Dialyzer preparation
Each dialyzer has its own specific characteristics and procedure for preparation for patient use. Manufacturers’ instructions are updated frequently as alterations are made or as improved techniques are developed. It is very important to read package inserts frequently to ensure adherence to current recommendations. Always check and follow the manufacturer’s instructions for use (IFU).
What are the essential parameters when a dialyzer is prepared for patient use?
The essential parameters in dialyzer preparation are as follows:
• All air in the dialyzer must be removed. Any air left in the dialyzer could be dialyzed across the membrane and into the patient’s vascular system. Air trapped in the wall of the hollow fibers will reduce the dialyzer clearance by preventing diffusion between the blood and dialysate compartments. Also, air will promote clotting in the hollow fibers of a dialyzer.
• Any particulate matter left in the dialyzer from the manufacturing process must be flushed out with the saline prime.
• All disinfectant used in the reprocessing procedures must be removed, and the dialyzer must be free of residual disinfectant.
• Dialyzers must always be flushed and primed with a physiologic saline solution (0.9 g NaCl/100 mL water) compatible with patient blood.
How is air removed from a dialyzer?
To remove air from a dialyzer, prime normal saline into the dialyzer from the bottom. This is accomplished by attaching the bloodlines to the dialyzer and then turning the dialyzer so that the venous end is up. Then run the saline in through the arterial bloodline, through the dialyzer into the venous bloodline, and into a basin. As the dialyzer is filled, the air is forced out the top of the dialyzer. Tap the dialyzer lightly, and turn it from side to side to ensure that all of the air is removed from the header.
How much saline should be used to prime the dialyzer?
Priming the dialyzer will require 500 to 1000 mL of saline. The amount depends on the type of dialyzer and whether it has been reprocessed. A new dialyzer should have 1000 mL of prime to remove the glycerin and particulate matter remaining from the manufacturing process. A reprocessed dialyzer requires approximately 500 mL because the prime will be recirculated with the dialysate flowing counterclockwise to remove any residual disinfectant.
Should anything be different when priming a reprocessed dialyzer?
Reprocessed dialyzers are filled with a disinfectant, and it is important that all disinfectant be removed and no air be introduced into the dialyzer. When air is introduced, it is very difficult to remove. All air must be removed from the arterial bloodline before attaching it to the dialyzer. This is accomplished by priming the arterial bloodline with saline, making sure all of the air is removed before attaching the line to the dialyzer. After this is done, turn the dialyzer venous end up and continue the priming procedure.
Do manufacturers make any recommendations regarding the priming of their dialyzers?
Yes, all manufacturers make recommendations for priming their dialyzers. Some dialyzers should have the blood compartment filled first; others should have the dialysate compartment filled first. Most hollow-fiber dialyzers require that you “wet” the membranes first before attaching the dialysate lines. This ensures that the dialyzer fibers will not collapse when exposed to dialysate. Dialysis personnel should read and follow the instructions that come with the dialyzers used in the particular facility.
Dialyzer reprocessing
Cleaning and disinfecting a dialyzer to be used again for that same patient’s treatment is dialyzer reprocessing or dialyzer reuse. Reuse of dialyzers is safe and cost effective. The guidelines in the Association for the Advancement of Medical Instrumentation’s (AAMI) Recommended Practice for the Reuse of Hemodialyzers (RD47) must be followed because the Centers for Medicare & Medicaid Services (CMS) have adopted them as standards governing the practice. Dialyzer manufacturers are now required by the U.S. Food and Drug Administration (FDA) to label their dialyzers so that users know that they are appropriate for reprocessing. The manufacturer must also recommend appropriate reprocessing techniques and the type of germicide to be used.
Dialyzer reprocessing may be performed manually or with an automated system. Reprocessing may be performed on-site at the provider facility, or the dialyzers may be transported to an off-site location. Bloodlines and other disposable items have been reused, but are regulated and restricted by the FDA and are rarely reused in the United States. The CMS has taken an official end-stage renal disease (ESRD) program position on reuse and has published specific written requirements. Some chemicals used to reprocess dialyzers are considered hazardous and are regulated by the Occupational Safety and Health Administration (OSHA).
What are some advantages to dialyzer reuse?
There are purported clinical advantages to the reuse of dialyzers. With each dialysis treatment, the patient’s blood leaves proteins on the wall of the membrane. These protein deposits create a secondary membrane that reduces the amount of exposure of the patient’s blood to the artificial membrane on subsequent treatments. Bleach, however, when used in the disinfection process, will decrease this protection because it strips the protein layers from the dialyzer.
On rare occasions a patient may react to a new dialyzer. These reactions are believed to be caused by either bioincompatible membranes or ethylene oxide residue left in the sterilized dialyzer. A reaction may occur shortly after initiation of dialysis, and could be life-threatening. When the dialyzer has been reprocessed for reuse, such reactions are not observed during subsequent treatments.
Reused dialyzers also help to contain the cost of each patient treatment, and with reuse there is a significant reduction of medical waste products and biohazardous trash.
How many times can a dialyzer be reused?
Some centers arbitrarily settle on three or five reuses per dialyzer, whereas other centers use a dialyzer until it has been determined that its effectiveness is no longer adequate to deliver the recommended dose of dialysis for the patient. Even these small numbers represent a significant savings. To determine cost effectiveness of reuse, divide the original cost of the dialyzer by the total cost of reprocessing. To qualify for reuse, a dialyzer must meet defined criteria: residual volume or total cell volume (TCV) must be 80% or greater of original volume, it must pass a pressure-holding test, and the appearance evaluation should show no more than a few clotted fibers. After each clinical use, the dialyzer is evaluated using these criteria and must meet them to be used again for a patient.
What are the basic steps for reuse?
The basic steps in most reprocessing programs are as follows: (1) flushing the dialyzer to remove most of the blood residuals; (2) cleaning, usually done with chemicals (bleach or Renalin) and reverse ultrafiltration; (3) testing to verify that the membrane is intact and that the dialyzer will remove waste products as expected; and (4) disinfection with either a chemical or heat.
What specific criteria are used to determine if a dialyzer may be reused?
The four main criteria for reuse are as follows:
• TCV measurement is the most widely used method to determine whether a reused dialyzer maintains adequate solute removal capability. In this test, the dialyzer is filled with water and then pumped dry, and the contained volume is measured in a graduated cylinder. This volume is the standard for that dialyzer and the value against which it will be compared after each use. If less than 80% of initial volume remains, the dialyzer is rejected for further patient use. A dialyzer with 80% of its initial volume still has 90% of its initial solute removal capability.
• Pressure testing of the dialyzer is performed to determine whether there are broken fibers that would lead to a blood leak during dialysis. Pressure is applied to the dialyzer and then held. If the pressure drop is too great, the dialyzer is discarded. This is sometimes referred to as leak testing.
• Some reuse machines test the dialyzer’s kUF (ultrafiltration coefficient). Although this is not a test to predict dialyzer clearance, it is an indication of how “open” the dialyzer membrane may be to large molecules.
• Finally, appearance or visual inspection is an important criterion. A dialyzer with larger streaks of residual blood, indicating a large number of clotted fibers, is cause for immediate rejection.
Is large solute clearance affected by reprocessing?
Yes. The extent of this effect depends on the dialyzer membrane and reprocessing technique; some membranes tend to become more open when exposed to bleach cleaning. Most membrane clearance of large solutes such as β2-microglobulin is decreased when Renalin is used. It is very important to understand how particular dialyzers are affected by the reprocessing technique used.
How are reprocessed dialyzers disinfected?
Peracetic acid (3% to 4%), formaldehyde or formalin (1% to 4%), glutaraldehyde (0.8%), and heated water with citric acid (1.5%) are the most commonly used chemical disinfectants for reprocessing. High-level disinfection must be used for the blood and dialysate compartments and low-level disinfection is used for the outer casing and port caps (CMS ESRD Conditions for Coverage, 2008).
What types of labeling are required for the reprocessed dialyzer?
The CMS Conditions for Coverage require that each dialyzer must be tested for TCV clearance prior to first use and must then be labeled with the patient’s name, number of previous uses, and the date and time the dialyzer was last processed.
Meticulous care must be taken to ensure that each dialyzer is used on only one patient. Careful attention must be given to patients with the same or similar names. Additional means of identification, such as the use of a social security number or birth date, is recommended as an additional check to verify that the correct dialyzer is being used on the patient. Some facilities will place a warning on the dialyzer to alert the staff member to exercise extra caution when placing the patient on that dialyzer. After the patient is at the treatment station, two people must verify that the first and last names on the dialyzer belong to that patient. Records should be maintained in the facility that track the history of the dialyzer from its first use to when it is discarded.
What exposure time is required for renalin and formaldehyde?
Renalin, a mixture of hydrogen peroxide, peracetic acid, and acetic acid, is a sterilant and requires a 0.5% solution for an 11-hour contact time. In contrast, aqueous formaldehyde, a high-level disinfectant, kills all microorganisms, including spores and viruses, with a minimum exposure of 24 hours and a 4% concentration of formalin at room temperature. A lower concentration, 1.5% formalin, is effective at 38°C (100°F) for a 24-hour exposure.
What happens if a dialyzer is not adequately disinfected?
If there is not sufficient exposure (concentration and time), bacteria in the dialyzer will not be killed and may even multiply. This could result in a patient becoming bacteremic when the blood is exposed to the dialyzer during a subsequent treatment.
What information should be verified before using a reprocessed dialyzer for a patient?
Several checks must be completed before using a reprocessed dialyzer. The most important is to verify that the dialyzer is being used for the correct patient. Other requirements include ensuring that the dialyzer contained an adequate level of disinfectant before it was rinsed and that all of the disinfectant was removed during the rinsing process. Finally, the dialyzer must pass all reuse testing, such as TCV and pressure tests.
What precautions are necessary when using chemical disinfectants?
The use of protective gear—including eye shield, gloves, and a waterproof gown—is necessary when using chemical disinfectants. Adequate ventilation (in adherence to OSHA guidelines) is also required. Any splashes on skin or eyes should be flushed with copious amounts of water, and appropriate medical care should be sought.
Note that OSHA requires that personnel be well informed about these hazardous chemicals and their potential toxicity. Every dialysis facility must have printed OSHA requirements and regulations related to the use of disinfectants. Training records of staff education and health monitoring records must be maintained. Material safety data sheets (MSDS) must be available for each chemical housed in the facility and for each chemical to which the employee may be exposed. The MSDS must be accessible to staff at all times.
What precautions should be taken when working with formaldehyde?
The OSHA standard, Title 29 of the Code of Federal Regulations (CFR), section 1910.1048, protects workers who have the potential to be exposed to formaldehyde. Formaldehyde is a suspected carcinogen associated with nasal and lung cancer. Airborne concentrations as little as 0.1 parts per million (ppm) may cause irritation to the nose, eyes, and throat. Allergic reactions may occur with exposure, causing wheezing, coughing, or asthmalike symptoms.
Air quality monitoring and patient education are used to protect staff from potential dangerous exposure. The OSHA has set permissible exposure limits at 0.75 ppm measured as an eight-hour time-weighted average (TWA). The OSHA standard for short-term exposure limit is 2 ppm during a 15-minute period. The action level is 0.5 ppm for an eight-hour TWA. The OSHA mandates that all staff be educated on the hazards of and how to work safely with formaldehyde on an annual basis. An emergency shower and eyewash station must also be available to the staff in the event of an exposure. Mandatory respiratory training must also be done on reuse personnel as well as fit testing for a respirator.
Are chemical disinfectants stable over time?
Renalin is broken down fairly rapidly by temperature greater than 27°C (80°F), exposure to light, and exposure to organic matter (such as blood). Time is another factor: after it has been diluted, Renalin has a relatively short shelf life. It is very important to test each dialyzer for Renalin potency just prior to preparing it for patient use. Formaldehyde is quite stable for long periods.
How should the dialyzer be prepared before the next run?
After the dialyzer is filled with disinfectant at the end of the reprocessing procedure, it is necessary to document the presence of the disinfectant by an appropriate chemical test. This helps to confirm that the dialyzer is stored with the disinfecting chemical. Before the next clinical use, the disinfectant must be removed. The bloodlines are connected to the dialyzer, and sterile saline is rinsed through the blood side of the dialyzer. Usually 250 to 500 mL of saline is run through the dialyzer and discarded. The arterial and venous bloodlines are then connected to establish a closed loop. The blood pump is started, and the recirculation of saline, with ultrafiltration, should remove any residual chemical left in the system. Essentially, the disinfectant is simply dialyzed out of the system.
Just before use, the recirculating saline in the dialyzer is sampled using the test appropriate for the disinfectant used. After the test is performed, the absence of the disinfectant must be documented. Only after a negative test has been confirmed is the dialyzer considered safe for patient use. Many dialysis units and some state agencies require two people to verify that the dialyzer is correct for a specific patient and has a negative disinfectant test before using the reprocessed dialyzer.
When renalin is the disinfectant used, is there a specific order in which the compartments are primed?
Renalin is a strong acid, so it is important to prime the blood compartment with normal saline before attaching the dialysate lines. If the dialysate compartment is primed first, reaction between the dialysate and Renalin will cause some of the carbon dioxide to come out of solution as a gas. These bubbles can be trapped in the fibers, creating an air gap between the blood and dialysate, resulting in poor diffusion.
Are there circumstances in which reuse is inappropriate for a particular patient?
Patients with systemic infections or with sepsis are generally excluded from reprocessing programs. Patients with hepatitis B cannot participate in reuse programs.
Are patients required to give their consent for reuse of dialyzers?
CMS requires that patients give consent in writing. The consent must be made part of the patient’s clinical record. If the patient does not give this written consent, reuse is not permitted.