FREE CHBT Hemodialysis Principles and Practices Questions and Answers
The fluid restriction for most patients undergoing in-center hemodialysis is equal to urine volume/day plus:
Since there is little or no urine production in patients with end-stage renal disease, excess fluid must be removed by dialysis. The volume of urine that the patient produces plus so-called insensible losses (e.g., breathing, stool, perspiration), around 600 mL/d, is the usual fluid replacement formula. Thus, a typical prescription would be urine volume plus 1 L (4 cups) a day. Close attention to dry weight (post-dialysis weight) and symptoms of dehydration (e.g., thirst, weight loss, poor skin turgor, hypotension) or fluid overload (e.g., edema, pulmonary congestion, hypertension) must be a part of the evaluation of every patient. Since loss of appetite and malnutrition are common in these patients, dietary considerations are very important, and consultation with a dietitian trained in renal failure is often necessary.
Biocompatibility is best illustrated by:
Biocompatibility refers to the interaction of the membrane with the blood contents. Touching of blood to the membrane may activate certain cellular or protein elements in the blood, causing immunologic reactions, such as allergic reactions or anaphylaxis. Release of deleterious cytokines or enhanced clotting may occur. Adsorption of blood proteins onto the fiber wall tends to improve biocompatibility since the material is no longer seen as "foreign" by immunocompetent cells. In general, synthetic membranes are more biocompatible than those of cellulose due to their ability to absorb proteins better than the latter. Reprocessed (cleaned and reused) dialyzers may be more biocompatible than new ones since they retain some adsorbed protein (unless bleach is used to strip off the protein).
Failure to excrete beta2-microglobulin in patients with kidney failure predisposes the patient to:
Beta2-microglobulin is a protein widely distributed on cell surfaces and in body fluids. It is a precursor of the protein amyloid, which is formed when the beta-microglobulin enters tissues and is converted to amyloid. Healthy kidneys remove excess beta,-microglobulin, but in renal failure, levels rise, and so-called amyloidosis occurs. This may lead to carpal tunnel syndrome, joint pain, bone cysts, compression fractures, and cutaneous bleeding. Nearly 20% of hemodialysis patients develop amyloidosis after 10 years and 80%-100% after 29 years. Pericarditis, inflammation, and fluid accumulation within the pericardium, is common in chronic renal disease as is peripheral neuropathy, most likely due to inadequate excretion of neurotoxic substances. Seizures may occur but are usually related to electrolyte abnormalities, especially hyponatremia.
Blood tests for ferritin are performed in hemodialysis patients:
Ferritin is the main storage protein for iron, required for hemoglobin synthesis, and is usually low in iron deficiency anemia. Most patients with chronic renal failure are anemic, usually from inadequate erythropoietin production by the kidney or bleeding, often gastrointestinal, or both. Erythropoietin levels may be checked, but drugs, such as Epogen or Procrit, that stimulate red cell production will not work effectively unless iron stores are adequate. The use of these erythropoiesis-stimulatory agents is quite common in hemodialysis patients, aiming for a hemoglobin level in the 10-12 g/dL range. Blood transfusions may thus be avoided. Iron supplementation may be required to keep the ferritin level above 200 ng/mL. It should be checked monthly. A potential source of blood loss should be investigated.
Which of the following phosphate binders would best control hyperphosphatemia with the fewest side effects in patients with end-stage kidney disease?
Hyperphosphatemia (elevated serum phosphate) is common in chronic renal failure patients since the kidneys are unable to excrete this substance. Low calcium and elevated phosphate levels are typical of these patients and lead to secondary hyperparathyroidism and bone loss (renal osteodystrophy). A low-phosphate diet, calcium supplements with vitamin D, and phosphate binders are all useful in limiting high phosphate levels. High-phosphate foods include chocolate, dairy products, dried beans, nuts, pizza, and cola drinks. Calcium supplements with vitamin D may also be useful in controlling the elevated phosphate. The most effective agents are phosphate binders, which bind to phosphate in the gastrointestinal tract and prevent absorption. Of these, the nonaluminum and calcium-containing compounds (e.g., lanthanum carbonate) are preferred because there is less toxicity.
Hemodialysis patients should be taught to:
Engaging the patient in his or her own care usually has positive benefits. This is especially true for patients who wish to do home dialysis. The technical staff should assess the patient's capacity for these techniques and their implications. The more skillful the patient is with needle placement to the access site, choosing the right foods, calculating weight and fluid status, and checking the dialyzer and dialysate, the more likely he or she will have a positive attitude toward the treatment and prognosis. The same is true for a spouse or other caregiver. Learning what medication is needed and watching out for specific symptoms are also important for patient education and safety.
All of the following statements about vitamins in dialysis patients are true EXCEPT:
Dialysis does remove some water-soluble vitamins, such as biotin, folate, niacin, pantothenic acid (vitamin B5), thiamine, and riboflavin so supplements of these are recommended. Patients should take 60-100 mg of vitamin C and 800-1000 mcg of folic acid daily. Exact doses in multivitamin tablets should be checked. Megadose vitamin therapy is not recommended. The healthy kidney may excrete high vitamin doses, but toxic levels may accumulate as dialysis is unlikely to handle large doses. This is especially true of fat-soluble vitamins A and D and possibly E and K. Over-the-counter herbs and food supplements should be discussed with a medical professional before using them.