Anesthesiology

Exstrophy of the bladder

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What the Anesthesiologist Should Know before the Operative Procedure

Classic exstrophy of the bladder represents 70% of the congenital malformations associated with the exstrophy-epispadias complex. The occurrence is 1/40,000 births. The other 30% of the spectrum are cloacal exstrophy (1/400,000 births), male epispadias (1/120,000 births), and female epispadias (1/400,000 births).

Classic bladder exstrophy (male to female ratio: 3-4:1) is a multisystem defect involving soft and bony tissues of the pelvis: urinary, genital and reproductive, pelvis (pubic diastesis), pelvic floor, and spine (7% anomalies).

Approaches to reconstructive repair of bladder exstrophy vary according to the age of the child and institutional preferences. There are essentially three types of patients coming to surgery: neonates for initial reconstruction within the first week of life, infants with a small bladder template for a delayed repair, and, finally, the child of any age with a prior failed bladder closure for a redo procedure.

The initial reconstruction includes closure of the bladder, abdominal wall with/without an epispadias repair depending on institutional preferences. If the stage approach is used, epispadias repairs are usually scheduled around the child's first birthday. Bladder reconstructions beyond the first week of life commonly include bilateral pelvic osteotomies and placement of external fixation. Postoperative immobilization is desirable but may vary between institutions, reaching from simple spica casting to traction for 4 to 6 weeks.

Patients with bladder exstrophy may require multiple procedures before they can achieve urinary continence including repeated cystoscopies to measure bladder capacity, bladder neck reconstruction, ureteral reimplantation, or bladder augmentation and continent stoma formation. In addition, they are at risk for complications such as urethral fistulae, stoma stenosis, or urolithiasis in the neobladder. Due to exposure to frequent surgical interventions and potential need for repeat urinary catheterizations, these patients are at risk for latex allergy.

After delivery and prior to the initial procedure, the child should be stabilized and evaluated for comorbidities (cardiac, pulmonary) and other congenital defects. Minimal or no need for cardiopulmonary support is preferable before taking the child to the operating room (OR). Assessment of the spine (radiograph, ultrasound) is recommended before considering any regional technique.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Initial surgery within the first week of life is preferable as the surgery can be limited to a bladder and abdominal wall closure. The pelvis is still malleable and symphysis pubis can be narrowed by simple adduction of the legs. Patients coming to surgery later will require pelvic osteotomies and external fixation, a more involved and riskier surgery.

Emergent: Exstrophy closure should not be an emergent procedure but this anomaly may be associated with others requiring immediate attention, such as gastrointestinal obstruction or meningomyelocele. Positioning of the patient can be challenging. Bladder tissue should remain covered with nonadhesive plastic wrap. Inability to measure urine output complicates assessment of fluid status. Invasive monitoring may be necessary.

Urgent: Surgery within the first few days of life falls in the postnatal adaptation period of the cardiopulmonary system. The foramen ovale remains open; the ductus arteriosus is not completely closed. Flow across the ductus is left to right but can revert to right to left with associated oxygen desaturation if the patient develops acidosis. Hypoxemia, hypercapnia, dehydration, hypothermia increase the risk of acidosis and should therefore be avoided. Similarly, pulmonary pathology due to transient tachypnea of the newborn (TTN), meconium aspiration, atelectasis, or neonatal pneumonia will increase this risk and should ideally have resolved prior to surgery.

Elective: Surgery beyond 1 week of age will include pelvic osteotomies to improve the chances of a successful repair. This surgery can be associated with significant blood loss. Infants coming for delayed repairs may be close to the physiological nadir in hemoglobin due to the transition from fetal to adult hemoglobin (4-5 months of age) and may be anemic even prior to coming to the OR.

2. Preoperative evaluation

After delivery, the child requires evaluation for other congenital defects and comorbidities. Minimal to no need for cardiopulmonary support is preferable before taking the patient to the OR. Most children will be ready by DOL 2-5.

Medically unstable conditions warranting further evaluation: These include signs of pulmonary compromise in the form of tachypnea or oxygen requirement. Transient tachypnea of the newborn, meconium aspiration. Hematological conditions such as anemia or significant hyperbilirubinemia

Delaying surgery: This may be indicated if: there is a need for cardiorespiratory support in the form of mechanical ventilation and/or pressor support; a need for neonatal exchange transfusion to treat hematologic conditions; or the repair of other congenital conditions takes precedence.

3. What are the implications of co-existing disease on perioperative care?

Neonatal patients whose cardiovascular system is still adapting to postnatal life require meticulous attention to detail concerning fluids, temperature, and gas exchange management.

Presence of neonatal pneumonia or meconium aspiration may require a delay in surgery. Development of chronic lung disease secondary to these conditions may extend the child's postoperative need for intensive care.

Spinal abnormalities exclude central regional anesthesia techniques requiring use of opioids for perioperative pain management. Respiratory depressant effect of opioids in neonatal population may result in a prolonged need for postoperative mechanical ventilation.

Perioperative evaluation

Physical exam looking for an active, alert, or comfortably resting, well-perfused, and well oxygenated neonate on room air. Routine laboratory studies including (complete blood count) CBC, type and screen, chemistry, bilirubin. Beware: serum chemistries obtained within the first few hours of life are more reflective of the maternal than of the neonate's homeostasis. ABG (arterial blood gas): if there is evidence of respiratory compromise.

Chest radiograph, ideally extending caudate to include pelvis: assessment of cardiac shape and any pulmonary infiltrates. Extension of radiograph may allow evaluation of lumbar and sacral spine. Spinal ultrasound, a noninvasive technique, to assess for lumbosacral anomalies if epidural anesthesia, is considered.

If the child has other anomalies or a cloacal exstrophy, a more extensive survey for associated anomalies may be indicated: cardiac echo, head ultrasound, abdominal ultrasound. The older child coming to surgery will require a review of the history and a physical exam, routine laboratory studies, and type and cross for 2 units of packed red blood cells (PRBCs).

Perioperative risk reduction strategies

Avoid surgery within the first 24 hours of life: pulmonary vascular resistance is still high but will further decrease with time. The risk of reversal to prenatal circulation (PDA right to left shunt, hypoxia) will be diminished.

b. Cardiovascular system

Acute/unstable conditions

Cyanotic congenital cardiac disease, congestive heart failure due to congenital cardiac disease, persistent pulmonary hypertension.

Baseline cardiac dysfunction – goals of management

Stabilization of cardiac function without need for mechanical ventilation or pressor support prior to exstrophy repair.

c. Pulmonary

Neonatal pneumonia or meconium aspiration

Stabilization of pulmonary status without need for mechanical ventilation prior to neonatal exstrophy repair.

Bronchopulmonary dysplasia (neonatal intensive care unit [NICU] graduate)/reactive airway disease/asthma (older child)

Continue usual therapy until day of surgery, administer bronchodilator in preop area, and consider steroids for 3 days prior to surgery if the child has had several recurrent but distinct episodes of wheezing. Refer to pulmonologist prior to surgery if child wheezes frequently and seems to be poorly controlled.

Obstructive sleep apnea (older child)

Refer to pulmonologist if the child has a history of pronounced snoring, day time sleepiness, and/or respiratory pauses prior to reconstructive surgery. Obstructive sleep apnea will increase the risk of opioid analgesic management and sedation managment in the postoperative period. The child may benefit from an adenoidectomy and tonsillectomy and/or bilevel positive airway pressure (BIPAP) prior to the exstrophy reconstruction.

d. Renal-GI:

Patients with bladder exstrophy have ureteral reflux and hydronephrosis. Thus they are at risk for recurrent urinary tract infections. Significant infections can lead to pyelonephritis and renal damage.

Associated gastrointestinal obstructions, such as anal stenosis, may require attention prior to reconstructive bladder surgery.

e. Neurologic:

Spinal anomalies are found in 7% of bladder exstrophy patients. The incidence is higher in patients with larger defects such as cloacal exstrophy. Meningomyelocele and sacral agenesis can be associated, primarily with the latter.

Acute issues:None, except in the case of associated meningomyelocele.

Chronic disease: None.

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Reconstruction in infant aged 4 to 5 months: physiological nadir of hemoglobin. Patient may be relatively anemic prior to surgery. It is more pronounced in former premature infants.

4. What are the patient's medications and how should they be managed in the perioperative period?

Neonate: Antibiotics (treatment for presumed neonatal sepsis); continue according to schedule after conferring with surgeons regarding intraoperative antibiotic needs.

Older child: Antibiotics (urinary tract infection [UTI] prophylaxis); continue at least until day prior to surgery.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Oxybutinin (control of bladder spasms): anticholinergic with effect on several muscarinic subtypes as well as calcium antagonist, commonly administered in its transdermal form. Should be discontinued no later than the day of surgery because it can potentiate the effects of anticholinergics, opioids, and sedatives, delaying emergence from anesthesia. Longer term is also associated with hypocalcemia.

i. What should be recommended with regard to continuation of medications taken chronically?

Renal: Antibiotics for UTI prophylaxis – continue at least until day prior to surgery.

j. How To modify care for patients with known allergies -

Perioperative antibiotic administration for prevention of surgical site infection needs to be adjusted.

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

Bladder exstrophy patients born before 2000 may be highly sensitized requiring meticulous attention to identification and removal of all latex-containing products. Younger patients have had very limited exposure to latex products due to the recent removal of latex from the medical environment.

l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]

Penicillin allergy: clindamycin or vancomycin.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia

Local anesthetics (LA)/ muscle relaxants: Local anesthetics: primarily to ester LA (p-aminobenzoic acid [PABA] metabolite), no cross-recativity to amide LA.

Proposed anesthetic plan: Use amide LA. Allergy to all LA: avoid regional technique.

Muscle relaxants: Usually due to IgE antibodies directed toward quaternary ammonium radical common to all neuromuscular blocking agents.

Proposed anesthetic plan: Endotracheal intubation under deep anesthesia without use of muscle relaxant, maintenance of anesthesia as a combined general regional technique, or opioid-based general technique without muscle relaxation.

5. What laboratory tests should be obtained and has everything been reviewed?

Hemoglobin is indicated for a baseline, either prior to the procedure or early during the case itself. Infants for delayed repairs at age 4 to 5 months may be anemic due to decrease in fetal hemoglobin. Pelvic osteotomies are associated with significant blood loss.

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

Hemoglobin levels: depending on age of child.

Electrolytes: as for other procedures in the pediatric age group

Coagulation panel: as for other procedures in the pediatric age group

Imaging: radiograph, ultrasound, and /or magnetic resonance imaging (MRI) of spine to rule out defect contraindicating regional anesthesia

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

General opioid-based anesthesia or a combined general-epidural anesthesia

Opioid-based or balanced anesthesia can be associated with respiratory depression in the neonatal age group. Continued need for mechanical ventilation necessitates availability of an intensive care bed. Older children undergoing reconstruction with pelvic osteotomies may have significant intraoperative blood loss. They may require continued close observation for hemodynamic stability in an intensive care setting. Ventilatory support is occasionally needed for the older age group.

Epidural anesthesia limits or abolishes the need for opioid analgesics, thus allowing a chance of endotracheal extubation at the end of the case for young infants.

Regional anesthesia

Epidural

Epidural catheters can be placed in the caudal or lumbar region. Caudal catheters should be advanced cephalad to position the tip in the lumbar region. Success of catheter position within 1 to 2 dermatomes of desired location can be as high as 80% but in older children (weight > 15-20 kg) this rate may be lower. Lumbar insertions are preferred in those patients. Catheters can be tunneled subcutaneously from the insertion site to one of the iliac crests to decrease the risk of infections. With close observation these catheters can be maintained for up to a month.

Local anesthetics include lidocaine, ropivacaine, and bupivacaine.

Neuraxial

Benefits:early extubation

Drawbacks:Potential need for deep vein thrombosis (DVT) prophylaxis in adolescent patients. Nursing staff on pediatric units is less aware of risk of complications when combining DVT prophylaxis and regional anesthesia.

General anesthesia

Drawbacks: Increased risk of respiratory depression and need for postoperative mechanical ventilatiion.

Monitored anesthesia care

In addition to standard American Society of Anesthesiologists (ASA) monitoring: central venous access – ideally peripherally inserted central venous catheters (PICC).

Benefits:

  1. Facilitates access for obtaining CBC and electrolytes at regular intervals during the procedure. CBC - most important during pelvic osteotomies, electrolytes - most important during bladder augmentations fluid administration needs to account for increase loss from exposed bowel. Urine output cannot be utilized to assess hydration status in bladder procedures.

  2. Maintains reliable intravenous access for days to weeks postoperatively.

Drawbacks: Increased risk of thrombosis, bacteremia, and sepsis.

6. What is the author's preferred method of anesthesia technique and why?

The preferred method of anesthesia for a patient with bladder exstrophy is a combined general/regional technique with intraoperative insertion of an epidural catheter to be maintained postoperatively for pain management. A central venous catheter or PICC provides access for monitoring hemoglobin and electrolytes in patients at risk for blood loss (osteotomies) and inadequate assessment of volume status (no urine output measure, open bowel in bladder augmentations. PICC is also ideal to assure continued access during a long postoperative inpatient stay.

What prophylactic antibiotics should be administered?

The choice of antibiotic and dosing will depend on the child's age.

What do I need to know about the surgical technique to optimize my anesthetic care?

Bladder exstrophy repair: Limited insensible fluid losses, no assessment of urinary output, neonatal patient - meticulous attention to fluid ins and outs required. After bladder closure orthopedic team may place the patient into traction or into a spica cast depending on institutional preferences.

Bladder exstrophy with pelvic osteotomies: Significant blood loss is possible which is not always visible as it disappears into the pelvic tissues. Pelvic osteotomies are performed first, followed by bladder closure, and completed by attaching pelvic external fixation devices and lower extremity traction. Hypovolemia and anemia are early risks, whereas electrolyte abnormalities and acidosis are risks later in the case.

What can I do intraoperatively to assist the surgeon and optimize patient care?

The judicious use of intravenous fluids. Overhydration will lead to "flooding the field" as the patient's urine collects in the field. It will also increase tissue edema, complicating eventual closure.

What are the most common intraoperative complications and how can they be avoided/treated?

Hypovolemia, acidosis, electrolyte abnormalities.

Cardiac complications

Acidosis in neonatal patients is associated with a return to a transitional circulation: open ductus arteriosus, open foramen with right-to-left shunting, and/or worsening hypoxia.

Pulmonary complications

Incorrect positioning of the endotracheal tube in the short trachea of the neonate can result in atelectasis.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

Neonates may be extubated after simple bladder exstrophy if they are awake and strong: flexed lower and upper extremities, lifting legs off bed. As the endotracheal tube may be the only noxious stimulus in a patient with epidural analgesia, preparations for immediate reintubations should be made in case the child becomes apneic after removal of the endotracheal tube.

c. Postoperative management

Postoperative analgesic management will depend on the intraoperative anesthetic.

Patients after a general anesthetic without epidural catheter: continuous opioid infusion, intravenous patient- or nursing/guardian-controlled analgesia dependent on institutional preferences and abilities.

Patients with epidural anesthesia: epidural infusions or patient controlled epidural analgesia. Epidural drug choices will depend on institutional preferences but usually include local anesthetics (lidocaine, bupivacaine, ropivacaine), opioids (fentanyl, hydromorphone), and/or clonidine. Doses need to be decreased in the neonate to avoid toxicity. Adjunctive analgesics may include acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), opioid agonist/antagonists such as nalbuphin or butorphanol. Diazepam may be helpful for bladder spasms.

What level bed acuity is appropriate?

Neonates should be admitted to an intensive care unit (ICU) setting as they are at risk for postsurgical and postoperative opioid associate apnea. Older children may go to a step-down unit to ensure adequate postoperative nursing observation of intravenous or epidural analgesia. Need for increased sedation to maintain limited mobility and ensure surgical healing may require an ICU setting for closer observation of synergistic effects of postoperative analgesics and sedatives.

What's the Evidence?

Kost-Byerly, S, Jackson, EV, Yaster, M. "Perioperative anesthetic and analgesic management of newborn bladder exstrophy repair". J Pediatr Urol. vol. 4. 2008. pp. 280-5.

(This article describes the perioperative management in more detail.)

Wild, AT, Sponseller, PD, Stec, AA. "The role of osteotomy in surgical repair of bladder exstrophy". Semin Pediatr Surg. vol. 20. 2011. pp. 71-8.

(Good review of orthopedic aspects of surgery.)
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