4. Renal Cancer
Renal cell carcinoma is frequently associated with paraneoplastic syndromes, such as erythrocytosis, hypercalcemia, hypertension, and nonmetastatic hepatic dysfunction. The classic triad of hematuria, flank pain, and palpable mass occurs in only 10% of patients, and the tumor often causes symptoms only after it has grown considerably in size. In fact, renal cell carcinoma is commonly discovered as an inci-dental finding in the course of working up a suppos-edly unrelated medical problem, such as in an MRI performed for evaluation of low back pain. This cancer has a peak incidence between the fifth and sixth decades of life, with 2:1 male to female ratio. Curative surgical treatment is undertaken for car-cinomas confined to the kidney, but palliative sur-gical treatment may involve more extensive tumor debulking. In approximately 5–10% of patients, the tumor extends into the renal vein and inferior vena cava as a thrombus. Staging includes CT or MRI scans and an arteriogram. Preoperative arte-rial embolization may shrink the tumor mass and reduce operative blood loss.
Preoperative evaluation of the patient with renal carcinoma should focus on defining the degree of renal impairment, searching for the presence of coexisting systemic diseases, and planning the anes-thetic management needs dictated by the scope of anticipated surgical resection. Preexisting renal impairment depends upon tumor size in the affected kidney as well as underlying systemic disorders such as hypertension and diabetes. Smoking is a well-established risk factor for renal carcinoma, and these patients have a high incidence of underlying coro-nary artery and chronic obstructive lung disease. Although some patients present with erythrocytosis, the majority are anemic. Preoperative blood trans-fusion to increase hemoglobin concentration above 10 g/dL should be considered when a large tumor mass is to be resected.
The operation may be carried out via an anterior subcostal, flank, or midline incision. Hand-assisted laparoscopic technique is often utilized for par-tial or total nephrectomy associated with a smaller tumor mass. Many centers prefer a thoracoabdomi-nal approach for large tumors, particularly when a tumor thrombus is present. The kidney, adrenal gland, and perinephric fat are removed en bloc with the surrounding (Gerota’s) fascia. General endotracheal anesthesia is used, often in combina-tion with epidural anesthesia.
The operation has the potential for extensive blood loss because these tumors are very vascular and often very large. Direct arterial pressure moni-toring should be used. Central venous cannulation is used for pressure monitoring and rapid transfu-sion. Transesophageal echocardiography should be strongly considered for all patients with extensive vena cava thrombus. Retraction of the inferior vena cava may be associated with transient arterial hypo-tension. Only brief periods of controlled hypoten-sion should be used to reduce blood loss because of its potential to impair function in the contralateral kidney. Reflex renal vasoconstriction in the unaf-fected kidney can also result in postoperative renal dysfunction. Fluid replacement should be sufficient to maintain urinary output greater than 0.5 mL/kg/h.
If combined general–epidural anesthesia is employed, administration of epidural local anes-thetic may be postponed until the risk of significant operative blood loss has passed as sympathectomy from epidural local anesthetic administration will potentiate the hypotensive effect of hemorrhage. As with all lengthy operative procedures, the risk of hypothermia should be minimized by utilizing a forced-air warming blanket and intravenous fluid warming. The postoperative course of open nephrec-tomy is extremely painful, and epidural analgesia is very useful in minimizing discomfort and accelerat-ing acute postoperative convalescence.
Some medical centers routinely perform compli-cated resections of renal cancers with tumor throm-bus extending into the inferior vena cava. Because of the degree of physiological trespass and potential for major blood loss associated with this operation, the anesthetic management (as for nephrectomy) can be challenging. A thoracoabdominal approach allows the use of cardiopulmonary bypass when necessary.The thrombus may extend only into the inferior vena cava but below the liver (level I), up to the liver but below the diaphragm (level II), or above the dia-phragm into the right atrium (level III). Surgery can significantly prolong and improve quality of life in selected patients, and in some patients, metastases may regress after resection of the primary tumor. A preoperative ventilation-perfusion scan may detect preexisting pulmonary embolization of the throm-bus. Intraoperative transesophageal echocardiog-raphy (TEE) is helpful in determining whether the uppermost margin of the tumor thrombus extends to the diaphragm, above the diaphragm, into the right atrium, or to the tricuspid valve. TEE can also be used to confirm the absence of tumor in the vena cava, right atrium, and right ventricle after success-ful surgery.
The presence of a large thrombus (level II orcomplicates anesthetic management. Invasive pressure monitoring and multiple large-bore intra-venous catheters are necessary because transfusion requirements are commonly 10–15 units of packed red blood cells. Transfusion of platelets, fresh frozen plasma, and cryoprecipitate may also be required. Problems associated with massive blood transfu-sion should be anticipated. Central venous catheterization should be performed cau-tiously to prevent dislodgement and embolization of tumor thrombus. A high central venous pressure is typical in the setting of significant caval throm-bus and reflects the degree of venous obstruction. Pulmonary artery catheters provide little informa-tion that cannot be obtained from a central line or TEE. Intraoperative TEE is preferable to a pulmo-nary catheter in every respect.
Complete obstruction of the inferior vena cava markedly increases operative blood loss because of dilated venous collaterals from the lower body that traverse the abdominal wall, retroperitoneum, and epidural space. Patients are also at significant risk for potentially catastrophic intraoperative pulmo-nary embolization of the tumor. Tumor emboliza-tion may be heralded by sudden supraventricular arrhythmias, arterial desaturation, and profound systemic hypotension. TEE is invaluable in this situation. Cardiopulmonary bypass may be used when the tumor occupies more than 40% of the right atrium and cannot be pulled back into the cava. Hypothermic circulatory arrest has been used in some centers. Heparinization and hypothermia greatly increase surgical blood loss.