Devita, Hellman, and Rosenberg's Cancer

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Chapter 6•Principles of Surgical Oncology 81

ANSWERS

Answer 6.1. The answer is A.

Benzocaine is an ester local anesthetic. Allergic reaction to ester local

anesthetics (cocaine, procaine, benzocaine, tetracaine) occurs due to sen-

sitivity to their metabolite, para-aminobezoic acid. This does not result in

cross-allergy to amide local anesthetics such as lidocaine, prilocaine, and

bupivacaine. Therefore, amides can be used as an alternative in patients

who are allergic to esters.

Answer 6.2. The answer is B.

Epidural anesthesia refers to injection of local anesthetic into the epidural

or peridural space. This potential space is bounded by the dura anteriorly

and the ligamentum flavum posteriorly and includes the lymphatics, are-

olar tissue, and epidural venous plexus. The primary site of action of the

local anesthetic is on the spinal nerve roots that traverse the space.

Answer 6.3. The answer is B.

Patients with widely metastatic disease undergoing palliative surgery have

a mortality rate of up to 20%. The underlying disease (metastatic cancer)

is the major determinant of operative risk in this case.

Answer 6.4. The answer is B.

Surgery in the elderly population is decided on a case-by-case basis. Physi-

ologic age does not always correlate with chronologic age. Approximately

half of surgical morbidity is attributed to perioperative cardiac events. The

American College of Cardiology has defined an algorithm to estimate risk

and the need for preoperative testing. Risk is stratified on the basis of the

intrinsic risk of the procedure, the patient’s cardiac history, and the exer-

cise tolerance of the patient. High-risk procedures carry a risk of cardiac

morbidity greater than 4% (noncarotid vascular surgery, thoracic pro-

cedures, abdominal procedures, major head and neck procedures, and

emergent procedures). Intermediate-risk procedures (1% to 4% risk of

cardiac morbidity) include carotid surgery, radical prostatectomy, and

orthopedic procedures. Low-risk procedures (<1% risk) include breast

surgery and soft-tissue biopsies. Patient risk factors include history of

congestive heart failure, diabetes, prior myocardial infarction, angina,

and ventricular arrhythmia. These patients should undergo some form of

preoperative risk assessment with cardiac stress testing before high-risk

surgery.

Answer 6.5. The answer is C.

This patient should be classified as American Society of Anesthesiologists

Class IV. A patient with Class IV has an incapacitating systemic disease

that is not correctable by operation, such as organic heart disease with

marked signs of cardiac insufficiency.