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 surgery ² 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.

General Principles of Urologic Surgery

With the exception of acute drainage of urinary obstruction (i.e., ultrasound-guided nephrostomy or cystostomy procedures) and torsion of the testis, most pediatric urologic surgeries are elective. In the vast majority of cases, these children are otherwise healthy or with stable medical conditions that do not require more than a careful history, physical examination, and review of the child’s medical record. Children who undergo urologic procedures may be suffering from emotional disturbance because of repeated interventions and sensitivity of the surgical site. This mandates special psychological attention before and after anesthesia. The occurrence of anaphylaxis resulting from exposure to latex-related products is of special concern in children with chronic urologic disorders.⁵³^–⁵⁶ Children with spina bifida are at greater risk for latex allergy than those without spina bifida,⁵⁷^–⁶⁰ presumably because of early and repeated exposure to latex urethral catheters, although every child with congenital malformations of the urinary tract and repeat latex exposure to mucous membranes beginning in the neonatal period is at significant risk for developing latex hypersensitivity.^61,⁶² Thus latex-free management is highly recommended in this population.⁶³^–⁶⁵

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 indicated⁶⁶^–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.

Laparoscopic Surgery

Although laparoscopic surgery was introduced more than 80 years ago, its role in pediatric surgery has only become notable in the past 10 to 15 years. To a large extent, this has been due to improved technology in optics and miniaturization of the instruments. An increasing number of general and urologic surgical procedures (including appendectomy, cholecystectomy, and splenectomy, as well as those to treat inguinal hernia and undescended testicles) are performed either laparoscopically or using robotic techniques in children of all ages, including neonates (Figs. 27-1 to 27-4).⁸³^–⁹¹ More sophisticated laparoscopic techniques have enabled the performance of complex surgical procedures, including Nissen fundoplication, colectomy, pyeloplasty, bowel pull-through, and removal of large organs, including the kidney and spleen.^89,⁹²^–⁹⁵ Technological advances now permit laparoscopic surgery in neonates and small infants, including those with hypoplastic left heart syndrome after stage 1 or 2 repair.^91,⁹⁶^–⁹⁸ It must be noted however that laparoscopic surgery in children with cyanotic heart disease carries with it a substantial risk that exceeds most other populations having this form of surgery. Although several reports suggest that infants and children of all ages, at all stages of palliative repair of their cyanotic heart disease, tolerate laparoscopic surgery,⁹⁸^–¹⁰⁰ the risk for those with Fontan physiology undergoing laparoscopic surgery is substantial. It is essential to understand that in Fontan physiology, pulmonary blood flow is passive, and decreases in venous return (whether from increases in intrathoracic pressure or head-up positioning) or increases in pulmonary vascular resistance (because of carbon dioxide absorption or decreased minute ventilation) could severely reduce the cardiac output.¹⁰¹ Creating a pneumoperitoneum, as in the case in laparoscopic surgery, and extreme positions increase IAP and arterial carbon dioxide tensions (increasing pulmonary artery pressure), reduce venous return, and increase the risk of reducing the cardiac output in children with Fontan physiology (see later discussion). Successful management of these children during laparoscopic surgery requires a multidisciplinary team that functions in concert to optimize the child’s outcome (1) by optimizing the child’s condition preoperatively and identifying any cardiac issues, (2) by recruiting surgeons who can complete the surgery quickly and efficiently, (3) by maintaining the children in the supine position throughout the surgery, (4) by maintaining normocapnia, (5) by monitoring the child with a transesophageal echo probe as needed, as well as with an arterial invasive pressure monitor for blood gas analysis, and (6) by insufflating the abdomen to the lowest (less than 8 mm Hg) IAP that is surgically feasible. Larger studies are required before children with cyanotic heart disease, particularly those with Fontan physiology, can routinely undergo laparoscopic surgery in any center except those with specialized teams to manage these children.

FIGURE 27-1 A child undergoing laparoscopic appendectomy, presented as a paradigm for the surgical set-up for any multiple trocar laparoscopic surgery. Three incisions were made, two in the anterior abdominal wall and the third in the umbilicus. The first two trocars carry instruments to manipulate the appendix, while the third holds the camera for viewing by all personnel in the operating room. All cables swing widely off the surgical field.

FIGURE 27-2 Wide-angle view of the operating room with surgeon and scrub nurse viewing the appendix being held by the grasper, shown on the overhead monitor.

FIGURE 27-3 Inside the abdominal cavity with a view of the inflamed appendix that has been mobilized. The peritoneal attachments must be peeled off the appendix before it is ligated and removed.

FIGURE 27-4 The appendix is ligated and inserted into a plastic container and withdrawn usually through the trocar or incision site without contaminating adjacent tissues. The appendix is shown in the surgeon’s hand after removal.

Laparoscopic surgery offers a number of advantages over open surgery, including more rapid emergence from anesthesia, faster ambulation, earlier discharge from the hospital, and reduced perioperative complications.¹⁰²^–¹⁰⁵ Robot-assisted surgical technology is discussed later.

Laparoscopic surgery involves the insufflation of gas into the abdominal cavity in order to visualize the intraabdominal organs. When preparing for laparoscopic surgery, if the surgery involves the upper abdomen, the stomach should be decompressed using a nasogastric or orogastric tube whereas if the surgery involves the lower abdomen, the bladder should be emptied using a urinary catheter. Surgical access to the peritoneal cavity is achieved with trocars introduced through three (or more) small (3 to 10 mm in diameter) incisions. Through the trocars, the laparoscopic instruments and a camera are then passed. Recently a laparo-endoscopic single site (LESS), single port, single incision laparoscopic surgery (SILS), single incision multiport laparoscopy (SIMPL), or “belly button” surgery has been developed, in which all instruments pass through a single incision and a single large trocar (often in the umbilicus).¹⁰⁶^–¹⁰⁹ Through the single trocar, the instruments and a camera are inserted.^109a (E-Figs. 27-1 through 27-3). “Clashing” (or colliding of objects) is a common problem because of the close proximity of the cables exiting the single trocar, as well as the proximity of the multiple hands performing the procedure. The clashing of cables has been resolved by fusing them into a single cable as they exit the trocar.

E-FIGURE 27-1 The “poor man’s” SIMPL device. Through a flap lifted in the umbilicus, a collapsible sheath is passed into the peritoneal cavity that opens once inside the abdomen to stabilize the sheath. On the skin surface, a ring stabilizes the sheath, over which a surgical glove is affixed. A finger tip on the glove is nicked and the gas insufflator (carbon dioxide feed) is inserted. The peritoneal cavity is then inflated to the desired pressure. Through adjacent finger tips, the camera and operating instruments are passed to perform the surgery. (Courtesy Dr. K. Vali, Pediatric Surgery, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

E-FIGURE 27-2 A commercially available SIMPL device for a child in which a single sheath is inserted through a flap lifted in the umbilicus. The ports and gas insufflator are mounted on the outside. For more information see Reference 109a. (Courtesy Dr. K. Vali, Pediatric Surgery, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

E-FIGURE 27-3 A commercially available SIMPL device in a child through which the camera and two laparoscopic instruments have access to the abdominal cavity. This is achieved through the umbilicus with one surgical incision. For more information, see Reference 109a. (Courtesy Dr. K. Vali, Pediatric Surgery, Women and Children’s Hospital of Buffalo, Buffalo, N.Y.)

Pneumoperitoneal pressure is a major concern for all laparoscopic approaches. Experimental evidence in adult and newborn pigs demonstrated that the risks of cardiorespiratory consequences and potentially fatal emboli were directly related to the peak pneumoperitoneal pressure.^110,¹¹¹ In infants and children, the optimal pneumoperitoneal pressure is the least pressure that enables adequate surgical access. Carbon dioxide should be insufflated through one of the trocars until the IAP reaches 6 to 15 mm Hg; most surgeons currently limit the IAP in neonates and young infants to 6 to 8 mm Hg and in children to 10 to 12 mm Hg.¹¹² The IAP is maintained throughout the surgery by intermittently insufflating additional CO₂. Although carbon dioxide is most commonly used, a number of gases have been investigated (see later discussion).¹¹³ Carbon dioxide is the preferred gas because it does not support combustion, is rapidly cleared from the peritoneal cavity at the end of surgery, and does not expand into bubbles or spaces.^93,^114,¹¹⁵ However, the increased IAP may cause mechanical difficulties, such as circulatory or respiratory depression, hypothermia due to dry gas leakage, pneumothorax or subcutaneous emphysema, endobronchial intubation resulting from the upward shift of tracheal bifurcation, and injury due to paracentesis. The major disadvantage of CO₂ is that it is rapidly absorbed from the peritoneum, with the absorption and washout of CO₂ being more rapid and the peak end-tidal partial pressure of CO₂ (Petco₂) less in infants than in older children.^116,¹¹⁷ The inverse relationship between age and rate of CO₂ absorption from the abdomen has been attributed to the thinner peritoneum and the reduced peritoneal fat deposits in the abdomen of infants compared with older children.¹¹⁷ Evidence indicates that only 10% to 20% of the Petco₂ originates from the insufflated CO₂ after 10 to 20 minutes of insufflation at an IAP of 10 to 15 mm Hg.¹¹⁸ During CO₂ insufflation, both the Petco₂ and Paco₂ increase up to 20 mm Hg or 20% to 50% above baseline.^94,^112,^114,^116,¹¹⁹ Hypercapnia may occur if surgery lasts more than 1 hour, particularly in neonates,¹²⁰ necessitating an increase in minute ventilation of 50% to 100% to maintain a physiologic pH.^93,¹²¹ Again, it must be emphasized that all of these adverse physiologic changes that occur with laparoscopic surgery could have catastrophic implications for children with Fontan physiology and that consideration to performing an open procedure may be the safest approach.

The difference between the partial pressures of arterial and end-tidal CO₂ (Pa−Petco₂) often increases during insufflation of CO₂,^119,¹²¹ although a number of studies reported negative Pa−Petco₂ gradients, particularly in infants. The explanation for these negative gradients has been elusive, but may be due to sampling or technical errors or ventilation-perfusion mismatch.^119,¹²¹ The Pa−Petco₂ gradient before and after pneumoperitoneum increases from a mean of 5.7 mm Hg to 13.4 mm Hg.¹²² In neonates and in children with cyanotic congenital heart disease, the Petco₂ may not reliably track the Paco₂ during CO₂ insufflation, leading some to recommend arterial blood gas monitoring to validate the Petco₂ measurements.^119,^122,¹²³

Increased Paco₂ may also trigger spontaneous respiratory efforts that could interfere with surgery. Additionally it may also initiate a sympathetic response, including an increase in the heart rate, blood pressure, and cerebral blood flow, as well as ventricular arrhythmias, although this occurs rarely today because sevoflurane has replaced halothane in many countries. A sudden increase in Petco₂ may also suggest a diagnosis of malignant hyperthermia. If this diagnosis proves to be difficult to confirm or reject (see Chapter 40), it may be necessary to desufflate the abdomen and determine if the clinical and laboratory findings suggestive of MH resolve. Insufflated CO₂ originating from the abdomen continues to be exhaled for the first 30 minutes after desufflation.¹¹⁸

Gas emboli have been reported in several laparoscopic studies, most of which were interesting curiosities of no clinical consequence, although in several, the result was profound cardiovascular collapse. Most consider the emboli to be intravascular CO₂ bubbles. Intravascular embolization of CO₂ may occur when the insufflation pressure exceeds the venous pressure, forcing CO₂ bubbles into the venous circulation, resulting in sudden cardiovascular collapse.¹²⁴ Continuous precordial Doppler or CO₂ partial pressure are effective in detecting a gas embolus, although the Doppler may be overly sensitive, with numerous false-positives. It has been suggested that many episodes of subclinical gas embolisms are unrecognized because the symptoms are mild and nonspecific. However, children with right-to-left shunts or potential right-to-left shunts, such as a patent foramen ovale, are vulnerable to the systemic effects of these emboli. Although CO₂ is soluble in blood and rapidly buffered, CO₂ emboli dissolve slowly in blood, taking 2 to 3 minutes to disappear.¹²⁵ Hence, large emboli may block blood flow in the heart for several minutes or more, before they dissolve. The minimum rate of infusion of CO₂ into blood that triggers cardiovascular collapse in pigs is 1.2 mL/kg/min¹²⁵; comparable data in humans are lacking. Anesthesiologists should be aware of the high-risk conditions that predispose to CO₂ emboli (e.g., increased abdominal insufflation pressure, hypovolemia and reduced venous pressure, spontaneous respirations, and resection of vessel-rich parenchymatous organs) and correct the condition or warn the surgeons.

Some investigators suggest that clinically important gas emboli are actually nitrogen, not carbon dioxide gas emboli.¹²⁴ Whereas transient emboli are thought to be composed of CO₂, emboli that persist may be nitrogen gas.¹²⁴ Nitrogen is insoluble in blood (blood/gas partition coefficient of 0.014), which explains its persistence as an embolus in blood. These emboli may arise from air either present in or entrained by the trocar during insufflation of the peritoneum, that is forced into a transected blood vessel while the carboperitoneum is pressurized.¹²⁴ This mechanism is a rare source for gas in the circulation, which may explain, in part, why the emboli that occur during laparoscopy very rarely result in cardiovascular instability and arrest.

In contrast to CO₂, insufflation with oxygen, air, and nitrous oxide for laparoscopic surgery has been eschewed because they all support combustion. However, repeat desufflations of the pneumoperitoneal gas during laparoscopy in pigs whose lungs were ventilated with 66% nitrous oxide in oxygen, has been shown to prevent concentrations of nitrous oxide from exceeding 10% in the pneumoperitoneal cavity.¹²⁶ Nitrous oxide is still not recommended for either insufflation or as an adjunctive anesthetic gas during laparoscopy, because it also expands into gas-filled cavities should gas emboli appear in the circulation.¹¹⁴ Its use during laparoscopic surgery may distend the bowel in bowel obstruction and obscure the surgeon’s view, as well as expand any CO₂ emboli that develop.

The inert gases argon and helium were also candidate gases for insufflation to create a pneumoperitoneum as they cannot be oxidized (and therefore ignited), although they are much more expensive than CO₂. When argon was used to create a pneumoperitoneum in pigs, embolization occurred more frequently than with CO₂.¹²⁷ In theory, both argon and helium can cause serious sequelae if embolized into the vascular system because they are insoluble in blood (blood/gas solubility of helium is 0.007 and argon is 0.029) and are likely to persist.^93,^114,^115,¹²⁷

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.