If acute intraabdominal compartment syndrome is suspected, then the IAP should be measured to determine if it exceeds the critical threshold of 20 to 25 mm Hg. Some suspect a compartment syndrome when the vesicular (bladder) pressure exceeds 10 to 12 mm Hg.^33,34 These pressures can be measured either via a nasogastric tube or bladder catheter.³⁵ The diagnosis of intra-abdominal compartment syndrome should be suspected when the triad of (1) massive abdominal distention, (2) increased bladder pressures and increased peak inspiratory airway pressures, and (3) evidence of renal and/or cardiac dysfunction are present.^29,36,37

Children with acute intraabdominal compartment syndrome can become extremely hemodynamically unstable. Although decompression of the abdomen by a laparotomy will immediately normalize the IAP, reperfusion of the ischemic tissues almost always releases a host of biologically active substances that cause serious hypotension. These substances may also precipitate acute renal failure and lead to a disseminated intravascular coagulopathy. As in the case of sepsis, the anesthesiologist must be fully prepared to address these challenges by having blood products in the operating room and vasopressors available before induction of anesthesia. Some children will require a patch abdominoplasty as a temporizing measure to protect abdominal organs with primary closure of the anterior abdominal wall at some time in the future.^29,36

Preoperative Laboratory Testing and Investigations

Most minor elective cases (e.g., umbilical or inguinal hernia repair) do not require any further preoperative work-up beyond a basic history and physical examination. Many centers require a preoperative urine (or hemoglobin) screen for pregnancy in females who have reached menarche.³⁸ More complex elective cases may warrant additional laboratory testing, including basic hematology screening and electrolyte profile.

Preoperative laboratory testing is strongly advised in more critically ill children. Liver and renal function tests, coagulation profile, and serum albumin concentration should be assessed and blood typed and crossmatched. In children who are septic or who have an acute intraabdominal compartment syndrome, a preoperative chest radiograph may indicate the severity of pulmonary involvement. An echocardiogram may be needed to assess myocardial contractility and volume status if there is evidence of cardiac dysfunction.

Monitoring Requirements

Routine elective cases rarely require more than standard monitoring equipment. In children undergoing major intraabdominal procedures, invasive arterial and central venous blood pressure monitoring may be indicated. A multiple-lumen central venous line inserted at the beginning of the procedure will facilitate administration of inotropic and/or vasoactive drugs, in addition to measuring central venous pressure; ultrasound-guided insertion is strongly recommended.³⁹ These lines are of great value in the immediate postoperative period for blood sampling, drug administration, ongoing assessment of intravascular volume status, and parenteral nutrition. Transesophageal echocardiographic or transesophageal Doppler evaluation may provide valuable intraoperative and postoperative information regarding the child’s volume status, as well as cardiac contractility.^40–50

A urinary catheter with a pediatric urinometer (i.e., a graduated collection receptacle), which provides an accurate measure of urine output is a useful monitor for most intraabdominal procedures. The measurement of hourly urine output safeguards against the development of hypovolemia and possible prerenal azotemia (see the section on laparoscopy for discussion of changes in urine output with increased IAP).

Monitoring IAP is important during laparoscopic surgery, although it will be of minimal value in omphalocele and gastroschisis surgeries, as long as the abdomen remains open. Once the abdomen is closed however, IAP will provide useful prognostic information regarding intraabdominal organ blood flow, circulatory stability, and respiratory embarrassment (see Chapter 36).³²

Choice of Anesthetic

The anesthesiologist may use his or her personal preference of anesthetic technique for the management of both elective and emergency intraabdominal surgery in children. However, airway management associated with intraabdominal surgery requires careful consideration. Even when the child is not at increased risk for regurgitation and aspiration, the risk of regurgitation can be increased if the surgeon manipulates the bowel, when the child is positioned head down, and if gas is insufflated into the peritoneal cavity (as occurs in laparoscopic procedures). A particular concern arises when the surgeon decides to decompress distended bowel. One method is to perform an enterotomy and directly drain the fluid, whereas the other is to massage (strip) the bowel in a retrograde direction until the contents can be vented with a nasogastric tube. The latter method has caused massive intestinal regurgitation that exceeded the capacity of the nasogastric tube, required clearance of the mouth with a Yankauer suction tip, and caused pulmonary aspiration.⁵¹ The laryngeal mask airway should not be used during intraabdominal surgery in general, and instead we strongly recommend the use of tracheal intubation with a cuffed tracheal tube as the standard in the majority of these cases.

Regional anesthetic techniques may be useful adjuncts in children undergoing both minor and major abdominal surgery. However, in critically unstable or septic children, the use of epidural anesthesia is not recommended, because sympathetic blockade may further exacerbate the hemodynamic instability, and there is an increased risk of epidural abscess formation. Simple local infiltration of the port insertion sites contributes to adequate postoperative analgesia in most children who have had laparoscopic procedures,⁵² whereas those who have had an open procedure will require IV opioids (see Chapter 43). Analgesia is commonly supplemented with NSAIDs and acetaminophen.

Reduced Renal Function

Children with chronic renal disease have impaired renal function, which may affect drug dosing and disposition, as well as cause secondary effects on the cardiovascular system. In the most severe cases, the child may require dialysis to balance fluids and electrolytes. In children with renal disease, it is essential to determine the degree of renal impairment by consulting the child’s nephrologist and reviewing the serum creatinine, blood urea nitrogen, sodium, and potassium concentrations (see also Chapter 26). Because renal impairment may also affect clotting, a coagulation profile, including platelet count, should be reviewed preoperatively if substantial blood loss is anticipated. These children are prone to fluid overload, particularly those who are anuric and dialysis dependent. Apart from clinical signs associated with fluid overload, measuring the child’s weight and comparing it with their normal weight is a simple means to assess the child’s current volume status. If cardiac function or volume status remains in doubt, an echocardiogram should be obtained. Children with chronic renal insufficiency often have impaired left ventricular function even before they require dialysis, so a preoperative echocardiogram may be indicated^66–70; pericardial effusion is also a concern in these children.^67,71,72

For children who are dialyzed, the most recent date of dialysis should be documented. Overhydration and/or hypervolemia should be corrected preoperatively with dialysis. Although dialysis corrects hyperkalemia and overhydration, and may transiently improve platelet function (peritoneal dialysis yielding more consistent improvement than hemodialysis), it is best to not perform dialysis within 12 hours of anesthesia, so as to avoid a relative hypovolemia and to allow sufficient time for body fluids to re-equilibrate (see Chapter 26).^73,74 Postdialysis laboratory indices of serum electrolytes (particularly potassium), hemoglobin or hematocrit, renal function (creatinine and blood urea nitrogen), and the child’s weight loss should be recorded. For children who undergo hemodialysis, IV access should not be established in the extremity ipsilateral to the arteriovenous fistula.

Systemic Hypertension

Systemic hypertension is common in renal insufficiency in adults, but far less common in children. Nonetheless, some children with urologic disorders develop significant systemic hypertension associated with disturbances in the renin-angiotensin system.^75–78 As in adults, it is important to control systemic hypertension before induction to avoid wide swings in blood pressure. In contrast to adults, however, hypervolemia is an important cause of hypertension in children with renal insufficiency and should be considered and treated preoperatively. Children and adults are often treated with similar antihypertensive medications.^77,78 These medications should be continued up to and including the morning of surgery to maintain intraoperative and postoperative hemodynamic stability. However, angiotensin-converting enzyme inhibitors are exceptions to this rule⁷⁹: consideration should be given to holding the medication at least 1 day before surgery to avoid intraoperative hypotension^80,81; conversely, holding the medication may be associated with rebound hypertension postoperatively. If these medications are not withheld, vasopressors may be required during anesthesia to stabilize the blood pressure.⁸² Because therapy-resistant renal hypertension is an indication for nephrectomy, one should anticipate and be prepared to treat wide fluctuations in blood pressure, including severe hypertension during the first stage of the operation and profound hypotension when the responsible kidney is removed. As a consequence, long-acting antihypertensive agents are best avoided during the early stages of a nephrectomy in a child.

Corticosteroid Medications

Children with renal disease may be chronically treated with corticosteroids as part of their medical management (e.g., children with proteinuria or who have undergone previous renal transplant surgery). In such cases, a stress dose of parenteral corticosteroids during surgery is indicated, with continued supplementation until the child resumes his or her normal corticosteroid medication by the enteral route. In more complex situations, consultation with a pediatric nephrologist or endocrinologist is warranted to optimize corticosteroid supplementation, although in more straightforward cases, a dose of 2.5 mg/kg of IV hydrocortisone two to three times each day is usually adequate (see Chapter 25).

Infection or Sepsis

Obstructive urinary tract disease or chronic renal insufficiency increases the risk for urinary tract infections. If treated properly, the infection is usually well controlled and should not interfere with anesthesia. However, in children who demonstrate overt signs of systemic illness or septicemia, the anesthetic and postoperative course may be difficult.

Monitoring Requirements

Standard noninvasive monitoring is adequate for the vast majority of urologic procedures in children, as they are of minor or moderate magnitude (e.g., circumcision, orchiopexy, pyeloplasty, and ureter neoimplantation). The anesthetic care that is required for infants and children undergoing penile surgery is routine, including a forced-air heating mattress to prevent hypothermia in surgeries lasting more than 1 hour. However, recognizing the minimal amount of skin that is exposed during this type of surgery, the child’s temperature often increases steadily during the surgery necessitating close monitoring of the child’s temperature to avoid iatrogenic overheating.

Invasive monitors (i.e., invasive blood pressure monitoring, central venous access for pressure measurements and administration of vasoactive drugs) are indicated for major surgical interventions, and in cases with concomitant problems (e.g., decreased renal function, significant hypertension, associated cardiac dysfunction, sepsis). If central venous access is deemed to be necessary, the coagulation status of the child should be evaluated, because platelet function may be substantially compromised. Ultrasound guidance improves safety in securing central venous access in cases in which a coagulopathy is present or suspected on clinical grounds (see Chapter 48). In the unstable child, even more complex monitoring (e.g., esophageal Doppler monitoring or transesophageal echocardiography) should be considered.

It is important to monitor urine output, although the volume of urine may not reflect renal homeostasis. During surgery that involves the bladder or in children who are anuric, urine output will not be available for part or all of the surgery. Hence, other indices of fluid status and perfusion must be used. Heart rate and systolic blood pressure are reliable indices of volume status and perfusion in most children, although central venous pressure and invasive arterial pressure measurement may be indicated in special cases. Surgeons may be heartened to observe urine flowing into the bladder after reimplantation of ureters and kidney transplantation. Preloading with an IV balanced salt solution may be useful in such circumstances; occasionally a loop diuretic is requested.

Pulmonary Effects

As the pressure within the peritoneal cavity increases, so too do the possible adverse respiratory effects, particularly at IAP greater than 15 cm H₂O. The respiratory manifestations of increased IAP include cephalad displacement of the diaphragm, decreased excursion of the diaphragm, and decreases in pulmonary and thoracic compliance, vital capacity, functional residual capacity, and closing volume.¹²⁸ Cephalad displacement of the diaphragm shifts ventilation to the nondependent parts of the lungs, creating ventilation-perfusion mismatch which may require that minute ventilation is increased from 50% to 100% to offset these effects. With a small functional residual capacity in children, cephalad displacement of the diaphragm further compresses the lungs, causing collapse of the small airways, ventilation-perfusion mismatch, and possibly hypoxemia. Pulmonary mechanics after insufflation of a pneumoperitoneum increases peak inspiratory pressures by 27% and decreases compliance by about 39%.¹²⁹ These physiologic changes are compounded by the extreme body tilting (i.e., extreme head-up or head-down positions) often requested by surgeons.^114,130 Positioning the child head down (i.e., Trendelenburg position) decreases compliance by 17% and pneumoperitoneum decreases compliance by 27%, requiring increases in peak inflation pressures of 19% and 32%, respectively.¹³¹ Pulmonary function appears to be restored more readily after laparoscopic than open surgery.⁹³ In some instances, the pneumoperitoneum and the extreme position shift the tracheal tube in a rostral direction, as far as 1.2 to 2.7 cm, possibly impacting on the carina or passing into a bronchus.¹³² With these changes, inspired oxygen concentrations in excess of 30% may be required, along with positive end-expiratory pressure to restore adequate oxygenation. A persistent 5% decrease in oxygen saturation has been associated with partial or intermittent endobronchial intubation.¹³³

Securing the airway for laparoscopic surgery requires particular attention. Cuffed tracheal tubes are preferred over uncuffed tubes to maintain an adequate minute ventilation.¹²³ If the child has a mature tracheotomy, the air leak around the tracheotomy must be assessed before surgery. If the leak is excessive, then the IAP may prevent adequate ventilation during surgery. In such a situation, the tracheotomy should be replaced with a cuffed tracheotomy or an armored (cuffed) tracheal tube. If the air leak around the tracheotomy is insignificant, then ventilation should be adequate in the presence of increased IAP during laparoscopic surgery.

Excessive IAP may cause gas to track across the diaphragm, causing a pneumomediastinum or pneumothorax.¹¹⁵ This is more common in hiatus hernia surgery and Nissen fundoplication, during which dissection of the esophagus may create passages for gas to traverse the diaphragm. Pneumomediastinum should be suspected if subcutaneous emphysema appears. If surgery creates a transdiaphragmatic passage for CO₂ to accumulate in the pleural space, the resulting pneumothorax may produce cardiorespiratory manifestations. A chest radiograph should be obtained if subcutaneous emphysema appears during or after surgery, or if there is a high index of suspicion that a pneumothorax has formed. In laparoscopic surgeries that are brief (less than 30 minutes), both laryngeal mask airways and ProSeal supraglottic airways have been used without complications, although most clinicians prefer cuffed tracheal tubes.^115,134 Both pressure- and volume-controlled ventilation have been used during laparoscopic abdominal surgery in infants and children. In a single randomized study, both ventilation strategies with 5 mm Hg positive end-expiratory pressure maintained effective ventilation and gas exchange.¹³⁵

Although pneumoperitoneum offers the surgeons excellent operating conditions, it is a source of cardiorespiratory compromise. An alternative to insufflating CO₂ to create a pneumoperitoneum is the gasless laparoscopic approach. This requires lifting the anterior abdominal wall to create an intra-abdominal tent.^115,136 Implementation of the gasless approach in pediatric medicine has been rather slow, presumably because of technical difficulties and the scarcity of instruments for infants and children.

Cardiovascular Effects

A pneumoperitoneum can adversely affect cardiovascular indices.^115,136 Three major factors contribute to cardiovascular changes: (1) IAP, (2) position (i.e., steep head-up or reverse Trendelenburg), and (3) release of neurohumoral vasoactive substances.¹²⁸ Increased IAP exerts a biphasic effect on venous return and cardiac output (CO). In neonatal pigs, the cardiac index (CI) decreased 55% when IAP exceeded 20 mm Hg.¹¹⁵ The magnitude of the increase in IAP determines the degree to which the circulation is depressed.^123,137 For example, at IAP less than 15 mm Hg, blood is compressed out of the splanchnic circulation increasing venous return which either increases or results in no effect on CO. In contrast, at IAP greater than 15 mm Hg, the inferior vena cava is compressed, reducing venous return and therefore CO. Studies in children yielded similar results. When the IAP exceeded 12 mm Hg, myocardial contractility¹³⁸ and venous return¹¹⁴ decreased mildly. In both infants and children, CO₂ insufflation to IAP 10 to 13 mm Hg decreased CI approximately 13%.^139–141 However, an IAP less than or equal to 5 mm Hg maintained the CI in infants during a CO₂ pneumoperitoneum.¹⁴² In all of the studies in infants and children in which the CI decreased during increased IAP (10 to 12 mm Hg), the CI returned to preinsufflation values when the abdomen was desufflated.^138,139,141 Left ventricular systolic function was diminished and septal wall motion abnormalities have been reported with an IAP of 10 to 12 mm Hg in children with a CO₂ pneumoperitoneum.^138,139 No significant changes in echocardiographic indices of left ventricular work, preload or afterload, have been noted if the IAP was less than 10 mm Hg during the pneumoperitoneum.¹¹² When standard indices of hemodynamics were measured in infants and young children during laparoscopic Nissen fundoplication, IAP less than or equal to 10 mm Hg yielded no significant changes in heart rate and blood pressure but a slight increase in CI.^142,143 If IAP is maintained at less than or equal to 10 mm Hg, then the impact on hemodynamics (and in particular, CO) should be clinically insignificant, because venous return is enhanced as a result of displacement of blood from the splanchnic bed, and afterload is not increased.^114,123,142

Body position during laparoscopic surgery may exaggerate cardiovascular changes. For Nissen fundoplication, a steep head-up position (greater than 20-degree incline) has been used, which reduces venous return.¹³⁰ In adult pigs, laparoscopic surgery for Nissen fundoplication increased pleural and mediastinal pressures that in turn, reduced CO episodically at an IAP of 15 mm Hg.¹⁴⁴ These decreases in CO were manifested by episodes of hypotension and hypoxia. When children were positioned in the steep head-up position, they developed transient hypotension and bradycardia that were reversed immediately with fluid loading and atropine.¹⁴⁵

It is imperative to continuously monitor IAP to minimize the cardiorespiratory effects of laparoscopic surgery and to avoid excessive insufflation pressures. In adults, induction of anesthesia, IAP to 14 mm Hg, and 10-degree head-up tilt decreased the CI more than 50%.¹⁴⁶ Some clinicians recommend a maximum IAP during laparoscopy in children of 6 to 8 mm Hg to limit the cardiorespiratory effects,¹⁴⁷ although the consensus appears to be closer to pressures of 10 to 12 mm Hg. In neonates and infants, 6 to 8 mm Hg appears to be the accepted peak IAP. Based on the current literature, the net cardiovascular effects of insufflating the abdomen to pressures less than or equal to 12 mm Hg, combined with the head-up position, are likely to be well-tolerated if adequate hydration is maintained and bradycardia is avoided.¹⁴⁵

Central Nervous System Effects

Laparoscopic surgery must be carefully evaluated if planned for a child with increased intracranial pressure, or in the presence of a ventriculoperitoneal (VP) shunt. The combination of increased IAP, increased systemic vascular resistance, increased Paco₂ tension, and Trendelenburg position (as in lower abdominal surgery) may dramatically increase intracranial pressure. In adults during extreme head-down position (40 degrees) for prolonged periods, such as in robot-assisted surgery in the pelvis, cerebral tissue oxygen saturation is well-maintained, as evidenced by near-infrared spectroscopy.¹⁴⁸ Under similar surgical conditions, intraocular pressure increased 100%, and scleral edema and blurred vision may develop.¹⁴⁹

Patency of a VP shunt should be evaluated before the procedure to prevent sudden increases in intracranial pressure during the procedure. Children with reduced brain compliance may sustain dramatic increases in intracranial pressure if the IAP is sufficient to attenuate the drainage of cerebrospinal fluid into the abdominal cavity. In these children, laparoscopic surgery may be relatively contraindicated.¹³⁰ The risks should be thoroughly explored and discussed with the neurosurgeon, general surgeon, anesthesiologist, and the family. Studies have reported a range of responses to laparoscopy in children with VP shunts, from dramatic increases in intracranial pressure to no change at all.^128,150,151 Accordingly, some advocate externalizing the shunt and clamping the distal (intraabdominal) end of the shunt before surgery to prevent carbon dioxide from passing retrograde up the shunt or from the laparoscopic pressure disrupting the shunt valve, although an IAP of 80 mm Hg is required for this to occur.¹⁵³ Others discourage externalizing the shunt as sequelae have been reported, and instead recommend monitoring the intracranial pressure to prevent and detect increases in intracranial pressure, and further recommend retraction of abdominal tissue during the laparoscopic surgery.¹⁵³ For the surgeon, using a SILS approach to laparoscopic surgery in these children reduces the risk of both traumatizing and infecting the VP shunt.¹⁵² A recent review demonstrated that laparoscopy in children with VP shunts is safe and not associated with an increased risk of shunt infection.¹⁵³ No single strategy can provide the optimal management for every child with a VP shunt undergoing laparoscopic surgery.

Renal Function and Fluid Requirements

Increased IAP decreases renal blood flow, renal function (creatinine clearance and glomerular filtration rate), and urine output.^123,128,154 The effects on renal function and renal filtration are poorly understood. Decreases in urine output during laparoscopic surgery in children vary, in part, with the age of the child: oliguria occurs in older children and anuria in infants less than 1 year of age.^128,130,155 The etiology of the renal dysfunction and oliguria is multifactorial, but includes direct and indirect effects of IAP on renal perfusion, antidiuretic hormone (ADH), endothelin, and nitric oxide (NO).^128,156 ADH concentrations increase as a result of reduced renal blood flow, resorbing water, and decreasing urine output. IAP increases renal endothelin (endothelin-1), resulting in renal venoconstriction, which reduces renal blood flow and urine output.^128,156 Inhibiting endogenous NO exacerbates the renal dysfunction during pneumoperitoneum through several mechanisms, including reduced renal perfusion and increased salt and water resorption (e.g., oliguria).¹⁵⁶ Thus pretreating patients with an NO donor (such as l-arginine or nondepressor doses of nitroglycerine) may attenuate the detrimental effects of a pneumoperitoneum on renal dysfunction, a supposition that awaits human studies.¹⁵⁶ Renal tubular injury does not contribute to the renal dysfunction associated with increased IAP.¹⁵⁷ In adult donor nephrectomy patients, an overnight infusion of fluids followed by a colloid bolus immediately before the pneumoperitoneum attenuated the adverse hemodynamic effects and reduced the magnitude of changes in creatinine clearance associated with increased IAP.¹⁵⁸ Comparable data in children have not been forthcoming.

Fluid administration during laparoscopic surgery should be carefully monitored. Open abdominal surgeries may require 10 to 15 mL/kg/hr to account for “third space fluid” losses resulting from extensive bowel manipulation. Although the existence of and manipulation of a real “third space” are debated, the conceptual fluid shift is real. During laparoscopic surgery, however, these fluid requirements are reduced because little fluid is lost and the bowels are minimally manipulated. In fact, care must be taken to avoid fluid overload during these surgeries. Urine output is often used as an index of preload in children undergoing abdominal surgery, but 88% of infants (less than 1 year of age) and 33% of children develop anuria or oliguria during laparoscopic surgery. Because these completely resolve within several hours of desufflation, it is not necessary to fluid challenge these children, as fluid overload is a real possibility.¹⁵⁵ Transient oliguria in children after laparoscopic surgery should not be viewed as an early indicator of impending renal dysfunction.

Pain Management

Postoperative pain after open general and urologic surgery is primarily directed at the pain from the skin and muscle incisions. With the small incisions used during laparoscopic surgery, perioperative pain is less than with open surgery.^159–161 Pain after laparoscopic surgery arises from several sources, including the incision sites, residual gas in the abdomen, referred pain from the diaphragm, and stretch on nerves from peculiar patient positions. A long-acting local anesthetic should be infiltrated around the incision sites at the end of laparoscopic surgery to prevent postoperative incisional pain. Some children develop pain after laparoscopic surgery, including back and shoulder pain. In these instances, multimodal pain therapy, including acetaminophen, nonsteroidal antiinflammatory agents, and (less commonly) opioids, are effective.^94,95,115 Recent evidence suggests that SIMPL for appendectomy causes less pain than surgery with a multiport system.¹⁶²

Nissen Fundoplication

This surgery is indicated for children with documented gastric fluid reflux that failed medical management. It involves mobilizing the muscles around the esophagus and suturing them tightly around the esophagus at the level of the lower esophageal sphincter. This surgery requires general anesthesia and tracheal intubation, and is usually performed laparoscopically.

Children who require a Nissen fundoplication often have a cerebral neurologic injury (i.e., cerebral palsy) that causes esophageal dysmotility. This dysmotility heralds esophageal reflux that, if severe, may result in aspiration pneumonia. If medical and gastric tube therapies fail, a Nissen fundoplication may be considered. The anesthetic considerations are few because this surgery is not associated with postoperative pain, large fluid shifts, or large blood loss. Positioning a bougie within the esophagus during surgery allows the surgeons to gauge how tight to tie the muscles around the esophagus; without a bougie, the muscles around the esophagus may be overtightened, causing an esophageal obstruction. Care must be taken to avoid dislodging the tracheal tube in the perioperative period. At the end of the procedure, it is common for the surgeon to request that 50 to 60 mL of air be insufflated into the stomach via the gastric tube to ensure that there are no anastomotic leaks. In general, this surgery is completed in less than 1 hour in experienced hands, with a complication rate of about 10% and an average hospital stay of about 1.6 days. Postoperative pain is easily managed.^165,166

Pectus Excavatum

Although this is a deformity of the chest wall, pediatric surgeons most often carry out the corrective procedure. Correction of the pectus excavatum by the classic approach involves an open procedure with fracture of the sternum, removal of multiple costal cartilages, and lifting of the sternum anteriorly with fixation, using one or two stainless steel bars. The Nuss procedure, a less invasive technique,^167,168 was initially a technique whereby a U-shaped bar was blindly passed through the thorax hugging the undersurface of the sternum. Once across the chest, the bar was flipped, through which process the sternum was pushed anteriorly without fracturing it, thus avoiding the creation of a flail chest by the removal of the costal cartilages. This procedure has since been modified, whereby the bar is passed through the thorax under direct vision, using thoracoscopy to reduce possible perforation of major structures (e.g., the heart or lungs).^169–171 Although the risk of this complication is reduced when the Nuss procedure is performed under direct vision, it may still occur.^172–174 Both blind and thoracoscopic approaches cause significant postoperative pain, which may be treated with patient-controlled analgesia, a thoracic epidural catheter, or a lumbar epidural catheter and epidural morphine (see Chapters 41 to 44).¹⁷⁵ Because these procedures are generally performed in teenagers, the thoracic epidural is preferably placed with the teenager awake but sedated. Compliance with inserting the epidural catheter while awake may be difficult in less mature teenagers. It is unclear whether the thoracic epidural provides improved analgesia compared with standard patient-controlled analgesia for this procedure.¹⁷⁶ It should be noted that these children will return for removal of the pectus bar after several years. Occasionally, the bar has become adherent to the pericardium or lung, resulting in a severe, sudden, and catastrophic rupture of a major vessel or chamber in the heart when the pectus bar is removed.¹⁷⁷ It would be prudent to establish ample IV access to provide the means to rapidly transfuse fluids and blood should a catastrophic blood loss occur.

Pheochromocytoma

Pheochromocytoma is a rare but potentially life-threatening neuroendocrine tumor that arises from the chromaffin cells of the adrenal medulla in 80% of cases, or extraadrenal paraganglionic tissue in 20% of cases.^178,179 Intraabdominal tumors are most commonly found around renal blood vessels or the corpora paraaortica (organs of Zu), which displays the largest collection of chromaffin tissue. Extraadrenal paragangliomas may occur anywhere in the body from the base of the skull to the pelvis.¹⁸⁰ Only cells that stain positive for chromaffin secrete catecholamines. These tumors derive their name from the dark grey-brown immunostaining of chromogranin A by chromium salts.¹⁸⁰ The Greek word “pheo,” meaning twilight, refers to the dark grey or twilight-colored immunostaining.

The incidence of pheochromocytoma in the general population is approximately 0.3 to 1 per million per year.¹⁸⁰ In children, the incidence of benign pheochromocytoma is 1 per 10 million and of the malignant form, 1 per 50 million. Approximately 10% to 20% of all pheochromocytomas are diagnosed in childhood, with an average age at the time of onset of 11 years.^179,180 In childhood, there is a preponderance of males, whereas during the reproductive years, there is a preponderance of females. The net effect throughout childhood is an equal distribution in the sexes.¹⁸¹ In contrast to adults, pheochromocytomas in children are more often benign, bilateral, multiple in number, and extra-adrenal.¹⁸⁰ With adequate preparation preoperatively and close monitoring intraoperatively, the mortality associated with extirpation of the tumor is less than 3% in children.¹⁷⁸

Most of these tumors are benign, with only 5% to 10% malignant (although some reports suggest a malignancy rate as great as 50%). Malignancies of pheochromocytomas have been found in the bones, lungs, lymph nodes, and liver.^178,179 A diagnosis of pheochromocytoma can be confirmed by positive staining for chromaffin cells. The paraganglioma tumors with mutations in succinate dehydrogenase subgroup B (see later discussion) are most likely to metastasize.¹⁷⁸ Malignant tumors are more likely to secrete dopamine than benign ones.¹⁷⁸ The 5-year survival of metastatic pheochromocytoma is 50%, with no effective treatment.¹⁷⁸ In adults, radical surgery and iobenguane I 123 therapy have been effective in 80% of adults, although only 5% go into remission.¹⁸²

In children, 40% to 60% of pheochromocytomas are inherited^179,180 in an autosomal dominant pattern,^179,180 with the remainder occurring spontaneously. Four hereditary syndromes associated with pheochromocytomas have been identified in five genes’ mutations^{178,183–185}: von Hippel-Lindau type 2, multi-glandular multiple endocrine neoplasia (MEN) type 2, neurofibromatosis 1, and paraganglionic syndromes (mitochondrial complex II succinate dehydrogenase type B and D). Two additional (nonhereditary) syndromes have also been associated with pheochromocytomas: Tuberous sclerosis and Carney triad. The gene defect responsible for the MEN syndromes is located on chromosome 10q11.2.¹⁷⁹ MEN type 2A (Sipple syndrome) includes medullary thyroid cancer, parathyroid adenoma, and pheochromocytoma. MEN type 2B includes medullary thyroid cancer, multiple neuromas, Marfan habitus, and pheochromocytoma. Pheochromocytomas associated with MEN secrete both epinephrine and norepinephrine.¹⁷⁸ These tumors are bilateral in 50% to 80% of cases, but rarely metastasize.¹⁷⁸ The von Hippel-Lindau syndrome type 2 (type 1 does not involve pheochromocytomas) is the most common cause of familial pheochromocytoma.¹⁸⁰ The von Hippel-Lindau gene is located on 3p25-26.^178,179 Pheochromocytoma is present in 10% to 20% of children with the gene. Three subtypes of the gene are distinguished by their association with other organs: type 2A involves hemangioblastomas of the central nervous system, endolymphatic sac tumors, and ependymal cystadenomas; type 2B involves all the organs in type 2A, as well as renal cell and pancreatic cysts and tumors. The only tissues associated with type 2C are pheochromocytomas. When associated with the von Hippel-Lindau gene, pheochromocytomas secrete exclusively norepinephrine.¹⁷⁸ These tumors occur bilaterally in the adrenal glands, but rarely metastasize.¹⁷⁹ Neurofibromatosis type 1 involves neurofibromas and café au lait spots. The genetic mutation is found on chromosome 17q11.2.¹⁷⁸ Pheochromocytomas occur in less than 5% of children with neurofibromatosis.¹⁷⁹

Paraganglioma syndromes arise from mutations in the gene that codes for succinate dehydrogenase on cytochrome oxidase II in the respiratory chain of mitochondria. Two genetic mutations involve pheochromocytomas: subgroup B, which is coded on chromosome 1p36 and subgroup D, which is coded on chromosome 11q23.^178,179 These mutations present with paragangliomas of the adrenal, extra-adrenal, and head and neck regions. Subgroup B occurs more commonly in children (approximately 20% of pheochromocytomas bear this mutation), with a 30% to 50% metastatic rate. Subgroup D is inherited strictly along paternal lines.¹⁷⁹

Tuberous sclerosis presents with the clinical findings of epilepsy, neurocognitive dysfunction, polycystic renal disease, and retinal phakomas. Tuberous sclerosis arises from two gene mutations located on chromosomes 9q34 and 1613.3, which code for the production of hamartin and tuberin, respectively. The wild types of these proteins suppress tumor production.

Carney triad, which usually occurs in young women, comprises gastric leiomyosarcoma (currently recognized as gastrointestinal stromal tumors), pulmonary chondroma, and extra-adrenal pheochromocytoma.

Pheochromocytomas can secrete epinephrine, norepinephrine, and/or dopamine. Most pheochromocytomas secrete norepinephrine as the predominant hormone; only 10% to 20% secrete epinephrine and dopamine as the predominant hormones. Hypertension is the most common presenting sign of this tumor. It is often accompanied by regular, intermittent headaches that are associated with nausea and vomiting. In children, nausea is a common presenting finding. The classic triad of headaches, sweating and palpitations, along with hypertension constitute the presenting signs in greater than 90% of patients with pheochromocytomas. Sustained hypertension is present in 60% to 90% of children with the tumor, but is not a requirement for the diagnosis.¹⁸⁶ In fact, there is no relationship between circulating catecholamine concentrations and overt symptoms. Epinephrine-secreting tumors can present as circulatory shock due to decreased intravascular volume, as a result of sustained high concentrations of catecholamines and their effects on vascular resistance. Tumors that secrete predominantly dopamine do not usually present with hypertension.

Other presenting findings include weight loss, nausea and vomiting, polyuria, visual disturbances, and anxiety.¹⁸⁶ Presenting signs may include pallor, orthostatic hypotension, tremor, and syncope, as well as abdominal pain, diarrhea and other gastrointestinal manifestations, hyperglycemia, low-grade fever, and behavioral disturbances. On occasion, catecholamine release may be triggered by anesthesia, micturition (as in a urinary bladder pheochromocytoma), foods, and drugs, such as metoclopramide, tricyclic antidepressants, glucagon, and radiology contrast dye. Pheochromocytomas have been described as the great mimic, giving support to a differential diagnosis that includes acute coronary infarction, carcinoid tumor, thyroid storm, and cocaine (or other amphetamine-like drug) overdose. In other emergent circumstances, surgery undertaken for acute appendicitis with an undiagnosed pheochromocytoma has been terminated prematurely once the diagnosis of a pheochromocytoma was strongly suspected. The acute appendicitis resolved with conservative nonoperative management while the pheochromocytoma was investigated, the patient was treated with α-adrenergic blocking agents, and the pheochromocytoma removed electively.¹⁸⁷

Surgical resection of pheochromocytoma is optimally managed on an elective basis, after the child’s medical status has been properly investigated, medical conditions are stabilized, the location of the tumor(s) determined and the α-adrenergic receptors completely blocked. Preoperative α-adrenergic blockade is critical, as its routine use has reduced perioperative complications during pheochromocytoma resection from 60% to 3%.¹⁸⁸ It must be emphasized that β-adrenergic blockade should NEVER be introduced until α-adrenergic blockade has been well-established, because this could cause unopposed paroxysmal systemic hypertension, acute coronary or stroke signs, and death. Thus preoperative preparation of these children first requires the institution of a noncompetitive α-adrenergic blocker, such as phenoxybenzamine. Phenoxybenzamine irreversibly alkylates α-adrenergic receptors reducing the risk of an α-adrenergic medicated paroxysmal increase in blood pressure during surgery. Phenoxybenzamine may be administered either orally or IV.¹⁸³ Oral doses between 0.25 and 1.0 mg/kg/day in divided doses are most common, although doses as great as 2 mg/kg/day have been used.^180,183 Oral bioavailability of phenoxybenzamine is only 20% to 30% with a 24-hour onset of action.¹⁸³ Children are usually treated for 3 to 15 days with oral phenoxybenzamine before surgery, although there is no means to reliably assess the completeness of α-adrenergic blockade.¹⁸³ Some think that α-adrenergic blockade has been established when the systolic blood pressure returns to normal limits for the child’s age.¹⁷⁹ Alternatively, IV phenoxybenzamine has been used to more rapidly and reliably block α₁ receptors, although aggressive monitoring for peripheral vasodilatation, decreases in blood pressure, and relative hypovolemia must be followed until the hemodynamics have equilibrated. The action of phenoxybenzamine is terminated only by synthesizing new α-adrenergic receptors. The disadvantage of irreversibly blocking α-adrenergic receptors, as conferred by phenoxybenzamine, is that reactive hypotension may follow removal of the tumor, with resistance to interventions that are intended to increase the peripheral vascular resistance. In contrast, phentolamine has also been used because it has a much shorter half-life than does phenoxybenzamine and it is reversible. Competitive α-adrenergic blockade with doxazosin, which also has a brief duration of action when compared with phenoxybenzamine, may be displaced from the α-adrenergic receptors by increased concentrations of circulating catecholamines.¹⁷⁸ It is important to reemphasize that β-adrenergic blockade should only be introduced once α-adrenergic receptor blockade has been established.

Perioperative fluid and electrolyte management in children as α-adrenergic blockade develops requires close monitoring. It is tempting to administer generous volumes of balanced salt solutions preoperatively to prevent hypotension, but this should be tempered with the understanding that children are at increased risk for catecholamine-induced pulmonary edema.¹⁸³ The plasma potassium concentration should be monitored closely as hypokalemia may develop as a result of increased renin concentrations.¹⁷⁹ Postoperative hypotension, a direct consequence of α-adrenergic receptor blockade, may be attenuated by augmenting the sodium intake in the diet preoperatively, and by the judicious use of IV balanced salt solutions in the perioperative period.¹⁸⁰

Circumcision

Circumcision is performed in neonates, infants, children, and adults under local, regional, or general anesthesia. The indications for circumcision include phimosis, recurrent balanitis, religious beliefs, or parental preference. Inhalational anesthesia with additional regional analgesia is preferred. Classic circumcision involves cutting the foreskin and cauterizing and suturing the skin edges. The duration of surgery is usually less than 1 hour. The type of anesthetic and airway management do not significantly affect perioperative outcomes. The most common complication arising from circumcision is bleeding.

In infants and children, circumcision is performed under general anesthesia. Multimodal pain therapy includes acetaminophen 30 to 40 mg/kg rectally or 10 to 15 mg/kg IV, parenteral opioids (i.e., morphine 0.05-0.1 mg/kg), and/or local anesthetic without epinephrine (dorsal penile block, caudal block, subcutaneous ring block, and topical lidocaine–prilocaine [EMLA]) (see Chapter 41).¹⁹⁵ A comparison of a subcutaneous ring block of the penis with a suprapubic penile block, showed the latter provided better analgesia.¹⁹⁶ When a caudal block was compared with penile blocks and parenteral analgesics, a Cochrane review concluded that, with a caudal block, both rescue analgesia and nausea and vomiting were reduced compared with parenteral analgesics, although the analysis was limited because of a dearth of studies.¹⁹⁷

Hypospadias and Chordee

This congenital malformation occurs in 1 of 250 liveborn males. It often occurs in isolation, without other congenital anomalies. Hypospadias refers to a malposition of the meatus of the urethra: rather than opening at the distal tip of the penis, the urethra opens along the undersurface of the penis anywhere from just proximal to the glans to the scrotum (Fig. 27-5). The majority of hypospadias defects are distal, occurring near or at the glans of the penis. Between 15% and 50% of hypospadii have an associated chordee, whereas 8% have an undescended testis. A small number of children with hypospadias have urethral openings remote from the glans of the penis, including the scrotum (Fig. 27-6, E-Figs. 27-4 and 27-5).

FIGURE 27-5 Classic hypospadias. Saline is injected to perform an erection test before surgical correction of the hypospadias. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

FIGURE 27-6 Scrotal hypospadias with the urethra opening in the midline of the scrotum. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

E-FIGURE 27-4 A penoscrotal hypospadias with the urethra opening at what is the fusion of the penis and the scrotum. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

E-FIGURE 27-5 Urethral hypoplasia and hypospadias. The ultrathin tissue of the urethra presents a surgical problem for providing sufficient tissue to correct the hypospadias. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Surgery is undertaken with an expected duration of between 1 and 4 hours depending on the severity of the hypospadias. It is important to establish an understanding with the urologist of the type of regional block that will suit the extent of surgery: those requiring a minor hypospadias repair (single-stage procedure, i.e., MAGPI [meatal advancement and glanuloplasty technique] or Mathieu repair) may be managed with a facemask, laryngeal mask airway, or tracheal tube. The anesthetic is at the discretion of the anesthesiologist; the children are outpatients and receive either a penile block or a single-shot caudal block. Those with more extensive hypospadias who require longer surgery will require either a laryngeal mask airway or a tracheal tube. They will be admitted to a hospital for one to two nights and need a strategy for continuous postoperative analgesia. For the latter, either a caudal catheter or a lumbar epidural catheter can be used during surgery to reduce the anesthetic requirements and postoperatively for analgesia. If opioids are avoided, a caudal-epidural block consisting of only local anesthetic does not cause delayed micturition after the urinary catheter has been removed.¹⁹⁸

Cryptorchidism and Hernias: Inguinal and Umbilical

These surgeries, together with hydrocele repair, are common outpatient procedures. Orchiopexy refers to mobilizing the undescended testis that is either in the inguinal canal or, less commonly, within the abdominal cavity (Fig. 27-7), and securing it firmly in the scrotum. Approximately 33% of preterm infant males are born with one undescended testis, whereas only 3% of full-term males are similarly afflicted. Although the incidence of undescended testis decreases to 1% by 3 months of age, the incidence remains at 1% thereafter. Cryptorchidism usually occurs in isolation, although it is associated with a number of conditions, including Prader-Willi syndrome, Noonan syndrome, and cloacal exstrophy.

FIGURE 27-7 Intraabdominal testis in the hernia ring, discovered during laparoscopy for an undescended testicle. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Undescended testes are categorized, based on physical examination, to include testes that are truly undescended, those that are ectopic, and those that are retracted. The retracted ones are not true undescended testis because they can be massaged into the scrotum and require no further treatment. In the case of true undescended testes, the testes must be located, mobilized, and then fixed within the scrotal sac to ensure viability. Failure to mobilize the testes out of the inguinal canal or abdomen may result in atrophy, torsion, testicular cancer, or hernias.

An inguinal hernia in a child is a congenital failure of the processus vaginalis to obliterate. In this case, a loop of bowel protrudes beyond the internal ring, causing a bulge in the inguinal region or scrotum. These protuberances may appear periodically, with complete resolution in the interim. On occasion, a small sac of fluid is present in the scrotum, known as a hydrocele, and is confused for a loop of bowel in the scrotum (E-Fig. 27-6). Hydroceles are removed electively with the same approach as for an inguinal hernia. On occasion, the loop of bowel does not reduce spontaneously from the hernia and remains trapped in the canal, necessitating a visit to the emergency department. A surgeon is often required to manually reduce the trapped bowel. In these cases, the hernia repair is then scheduled as an urgent or elective surgery, depending on whether there is suspicion of persistent or potential recurrent ischemia to the bowel. In some cases, the entrapped bowel cannot be reduced and an incarcerated hernia or obstructed bowel is diagnosed. Incarcerated hernias and bowel obstructions are surgical emergencies that require general anesthesia, and muscle relaxation to reduce the strangulated bowel. The emergency nature of the surgery requires careful questioning regarding the time interval between the last meal and the onset of abdominal pain and strangulated bowel. It is usually assumed that these children have a full stomach. At the time of open reduction, if the bowel does not appear to have adequate perfusion, a segment of the ischemic or necrotic bowel may have to be resected.

E-FIGURE 27-6 Right hydrocele in the scrotum, evidenced by the swollen right sac. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Management of cryptorchidism and inguinal hernia requires general anesthesia (facemask, laryngeal mask airway, or tracheal tube) and an adequate pain management strategy. Multimodal pain therapy, as described earlier, may be used together with a regional block. When the surgeon pulls on the foreskin, hernia sac, or testis during surgery, laryngospasm may occur if the depth of anesthesia is inadequate. Anesthesia can be deepened most rapidly by an IV bolus of propofol, although some increase the inspired concentration of inhalational anesthetic. Regional blocks (ilioinguinal, iliohypogastric, scrotal block; caudal-epidural block; or transversus abdominis plane block) are used for both orchiopexy and inguinal hernia surgery, using either a landmark-based or ultrasound-guided method¹⁹⁹ (see Chapter 41).

An umbilical hernia is a 1- to 5-cm defect in the anterior abdominal wall (usually halfway between the umbilicus and the xiphisternal junction), with intermittent protuberance of bowel through the defect. This defect occurs in 15% of children, more commonly in children of African rather than European descent, and equally in males and females. Many resolve spontaneously in the first year of life. It also occurs frequently in preterm and low birth weight infants. If the defect is small, then a laryngeal mask airway may be sufficient to manage the airway, provided a deep level of anesthesia is maintained when the suture needles pass through each side of the rectus muscle. If the defect is large, tracheal intubation and, depending on the surgeon, muscle relaxation may be required. Deepening anesthesia while the defect is being closed by increasing the inspired concentration of inhalational anesthetic or administering an IV bolus of propofol (1 to 2 mg/kg) provides adequate relaxation to reduce the defect in most cases.

Torsion of the Testis

Presentation of a male with sudden onset of acute scrotal pain in the absence of trauma requires immediate investigation and possible surgery to preserve a potentially viable testis. The differential diagnosis of acute onset of torsion of the testis (Fig. 27-8) includes torsion of the testicular appendix, torsion of the spermatic cord, epididymitis, and incarcerated hernia. The majority of testes can be saved if surgery is performed within 6 hours of the onset of pain if the diagnosis is confirmed by Doppler ultrasonography or suspected on clinical grounds.²⁰⁰ The salvage rate for the testis decreases to 50% if surgery is undertaken 6 to 12 hours after the onset of pain. Children with suspected acute testicular torsion are assumed to have a full stomach and require RSI and tracheal intubation. Although pain at the time of induction of anesthesia may be intense, when the torsion is relieved, the pain abates. Hence, at the conclusion of surgery many of these children no longer have substantive pain that warrants aggressive treatment.

FIGURE 27-8 Torsion of the newborn testis. (Courtesy Dr. Daniel P. Doody, MD, Pediatric Surgery, MassGeneral Hospital for Children, Boston.)

Posterior Urethral Valves

Posterior urethral valves (PUV) is a spectrum of urethral obstruction that varies from mild to severe. The diagnosis is often made antenatally (preferably by 24 weeks gestation) by ultrasound identification of bladder distention, megaureters, and hydronephrosis. When PUV is diagnosed antenatally, the severity of the disease tends to be greater.²⁰¹ Decompression of the urogenital system may be achieved by a vesicoamniotic shunt in utero. Although some recommend that an intervention should be undertaken as quickly as possible to minimize the impact on renal function, evidence suggests that early intervention does not substantively affect the outcome, because renal damage may have already occurred in utero.^202,203

Postnatally, a lack of or decrease in urine output, urinary retention, or a poor urine stream may be the only indications of the presence of these valves.²⁰⁴ Affected children can have associated renal insufficiency resulting from congenital renal dysplasia and urethral valve obstruction. Because the renal concentrating mechanism is often impaired, these infants commonly present with greater than normal urine output. Consequently, careful monitoring of urine output and balanced salt solution infusion rate is necessary. Primary valve ablation is required to decompress the urogenital system.

Several indices have been postulated as predictors of poor long-term renal function in infants with PUV, including a creatinine 0.8 mg/dL or greater at birth, antenatal diagnosis, proteinuria, moderate or severe hydronephrosis, and renal dysplasia.^201,205 A recent analysis indicated that a nadir creatinine greater than 1 mg/dL and bladder dysfunction were the only independent predictors of long-term renal dysfunction.²⁰⁶

Children with PUV are scheduled for elective surgery. A general anesthetic is required, with the specific management left to the discretion of the anesthesiologist. There are few special considerations needed.

Prune-Belly Syndrome

Prune-belly syndrome is a disorder that occurs predominantly (97% of the time) in males, with an incidence of 1 in 40,000 births. Affected infants present with a range of findings, from stillborn to a full-term neonate, with a host of possible organ and chromosomal abnormalities.²⁰⁵ Affected organs may involve orthopedic in 50% (congenital hip dislocation and scoliosis), gastrointestinal in 30% (malrotation and volvulus), congenital heart disease in 10% (tetralogy of Fallot and ventricular septal defect), and chromosomal defects (trisomy 18 and trisomy 21).²⁰⁵

In utero, the child’s abdomen often swells with fluid (in the presence of oligohydramnios) that is resorbed by birth, leaving the characteristic wrinkled redundant abdominal wall (Fig. 27-9 and E-Fig. 27-7). The pathophysiology of this syndrome is unclear, but it has been suggested that a urethral obstruction in utero leads to dilatation of the urethra (megaurethra is a common finding), which, combined with bladder distention and ascites, causes distention of the abdomen in utero. This ultimately leads to vesicoureteral reflux and ureteral dilatation in 80% of affected children.

FIGURE 27-9 Prune-belly syndrome. View of the distended, weak muscled abdomen in a child with prune-belly syndrome. The muscle wall is so thin that the abdominal surface is bulging in front of the bowels. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

E-FIGURE 27-7 View of the distended, weak-muscled abdomen in a child with prune-belly syndrome. The muscle wall is so thin that bowel peristalsis may be visualized on the abdominal surface. (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Abdominal overdistention in utero causes weak rectus abdominis muscles that undermine the child’s ability to exhale forcefully, and to generate a strong cough to clear secretions. As a result, chronic aspiration pneumonia may contribute to an early demise. Some have suggested that aggressive intervention to correct the weak rectus muscles by plication and muscle transfer may improve respiratory function,^207,208 reduce back strain and pain, decreased bladder volume, and arrest scoliosis.²⁰⁹ However, this view is not shared by others who prefer to observe the child for signs of regurgitation and aspiration before intervening.²¹⁰ Controlling the type of feeds, preventing gastrointestinal reflux disease, and using antibiotics to treat pneumonia permit the child to grow. Constipation is a frequent problem that may be exacerbated by their inability to increase their IAP during defecation. Stool softeners are often prescribed to prevent constipation and abdominal distention. Pneumonia must be aggressively treated and completely resolved before entertaining surgery. Percutaneous endoscopic gastroscopy tubes are generally eschewed in these children when feeding is a problem, as abdominal wall surgery is difficult. These children often require urologic surgery to correct vesicoureteral reflux and orchiopexy. Urethral obstruction may be due to the angulation of the urethra within the prostate.

Trisomy 18, the second most common autosomal trisomy, occurs in 1 in approximately 7,000 live births, and is associated with prune-belly syndrome. In contrast to the simple prune-belly syndrome, 60% to 80% of these infants are female. Trisomy 18 is characterized by severe neurologic developmental problems (including microcephaly), micrognathia and/or retrognathia, microstomia, auricular abnormalities, and others. In fact, 95% die in utero, with only 5% to 10% surviving 1 year and only 1% reaching 10 years of age. Mortality results from cardiac anomalies (90% of affected children have a ventricular septal defect, valvular heart defect, atrial septal defect, hypoplastic left heart syndrome, tetralogy of Fallot, or other cardiac defect), renal anomalies, failure to thrive, and apnea.^211,212 Additional findings include pulmonary hypoplasia and gastrointestinal anomalies (including prune-belly syndrome, omphalocele, ileal atresia, and esophageal atresia).

General anesthesia with tracheal intubation is required for most surgeries in these children. Controlled ventilation is recommended, because of the variability in the strength of the abdominal muscles. It is prudent to suction the lungs once the trachea has been intubated, in order to assess the severity of secretions. As little muscle relaxant as possible should be used during the surgery, with preferably no muscle relaxant administered during the last hour, to ensure the child’s strength has had time to recover to have a successful extubation. Although opioids should be used cautiously, regional anesthesia may be preferred, in view of their difficulty with clearing secretions from the tracheobronchial tree.²¹³

Ureteral Reimplantation

Vesicoureteral reflux, in which urine passes retrograde up the ureter, is a congenital disorder affecting 0.5% to 2% of children. Recurrent episodes of pyelonephritis may occur, leading to renal scarring and reduced renal function, depending on the severity of the reflux. The pathology is thought to be an anatomically abnormal insertion of the ureter into the bladder that fails to close tight when the bladder fills and contracts. A voiding cystourethrogram is the test required to diagnose the reflux and assess its severity. Mild forms of vesicoureteral reflux are managed with daily antibiotics until the child outgrows the reflux. However, more severe forms or those who develop kidney infections despite antibiotic therapy, require surgical correction. The classic surgical approach for vesicoureteral reflux is an open procedure in which the affected ureters are reimplanted into the bladder wall, re-creating a normal muscle flap valve.²¹⁴ This involves a lower abdominal incision and 3 to 4 hours of surgery. Postoperatively, the pain is often intense, necessitating 2 to 3 days of continuous infusion of local anesthetic via an indwelling caudal or epidural catheter.

More recently, laparoscopic techniques have been developed, with and without robotic control, for reimplantation of the ureters.²¹⁴ Preliminary evidence suggests an excellent success rate (greater than 90%) for this approach,²¹⁵ although the time for the surgery is more than twice the open technique and more complications were identified in children with small bladders.

Surgical alternatives in the past 20 years have spawned a number of compounds for injection into the terminal submucosal tract of the ureter, by passing a needle through a specially designed cystoscope. Initially, polytetrafluoroethylene (Teflon) was injected endoscopically, but a safer, more durable polymer has been developed over the past 20 years that is a mixture of dextranomer and hyaluronic acid (Deflux). In this way, surgeons create a swelling just inferior to the opening of the ureter into the bladder that prevents urine from refluxing (Fig. 27-10, before and after injection of polymer). The technique is successful in 80% of cases after one injection and in greater than 90% after two injections. Although this procedure still requires general anesthesia, its advantages far outweigh any disadvantages, in that the duration of the procedure is very brief (usually 15 to 30 minutes), the procedure avoids an abdominal incision, causes no postoperative pain, and its greatest advantage is that the child can be an outpatient. However, the results of this injection technique continue to be monitored because long-term outcomes and sequelae have not been determined.

FIGURE 27-10 A female with ureteral reflux. Preinjection (at left) with the bladder orifice wide open. There is no valve to prevent the backwash of urine up the ureter. Polymer was injected into the submucosa of the bladder, raising a mound to seal off the orifice of that ureter. Postinjection (at right) with the orifice now appearing as a dimple on the peak of the mound (arrow). (Courtesy Dr. P. Williot, Pediatric Urology, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Pyeloplasty

Pyeloplasty is performed to decompress the renal pelvis either because of intrinsic (congenital) or extrinsic (major vessel) compression of the ureter. A distended renal pelvis is often diagnosed antenatally and, in some instances, decompressed in utero by percutaneous nephrostomy. The ureteric narrowing often occurs at the ureteropelvic junction, where the ureter exits the renal pelvis. Surgery involves disconnecting the ureter at the renal pelvis, reshaping it, and then reinserting it into the kidney. Such surgery is often performed in the lateral or prone position, with the table jackknifed. The duration of this surgery is approximately 2 hours, with a success rate of approximately 95%. Dissection is often retroperitoneal, but the incision is placed immediately below the rib cage. This procedure has been performed laparoscopically and with the use of robotics.^105,215b

Anesthetic considerations include the prone or lateral decubitus position (complicated by placing the table in the “jackknife position”), postoperative pain, and adequate fluid resuscitation. IV access should be established in an upper extremity to maintain adequate atrial filling pressures. If the table is placed in the jackknife position, it is very important to measure the child’s blood pressure before and after the table is jackknifed, because venous return may become severely compromised, necessitating reducing the extent of the jackknife and resuscitating the child with fluid. The laparoscopic approach to pyeloplasty in children is new. In renal surgery, CO₂ is insufflated in the retroperitoneal space to provide surgical access.²¹⁶ Because of the anatomic differences between the retroperitoneal and intraperitoneal spaces, greater pressures may be required to provide adequate surgical visibility. A mean retroperitoneal pressure of 12 mm Hg increases Petco₂ and peak inspiratory pressures, and decreases blood pressure.²¹⁷ Early evidence indicates that laparoscopic surgery yields similar outcomes to the open approach, although the duration of surgery is approximately one-third greater.^218,219 In part, this has been attributed to the learning curve of this technique. Evidence suggests that the laparoscopic approach decreases the length of hospital stay and may decrease postoperative pain^105,219 (see previous discussion of pain management after laparoscopic surgery).

Nephrectomy

Indications for nephrectomy and partial nephrectomy in children include nonfunctioning kidney, dysplastic kidney, urolithiasis, Wilms or other tumor, end-stage renal failure (pretransplantation or to control hypertension), hemolytic uremic syndrome, and polycystic disease. Children who require a nephrectomy will require a thorough preoperative assessment in terms of history, physical examination, and laboratory testing, depending on their underlying pathology. These children are often anemic because of chronic disease and possibly decreased erythropoietin concentrations. If the child is being staged for kidney transplant, the nephrologists may prefer to avoid blood transfusions at this time. If time is available and the patient is anemic, oral FeSO₄ and vitamin C should be commenced 3 to 6 weeks before surgery (vitamin C increases gut absorption of FeSO₄) to increase the hemoglobin concentration, particularly if erythropoietin supplementation is planned.^220,221 These children are often small in size and this should be considered when preparing the anesthetic equipment.

Nephrectomies are commonly performed using a retroperitoneal approach with the child in the lateral decubitus position and the table jackknifed. The incision is usually large and located just subcostal to the twelfth rib. If an open approach is planned, a low thoracic epidural catheter may be placed before positioning the child. If, however, a laparoscopic or robotic-assisted approach is planned,⁸⁹ then no neuraxial block is necessary but the same surgical approach occurs. Outcomes after laparoscopic nephrectomy in children are similar to those after an open procedure, according to the experience from one center,²²² although recent evidence points to less pain and earlier discharge from the hospital.⁸⁹

Neuroblastoma

The adrenal glands are located in the retroperitoneal space, adjacent to the superior pole of the kidneys. Masses that arise in the adrenal gland may be tumors, hemorrhage, infections, or cysts. The tumors in the adrenal glands may arise from the cortex (as in adenoma) or medulla (including the sympathetic chain, as in neuroblastoma or ganglioneuroma), and may be either hyperfunctioning or nonfunctioning.

Neuroblastoma is the most common extracranial solid tumor that presents in childhood, comprising 10% of all tumors and 15% of all deaths from tumors.²²³ It is the second most common abdominal tumor, after Wilms tumor. Its incidence is approximately 1 in 100,000 children in the United States.^224,225 Neuroblastomas arise in the abdomen in 75% of cases and along the sympathetic chain anywhere from the neck to the pelvis in 25%. Only one-third of those that arise in the abdomen arise in the adrenal glands. The median age at presentation is 2 years, with up to 90% occurring in children under 5 years of age. In some series, up to 50% of the cases appear in the first month of life, with some diagnosed antenatally. This tumor occurs equally in boys and girls. Reports of familial neuroblastoma are rare. However, these tumors may be associated with other disorders, including Beckwith-Wiedemann syndrome, neurofibromatosis, Hirschsprung disease, and central hypoventilation syndrome.²²³

Most neuroblastomas are first detected as palpable masses in the abdomen. Symptomatic presentation may present as local pressure on adjacent organs or structures (liver, kidney, or spine), as metastases (lymph nodes, bone marrow, liver, and skin), or with manifestations of excess neurohumoral production (i.e., from catecholamine [e.g., systemic hypertension] or vasoactive intestine polypeptides [e.g., diarrhea]).²²³ Urinary catecholamines are increased in greater than 90% of children (more than 1 year of age) with neuroblastoma. In a minority of instances, the diagnosis is made through incidental examination, either by radiography or ultrasonography.

Staging of these tumors follows two protocols.²²⁴ The International Neuroblastoma Staging System depends on tumor resectability, lymph node involvement, and metastases. However, if patients are not surgical candidates, the staging score holds little relevance. To further stage these tumors, a second scoring system was developed, the International Neuroblastoma Risk Group classification system, which is based on the preoperative radiologic findings only. Survival likelihood depends on a low score, extraabdominal (as opposed to intraabdominal) primary tumor, and younger age. Therapeutic intervention is tailored to the staging of the tumor at presentation and the size of the tumor. Those with favorable tumor biology, no distant metastases, and younger than 18 months of age, are often curable with surgical resection alone. Those with less favorable tumor biology, metastases, and a large tumor size that may present a challenge surgically, are ideally treated with a combination of chemotherapy, radiation, and/or bone marrow transplantation to reduce the tumor size first, and then with surgical resection. Patients with less favorable biology present a challenge for surgical resection because of local infiltration, large tumor size, and vascular extension. Debulking the tumor with incomplete resection has been met with mixed reviews. The most promising treatments for neuroblastomas with poor prognoses include molecular profiling of the tumor.²²⁴ The long-term survival after treating these tumors is 88% for infants and children less than 18 months of age, 49% for children 18 months to 12 years of age, and 10% for those 12 years old or older.²²⁶ Preoperative assessment requires a general systems review, with particular focus on the organ systems involved with the tumor. These tumors may present as a large intra-abdominal mass that compromises respiration, most commonly manifested as tachypnea. Those with catecholamine-secreting tumors may also present with chronic hypertension. This is mitigated to a large extent if the tumor is shrunk preoperatively, but intraoperative hypertensive episodes still occur in 25% of the children (with urinary catecholamines) during surgery. Children with catecholamine-secreting neuroblastomas should have both α-adrenergic and β-adrenergic blockades established preoperatively (see previous discussion of pheochromocytoma) to avoid swings in blood pressure during manipulation of the tumor.²²⁷ Less frequently, chronic diarrhea from vasoactive intestine polypeptides may cause chronic dehydration and electrolyte derangements that require correction.

The anesthetic plan depends on the nature and extent of the surgery. A general anesthetic with tracheal intubation and controlled respiration, as well as standard anesthetic monitors, is required. These should be supplemented with invasive monitoring, including arterial and central venous access for catecholamine secreting tumors, large tumors, and those that are expected to bleed excessively. Anticipation of massive blood loss will necessitate using large bore upper extremity IV access, blood warmers, and possibly a rapid transfusion device. No specific anesthetic regimen has been recommended for these surgeries.

Although the blood pressure may be controlled with established α-adrenergic blockade, manipulation and squeezing of the tumor during its removal may cause a surge in catecholamine release, necessitating the use of antihypertensive medications intraoperatively (see previous discussion of pheochromocytoma).²²⁷ Labetalol may be effective in children with hypertension during resection of neuroblastomas²²⁷; however, it may cause paroxysmal hypertension and heart failure in children who have only β-adrenergic blockade established, because of the predominant β-adrenergic blocking action of labetalol.

Wilms Tumor

Renal tumors comprise 2.5% to 7% of tumors in children. Wilms tumor is the most common abdominal tumor in children, with an incidence of 8 in 1,000,000 children less than 15 years old, and the most common solid renal tumor beyond the first year of life.^225,228 These tumors arise from persistent immature parenchymal renal tissue (referred to as Wilms tumorlet cells) often in the periphery of the kidney (as opposed to the collecting ducts), enclosed by a pseudocapsule (Fig. 27-11). They may achieve a large size before detection, often compressing adjacent renal parenchyma. Histologically, the tumor often includes up to three distinct tissue cell lines: epithelial, blastemal, and stromal cells.²²⁸ The presence of anaplastic cells (in 4% of Wilms tumors) and, more specifically, whether the cells are focal or diffuse in the tumor, and older age at the time of presentation suggests a less favorable response to chemotherapy and less favorable long-term prognosis.²²⁸ With tailored multimodal therapy, the survival from Wilms tumor in the past several decades has increased dramatically, from 30% to 90%.

FIGURE 27-11 A Wilms tumor was mobilized and exteriorized from the abdomen. Note that it is encapsulated and contiguous with the left kidney.

(Courtesy Daniel P. Doody, MD, Pediatric Surgery, MassGeneral Hospital for Children, Boston.)

Eighty percent of the children with of Wilms tumor present between 1 and 5 years of age (peaking at 3 to 4 years of age), with no gender or racial bias.^225,228 Presentation of Wilms tumor is similar to that of other intraabdominal tumors in the form of an incidental mass on physical examination; approximately 6% are bilateral. Congenital anomalies coexist with Wilms tumors in 12% of children, notably in genitourinary anomalies (5%), hemihypertrophy (2.5%), and aniridia (1%).²²⁸ A number of genetic syndromes predispose to Wilms tumors, including Beckwith Wiedemann syndrome.²²⁵ Wilms tumors occur twice as frequently in children with horseshoe kidneys than in those with normal kidneys, and is also more frequent in those with multicystic dysplastic kidneys.

Preoperatively, most children with Wilms tumors appear well, presenting with constitutional findings, including weight loss, loss of appetite, and malaise. Occasionally, they have an associated syndrome that should be detailed. Physical examination includes a palpable abdominal mass in 75% to 90% of children. Laboratory investigations before nephrectomy include routine complete blood count, electrolytes, renal function, as well as coagulation indices. Polycythemia may be present from tumor-induced excess erythropoietin production. Acquired Von Willebrand disease is present in less than 10% of these children.²²⁵ Blood should be cross-matched for the surgery. Microscopic hematuria occurs in 25% of children whereas gross hematuria is rare,²²⁸ suggesting tumor invasion of the collecting ducts. Systemic hypertension is present in 25% of children, presumably as a result of hyperreninemia. Preoperative investigations should include radiography and ultrasonography, the latter highlighting hyperechogenic structures within the kidney. Tumor extension into the ipsilateral renal vein and inferior vena cava must be examined before embarking on surgery, as chemotherapy may lead to involution of these tumors (Fig. 27-12).²²⁵ Magnetic resonance imaging and computed tomography are valuable tools for delimiting the tumor borders within the kidney, as well as metastases in the lungs or other organs.²²⁵ Most recent summaries of the radiologic investigations may determine the need for additional interventions, including echocardiogram and lung scan to determine the presence of tumor in the heart and lungs, respectively. An echocardiogram may be specifically required to evaluate myocardial function if doxorubicin and other anthracycline chemotherapeutic agents had been administered.²²⁵

FIGURE 27-12 Coronal view of the CT scan of a Wilms tumor. Note the massive tumor enveloping the inferior vena cava, as the vena cava is only visible where it enters the liver in the upper midportion of the radiograph (arrow).

(Radiograph courtesy Daniel P. Doody, MD, Pediatric Surgery, MassGeneral Hospital for Children, Boston.)

Anesthetic management of children with Wilms tumor is similar to that with neuroblastoma. No specific anesthetic regimen is preferred. Invasive monitoring and large bore IV access (upper extremities to avoid interference from tumor extension into the inferior vena cava) with adequate blood warming capability is mandatory. Anesthesia may be further complicated by hypertension (precipitated by tumor handling), coagulopathy (acquired von Willebrand disease), extension of the tumor into the proximal inferior vena cava or right atrium, pulmonary tumor emboli, acute right heart failure, and considerations concerning preoperative or previous treatment with chemotherapeutic drugs.²²⁵ These drugs may impair hepatic or hematopoietic function (actinomycin D), cause inappropriate antidiuretic hormone release (vincristine), or myocardial damage (doxorubicin).²²⁵ Pain may be controlled using either IV or regional anesthesia, though the risk of a coagulopathy must be ruled out before administering an epidural block.

Bladder and Cloacal Exstrophy

Bladder exstrophy is a rare congenital anomaly of the genitourinary tract occurring in 1 in 50,000 births with a 2 : 1 male to female ratio.²²⁹ It occurs as a failure of the abdominal wall to close during fetal development and results in defects of the anterior wall of the bladder and overlying midline abdominal wall. Bladder exstrophy may present with a spectrum of anomalies, including widening of the symphysis pubis, and genital anomalies, such as epispadias, bifid clitoris, and undescended testes (Fig. 27-13). Some regard bladder and cloacal exstrophies as distinct entities, whereas others consider them both extremes in a continuum of antenatal defects. Cloacal exstrophy includes features of bladder exstrophy plus an omphalocele and spinal defects, and always includes imperforate anus. Because the antenatal diagnosis of bladder exstrophy using ultrasound may be technically difficult, and thus dependent on indirect signs (absence of bladder filling, a low-set umbilicus, widening of the pubic ramus, small external genitalia, or a lower abdominal mass), the diagnosis is confirmed at birth when the anterior abdominal wall defect with the exposed bladder mucosa are evident.

FIGURE 27-13 Bladder exstrophy in a neonate. Note the open anterior abdominal wall, protuberant bladder, distorted genitalia, and splayed hips.

Therapy is aimed at the surgical reconstruction of the bladder with preservation of renal function while achieving urinary continence and satisfactory appearance of the external genitalia. Surgical repair is usually achieved via a planned surgical approach.^230,231 In a very carefully selected group of infants, surgical management may be carried out as a single-stage procedure.²³² Alternatively, a planned staged surgical repair may be chosen with management directed at closure of the bladder, posterior urethra, and abdominal wall. In addition, a bilateral iliac osteotomy is often performed to facilitate surgical closure, decrease the stress on the midline soft tissues, and reduce the risk of postoperative wound dehiscence.

Wound dehiscence, bladder prolapse, and multiple attempts at bladder closure are among the risk factors for decreased bladder growth and the inability for the later development of continence.²³³ In addition to the immediate postoperative complications, children who have undergone surgical repair of bladder exstrophy carry an increased risk for the development of renal, bladder, and colon adenocarcinoma.²³⁴ Children who require frequent bladder catheterizations or repeat surgeries are at risk for developing latex allergy if latex products are used.⁵⁶ Today, most bladder catheters exclude latex.

Surgical management of the epispadias is usually performed at 6 to 12 months of age, and reconstruction of the bladder neck by 5 years, the latter to allow for bladder training. After the initial surgical repair, children are immobilized for 4 to 6 weeks,²³⁵ with a successful outcome likely when a modified Buck traction with an external fixator or a modified Bryant traction²³⁶ and adequate postoperative analgesia are used.²³⁷

The preoperative assessment should evaluate the presence and severity of all congenital anomalies, particularly cardiac abnormalities. Signs or symptoms of renal insufficiency and electrolyte balance may be present. If the child has renal insufficiency, the dose and frequency of administration of potentially nephrotoxic drugs, as well as the commonly used anesthetic drugs, must be carefully evaluated. Typically, surgery is performed with the child in the supine and lithotomy positions. The duration of surgery is often prolonged, requiring alternating urologic and orthopedic teams for their respective segment of the surgery, and repositioning the child depending on the stage of the surgery. These neonates require judicious management of fluids, blood loss, and temperature control, as is typical for surgical procedures in the neonatal period. In formulating the anesthetic plan, the anesthesiologist must partner with the surgical teams to ensure an optimal strategy for balanced salt solutions, colloids, and blood products. This allows for optimal intraoperative management, as well as planning for a multimodal perioperative pain management strategy and postoperative ventilatory support, if needed. After applying the standard monitors, anesthesia may be induced either by inhalation or IV; after induction, at least one large bore peripheral IV should be placed. A second IV may be placed, or a central venous catheter and possibly an arterial catheter. In general, if blood loss occurs, it is slow and steady, but if posterior iliac osteotomies are performed, the blood loss may become brisk, requiring aggressive fluid resuscitation and administration of blood products. Beat-to-beat variability of arterial blood pressure and serial laboratory evaluations are valuable during goal directed resuscitation. Appropriate padding, a fluid warmer, and a forced-air heating system should be standard. The anesthetic plan varies according to the age of the child and whether the surgery is completed in a single or staged repair. Postoperatively, children are transferred directly to the pediatric intensive care unit for recovery. Careful attention must be paid to maintain fluid and electrolyte homeostasis, to prevent reduced oxygen carrying capacity, and to assure adequate analgesia.

A general anesthetic in combination with an epidural or caudal continuous infusion technique is often used if there are no associated spine abnormalities.²³⁸ Opioids (other than remifentanil) have had a limited role in neonates because of their potential to cause postoperative respiratory depression, although pediatric anesthesiologists today are much more aggressive in anticipating pain and administering opioids to neonates and infants, even if it delays extubation.

Maintenance of anesthesia may be achieved using an inhalation anesthetic, small doses of opioids, and intermittent boluses (0.5 to 1 mL/kg) or continuous infusions of bupivacaine (0.125% to 0.25%) or ropivacaine (0.2%) with or without epinephrine through a lumbar or caudal epidural catheter. Caudal or epidural analgesia may be provided by advancing the catheter to the appropriate surgical dermatomal level after induction of anesthesia. The catheter is either secured directly to the skin or tunneled using the epidural insertion needle.²³⁹ A continuous infusion of a local anesthetic may be used and maintained for up to 3 days to provide analgesia and a mild motor blockade that favors immobility. However, care must be taken to avoid systemic toxicity. Neonates are at increased risk for developing local anesthetic toxicity because of their low serum protein concentration and metabolism. Albumin and α1-acid glycoprotein are reduced in this age group,²⁴⁰ which reduces protein binding and increases the free-fraction of bupivacaine. This free form is metabolized to a lesser extent in the neonate because of immature metabolic pathways, and contributes to an increased risk of cardiac and systemic toxicity.^241,242 This is especially true of the amide local anesthetics. If the epidural infusion is maintained beyond 48 to 72 hours, serum concentrations of local anesthetic should be sampled once or twice a day to guide therapy and minimize the risk of complications. Because serum concentrations of bupivacaine increase after only 48 hours of a continuous epidural infusion,²⁴¹ and serum concentrations are difficult to assay, lidocaine 0.1% (0.8 mg/kg/hr) may be preferable. Ropivacaine is also currently being used for infusions that last less than 72 hours.²⁴³

The outcome of this complex surgery is determined primarily by the surgical expertise. Urologic incontinence, bladder prolapse, and epispadias revisions will require additional urologic surgery, as well as possible osteotomies, for satisfactory closure and surgical outcomes. Renal function is usually well-maintained throughout. Complications of complete repair are reported to be similar to those of the staged repair, but usually involve additional soft tissue defects.²⁴⁴