Preoperative Assessment of the Pediatric Patient With Cancer

Introduction

Childhood cancers make up less than 1% of all newly diagnosed cancers each year. However, with increasing survival rates, an increasing number of pediatric patients will present for surgery and/or procedures related to their cancer diagnosis. Many of these patients will require anesthesia, often multiple times, and thorough preoperative assessment and optimization is therefore essential to ensure successful outcomes from cancer surgery.

The preoperative assessment and optimization of a pediatric patient with cancer can be complex. The disease process itself along with associated cancer-related treatments can impact the preoperative physiologic reserve and the perioperative management of these patients. A comprehensive, multidisciplinary approach to evaluation and optimization needs to be undertaken for the best outcomes, including patient and parental satisfaction. However, since surgery or procedures related to a diagnosis of cancer are often not elective, a sense of urgency can sometimes preclude medical optimization.

Children with cancer are typically evaluated by their primary oncologist prior to being referred for procedures under anesthesia. As a result, details of their primary diagnosis, coexisting medical conditions, types of cancer-related treatment undergone, complications associated with those treatments, and the results of laboratory or diagnostic imaging procedures may be available for review. A preoperative clinic visit to evaluate patients prior to the day of surgery or procedure is ideal but not always feasible. This chapter will focus on the important aspects of preoperative evaluation and optimization as they specifically relate to the pediatric patient with cancer.

Neurologic Evaluation

An altered neurologic status may be secondary to tumor progression or related to cancer therapy. Platinum agents, l-asparaginase, ifosfamide, methotrexate, cytarabine, etoposide, vincristine, cyclosporine A, and craniospinal irradiation have been associated with neurotoxic side effects. Commonly associated acute complications include altered mental status, seizures, cerebral infarctions, encephalopathy, hearing loss, vision changes, and peripheral neuropathies. A comprehensive preoperative neurologic evaluation to document the baseline neurologic status, as well as to determine optimal perioperative management strategies, is encouraged.

Patients should continue their regular antiepileptic medications on the morning of surgery, and regular dosing should be reestablished as early as possible after surgery. When multiple doses are likely to be missed, antiepileptic drugs should be administered parenterally, if possible.

Cardiac Evaluation

Some chemotherapeutic agents, particularly cytotoxic antibiotics of the anthracycline class (doxorubicin, daunorubicin, idarubicin, and epirubicin), are commonly associated with cardiotoxicity. Other commonly used drugs in pediatric patients with cancer, for example methadone and the 5-HT3 antagonist ondansetron, may prolong the QT interval and potentially decrease the threshold for cardiac arrhythmias. Chest irradiation, with or without concurrent anthracycline treatment, can potentially lead to pericarditis, pericardial effusions, cardiomyopathy, endocardial fibrosis, valvular fibrosis, conduction abnormalities, and/or coronary artery disease. Children receiving cardiotoxic cancer therapies should undergo periodic cardiac evaluations starting with baseline electrocardiography and echocardiography. In children, physical examination alone has been shown to miss the early signs of chemotherapy-related congestive heart failure in more than 50% of patients. The stress of surgery can also unmask a subclinical cardiomyopathy. Therefore past cardiovascular physical examinations and laboratory studies should be thoroughly reviewed prior to induction of anesthesia.

Pulmonary Evaluation

Pulmonary dysfunction may be associated with the primary disease process or side effects of cancer therapies. A history of treatment with bleomycin, carmustine, lomustine, busulfan, cyclophosphamide, or chest irradiation should warrant an in-depth evaluation of pulmonary status. Symptoms of chronic cough, dyspnea on exertion, and wheezing should be further examined by chest radiography and possibly pulmonary function tests. Pulmonary function tests in children play an important role in evaluating the child with known or suspected lung dysfunction, and they provide baseline measurements, especially prior to undergoing a surgical treatment, which could potentially alter respiratory mechanics. Additionally, pulmonary function tests, chest radiography, and oxygen saturation measurement may be indicated in patients with unexplained symptoms or abnormal findings on physical examination. Obstructive lesions, such as anterior mediastinal masses, neck masses, or oropharyngeal masses, should be evaluated by computed tomography or magnetic resonance imaging. Clinically symptomatic pleural effusions may benefit from therapeutic thoracentesis prior to surgery to enhance physiologic reserve.

Gastrointestinal Evaluation

Gastrointestinal symptoms, such as vomiting, gastroparesis, and obstruction, may occur in pediatric patients with cancer. These symptoms may place the child at risk for malnutrition, electrolyte and acid-base disturbances, and increase the risk for pulmonary aspiration during anesthesia. Chemotherapy-associated nausea and vomiting has been estimated to occur in up to 70% of the pediatric population. The risk of postoperative vomiting has been shown to be higher in children than in adults. Factors that increase the risk of postoperative vomiting include age >3 years, girls who are postpubertal, a previous history of motion sickness, and those who have a personal or family history of postoperative vomiting. A focused gastrointestinal assessment should be performed preoperatively, and any pertinent imaging should be reviewed in order to formulate the safest anesthetic plan and perioperative management.

Hepatic/Renal Evaluation

Chemotherapy, radiation, and hematopoietic stem cell transplant, with associated preconditioning regimens, may be associated with hepatotoxicity, nephrotoxicity, or both. The most common agents associated with hepatic dysfunction in children are methotrexate, actinomycin D, and 6-mercaptopurine. Similar to patients with known liver dysfunction, impaired drug metabolism, hypoglycemia, and decreased coagulation factor production should be considered in children with potential hepatic impairment.

The most common nephrotoxic agents in children are alkylating agents, such as cisplatin, as well as ifosfamide, cyclophosphamide, and methotrexate. Patients with a history of previous nephrotoxicity have the potential for decreased renal excretion of drugs, electrolyte and/or acid-base derangements, and hypertension. Nephrotoxicity can be further compounded by factors such as perioperative administration of nephrotoxic medications and sustained perioperative hypotension. Renal and liver function tests may therefore be clinically indicated prior to surgery.