CCHT Dialyzer Reprocessing and Reuse 2 — Questions and Answers

Question 1: Which chemical is most commonly used as a germicide during manual dialyzer reprocessing?

Glutaraldehyde
Peracetic acid (Correct answer)
Bleach (sodium hypochlorite)
Formaldehyde

Correct answer: Peracetic acid

Peracetic acid (PAA) is the most commonly used germicide for dialyzer reprocessing because it is effective, relatively safe, and dissipates rapidly. Formaldehyde was historically used but has largely been replaced due to health hazards.

Peracetic acid (PAA) has become the preferred germicide in dialyzer reprocessing programs. It is a strong oxidizing agent that effectively kills bacteria, viruses, and spores. One of its key advantages is that it decomposes into acetic acid, oxygen, and water—none of which are hazardous residues. Formaldehyde was the original standard germicide but fell out of favor due to its classification as a probable human carcinogen and the associated occupational exposure risks for dialysis staff. Glutaraldehyde has also been used but presents dermal and respiratory sensitization risks. The AAMI standards (ANSI/AAMI RD52) govern dialyzer reprocessing and set requirements for germicide concentration, contact time, and residual testing before the dialyzer is returned to patient use. Staff must verify that germicide residuals are below safe thresholds before connecting a reprocessed dialyzer. Proper rinsing after germicide exposure is critical to prevent patient harm. Symptoms of germicide exposure in patients include headache, nausea, hemolysis, and cardiovascular instability. The technician must document each reprocessing cycle including the germicide lot number, concentration test result, and reuse count.

Question 2: What is the minimum acceptable total cell volume (TCV) for a reprocessed dialyzer to be approved for reuse?

70% of the original TCV
80% of the original TCV (Correct answer)
90% of the original TCV
95% of the original TCV

Correct answer: 80% of the original TCV

AAMI guidelines require that a reprocessed dialyzer retain at least 80% of its original total cell volume (TCV). A dialyzer that falls below this threshold must be discarded because reduced fiber volume indicates inadequate clearance capability.

Total cell volume (TCV) is a measure of the internal priming volume of the dialyzer's hollow fibers. It serves as a surrogate marker for the effective membrane surface area available for solute clearance and ultrafiltration. During each use, protein deposits and cellular debris can clog hollow fibers, reducing TCV. AAMI/ANSI RD52 standards specify that a dialyzer must retain at least 80% of its original TCV to be approved for reuse. If the measured TCV falls below 80% of the baseline, the dialyzer must be discarded regardless of reuse count. TCV is measured using an air pressure test or water displacement method, depending on the facility protocol. The original TCV is established during the first processing of a new dialyzer, and each subsequent measurement is compared against that baseline. Monitoring TCV trends over multiple reuses can also help identify patients who consistently clog fibers more quickly, potentially indicating hyperlipidemia, high-protein states, or clotting tendency. Facilities must document TCV on each reprocessing record to comply with CMS Conditions for Coverage and AAMI standards.

Question 3: A technician notices the reuse count on a dialyzer has reached the facility's maximum allowed reuses. What is the correct action?

Continue using the dialyzer if TCV is still within acceptable limits
Discard the dialyzer and document the disposal (Correct answer)
Reprocess the dialyzer one additional time with double germicide concentration
Report to the nephrologist before discarding

Correct answer: Discard the dialyzer and document the disposal

When a dialyzer reaches the facility's maximum reuse count, it must be discarded regardless of TCV or visual appearance. The reuse limit is a safety boundary set by the facility based on manufacturer data, regulatory standards, and clinical policy.

Dialyzer reuse programs operate under strict protocols that include a maximum reuse count, which is the maximum number of times a single dialyzer may be processed and used for a patient. This number is typically set between 20 and 30, though individual facility policies may differ based on the dialyzer model and manufacturer recommendations. Once the maximum reuse count is reached, the dialyzer must be discarded. This is a hard stop—no additional testing or physician approval overrides this limit. Even if TCV and visual inspection appear acceptable, continued use beyond the limit violates facility policy and regulatory standards. The rationale for maximum reuse counts includes the potential for cumulative membrane degradation, increased risk of pyrogenic reactions from biofilm buildup, and diminishing clearance efficiency not fully detected by TCV alone. Additionally, repeated chemical exposure may degrade the dialyzer housing and potting material. Proper disposal documentation is required, including patient ID, reuse count, date, and reason for discard. This creates an auditable record for CMS surveys and quality improvement reviews. Staff should also confirm that the correct dialyzer is being discarded by cross-referencing the patient label on the dialyzer with the treatment record.

Question 4: Before returning a reprocessed dialyzer to a patient, which test must be performed to ensure patient safety?

Dialysate conductivity test
Germicide residual test (Correct answer)
Blood leak detector calibration
Ultrafiltration coefficient verification

Correct answer: Germicide residual test

A germicide residual test must be performed to confirm that germicide levels in the dialyzer are below the safe threshold before use. Exposing a patient to residual germicide can cause serious adverse reactions including hemolysis and cardiovascular compromise.

The germicide residual test is a mandatory safety check performed on every reprocessed dialyzer before it is connected to a patient. This test confirms that germicide concentration within the dialyzer blood compartment has fallen to safe levels following the required rinsing procedure. For peracetic acid systems, the maximum allowable residual is typically 3 parts per million (ppm) or as specified by the manufacturer. Test strips or colorimetric test kits are used to measure residual concentration. If the residual exceeds the safe threshold, the dialyzer must be rinsed again and retested before use. Adverse effects of germicide exposure include headache, nausea, vomiting, chest tightness, hemolysis (from peracetic acid or bleach), and in severe cases, cardiovascular collapse. Patients may not be able to articulate these symptoms early in treatment, so the preventive value of residual testing cannot be overstated. The residual test result must be documented on the reprocessing record along with the technician's initials and the time of testing. Failure to perform this test before use is a serious safety violation that can result in patient harm and regulatory sanctions. The entire reprocessing process—including residual testing—must be performed according to validated facility protocols that comply with AAMI RD52.

Question 5: Which of the following best describes the purpose of pressure testing a dialyzer during reprocessing?

To measure ultrafiltration rate
To verify membrane integrity and detect fiber bundle leaks (Correct answer)
To confirm the dialysate flow path is patent
To check the blood pump segment for cracks

Correct answer: To verify membrane integrity and detect fiber bundle leaks

Pressure testing during reprocessing verifies the integrity of the dialyzer membrane. A drop in pressure indicates that fibers are broken or leaking, which would allow blood and dialysate to mix during treatment—a serious patient safety risk.

Dialyzer pressure testing is performed during reprocessing to assess the structural integrity of the hollow fiber membrane. The test involves pressurizing one compartment (usually the blood compartment) with air and monitoring for pressure decay over a set time period. A significant pressure drop indicates compromised fibers or membrane rupture. A failed pressure test means blood and dialysate could mix during treatment. This is dangerous for several reasons: dialysate entering the blood compartment can cause electrolyte imbalances, while blood entering the dialysate can expose the patient to contaminated fluid and complicate machine operation. The pressure test is typically performed immediately after the hydraulic performance test (TCV measurement) and before germicide instillation. If the dialyzer fails the pressure test, it must be discarded immediately and cannot be reprocessed further. All pressure test results must be logged in the reprocessing record. Many facilities use automated reprocessing machines that perform pressure testing as part of a programmed cycle, reducing operator variability. However, technicians must still understand the purpose and pass/fail criteria to respond appropriately when the machine flags a failure. Manual override of a failed pressure test to approve a dialyzer for use is never acceptable.

Question 6: What information must be documented on the label of a reprocessed dialyzer?

Patient name, dialyzer model number, and germicide brand name
Patient name or ID, reuse count, and date of last reprocessing (Correct answer)
Nurse's initials, reuse count, and TCV percentage
Physician name, germicide concentration, and date of first use

Correct answer: Patient name or ID, reuse count, and date of last reprocessing

Reprocessed dialyzer labels must include the patient identifier, the reuse count, and the date of the most recent reprocessing. This information is essential for tracking and verifying the dialyzer is correctly matched to the patient and within policy limits.

Accurate labeling of reprocessed dialyzers is a critical patient safety requirement. The minimum information required on the dialyzer label includes: the patient's full name or unique patient identifier, the reuse count (number of times the dialyzer has been processed and used), and the date of the most recent reprocessing. This information serves multiple purposes. The patient identifier ensures the correct dialyzer is given to the correct patient—dialyzer mix-ups, though rare, can occur in high-volume units and may cause immunologic reactions. The reuse count allows staff to verify the dialyzer has not exceeded the facility's maximum reuse limit. The date of reprocessing helps staff determine whether the dialyzer has been stored within the acceptable shelf-life period (typically 7 days for germicide-filled dialyzers). Before connecting the dialyzer, the nurse or technician must perform a two-identifier verification, matching the dialyzer label to the patient's treatment record. This is analogous to a medication verification step and is a required element under CMS Conditions for Coverage for ESRD facilities. Additional information that may appear on the label includes the germicide type, TCV value, and the initials of the reprocessing technician. Facilities may use automated systems that print standardized labels directly from the reprocessing database, reducing transcription errors.

CCHT Dialyzer Reprocessing and Reuse 2

Which chemical is most commonly used as a germicide during manual dialyzer reprocessing?