Chapter 16: Acute Kidney Injury
Slow continuous ultrafiltration is also known as isolated ultrafiltration and is used to a. remove plasma water in cases of volume overload. b. remove fluids and solutes through the process of convection. c. remove plasma water and solutes by adding dialysate. d. combine ultrafiltration, convection, and dialysis.
ANS: A Slow continuous ultrafiltration (SCUF) is also known as isolated ultrafiltration and is used to remove plasma water in cases of volume overload. Continuous venovenous hemofiltration (CVVH) is used to remove fluids and solutes through the process of convection. Continuous venovenous hemodialysis (CVVHD) is similar to CVVH in that ultrafiltration removes plasma water. It differs in that dialysate solution is added around the hemofilter membranes to facilitate solute removal by the process of diffusion. Continuous venovenous hemodiafiltration (CVVHDF) combines ultrafiltration, convection, and dialysis to maximize fluid and solute removal.
The patient's serum creatinine level is 0.7 mg/dL. The expected BUN level should be a. 1 to 2 mg/dL. b. 7 to 14 mg/dL. c. 10 to 20 mg/dL. d. 20 to 30 mg/dL.
ANS: B The normal BUN/creatinine ratio is 10:1 to 20:1. Therefore, the expected range for this creatinine level would be 7 to 14 mg/dL.
In calculating the glomerular filtration rate (GFR) results for women, the creatinine clearance is usually: a. the same as for men. b. greater than that for men. c. multiplied by 0.85. d. multiplied by 1.15.
ANS: C For women, the calculated result is multiplied by 0.85 to account for the smaller muscle mass as compared to men.
A normal urine output is considered to be a. 80 to 125 mL/min. b. 180 L/day. c. 80 mL/min. d. 1 to 2 L/day.
ANS: D At a normal glomerular filtration rate (GFR) of 80 to 125 mL/min, the kidneys produce 180 L/day of filtrate. As the filtrate passes through the various components of the nephrons' tubules, 99% is reabsorbed into the peritubular capillaries or vasa recta. Eventually, the remaining filtrate (1% of the original 180 L/day) is excreted as urine, for an average urine output of 1 to 2 L/day.
What is a minimally acceptable urine output for a patient weighing 75 kg? a. Less than 30 mL/hour b. 37 mL/hour c. 80 mL/hour d. 150 mL/hour
ANS: B Normal urine output is 0.5 to 1 mL/kg of body weight each hour.
The nurse is caring for a patient receiving peritoneal dialysis. The patient suddenly complains of abdominal pain and chills. The patient's temperature is elevated. The nurse should a. assess peritoneal dialysate return. b. check the patient's blood sugar. c. evaluate the patient's neurological status. d. inform the provider of probable visceral perforation.
ANS: A Peritonitis is the most common complication of peritoneal dialysis therapy and is usually caused by contamination in the system. Peritonitis is manifested by abdominal pain, cloudy peritoneal fluid, fever and chills, nausea and vomiting, and difficulty in draining fluid from the peritoneal cavity.
The critical care nurse is responsible for monitoring the patient receiving continuous renal replacement therapy (CRRT). In doing so, the nurse should a. assess that the blood tubing is warm to the touch. b. assess the hemofilter every 6 hours for clotting. c. cover the dialysis lines to protect them from light. d. use clean technique during vascular access dressing changes.
ANS: A The critical care nurse is responsible for monitoring the patient receiving CRRT. The hemofilter is assessed every 2 to 4 hours for clotting (as evidenced by dark fibers or a rapid decrease in the amount of ultrafiltration without a change in the patient's hemodynamic status). The CRRT system is frequently assessed to ensure filter and lines are visible at all times, kinks are avoided, and the blood tubing is warm to the touch. The ultrafiltrate is assessed for blood (pink-tinged to frank blood), which is indicative of membrane rupture. Sterile technique is performed during vascular access dressing changes.
Daily weights are being recorded for the patient with a urine output that has been less than the intravenous and oral intake. The weight yesterday was 97.5 kg. This morning it is 99 kg. The nurse understands that this corresponds to a(n) a. fluid retention of 1.5 liters. b. fluid loss of 1.5 liters. c. equal intake and output due to insensible losses. d. fluid loss of 0.5 liters.
ANS: A A 1-kg gain in body weight is equal to a 1000-mL fluid gain. This patient has gained 1.5 kg, or 1.5 liters of fluid.
Acute kidney injury from postrenal etiology is caused by a. obstruction of the flow of urine. b. conditions that interfere with renal perfusion. c. hypovolemia or decreased cardiac output. d. conditions that act directly on functioning kidney tissue.
ANS: A Acute kidney injury resulting from obstruction of the flow of urine is classified as postrenal or obstructive renal injury. Conditions that result in AKI by interfering with renal perfusion are classified as prerenal and include hypovolemia and decreased cardiac output. Conditions that produce AKI by directly acting on functioning kidney tissue are classified as intrarenal.
Continuous venovenous hemofiltration is used to a. remove fluids and solutes through the process of convection. b. remove plasma water in cases of volume overload. c. remove plasma water and solutes by adding dialysate. d. combine ultrafiltration, convection, and dialysis.
ANS: A Continuous venovenous hemofiltration (CVVH) is used to remove fluids and solutes through the process of convection. Slow continuous ultrafiltration (SCUF) is used to remove plasma water in cases of volume overload. Continuous venovenous hemodialysis (CVVHD) is similar to CVVH in that ultrafiltration removes plasma water. It differs in that dialysate solution is added around the hemofilter membranes to facilitate solute removal by the process of diffusion. Continuous venovenous hemodiafiltration (CVVHDF) combines ultrafiltration, convection, and dialysis to maximize fluid and solute removal.
The nurse is caring for a patient who has undergone major abdominal surgery. The nurse notices that the patient's urine output has been less than 20 mL/hour for the past 2 hours. The patient's blood pressure is 100/60 mm Hg, and the pulse is 110 beats/min. Previously, the pulse was 90 beats/min with a blood pressure of 120/80 mm Hg. The nurse should a. contact the provider and expect a prescription for a normal saline bolus. b. wait until the provider makes rounds to report the assessment findings. c. continue to evaluate urine output for 2 more hours. d. ignore the urine output, as this is most likely postrenal in origin.
ANS: A Most prerenal causes of AKI are related to intravascular volume depletion, decreased cardiac output, renal vasoconstriction, or pharmacological agents that impair autoregulation and GFR (Box 16-2). These conditions reduce the glomerular perfusion and the GFR, and the kidneys are hypoperfused. For example, major abdominal surgery can cause hypoperfusion of the kidney as a result of blood loss during surgery or as a result of excess vomiting or nasogastric suction during the postoperative period. The body attempts to normalize renal perfusion by reabsorbing sodium and water. If adequate blood flow is restored to the kidney, normal renal function resumes. Most forms of prerenal AKI can be reversed by treating the cause.
A 100-kg patient gets hemodialysis 3 days a week. In planning the care for this patient, the nurse recommends a. a diet of 2500 to 3500 kcal per day. b. protein intake of less than 50 grams per day. c. potassium intake of 10 mEq per day. d. fluid intake of less than 500 mL per day.
ANS: A Nutritional recommendations include the following: caloric intake of 25 to 35 kcal/kg of ideal body weight per day (2500 to 3500 kcal) and protein intake of no less than 0.8 g/kg body weight. Patients who are extremely catabolic such as those on hemodialysis should receive protein in the amount of 1.5 to 2 g/kg of ideal body weight per day, 75% to 80% of which contains all the required essential amino acids; sodium intake of 0.5 to 1.0 g/day; potassium intake of 20 to 50 mEq/day; calcium intake of 800 to 1200 mg/day; fluid intake equal to the volume of the patient's urine output plus an additional 600 to 1000 mL/day.
The patient's potassium level is 7.0 mEq/L. Besides dialysis, which of the following actually reduces plasma potassium levels and total body potassium content safely in a patient with renal dysfunction? a. Sodium polystyrene sulfonate b. Sodium polystyrene sulfonate with sorbitol c. Regular insulin d. Calcium gluconate
ANS: A Only dialysis and administration of cation exchange resins (sodium polystyrene sulfonate) actually reduce plasma potassium levels and total body potassium content in a patient with renal dysfunction. In the past, sorbitol has been combined with sodium polystyrene sulfonate powder for administration. The concomitant use of sorbitol with sodium polystyrene sulfonate has been implicated in cases of colonic intestinal necrosis; therefore, this combination is not recommended. Other treatments, such as administration of regular insulin and calcium gluconate, "protect" the patient for only a short time until dialysis or cation exchange resins can be instituted.
Renin plays a role in blood pressure regulation by a. activating the renin-angiotensin-aldosterone cascade. b. suppressing angiotensin production. c. decreasing sodium reabsorption. d. inhibiting aldosterone release.
ANS: A Specialized cells in the afferent and efferent arterioles and the distal tubule are collectively known as the juxtaglomerular apparatus. These cells are responsible for the production of a hormone called renin, which plays a role in blood pressure regulation. Renin is released whenever blood flow through the afferent and efferent arterioles decreases. A decrease in the sodium ion concentration of the blood flowing past the specialized cells (e.g., in hypovolemia) also stimulates the release of renin. Renin activates the renin-angiotensin-aldosterone cascade, which ultimately results in angiotensin II production. Angiotensin II causes vasoconstriction and release of aldosterone from the adrenal glands, thereby raising blood pressure and flow and increasing sodium and water reabsorption in the distal tubule and collecting ducts.
The patient is in need of immediate hemodialysis, but has no vascular access. The nurse prepares the patient for insertion of a. a percutaneous catheter at the bedside. b. a percutaneous tunneled catheter at the bedside. c. an arteriovenous fistula. d. an arteriovenous graft.
ANS: A Temporary percutaneous catheters are commonly used in patients with acute kidney injury because they can be used immediately. Occasionally a percutaneous tunneled catheter is placed if the patient needs ongoing hemodialysis; however, these catheters are usually inserted in the operating room. An arteriovenous fistula is an internal, surgically created communication between an artery and a vein. This method produces a vessel that is easy to cannulate but requires 4 to 6 weeks before it is mature enough to use. Arteriovenous grafts are created by using different types of prosthetic material, most commonly polytetrafluoroethylene and Teflon. Grafts are placed under the skin and are surgically anastomosed between an artery and a vein. The graft site usually heals within 2 to 4 weeks.
The most common cause of acute kidney injury in critically ill patients is a. sepsis. b. fluid overload. c. medications. d. hemodynamic instability.
ANS: A The etiology of AKI in critically ill patients is often multifactorial and develops from a combination of hypovolemia, sepsis, medications, and hemodynamic instability. Sepsis is the most common cause of AKI.
Complications common to patients receiving hemodialysis for acute kidney injury include which of the following? (Select all that apply.) a. Hypotension b. Dysrhythmias c. Muscle cramps d. Hemolysis e. Air embolism
ANS: A, B Hypotension is common and is usually the result of preexisting hypovolemia, excessive amounts of fluid removal, or excessively rapid removal of fluid. Dysrhythmias may occur during dialysis. Causes of dysrhythmias include a rapid shift in the serum potassium level, clearance of antidysrhythmic medications, preexisting coronary artery disease, hypoxemia, or hypercalcemia from rapid influx of calcium from the dialysate solution. Muscle cramps occur more commonly in chronic renal failure. Hemolysis, air embolism, and hyperthermia are rare complications of hemodialysis.
Noninvasive diagnostic procedures used to determine kidney function include which of the following? (Select all that apply.) a. Kidney, ureter, bladder (KUB) x-ray b. Renal ultrasound c. Magnetic resonance imaging (MRI) d. Intravenous pyelography (IVP) e. Renal angiography
ANS: A, B, C Noninvasive diagnostic procedures are usually performed before any invasive diagnostic procedures are conducted. Noninvasive diagnostic procedures that assess the renal system are radiography of the kidneys, ureters, and bladder (KUB); renal ultrasonography; and magnetic resonance imaging. Invasive diagnostic procedures for assessing the renal system include intravenous pyelography, computed tomography, renal angiography, renal scanning, and renal biopsy.
The patient is admitted with acute kidney injury from a postrenal cause. Acceptable treatments for that diagnosis include: (Select all that apply.) a. bladder catheterization. b. increasing fluid volume intake. c. ureteral stenting. d. placement of nephrostomy tubes. e. increasing cardiac output.
ANS: A, C, D The location of the obstruction in the urinary tract determines the method by which the obstruction is treated and may include bladder catheterization, ureteral stenting, or the placement of nephrostomy tubes. Fluid volume intake may be recommended to treat prerenal causes of AKI. Increasing cardiac output would be indicated in certain prerenal causes of AKI.
The patient is in the critical care unit and will receive dialysis this morning. The nurse will (Select all that apply.) a. evaluate morning laboratory results and report abnormal results. b. administer the patient's antihypertensive medications. c. assess the dialysis access site and report abnormalities. d. weigh the patient to monitor fluid status. e. give all medications except for antihypertensive medications.
ANS: A, C, D The patient receiving hemodialysis requires specialized monitoring and interventions by the critical care nurse. Laboratory values are monitored and abnormal results reported to the nephrologist and dialysis staff. The patient is weighed daily to monitor fluid status. On the day of dialysis, dialyzable (water-soluble) medications are not given until after treatment. The dialysis nurse or pharmacist can be consulted to determine which medications to withhold or administer. Supplemental doses are administered as ordered after dialysis. Administration of antihypertensive agents is avoided for 4 to 6 hours before treatment, if possible. Doses of other medications that lower blood pressure (narcotics, sedatives) are reduced, if possible. The percutaneous catheter, fistula, or graft is assessed frequently; unusual findings such as loss of bruit, redness, or drainage at the site must be reported. After dialysis, the patient is assessed for signs of bleeding, hypovolemia, and dialysis disequilibrium syndrome.
The most common reasons for initiating dialysis in acute kidney injury include which of the following? (Select all that apply.) a. Acidosis b. Hypokalemia c. Volume overload d. Hyperkalemia e. Uremia
ANS: A, C, D, E The most common reasons for initiating dialysis in acute kidney injury include acidosis, hyperkalemia, volume overload, and uremia. Dialysis is usually started early in the course of the renal dysfunction before uremic complications occur. In addition, dialysis may be started for fluid management when total parenteral nutrition is administered.
Identify which substances in the glomerular filtrate would indicate a problem with renal function. (Select all that apply.) a. Protein b. Sodium c. Creatinine d. Red blood cells e. Uric acid
ANS: A, D The glomerular capillary membrane is approximately 100 times more permeable than other capillaries. It acts as a high-efficiency sieve and normally allows only substances with a certain molecular weight to cross. Normal glomerular filtrate is basically protein free and contains electrolytes, including sodium, chloride, and phosphate, and nitrogenous waste products, such as creatinine, urea, and uric acid, in amounts similar to those in plasma. Red blood cells, albumin, and globulin are too large to pass through the healthy glomerular membrane.
The patient has elevated blood urea nitrogen (BUN) and serum creatinine levels with a normal BUN/creatinine ratio. These levels most likely indicate a. increased nitrogen intake. b. acute kidney injury, such as acute tubular necrosis (ATN). c. hypovolemia. d. fluid resuscitation.
ANS: B A normal BUN/creatinine ratio is present in ATN. In ATN, there is actual injury to the renal tubules and a rapid decline in the GFR; hence, BUN and creatinine levels both rise proportionally as a result of increased reabsorption and decreased clearance. Hypovolemia would result in prerenal condition, which usually increases the BUN/creatinine ratio.
The patient is complaining of severe flank pain when he tries to urinate. His urinalysis shows sediment and crystals along with a few bacteria. Using this information along with the clinical picture, the nurse realizes that the patient's condition is a. prerenal. b. postrenal. c. intrarenal. d. not renal related.
ANS: B Analysis of urinary sediment and electrolyte levels is helpful in distinguishing among the various causes of acute kidney injury. Postrenal conditions may present with stones, crystals, sediment, bacteria, and clots from the obstruction. Coarse, muddy brown granular casts are classic findings in ATN (intrarenal), along with microscopic hematuria and a small amount of protein. In prerenal conditions, the urine typically has no cells but may contain hyaline casts. The flank pain and urinalysis definitely indicate a renal condition.
A normal glomerular filtration rate is a. less than 80 mL/min. b. 80 to 125 mL/min. c. 125 to 180 mL/min. d. more than 189 mL/min.
ANS: B At a normal glomerular filtration rate (GFR) of 80 to 125 mL/min, the kidneys produce 180 L/day of filtrate. As the filtrate passes through the various components of the nephrons' tubules, 99% is reabsorbed into the peritubular capillaries or vasa recta.
The term used to describe an increase in blood urea nitrogen (BUN) and serum creatinine is a. oliguria. b. azotemia. c. acute kidney injury. d. prerenal disease.
ANS: B Azotemia refers to increases in blood urea nitrogen and serum creatinine. Oliguria is defined as urine output less than 0.5 mL/kg/hr. Elevation of BUN and creatinine can be the result of acute kidney injury or chronic kidney diseases. Conditions that result in AKI by interfering with renal perfusion are classified as prerenal.
The patient undergoes a cardiac catheterization that requires the use of contrast dyes during the procedure. To detect signs of contrast-induced kidney injury, the nurse should a. not be concerned unless urine output decreases. b. evaluate the patient's serum creatinine for up to 72 hours after the procedure. c. obtain an order for a renal ultrasound. d. evaluate the patient's postvoid residual volume to detect intrarenal injury
ANS: B Contrast- induced kidney injury is diagnosed by an increase in serum creatinine of 25%, or 0.5 mg/dL, within 48 to 72 hours following the administration of contrast. Urine output usually remains normal. The renal ultrasound and postvoid residual assessment are not warranted.
The patient is admitted to the unit with the diagnosis of rhabdomyolysis. The patient is started on intravenous (IV) fluids and IV mannitol. What action by the nurse is best? a. Assess the patient's hearing. b. Assess the patient's lungs. c. Decrease IV fluids once the diuretic has been administered. d. Give extra doses before giving radiological contrast agents.
ANS: B Mannitol, an osmotic diuretic often used in acute kidney injury caused by rhabdomyolysis, increases plasma volume. Patients may be at risk for the development of pulmonary edema due to the rapid expansion of intravascular volume triggered by mannitol. Hearing is assessed with the administration of loop diuretics, such as furosemide, which have been associated with deafness. Aggressive fluid administration is required in rhabdomyolysis. Diuretics may increase the risk of acute kidney injury from volume depletion when they are given before procedures requiring radiological contrast agents or if the patient is hypovolemic. Adequate hydration before the administration of diuretics is essential.
Peritoneal dialysis is different from hemodialysis in that peritoneal dialysis a. is more frequently used for acute kidney injury. b. uses the patient's own semipermeable membrane (peritoneal membrane). c. is not useful in cases of drug overdose or electrolyte imbalance. d. is not indicated in cases of water intoxication.
ANS: B Peritoneal dialysis is the removal of solutes and fluid by diffusion through a patient's own semipermeable membrane (the peritoneal membrane) with a dialysate solution that has been instilled into the peritoneal cavity. This renal replacement therapy is not commonly used for the treatment of acute kidney injury because of its comparatively slow ability to alter biochemical imbalances. Clinical indications for peritoneal dialysis include acute and chronic kidney injury, severe water intoxication, electrolyte disorders, and drug overdose.
The patient has a temporary percutaneous catheter in place for treatment of acute kidney injury. The catheter has been in place for 5 days. The nurse should a. prepare to assist with a routine dialysis catheter change. b. evaluate the patient for signs and symptoms of infection. c. teach the patient that the catheter is designed for long-term use. d. use one of the three lumens for fluid administration.
ANS: B Routine replacement of hemodialysis catheters to prevent infection is not recommended. The decision to remove or replace the catheter is based on clinical need and/or signs and symptoms of infection. The typical catheter has a single or double lumen and is designed only for short-term renal replacement therapy during acute situations. The catheter is not used for fluid and medication administration.
The critical care nurse knows that in critically ill patients, renal dysfunction a. is a very rare problem. b. affects nearly two thirds of patients. c. has a low mortality rate once renal replacement therapy has been initiated. d. has little effect on morbidity, mortality, or quality of life.
ANS: B The kidney is the primary regulator of the body's internal environment. With sudden cessation of renal function, all body systems are affected by the inability to maintain fluid and electrolyte balance and eliminate metabolic waste. Renal dysfunction is a common problem in critically ill patients, with nearly two thirds of patients experiencing some degree of renal dysfunction. The most severe cases, requiring renal replacement therapy, have a reported mortality rate of 50% to 60%. Acute kidney injury that progresses to chronic renal failure is associated with increased morbidity, mortality, and reduced quality of life.
The nurse is caring for an elderly patient who was admitted with renal insufficiency. An expected laboratory finding for this patient may be a. an increased glomerular filtration rate (GFR). b. a normal serum creatinine level. c. increased ability to excrete drugs. d. hypokalemia.
ANS: B The most important renal physiological change that occurs with aging is a decrease in the GFR. After age 40, renal blood flow gradually diminishes at a rate of 10% per decade. With advancing age, there is also a decrease in renal mass, the number of glomeruli and peritubular density. Serum creatinine levels may remain the same in the elderly patient, even with a declining GFR, because of decreased muscle mass and hence decreased creatinine production. Tubular changes include a diminished ability to excrete drugs, including radiocontrast dyes used in diagnostic testing, which necessitates a decrease in drug dosing to avoid nephrotoxicity. Many medications, including antibiotics, require dose adjustments as kidney function declines. Age-related changes in renin and aldosterone levels also occur, which can lead to fluid and electrolyte abnormalities. Renin levels are decreased by 30% to 50% in the elderly, resulting in less angiotensin II production and lower aldosterone levels. Together these can cause an increased risk of hyperkalemia. The aging kidney is also slower to correct an increase in acids, causing a prolonged metabolic acidosis and the subsequent shifting of potassium out of cells and worsening hyperkalemia.
The patient has been admitted to the hospital with nausea and vomiting that started 5 days earlier. Blood pressure is 80/44 mm Hg and heart rate is 122 beats/min; the patient has not voided in 8 hours, and the bladder is not distended. The nurse anticipates a prescription for "stat" administration of a. a blood transfusion. b. fluid replacement with 0.45% saline. c. infusion of an inotropic agent. d. an antiemetic.
ANS: B This scenario indicates hypovolemia from the nausea and vomiting, requiring volume replacement. Hypovolemia resulting from large urine or gastrointestinal losses often requires the administration of a hypotonic solution, such as 0.45% saline. Blood products would be indicated only in the presence of bleeding following assessment of hemoglobin and hematocrit levels. The inotrope is contraindicated in the presence of volume depletion. An antiemetic may be needed; however, the priority to prevent shock and acute kidney injury is fluid administration.
Which of the following patients is at the greatest risk of developing acute kidney injury? A patient who a. has been on aminoglycosides for the past 6 days b. has a history of controlled hypertension with a blood pressure of 138/88 mm Hg c. was discharged 2 weeks earlier after aminoglycoside therapy of 2 weeks d. has a history of fluid overload as a result of heart failure
ANS: C Acute kidney injury can be caused by aminoglycoside nephrotoxicity, especially prolonged use of the drug (more than 10 days). Symptoms of acute kidney injury are usually seen about 1 to 2 weeks after exposure. Because of this delay, the patient must be questioned about any recent medical therapy for which an aminoglycoside may have been prescribed. The blood pressure of 138/88 mm Hg controlled by medication would not cause acute kidney injury, nor would fluid overload from exacerbation of heart failure.
The patient has just returned from having an arteriovenous fistula placed. The patient asks, "When will they be able to use this and take this other catheter out?" The nurse should reply, a. "It can be used immediately, so the catheter can come out anytime." b. "It will take 2 to 4 weeks to heal before it can be used." c. "The fistula will be usable in about 4 to 6 weeks." d. "The fistula was made using graft material, so it depends on the manufacturer."
ANS: C An arteriovenous fistula is an internal, surgically created communication between an artery and a vein. This method produces a vessel that is easy to cannulate but requires 4 to 6 weeks before it is mature enough to use.
The patient is admitted with complaints of general malaise and fatigue, along with a decreased urinary output. The patient's urinalysis shows coarse, muddy brown granular casts and hematuria. The nurse determines that the patient has: a. acute kidney injury from a prerenal condition. b. acute kidney injury from postrenal obstruction. c. intrarenal disease, probably acute tubular necrosis. d. a urinary tract infection.
ANS: C Analysis of urinary sediment and electrolyte levels is helpful in distinguishing among the various causes of acute kidney injury. Coarse, muddy brown granular casts are classic findings in ATN. Microscopic hematuria and a small amount of protein also may be seen. In prerenal conditions, the urine typically has no cells but may contain hyaline casts. Postrenal conditions may present with stones, crystals, sediment, bacteria, and clots from the obstruction. Bacteria would be present in a urinary tract infection.
Continuous venovenous hemodialysis is used to a. remove fluids and solutes through the process of convection. b. remove plasma water in cases of volume overload. c. remove plasma water and solutes by adding dialysate. d. combine ultrafiltration, convection and dialysis
ANS: C Continuous venovenous hemodialysis (CVVHD) is similar to CVVH in that ultrafiltration removes plasma water. It differs in that dialysate solution is added around the hemofilter membranes to facilitate solute removal by the process of diffusion. Continuous venovenous hemofiltration (CVVH) is used to remove fluids and solutes through the process of convection. Slow continuous ultrafiltration (SCUF) is also known as isolated ultrafiltration and is used to remove plasma water in cases of volume overload. Continuous venovenous hemodiafiltration (CVVHDF) combines ultrafiltration, convection, and dialysis to maximize fluid and solute removal.
The patient is getting hemodialysis for the second time when he complains of a headache and nausea and, a little later, of becoming confused. The nurse realizes these are symptoms of a. dialyzer membrane incompatibility. b. a shift in potassium levels. c. dialysis disequilibrium syndrome. d. hypothermia.
ANS: C Dialysis disequilibrium syndrome often occurs after the first or second dialysis treatment or in patients who have had sudden, large decreases in BUN and creatinine levels as a result of the hemodialysis. Because of the blood-brain barrier, dialysis does not deplete the concentrations of BUN, creatinine, and other uremic toxins in the brain as rapidly as it does those substances in the extracellular fluid. An osmotic concentration gradient established in the brain allows fluid to enter until the concentration levels equal those of the extracellular fluid. The extra fluid in the brain tissue creates a state of cerebral edema for the patient, which results in severe headaches, nausea and vomiting, twitching, mental confusion, and occasionally seizures. Dialyzer membrane incompatibility may cause hypotension. Hyperthermia, not hypothermia, may result if the temperature control devices on the dialysis machine malfunction. Potassium shifts may occur but would be manifested in cardiac dysrhythmias.
The nurse is assessing a patient with a new arteriovenous fistula, but does not hear a bruit or feel a thrill. Pulses distal to the fistula are not palpable. The nurse should a. reassess the patient in an hour. b. raise the arm above the level of the patient's heart. c. notify the provider immediately. d. apply warm packs to the fistula site and reassess.
ANS: C Inadequate collateral circulation past the fistula or graft may result in loss of this pulse. The physician is notified immediately if no bruit is auscultated, no thrill is palpated, or the distal pulse is absent. Loss of bruit and thrill indicate a loss of blood flow, most likely due to clotting. The patient will need to return to surgery as soon as possible for declotting. Raising the arm above the level of the heart will not help. Warm packs may or may not help.
The patient is diagnosed with acute kidney injury and has been getting dialysis 3 days per week. The patient complains of general malaise and is tachypneic. An arterial blood gas shows that the patient's pH is 7.19, with a PCO2 of 30 mm Hg and a bicarbonate level of 13 mEq/L. The nurse prepares to a. administer morphine to slow the respiratory rate. b. prepare for intubation and mechanical ventilation. c. administer intravenous sodium bicarbonate. d. cancel tomorrow's dialysis session.
ANS: C Metabolic acidosis is the primary acid-base imbalance seen in acute kidney injury. Treatment of metabolic acidosis depends on its severity. Patients with a serum bicarbonate level of less than 15 mEq/L and a pH of less than 7.20 are usually treated with intravenous sodium bicarbonate. The goal of treatment is to raise the pH to a value greater than 7.20. Rapid correction of the acidosis should be avoided, because tetany may occur as a result of hypocalcemia. Renal replacement therapies also may correct metabolic acidosis because it removes excess hydrogen ions and bicarbonate is added to the dialysate and replacement solutions; therefore, dialysis would not be canceled. The tachypnea is a compensatory mechanism for the metabolic acidosis, and treatments to decrease the respiratory rate are not indicated. Treatment is aimed at correcting the metabolic acidosis, and this scenario does not provide data to support the need for intubation.
The nurse is caring for a patient who has a temporary percutaneous dialysis catheter in place. In caring for this patient, the nurse should a. apply a sterile gauze dressing to maintain sterility. b. replace the transparent dressing every 10 days to prevent manipulation. c. assess the catheter site for redness and/or swelling. d. use the catheter for drawing blood samples to reduce patient discomfort.
ANS: C Tenderness at the insertion site, swelling, erythema, or drainage should be reported to the physician. Transparent, semipermeable polyurethane dressings are recommended as they allow continuous visualization for assessment of signs of infection. Replace transparent dressings on temporary percutaneous catheters at least every 7 days and no more than once a week for tunneled percutaneous catheters unless the dressing is soiled or loose. The catheter is not used for the administration of fluids or medications or for the sampling of blood unless a specific order is obtained to do so.
Conditions that produce acute kidney injury by directly acting on functioning kidney tissue are classified as intrarenal. The most common intrarenal condition is a. prolonged ischemia. b. exposure to nephrotoxic substances. c. acute tubular necrosis (ATN). d. hypotension for several hours.
ANS: C The most common intrarenal condition is ATN. This condition may occur after prolonged ischemia (prerenal), exposure to nephrotoxic substances, or a combination of these. Some patients have ATN after only several minutes of hypotension or hypovolemia, whereas others can tolerate hours of renal ischemia without having any apparent tubular damage.
The patient is on intake and output (I&O), as well as daily weights. The nurse notes that output is considerably less than intake over the last shift, and daily weight is 1 kg more than yesterday. The nurse should a. draw a trough level after the next dose of antibiotic. b. obtain an order to place the patient on fluid restriction. c. assess the patient's lungs. d. insert an indwelling catheter.
ANS: C The scenario indicates retention of fluid; therefore, the nurse must assess for symptoms of fluid overload, for example, by auscultating the lung fields. Adequate hydration is essential and fluid restriction would be determined by the provider upon physical examination and analysis of laboratory results. An indwelling urinary catheter should not routinely be inserted because it increases the risk of infection. A trough level is drawn just before the next dose of a drug is given and is an indicator of how the body has cleared the drug; it would not be done secondary to imbalanced intake and output.
An advantage of peritoneal dialysis is that a. peritoneal dialysis is time intensive. b. a decreased risk of peritonitis exists. c. biochemical disturbances are corrected rapidly. d. the danger of hemorrhage is minimal.
ANS: D Advantages of peritoneal dialysis include that the equipment is assembled easily and rapidly, the cost is relatively inexpensive, the danger of acute electrolyte imbalances or hemorrhage is minimal, and dialysate solutions can be individualized. In addition, automated peritoneal dialysis systems are available. Disadvantages of peritoneal dialysis include that it is time intensive, requiring at least 36 hours for a therapeutic effect to be achieved; biochemical disturbances are corrected slowly; access to the peritoneal cavity is sometimes difficult; and the risk of peritonitis is high.
The patient is in a progressive care unit following arteriovenous fistula implantation in his left upper arm, and is due to have blood drawn with his next set of vital signs and assessment. When the nurse assesses the patient, the nurse should a. draw blood from the left arm. b. take blood pressures from the left arm. c. start a new intravenous line in the left lower arm. d. auscultate the left arm for a bruit and palpate for a thrill.
ANS: D An arteriovenous fistula should be auscultated for a bruit and palpated for the presence of a thrill or buzz every 8 hours. The extremity that has a fistula or graft must never be used for drawing blood specimens, obtaining blood pressure measurements, administering intravenous therapy, or giving intramuscular injections. Such activities produce pressure changes within the altered vessels that could result in clotting or rupture.
Continuous renal replacement therapy (CRRT) differs from conventional intermittent hemodialysis in that a. a hemofilter is used to facilitate ultrafiltration. b. it provides faster removal of solute and water. c. it does not allow diffusion to occur. d. the process removes solutes and water slowly.
ANS: D CRRT is a continuous extracorporeal blood purification system managed by the bedside critical care nurse. It is similar to conventional intermittent hemodialysis in that a hemofilter is used to facilitate the processes of ultrafiltration and diffusion. It differs in that CRRT provides a slow removal of solutes and water as compared to the rapid removal of water and solutes that occurs with intermittent hemodialysis.
In determining the glomerular filtration rate (GFR) or creatinine clearance, a 24-hour urine is obtained. If a reliable 24-hour urine collection is not possible, a. it is not possible to determine the GFR. b. the BUN may be used to determine renal function. c. an elevated BUN/creatinine ratio can be used. d. a standardized formula may be used to calculate GFR.
ANS: D Historically, timed 24-hour urine collections have been used to evaluate GFR or creatinine clearance. If a reliable 24-hour urine collection is not possible, the Cockcroft and Gault formula may be used to determine the creatinine clearance from a serum creatinine value. The BUN level is not a reliable indicator of kidney function because the rate of protein metabolism is not constant. An increased BUN/creatinine ratio is typically noted with prerenal conditions, but does not provide an estimate of GFR.
The nurse is caring for a patient who has sustained blunt trauma to the left flank area, and is evaluating the patient's urinalysis results. The nurse should become concerned when a. creatinine levels in the urine are similar to blood levels of creatinine. b. sodium and chloride are found in the urine. c. urine uric acid levels have the same values as serum levels. d. red blood cells and albumin are found in the urine.
ANS: D Normal glomerular filtrate is basically protein free and contains electrolytes, including sodium, chloride, and phosphate, and nitrogenous waste products, such as creatinine, urea, and uric acid, in amounts similar to those in plasma. Red blood cells, albumin, and globulin are too large to pass through the healthy glomerular membrane. Their presence in urine may indicate glomerular damage.
The nurse is caring for a patient with acute kidney injury who is being treated with hemodialysis. The patient asks if he will need dialysis for the rest of his life. Which of the following would be the best response? a. "Unfortunately, kidney injury is not reversible; it is permanent." b. "Kidney function usually returns within 2 weeks." c. "You will know for sure if you start urinating a lot all at once." d. "Recovery is possible, but it may take several months."
ANS: D Renal dysfunction is potentially reversible during the initiation phase. This phase spans several hours to 2 days, during which time the normal renal processes begin to deteriorate, but actual intrinsic renal damage has not yet occurred. During the maintenance phase, intrinsic renal damage is established, and the GFR stabilizes at approximately 5 to 10 mL/min. This phase usually lasts 8 to 14 days, but it may last up to 11 months. The longer a patient remains in this stage, the slower the recovery and the greater the chance of permanent renal damage will be. The recovery phase is the period during which the renal tissue recovers and repairs itself. A gradual increase in urine output and an improvement in laboratory values occur. Recovery may take as long as 4 to 6 months.
The removal of plasma water and some low-molecular weight particles by using a pressure or osmotic gradient is known as a. dialysis. b. diffusion. c. clearance. d. ultrafiltration.
ANS: D Ultrafiltration is the removal of plasma water and some low-molecular weight particles by using a pressure or osmotic gradient. Ultrafiltration is primarily aimed at controlling fluid volume, whereas dialysis is aimed at decreasing waste products and treating fluid and electrolyte imbalances. Diffusion (or clearance) is the movement of solutes such as urea from the patient's blood to the dialysate cleansing fluid, across a semipermeable membrane (the hemofilter).
