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An 18-month-old boy presents with abdominal distention and a firm, mobile, nontender mass on the right side. His BP is 140/60. Abdominal CT reveals a right renal mass with no extension to surrounding structures. Chest x-ray (CXR) is clear. Urinalysis is positive for red blood cells. He is treated with captopril and scheduled for a right nephrectomy.
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PREOPERATIVE CONSIDERATIONS
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Wilms’ tumor is the most common childhood abdominal malignancy. While these tumors are usually confined to a single kidney, 5% are bilateral, and a small number of patients have intravascular tumor extension to the inferior vena cava (IVC) and right atrium. About 10% are associated with syndromes such as Beckwith-Wiedemann, Soto’s, Denys-Drash, WAGR (Wilms’ tumor, aniridia, genitourinary anomalies, and mental retardation), and trisomy 18.
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The most common presentation is in an otherwise healthy child with increasing abdominal girth and a palpable mass. Malaise, vomiting, constipation, weight loss, anemia, pain, fever, and hematuria can also occur. Hypertension, possibly due to high renin levels, is present in more than 50% of patients at the time of diagnosis and is usually managed with an angiotensin-converting enzyme inhibitor. Other paraneoplastic phenomena may include acquired von Willebrand’s disease and hyperaldosteronism.
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Preoperative workup should include imaging assessment of local tumor extension (abdominal CT/MRI, pyelogram, and vena cavogram, and echocardiogram if the tumor extends to the IVC and the right atrium) and workup for metastatic disease (CXR or chest CT). Patients with bilateral disease, unresectable disease, or IVC or atrial extension will undergo chemotherapy and radiation treatment prior to resection. Commonly used chemotherapy drugs and their side effects include actinomycin (hepatic dysfunction, myelosuppression, coagulopathy, gastrointestinal upset, immunosuppression), vincristine (peripheral neuropathy, syndrome of inappropriate antidiuretic hormone), and doxorubicin (arrhythmias and cardiomyopathy). Lab studies needed include complete blood cell count, serum chemistries, coagulation studies, and type and cross. Anemia can result from tumor bleeding or myelosuppression. Hypokalemia can result from vomiting, renal potassium wasting (due to hyperaldosteronism), and polydipsia (due to high renin levels). Renal dysfunction is uncommon. Anemia, thrombocytopenia, and electrolyte abnormalities should be corrected preoperatively, and the patient should be well hydrated.
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ANESTHETIC MANAGEMENT
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Because of abdominal distention and delayed gastric emptying, treat patient as having a full stomach. Rapid-sequence induction is usually appropriate if airway assessment is normal.
Patients with overgrowth syndromes causing macroglossia or trisomy 18 causing micrognathia may require specialized airway equipment for intubation.
Ventilation may become difficult during the case, as intra-abdominal pressure increases as a result of surgical retraction. Consider the use of a low-pressure cuffed endotracheal tube.
Hypotension on induction may occur if the patient is not well hydrated. Exaggerated hypertension can also occur with intubation if it is present preoperatively.
Prepare for large intraoperative blood loss and third space fluid losses. This includes access (two large-bore IVs), monitoring (arterial line and possibly central line), and blood products.
Muscle relaxant ...