During routine rounds in hemodialysis, we found purple discoloration of  tubings in 2 patients in the same shift.

Patient 1: 24-year-old male k/c/o IgA Nephropathy, CKD on MHD (twice a week) through left sided radiocephalic AV fistula since last 2 years.

Patient 2: 60-year-old female k/c/o DM, CKD on MHD (twice a week) through left sided radiocephalic AV fistula since last 3 years.

There was no significant history of any dialysis related issues, in both the patients. Surprisingly, both the patients were vitally stable after this purple discoloration of tubings. So, we tried to look for a technical reason for this occurrence.

The dialyzer was used for the second time in the first patient and the third time in second patient. Usually, the dialyzer is reused 4 times as per the policy of the dialysis unit. Patient’s AVF needle/dialyzer was surprisingly not discolored. So, we reviewed the quality/expiry dates of tubing but they were good to use. On investigating further, we came to know that a cleansing/disinfection agent for dialyzer reuse was changed recently. Previously Formalin was in use in the dialysis unit but it was recently changed to a solution that contains paracetic acid, hydrogen peroxide and acetic acid. So, further inquiry was done related to the use of this solution and we came to know that 3 liters of this solution was diluted in 7 liters of RO water so the strength of the final solution was 30 percent instead of the routine requirement of 3.5 percent for the disinfection procedure. This dilution related issue was corrected immediately and after that, this discoloration related issue was resolved. Here, the important thing was the concentration and the dilution issues of the cleansing/disinfecting agent during dialyzer reprocessing/reuse.

DISCUSSION

INTRODUCTION

Dialysis facilities that reuse dialyzers must follow strict guidelines set forth by the AAMI (Association for the Advancement of Medical Instrumentation)

The AAMI guidelines make provisions for the patient’s safety, as listed below:

• A dialyzer must be clearly labelled with the patient’s name and should only be used for the same patient.
• A dialyzer must be tested after each use to make sure it is working properly.
• A dialyzer must be tested after rinsing for any traces of disinfectant that may remain.
• Patients must be monitored for any reactions due to reuse.

REQUIREMENTS FOR REPROCESSING DIALYZERS

1. WATER

• This should be of AAMI standard or preferably of ultrapure quality.
• The water line pressure should be 13 kg/cm2 (20 psi), and every washing area should be equipped with 2 outlets or a T connection.
• Two different fittings will be required on the water line at each reprocessing area, a standard tubing to clean the blood compartment, and a Hansen connector for backwashing the dialysate compartment.
• Fittings should be of 316 SS or medical grade PVC only
• A prolonged rinse with Reverse Osmosis (RO) water followed by reverse ultra-filtration has been shown to be an effective means of cleaning dialyzers without the addition of chemicals

2. CLEANING AND DISINFECTING AGENTS

• While selecting disinfectant we need to see for – Elimination of organic pollution, Inorganic component removal capacity, Disinfection efficacy, Safety and Environmental pollution.
• These agents should preferably be available online in the reprocessing areas.
• Overhead tanks containing the chemicals may be of 25 to 50 liters capacity and should be 
refilled with fresh solutions every week, after cleaning.
• All tanks and piping for sodium hypochlorite should be composed of medical grade PVC, and those for formaldehyde, glutaraldehyde, and peracetic acid should be composed of 316SS.

As per Indian Haemodialysis guidelines, common cleansing/disinfecting agents in use are mentioned below but regardless of the type of cleaning or disinfecting agent used in the facility, a thorough water rinse must be done prior to adding chemicals and after cleaning and disinfecting. Safety tests must be done after the final rinse to confirm the absence of any chemical used. It is dangerous to rely on a timed rinse without the use of a valid safety test. Residual testing prevents patient injury due to chemical exposure.

a) Sodium Hypochlorite 1–2%

• Sodium hypochlorite (bleach) is a cold disinfectant.
• Commercially available cans are 10% and they need to be diluted to the above concentration.
• There is formation of free chlorine that is a strong oxidant. It cleans and eliminates cellular debris.
• The advantages are that it is cheap, effective and safe.
• Residual testing for sodium hypochlorite is done with chlorine reagent test strips with a limit of 0.5 parts per million (ppm). It is a very sensitive method. Sodium hypochlorite in minute amounts greater than 1:25,000 produces hemolysis.
• Failure to perform residual testing will result in acute hemolysis or slow hemolysis that may go undetected.
• Sodium hypochlorite (bleach), diluted to 0.6% or less, dissolves proteinaceous deposits that may occlude fibers. Bleach increases albumin losses in high-flux cellulose triacetate (CT 190) and polysulfone.
• Polyvinylpyrrolidone dialyzers Albumin losses are generally not clinically significant unless bleach is used on high-flux membranes with exceptionally high water permeability.

b) Hydrogen Peroxide

• Used as a cleaning agent.
• 1% or less concentration.
• It does not remove protein deposits.
• RO water should be used for dilution.
• Must be stored in airtight container as it is unstable.
• This is instilled in the dialysate compartment of the dialyzer rather than the blood compartment.
• Though hydrogen peroxide has been shown to have a lower potency than hypochlorite, 2 Indian studies showed good results after reuse with this agent.
• Test strips detect peroxide residues with limit of 0.5mg/l.
• Range: 0-0.5-2.5-5-10-25mg/l H₂O₂.
• Colour change: white > blue.
• Residues should be NIL.

c) Formaldehyde (4%)

• It is the most common disinfectant used for fluid delivery systems.
• Formaldehyde has no cleaning properties. Formaldehyde denatures protein and fixes most cellular debris.
• Formaldehyde is a cold sterilant that effectively kills all microorganisms, including spores and resistant viruses but with risk of serious septicemia, if inadequate formaldehyde concentrations are being used.
• Commercially available as 40%, this can be diluted with the water used for reprocessing to give a final strength of 4%. Concentrations lower than 4% formaldehyde do not adequately kill Mycobacterium chelonae in water
• It is an inexpensive and stable solution with a long shelf-life. Formaldehyde is a gas that is dissolved in water to form the compound formalin.
• The formaldehyde gas is irritating to the eyes and has an offensive odour. Gloves must always be worn when handling formaldehyde to prevent dermatitis and allergic sensitivities. The room must be well ventilated. Any splashing must be minimized. A face shield gives total protection to the face. Minimally, eye protection (goggles) must be worn when handling formaldehyde.
• Sensitive residual testing is now available with limit of 1.0 ppm. The same principles apply as described for peracetic acid. In the past, safety tests for formaldehyde used Schiff’s reagent. Schiff’s reagent will test to 5 ppm. The newer indicator test strips are more sensitive.

d) Glutaraldehyde (2%)

• This has to be freshly prepared and activated.
• The chemical potency of the solution may be tested with Schiff’s reagent which 
produces a magenta colour similar to that seen with formaldehyde.
• Glutaraldehyde should be used for preserving the end caps, universal connectors, O-rings, and dialyzer caps when not in use.
• The solution should be replaced at intervals of not less than 10 days.
• Small containers containing glutaraldehyde should be available both at the dialysis 
stations and at the reprocessing areas.

e) Peracetic Acid (Renalin/Hemoclean, etc.)

Hemoclean/Renalin

• A mixture of peracetic acid, hydrogen peroxide, & acetic acid
  • PERACETIC ACID: Disinfection during short term.
  • HYDROGEN PEROXIDE: Disinfection during long terms, Isolate protein pollutants.
  • ACETIC ACID: Cleaning effect (Remove inorganic pollutants)
• Strong bactericidal, sporicidal, fungicidal, & virucidal.
• It is probably the cold sterilant of choice for fluid delivery systems. Unlike formaldehyde, this mixture leaves no toxic residues. It decomposes into oxygen and acetic acid after reacting with organic material.
• The mixture is a strong oxidant that readily cleans all cellular debris, precipitates, and scale in the machines when used routinely.
• Minimum concentration 1%. It can be used as cleaning agent & sterilant. The undiluted solution should be diluted to prepare 2 solutions of the following:
  • 2% (200 ml in 10 liters of water) as a cleaning agent and
  • 3.5% (350 ml in 10 liters of water) as a disinfectant
• Minimum dwell time 11 hours.
• Stable for 1 week.
• Avoid direct sunlight exposure of solution.
• The odour is pungent.
• Test strips are available to check for the presence or absence of the peracetic acid mixture. Indicator test strips ensure the adequate presence of this cold sterilant in the machines and residual test strips test confirms absence.
• Range of indicator test strips: 0-500-1000-1500-2000 mg/l peracetic acid.
• Colour change: bright yellow > red.
• If the sterilant inside the dialyser shows less than 500 PPM it should not be used ideally as it suggests there is inadequate strilent effect. Now some other Countries specially Japan has increased this limit to 800 PPM.
• Once the confirmation is done that the potency is more than 500 or 800 PPM then prime the dialyser with NS.
• After the peracetic acid mixture is rinsed from the machine, residual test strips test for the absence of the peracetic acid mixture. The dialyzer should be primed with at least 2000 ml of 0.9% normal saline using the dialysis machine blood pump at a speed of 150 ml/ min. The dialysate lines should be connected and the dialysate compartment filled with dialysate flowing at 500 ml/ min prior to starting the priming procedure. Failure to “dialyze” the disinfectant out may result in inadequate removal and reactions after starting dialysis.
• After 2000 ml of saline priming, effluent from the venous line should be checked for the presence of residual disinfectant.
• The residual testing is very sensitive with limit <1 ppm.
• Because the peracetic acid mixture is a strong oxidant, its handling requires careful attention to avoid chemical burns. Gloves and face protection are mandatory. Accidental contact exposure to this chemical requires water flushes and medical attention similar to formaldehyde.

REPROCESSING OF TUBINGS 


• No literature supports the reuse of blood tubings, however, they are reused in most units.
• The tubings are washed free of blood by treated water of AAMI or EU standard, and then with a 1.6% solution of sodium hypochlorite.
• The arterial and venous bubble chambers are gently tapped to release clots, and the side tubings are all cleared by clamping the outlets to dislodge any adherent material.
• The tubings are again rinsed with water and then connected to a supply of 4% formaldehyde, which is allowed to completely displace water and air from the tubings.

TESTS OF PERFORMANCE

• No objective tests of performance are available for blood tubings.
• The tubings are discarded if the normal elasticity appears to be lost, if there are visible cracks, if there is a change from the normal transparent appearance, or damage to any of the hubs.
• A test that is sometimes useful is to compare the elasticity of the pump segment with that of new tubing on a blood pump.
• Failure to give 90% of the flow obtained with a new tubing segment or “slipping” of the tubing or a “slapping sound” from the rollers may indicate a malfunction of the pump segment of the tubing and require it to be discarded.

Source: Indian Haemodialysis guidelines, TEXTBOOK OF DIALYSIS THERAPY

Article Courtesy – Dr. Jigar Shrimali

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