I85PREP
⌘ K
BONENT CHT study materials
BONENT CHT study resources

BONENT CHT practice questions

One question at a time. Build your BONENT CHT understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Clinical Practice / Patient Care

Immediately before cannulating a patient's arteriovenous fistula, the technician must:

  1. Perform hand hygiene and don clean gloves Correct answer.
  2. Apply lotion to the access arm to improve needle glide
  3. Palpate the access site with bare hands after the antiseptic has been applied
  4. Wipe the access site once with a dry gauze pad

Explanation

Clean gloves are required for cannulation, and hand hygiene must precede glove use for every patient contact. The skin site is then prepped with an approved antiseptic and allowed to dry, and the site is not touched with bare hands afterward.

Question 2Clinical Practice / Patient Care

Which finding best indicates that an arteriovenous fistula is functioning?

  1. Cool, pale skin distal to the access
  2. Sharp pain reported at the access site
  3. A weak bruit with no palpable thrill
  4. A palpable thrill and an audible bruit Correct answer.

Explanation

A functioning fistula produces turbulent flow that can be felt as a thrill and heard as a bruit. Loss of either finding suggests stenosis or thrombosis and must be reported before cannulation is attempted.

Question 3Clinical Practice / Patient Care

The main purpose of priming the extracorporeal circuit before starting treatment is to:

  1. Fill the blood lines and dialyzer with saline and remove air Correct answer.
  2. Warm the dialysate to body temperature
  3. Verify the conductivity of the dialysate
  4. Sterilize the dialyzer before first use

Explanation

Priming displaces air from the blood compartment and fills the lines and dialyzer with saline so the patient is not exposed to air emboli or a sudden bolus of air on connection. Dialyzer sterility is established by the manufacturer, not by priming.

Question 4Clinical Practice / Patient Care

To determine how much fluid to remove during a treatment, the technician first needs to:

  1. Review the patient's most recent potassium level
  2. Compare the pre-dialysis weight with the prescribed target weight Correct answer.
  3. Measure the patient's standing height
  4. Calculate the dialyzer's urea clearance

Explanation

The fluid to remove equals the difference between the pre-treatment weight and the prescribed target (dry) weight, plus any fluid given during the treatment. Height, potassium, and clearance do not determine the ultrafiltration goal.

Question 5Clinical Practice / Patient Care

A patient becomes dizzy and diaphoretic with a blood pressure of 82/48 mmHg midway through treatment. The technician's first action should be to:

  1. Administer the patient's scheduled antihypertensive medication
  2. Increase the ultrafiltration rate to finish the treatment on schedule
  3. Place the patient in Trendelenburg position and reduce or stop ultrafiltration Correct answer.
  4. Increase the dialysate temperature to warm the patient

Explanation

Symptomatic hypotension during dialysis is usually caused by intravascular volume depletion, so ultrafiltration is reduced or stopped and the patient is positioned to improve venous return. The nurse is notified and isotonic saline may be given per protocol.

Question 6Clinical Practice / Patient Care

Severe muscle cramping near the end of a treatment with a high ultrafiltration rate is most often caused by:

  1. Air trapped in the arterial line
  2. Dialysate temperature set at 37 degrees Celsius
  3. Rapid fluid removal with extracellular volume depletion Correct answer.
  4. Excess heparin in the circuit

Explanation

Cramps during dialysis most often reflect rapid or excessive fluid removal with contraction of the extracellular volume. Treatment includes slowing ultrafiltration, gentle massage, and sometimes hypertonic saline per protocol.

Question 7Clinical Practice / Patient Care

Blood and dialysate flow through the dialyzer in which relationship?

  1. Blood flows in the same direction as the dialysate
  2. Blood flows countercurrent to the dialysate flow Correct answer.
  3. Blood flow is intermittent and synchronized with the dialysate pump
  4. Blood flows from the dialysate compartment into the blood compartment

Explanation

Countercurrent flow, with blood moving one way and dialysate the other, maintains a concentration gradient along the whole length of the membrane and maximizes solute and fluid removal.

Question 8Clinical Practice / Patient Care

After withdrawing the needles at the end of treatment, the technician should:

  1. Place a tourniquet above the access for 20 minutes
  2. Apply firm pressure directly over each puncture site until bleeding stops Correct answer.
  3. Apply light pressure for 30 seconds and then release
  4. Have the patient bend the arm sharply at the elbow

Explanation

Direct, firm pressure over each needle site provides hemostasis without occluding the access. Bending the arm or using a tourniquet risks thrombosis and does not reliably compress the puncture point.

Question 9Clinical Practice / Patient Care

A blood leak alarm sounds during treatment. The technician should first:

  1. Give protamine to reverse the heparin effect
  2. Increase the dialysate flow rate to flush the detector
  3. Continue the treatment and document the alarm at the end
  4. Stop the blood pump, then check the dialysate for visible blood before returning any blood Correct answer.

Explanation

A blood leak alarm means the dialyzer membrane may have ruptured, allowing blood into the dialysate. The blood pump is stopped and the dialysate inspected; if blood is confirmed, the blood is not returned and the dialyzer is replaced per policy.

Question 10Clinical Practice / Patient Care

A patient suddenly develops dyspnea, chest pain, and cyanosis, and air is visible in the venous line. The technician should:

  1. Stop the blood pump, position the patient in Trendelenburg on the left side, and give oxygen Correct answer.
  2. Lower the patient's head and continue treatment at a slower blood flow
  3. Recirculate the blood through the arterial line to trap the air
  4. Increase the blood flow to push the air through the dialyzer

Explanation

These findings suggest air embolism. Stopping the pump prevents further air entry, and the left lateral Trendelenburg position helps trap air in the right ventricular apex while oxygen is administered and emergency help is summoned.

Question 11Clinical Practice / Patient Care

A new patient with a very high blood urea nitrogen develops headache, confusion, and vomiting near the end of the first treatment. These findings most likely represent:

  1. Air embolism
  2. Hypoglycemia
  3. Dialysis disequilibrium syndrome Correct answer.
  4. A dialyzer hypersensitivity reaction

Explanation

Rapid urea removal in a patient with a very high starting urea draws water into brain cells and causes cerebral edema, producing headache, confusion, vomiting, and seizures. Prevention includes shorter, gentler first treatments and lower blood flows.

Question 12Clinical Practice / Patient Care

Unfractionated heparin is given during hemodialysis primarily to:

  1. Prevent clotting in the extracorporeal circuit Correct answer.
  2. Prevent infection at the vascular access
  3. Raise the patient's blood pressure
  4. Improve clearance of middle molecules

Explanation

Heparin anticoagulates the blood so it does not clot as it passes through the tubing and dialyzer. The dose is prescribed and adjusted for bleeding risk, and clotting times are monitored per protocol.

Question 13Clinical Practice / Patient Care

Which practice is correct when connecting a tunneled central venous catheter for hemodialysis?

  1. Cleanse the exit site with alcohol only and wear no gloves
  2. Leave both lumens uncapped between treatments
  3. Use sterile technique, with the patient and staff wearing masks Correct answer.
  4. Flush the lumens with tap water between treatments

Explanation

Catheter hubs are a direct route into the bloodstream, so sterile technique with masks for patient and staff is required to prevent catheter-related bloodstream infection. The exit site is cleansed with an approved antiseptic and the lumens are capped when not in use.

Question 14Clinical Practice / Patient Care

During cannulation a patient reports sharp pain and the area around the needle swells rapidly. The technician should:

  1. Continue treatment and apply ice to the swollen area
  2. Reposition the needle without stopping the blood pump
  3. Stop the blood pump, remove the needle, and apply pressure to the site Correct answer.
  4. Increase the blood flow to overcome the resistance

Explanation

These are signs of infiltration, with the needle tip outside the vessel and blood extravasating into tissue. The pump is stopped, the needle removed, and firm pressure applied; a new site is chosen for the return or the treatment is rescheduled per protocol.

Question 15Clinical Practice / Patient Care

The dialysate temperature display reads 41 degrees Celsius and the patient reports feeling hot and flushed. The technician should:

  1. Continue treatment, because warmer dialysate improves clearance
  2. Increase the blood flow to cool the patient
  3. Add ice directly to the dialysate container
  4. Stop the blood pump, notify the nurse, and correct the temperature to the prescribed setting Correct answer.

Explanation

Dialysate above the prescribed range can cause hyperthermia and hemolysis, so treatment is interrupted and the temperature corrected by licensed staff. Normal prescriptions are close to body temperature, roughly 36 to 37 degrees Celsius.

Question 16Clinical Practice / Patient Care

Which set of findings best suggests that a patient is being dialyzed below the dry weight?

  1. Cramping, hypotension, and fatigue near the end of treatment Correct answer.
  2. Increased ultrafiltration volumes tolerated without symptoms
  3. Rising pre-dialysis blood pressure and weight gain between treatments
  4. A stronger thrill and bruit than usual

Explanation

When too much fluid is removed, patients develop cramps, hypotension, dizziness, and marked fatigue as treatment progresses. The target weight should be reassessed by the care team rather than the ultrafiltration goal simply increased.

Question 17Clinical Practice / Patient Care

Which food should a hemodialysis patient be taught to limit because of its high potassium content?

  1. Bananas and oranges Correct answer.
  2. White rice
  3. Egg whites
  4. Olive oil

Explanation

Bananas, oranges, potatoes, tomatoes, and dried fruits are high in potassium and can cause dangerous hyperkalemia in patients with little renal excretion. Patients are taught portion limits and leaching techniques for high-potassium vegetables.

Question 18Clinical Practice / Patient Care

Phosphate binders prescribed for a hemodialysis patient are most effective when taken:

  1. Once weekly at bedtime
  2. Only when the patient feels itchy
  3. With meals or snacks Correct answer.
  4. On an empty stomach one hour before meals

Explanation

Binders must be present in the gut lumen along with dietary phosphate, so they are taken with each meal or snack. Timing rather than total daily dose determines how much phosphorus is bound and excreted in the stool.

Question 19Clinical Practice / Patient Care

A patient with hepatitis B surface antigen positivity is receiving hemodialysis. Which precaution is required?

  1. A dedicated machine and a separate room or area, with standard and transmission-based precautions Correct answer.
  2. Standard precautions only, with no restrictions on machine assignment
  3. Reverse isolation, with staff wearing sterile gowns for all contact
  4. No special precautions if the patient wears a mask

Explanation

Hepatitis B is easily transmitted in dialysis units, so infected patients are dialyzed in a separate area on a dedicated machine with dedicated supplies and standard plus transmission-based precautions. Hepatitis B vaccination of all susceptible patients and staff is also part of the control strategy.

Question 20Clinical Practice / Patient Care

A patient's pre-dialysis weight is 70.0 kg and the prescribed target weight is 67.5 kg. Ignoring any fluids given during treatment, the ultrafiltration goal is:

  1. 2500 mL Correct answer.
  2. 3000 mL
  3. 2000 mL
  4. 1500 mL

Explanation

One kilogram of body weight corresponds to about one liter of fluid, so a 2.5 kg difference equals roughly 2500 mL to remove. Any saline or other fluid administered during treatment must be added to that goal.

Question 21Clinical Practice / Patient Care

During treatment with blood flow at 400 mL/min, the pre-pump arterial pressure reads minus 250 mmHg. The most likely cause is:

  1. A high dialysate conductivity
  2. An infiltrated venous needle
  3. Poor arterial needle position or an access stenosis Correct answer.
  4. An elevated patient blood pressure

Explanation

A markedly negative pre-pump pressure means the pump is drawing harder than the access can supply, as occurs with a poorly positioned arterial needle, kinking, or inflow stenosis. The technician checks the needle and tubing and notifies the nurse before adjusting blood flow.

Question 22Clinical Practice / Patient Care

A patient arrives for treatment reporting new chest pain and shortness of breath, with a blood pressure of 200/110 mmHg. The technician should:

  1. Send the patient home with instructions to take an extra antihypertensive dose
  2. Withhold treatment and immediately notify the nurse or physician Correct answer.
  3. Begin treatment as scheduled and reassess in one hour
  4. Start treatment with a high ultrafiltration rate to lower the blood pressure

Explanation

New chest pain and dyspnea with severe hypertension require urgent medical evaluation before dialysis is started. Technicians do not independently treat or dismiss such findings; they hold treatment and escalate to licensed staff.

Question 23Clinical Practice / Patient Care

Which set of findings most strongly suggests hemolysis during dialysis?

  1. Pale plasma with a rising blood pressure
  2. Dark cherry-red blood in the venous line with back pain and a falling hematocrit Correct answer.
  3. Bright red blood with a rising hematocrit
  4. Clear dialysate with a normal venous pressure

Explanation

Hemolysis releases hemoglobin, turning the blood and plasma dark red, and causes back or chest pain, dyspnea, and a falling hematocrit. Common causes include hypotonic dialysate, contaminated water, and overheated dialysate, so treatment is stopped and the blood is not returned.

Question 24Clinical Practice / Patient Care

A patient's pre-dialysis blood urea nitrogen is 80 mg/dL and the post-dialysis value is 24 mg/dL. The urea reduction ratio is approximately:

  1. 70% Correct answer.
  2. 75%
  3. 64%
  4. 60%

Explanation

The urea reduction ratio is the pre-dialysis value minus the post-dialysis value, divided by the pre-dialysis value, times 100. Here (80 minus 24) divided by 80 equals 0.70, or 70 percent.

Question 25Clinical Practice / Patient Care

A low venous pressure alarm sounds and blood is visible on the floor beneath the patient's chair. The technician should first suspect:

  1. The arterial needle resting against the vessel wall
  2. An empty dialysate supply
  3. Failure of the heparin pump
  4. Dislodgement of the venous needle Correct answer.

Explanation

Loss of resistance in the venous line combined with blood at the chair indicates the venous needle has come out and the patient is being deprived of returned blood while losing blood externally. The pump is stopped immediately, the site compressed, and the nurse summoned.

Question 26Clinical Practice / Patient Care

Before cannulating a patient's arteriovenous fistula, the technician performs hand hygiene and then should:

  1. skip gloves because the site will be cleansed afterward
  2. wear a gown and mask instead of gloves
  3. put on clean, nonsterile gloves Correct answer.
  4. put on sterile surgical gloves

Explanation

Standard precautions require clean, nonsterile gloves for routine vascular access cannulation. Sterile gloves are reserved for procedures requiring sterile technique, such as catheter care. Gloving is performed after hand hygiene and before touching the access site.

Question 27Clinical Practice / Patient Care

When inserting a needle into an arteriovenous fistula, the needle bevel should face:

  1. upward away from the skin Correct answer.
  2. downward toward the skin
  3. sideways parallel to the skin
  4. toward the technician's hand

Explanation

The bevel is the slanted opening at the needle tip, and facing it upward allows it to enter the skin and vessel smoothly. A bevel-down or sideways orientation increases trauma and the risk of infiltration. Correct bevel orientation is a basic cannulation principle.

Question 28Clinical Practice / Patient Care

Which assessment finding best confirms that an arteriovenous fistula is functioning?

  1. a visible pulse at the anastomosis
  2. a palpable thrill and an audible bruit Correct answer.
  3. mild swelling around the access
  4. warm skin over the access area

Explanation

A thrill is the vibration felt over a patent access, and a bruit is the swishing sound heard with a stethoscope; together they indicate blood flow through the fistula. Warm skin and mild swelling are nonspecific findings. A palpable pulse alone does not confirm adequate flow.

Question 29Clinical Practice / Patient Care

A hemodialysis patient reports drinking about 2 liters of fluid each day. Which instruction is most appropriate?

  1. You may drink as much fluid as you want as long as you avoid salt
  2. Only fluids taken with meals count toward your daily limit
  3. You should stop all fluid intake between treatments
  4. You should follow the daily fluid limit prescribed by your care team Correct answer.

Explanation

Fluid limits are individualized, commonly around 500 to 1000 mL per day plus urine output, and are set by the care team. All fluids, including soups, ice, and gelatin, count toward the limit. Telling a patient to avoid all fluids is unsafe and not a prescribed restriction.

Question 30Clinical Practice / Patient Care

During treatment, a patient becomes pale and diaphoretic and reports nausea; the blood pressure is 85/50 mmHg. The technician should first:

  1. return the blood immediately and end the treatment
  2. increase the ultrafiltration rate to finish the treatment on time
  3. give the patient a hot drink and continue treatment as ordered
  4. place the patient supine with the legs elevated and reduce or stop ultrafiltration Correct answer.

Explanation

These findings indicate intradialytic hypotension, which is managed by stopping or reducing ultrafiltration and improving venous return with a supine or Trendelenburg position. A saline bolus is often given per protocol or order. Treatment is not routinely terminated unless the patient does not respond.

Question 31Clinical Practice / Patient Care

The arterial needle for an arteriovenous fistula is typically directed:

  1. straight down into the access at a 90-degree angle
  2. toward the venous outflow, following the direction of blood flow
  3. toward the arterial anastomosis, against the direction of blood flow Correct answer.
  4. parallel to the skin with the bevel facing down

Explanation

The arterial needle is placed with its tip pointing toward the arterial anastomosis so that it draws blood before the access has circulated through the limb. The venous needle points toward the venous outflow to return blood in the direction of flow. Separating the two directions helps maintain flow and reduce recirculation.

Question 32Clinical Practice / Patient Care

A hemodialysis machine displays a low conductivity alarm. The technician should first:

  1. increase the blood flow rate
  2. recalibrate the blood pump
  3. check that the dialysate concentrate is connected and not empty Correct answer.
  4. administer a saline bolus

Explanation

Low conductivity usually means the dialysate is not receiving enough concentrate, often because a concentrate container is empty or a connector is loose. The concentrate supply and connections should be checked before treatment continues. Dialysis should not proceed until conductivity is within the acceptable range.

Question 33Clinical Practice / Patient Care

A patient uses the buttonhole technique for cannulation. Which practice is correct?

  1. Use a sharp needle at a new site for each treatment
  2. Rotate the needle among several sites within the same buttonhole tract
  3. Use a blunt needle along the established tract at the same angle each time Correct answer.
  4. Cannulate the buttonhole tract before cleansing the site

Explanation

Buttonhole cannulation creates a stable tract that is entered with a blunt needle at the same angle and depth each time. Using sharp needles or changing the angle disrupts the tract and causes trauma. The site is cleansed before cannulation, as with any access.

Question 34Clinical Practice / Patient Care

Which medication is used to reverse the effect of unfractionated heparin if bleeding occurs after dialysis?

  1. protamine sulfate Correct answer.
  2. calcium gluconate
  3. sodium citrate
  4. vitamin K

Explanation

Protamine sulfate binds heparin and neutralizes its anticoagulant effect. It is used when heparin-related bleeding is significant. Vitamin K reverses warfarin, not heparin, and citrate and calcium do not reverse heparin.

Question 35Clinical Practice / Patient Care

During several consecutive treatments, a patient's venous pressure has risen steadily while blood flow and needle position remain unchanged. This trend most suggests:

  1. a low dialysate conductivity
  2. excessive anticoagulation
  3. narrowing of the venous outflow or access stenosis Correct answer.
  4. a leaking venous needle

Explanation

A progressive rise in venous pressure with stable blood flow and needle position points to increased resistance downstream, such as venous stenosis. A leaking needle would more likely lower venous pressure and cause hematoma. The trend should be reported for access evaluation.

Question 36Clinical Practice / Patient Care

Thirty minutes into treatment, a patient develops chills, fever, and hypotension. The technician should:

  1. increase the dialysate temperature to make the patient more comfortable
  2. stop the blood return, notify the care team, and obtain blood cultures as ordered Correct answer.
  3. slow the blood flow and reassess in 30 minutes
  4. give an oral antipyretic and continue treatment as ordered

Explanation

Fever with chills and hypotension during dialysis suggests a pyrogen reaction or bacteremia, and returning the extracorporeal blood could deliver more contaminants to the patient. Treatment should be stopped without returning blood and the care team notified promptly. Blood cultures are obtained as ordered to identify the source.

Question 37Clinical Practice / Patient Care

A patient's arteriovenous graft arm is swollen and tender after treatment, with no bleeding at the needle sites. The technician should:

  1. massage the area firmly
  2. cannulate the graft again to relieve the pressure
  3. apply a tight tourniquet to the arm
  4. elevate the arm and notify the care team Correct answer.

Explanation

Swelling and tenderness without external bleeding may indicate a hematoma, infiltration, or outflow problem, and the arm should be elevated while the care team is notified. A tight tourniquet or massage could worsen bleeding or dislodge a clot. The access should not be re-cannulated to relieve pressure.

Question 38Clinical Practice / Patient Care

Within minutes of starting dialysis with a new dialyzer, a patient develops burning at the access, facial flushing, and chest tightness. The most likely cause is:

  1. a first-use reaction to the dialyzer membrane Correct answer.
  2. disequilibrium syndrome
  3. hypoglycemia
  4. an air embolism

Explanation

A first-use or anaphylactoid reaction occurs early in treatment and presents with burning at the access, flushing, chest tightness, and sometimes hypotension. Treatment is stopped and the blood is not returned. Disequilibrium develops later and causes neurologic symptoms, while air embolism and hypoglycemia have different presentations.

Question 39Clinical Practice / Patient Care

During dialyzer reprocessing, the measured total cell volume falls below 80% of the initial value. The dialyzer should be:

  1. reused after an extra rinse
  2. discarded and not reused Correct answer.
  3. used with a lower blood flow rate
  4. tested again after the next treatment

Explanation

Total cell volume reflects the membrane's ability to clear solutes, and a value below 80% of the initial measurement indicates reduced performance. The dialyzer is discarded rather than reused. Rinsing or changing blood flow does not restore membrane function.

Question 40Clinical Practice / Patient Care

Which finding best indicates access recirculation during dialysis?

  1. a bruit that becomes louder after needle insertion
  2. a urea level in the arterial line that is close to the venous line level Correct answer.
  3. a rise in venous pressure when the blood pump is stopped
  4. a fall in arterial pressure when ultrafiltration is increased

Explanation

Recirculation means cleared blood returning through the venous needle is drawn back into the arterial needle, so arterial and venous urea concentrations become similar. A significant difference normally exists between the two lines. Pressure changes and bruit intensity do not measure recirculation.

Question 41Water Treatment and Dialysis Delivery Systems

What is the primary purpose of the activated carbon filter in a hemodialysis water treatment system?

  1. Removing chlorine and chloramine Correct answer.
  2. Removing bicarbonate from the water
  3. Removing calcium and magnesium ions
  4. Removing bacteria and endotoxin

Explanation

Activated carbon removes free chlorine and chloramine through adsorption and catalytic reduction. Chlorine must be removed because it can cause hemolysis and damage dialyzer membranes. Hardness ions are removed by a softener, and bacteria/endotoxin are removed mainly by reverse osmosis and ultrafiltration.

Question 42Water Treatment and Dialysis Delivery Systems

A water softener in a dialysis water system is used primarily to remove which substances?

  1. Calcium and magnesium Correct answer.
  2. Chlorine and chloramine
  3. Dissolved carbon dioxide
  4. Bacteria and endotoxins

Explanation

A softener uses cation exchange resin to exchange calcium and magnesium for sodium. Removing hardness prevents scale formation on RO membranes and precipitation in dialysate. Chlorine removal is the job of the carbon filter.

Question 43Water Treatment and Dialysis Delivery Systems

What is the main function of the reverse osmosis membrane in a dialysis water system?

  1. Removing only chlorine from the water
  2. Adjusting the pH of the product water
  3. Removing dissolved ions, bacteria, and endotoxins Correct answer.
  4. Adding minerals back to the product water

Explanation

Reverse osmosis forces water through a semipermeable membrane that rejects most dissolved ions, bacteria, and endotoxins. It is the principal purification step for dialysis water. Chlorine removal occurs upstream in the carbon filter.

Question 44Water Treatment and Dialysis Delivery Systems

Ultraviolet light used in dialysis water treatment works primarily by:

  1. Inactivating microorganisms at 254 nm Correct answer.
  2. Precipitating calcium salts
  3. Removing endotoxin
  4. Adsorbing organic compounds

Explanation

UV lamps emit light near 254 nm, which damages microbial nucleic acids and inactivates bacteria. UV does not remove endotoxin or dissolved ions, and it does not soften water. It is typically placed after RO to control bacterial proliferation.

Question 45Water Treatment and Dialysis Delivery Systems

AAMI standards set the maximum bacterial count for conventional dialysis water at:

  1. 1000 CFU/mL
  2. 10 CFU/mL
  3. 100 CFU/mL Correct answer.
  4. 200 CFU/mL

Explanation

Conventional dialysis water must contain no more than 100 CFU/mL of bacteria. The 200 CFU/mL limit applies to dialysate, not to the water itself. Ultrapure water has a stricter limit of 0.1 CFU/mL.

Question 46Water Treatment and Dialysis Delivery Systems

The AAMI maximum endotoxin concentration for conventional dialysate is:

  1. 5 EU/mL
  2. 0.5 EU/mL
  3. 0.25 EU/mL
  4. 2 EU/mL Correct answer.

Explanation

Conventional dialysate must not exceed 2 EU/mL of endotoxin. The 0.25 EU/mL limit applies to conventional dialysis water. Ultrapure dialysate has a much lower limit of 0.03 EU/mL.

Question 47Water Treatment and Dialysis Delivery Systems

Conductivity measured in dialysate primarily reflects:

  1. Dissolved chlorine
  2. Endotoxin concentration
  3. Bacterial contamination
  4. Total dissolved ions Correct answer.

Explanation

Conductivity reflects the ability of the solution to carry current, which depends on the concentration of dissolved ions. It is used to verify correct proportioning of concentrate and water. It does not measure bacteria, endotoxin, or chlorine.

Question 48Water Treatment and Dialysis Delivery Systems

Normal dialysate conductivity during a hemodialysis treatment is approximately:

  1. 4 mS/cm
  2. 11 mS/cm
  3. 8 mS/cm
  4. 14 mS/cm Correct answer.

Explanation

Dialysate with a sodium concentration near 140 mEq/L has a conductivity of about 13.5 to 14.5 mS/cm. Values far outside this range suggest improper proportioning or a water quality problem. Lower values would represent excessively dilute dialysate.

Question 49Water Treatment and Dialysis Delivery Systems

In a standard three-stream proportioning system, the typical ratio of acid concentrate to bicarbonate concentrate to water is:

  1. 1 : 1.83 : 34 Correct answer.
  2. 1 : 1 : 1
  3. 1 : 34 : 1.83
  4. 34 : 1.83 : 1

Explanation

A common three-stream system proportions one part acid concentrate, about 1.83 parts bicarbonate concentrate, and 34 parts treated water. This yields the final electrolyte and buffer concentrations intended for treatment. The other ratios would produce grossly incorrect solute concentrations.

Question 50Water Treatment and Dialysis Delivery Systems

The high-temperature alarm on a hemodialysis machine typically activates at approximately:

  1. 41 degrees C Correct answer.
  2. 43 degrees C
  3. 39 degrees C
  4. 37 degrees C

Explanation

Dialysate is normally kept near 37 degrees C, and the independent high-temperature alarm usually triggers around 41 degrees C. This protects the patient from hemolysis and burns. Alarms set only slightly above normal temperature would cause frequent nuisance alarms.