Oncologic Disease
Patients with malignant tumors may be otherwise healthy or may
be desperately ill with nutritional, neurologic, metabolic, endocrinologic, electrolyte,
cardiac, pulmonary,
renal, hepatic, hematologic, or pharmacologic disabilities. Thus, determining the
other disabilities accompanying malignant tumors requires evaluation of all systems.
Abnormalities frequently accompanying such tumors include hypercalcemia either by
direct bone invasion or by ectopic elaboration of parathyroid hormone or other bone-dissolving
substance, uric acid nephropathy, hyponatremia (especially with small cell, or oat
cell, carcinoma of the lung), nausea, vomiting, anorexia and cachexia, fever, tumor-induced
hypoglycemia, intracranial metastases (10% to 20% of all cancers), peripheral nerve
or spinal cord disorders, meningeal carcinomatosis, toxic neuropathies secondary
to anticancer therapy, and paraneoplastic neurologic syndromes (dermatomyositis,
Eaton-Lambert syndrome, myopathies, and distal neuropathies).
Many patients with malignant tumors are given large doses of analgesics
and should be kept comfortable during the perioperative period. Avoiding drug dependence
is of no practical importance in terminally ill patients.[924]
[925]
Marijuana (tetrahydrocannabinol) depresses
the CNS vomiting center and may be more effective than the phenothiazines or butyrophenones
in suppressing the nausea associated with cancer and its therapy; marijuana decreases
anesthetic requirements 15% to 30%.[926]
Immunomodulators,
stimulating factors or cytokines, gene identification,[927]
[928]
and drugs for treating side effects (e.g.,
midazolam or ondansetron) have given new hope for safer, more effective therapy with
fewer limiting side effects. The effect of ondansetron in preventing vomiting and
the effect of midazolam in preventing "memory-stimulated vomiting" have been important
additions.
The toxicity of cancer chemotherapy is related to the drugs used
and the dose. For radiation therapy, damage occurs when the following doses are
exceeded: lungs, 1500 rad; kidneys, 2400 rad; heart, 3000 rad; spinal cord, 4000
rad; intestine, 5500 rad; brain, 6000 rad; and bone, 7500 rad. The toxicities of
biologic and immunomodulating therapies are related to the change in immune function
that they cause.[621]
[896]
[897]
[899]
Alkylating
agents cause bone marrow depression, including thrombocytopenia, as well as alopecia,
hemorrhagic cystitis, nausea, and vomiting. The alkylating agents, including cyclophosphamide
and mechlorethamine, can act as anticholinesterase and prolong neuromuscular blockade.
[929]
The antineoplastic alkaloid vincristine produces
peripheral neuropathy and SIADH, and vinblastine produces myelotoxicity. Cisplatin
is also associated with peripheral neuropathy and severe nausea. Nitrosoureas can
produce severe hepatic and renal damage, as well as bone marrow toxicity, myalgia,
and paresthesia. Folic acid analogs such as methotrexate have been linked to bone
marrow depression, ulcerative stomatitis, pulmonary interstitial infiltrates, GI
toxicity, and occasionally, severe liver dysfunction. Fluorouracil and floxuridine,
both pyrimidine analogs, cause bone marrow toxicity, megaloblastic anemia, nervous
system dysfunction, and hepatic and GI alterations. Purine analogs (mercaptopurine,
thioguanine) have bone marrow depression as their primary toxic effect. Anthracycline
antibiotics (doxorubicin, daunorubicin, mithramycin, mitomycin C, bleomycin) can
all cause pulmonary infiltrates; cardiomyopathy (especially doxorubicin and daunorubicin);
myelotoxicity; and GI, hepatic, and renal disturbances.
The wisdom of anesthetizing patients given bleomycin has been
questioned. A retrospective study by Goldiner and coauthors[930]
reported postoperative deaths in five consecutive patients given bleomycin. All
five patients died of postoperative respiratory failure. Using the same anesthetic
technique, Goldiner and coworkers[930]
then anesthetized
12 patients, limited the inspired oxygen concentration to 22% to 25% perioperatively,
and replaced much of the blood loss with colloids rather than crystalloids. None
of the 12 patients died. These investigators postulated that bleomycin caused epithelial
cell edema that progressed to necrosis of type I alveolar cells, fluid leakage into
the alveolar space, and the formation of "hyaline membranes" similar to that associated
with oxygen toxicity.[931]
Goldiner and colleagues
[930]
believe that this pathophysiologic similarity
indicates a possible synergistic relationship between oxygen and bleomycin. However,
LaMantia and coworkers[932]
retrospectively analyzed
the changes in 16 patients undergoing surgery after bleomycin therapy. Thirteen
patients were given oxygen at inspired concentrations of 37% to 45%. No instances
of postoperative respiratory failure occurred. Animal data do not support this effect
of bleomycin in altering the toxicity of hyperoxia.[933]
Thus, data are currently available to support all practices regarding oxygen administration
to patients given bleomycin. We prefer to keep inspired oxygen concentrations at
the lowest level that provides adequate tissue oxygenation. When in doubt about
side effects in patients undergoing cancer chemotherapy, our practice is to seek
advice from two experts.
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