This week our outpt dialysis unit closed because chloramine levels were too high. Another source has since informed me that the levels have been high for some time. I have been working dialysis for two years and this makes the second time they have closed their doors due to a gas leak and now this as I have mentioned. My concern lies with the patients, myself and my unborn baby. Does anyone understand how and what tests the unit performs to determine high chloramines? I need a response asap. Thank you.
Acceptable limits for chloramines per AAMI are 0.1 mg / liter. Elevated levels that are allowed to be utilized in dialysate can cause hemolytic anemia. Chloramine is a chemical frequently added to municipal water supplies to control bacterial contamination.
Ion exchange resins remove all charged ions from the water supply and should be used in conjunction with activated charcoal to remove nonionic contaminants shuch as chlormaine. In dialysis facilities, it becomes most economically efficient to purify the water first by reverse osmosis followed by use of ion exchange resins and charcoal.
What does this really mean? Chloramines are oxidizing agents, and uremic erythrocytes (the red blood cell of the ESRD patient) are unusually susceptible to oxidative injury. When the red blood cell of an ESRD patient is exposed to chloramine, the hemoglobin in the red blood cell oxidizes and clumps to form microscopically visible structures called Heinz bodies. This is the hemolysis or hemolytic anemia that is referred to above.
The water supply at any dialysis facility should be tested periodically for the presence of contaminants. The elimination of copper tubing, the use of carbon filters, and the use of a reverse osmosis or deionization system for preparing water for dialysis greatly reduce the incidence of hemolytic anemia.
If your facility closed because it recognized that it had chloramine break through, that would indicate that they were checking the water system on a frequent, regular basis, detected the problem, and while attempting to resolve it, diverted the patients for their safety. I think they should be commended for their follow through and appropriate treatment.
Most clinics maintain a log of chlorine / chloramine checks, which are done before the first shift and then periodically throughout the day. Additionally, most clinics require a second signature for verification of the safety of the water for use.
In most cases, the risk presented with the chloramine contamination would be slim to you. However, I would advise you to check with your primary care physician regarding your health, and the health of your unborn baby.
I don't feel that I can speak to the gas leak you mentioned above simply since I do not know what type of gas, the circumstances, or other details.
Please let us know how things turn out in your facility.
"In dialysis facilities, it becomes most economically efficient to purify the water first by reverse osmosis followed by use of ion exchange resins and charcoal."
This statement is incorrect, for 2 reasons:
Today in the vast majority of systems using reverse osmosis, the membranes used are of the "Thin Film Composite" variety which are not chlorine tolerant. Therefore it is necessary to remove the chlorine / chloramines prior to the R.O.
The exception is if cellulose acetate membranes are being used, which have a high chlorine tolerance but also are susceptable to bacterial degrading. In this case chlorine is desired in the feed water and carbon filtration can be post R.O. However charcoal or carbon beds provide an excellant environment for bacteria to proliferate. Since R.O will reject up to 99% of microbiological contaminants, it is best to place the carbons pre-R.O.
The original poster stated that the unit was closed due to high chloramine levels.
Chloramine is a compound of free chlorine and ammonia and is used as a bacteriostatic agent in drinking water and is commonly found in municipal supply (tap) water.
Chloramine may also be referred to as Combined Chlorine.
Acceptable levels for water used in dialysis are:
Free Chlorine = <0.5 ppm or mg/L
Chloramine = <0.1 ppm or mg/L
Removal of chlorine / chloramines in dialysis is generally done by passing the water through a carbon bed. Carbon removes chlorine , chloramine and other organic contaminants by adsorption.
The efficiency of this removal is based on empty bed contact time, (EBCT), a formula which uses flow rate or volume of water to be processed and the cubic feet of carbon media to determine the amount of time which the water is in contact with the carbon.
For chloramine removal EBCT should be 10 minutes.
To calculate volume of carbon needed at a given EBCT, V = (Q x EBCT)/7.48
V = volume of carbon in cubic ft
Q = water flow rate in gal/min (gpm)
EBCT - desired contact time
7.48 = number to covert gal/min to cubic ft
For 10 gpm flow rate and 10 minute contact time:
V = (10 x 10)/7.48 or 100/7.48 = 13.36 cu ft
of carbon needed.
The standrad EBCT in dialysis is 6 minutes for free chlorine and 10 minutes for chloramines.
Also 2 carbon beds should be utilized in a worker/ polisher configuration where the first tank removes all chlorine / chloramine under normal operating conditions with the 2nd tank serving as a back-up in the event of a breakthrouigh of the first tank.
Carbon beds can be either permanent backwashable or exchange type. Backwashable carbon tanks have a controller that automatically cycles the tank in a backwash / flush mode at set intervals. Exchange tanks are usually supplied by a vendor and replaced on a fixed schedule.
Reasons for elevated chlorine / chloramine levels or breakthrough are:
1) EBCT is not sufficient for the volume of
water being used. If a direct feed R.O. system is used (no storage tank), normal
increases in flow rates can occur when
certain processes are being peformed in
addition to dialysis such as reuse, bicarb preparation or rinsing of bicarb mixers and containers. EBCT should be calculated on peak flow rates, which take into account the highest volume of water used at any given point in time.
2) Elevated ph, adsorption of chlorine is
affected by ph, the higher the ph, the
slower the adsorption rates. the ph of municipal water is generally stable
however, transitory elevations in the ph
can occur. Further due to EPA requirements for the reduction of lead in municipal water, some suppliers have raised the normal ph from around neutral (7.0) to above 8.0. This increase combined with marginal EBCT could allow periodic breakthrough of chloramine.
3) Significant increase in chlorine /
chloramine levels in supply water. In municipal water Total Chlorine levels are generally at or below .5 ppm.
4) Carbon beds are approaching exhaustion.
Carbon has a finite life as adsorption is process where the chlorine molecules attach to the surface of the carbon grains. Breakthrough occurs when the available surface area is insufficient for the volume water processed.
5) Improper backwashing of carbon beds. As water flows through a carbon bed the bed compacts and channels develop through the bed. Since the resistence to the flow is less through these channels, more water flows through the channels decreasing the contact with usable carbon. Backwashing is a process where the water flow is reversed through carbon bed to break up the channels to re-settle the bed and to flush out particulates and other debris trapped in the bed. Carbon beds should be backwashed at least once per week.
Exchange carbons are usually non-backwashable and should be exchanged at least on a quarterly basis.
Chlorine and chloramine is most commonly tested by using a DPD reagent. The reagents can detect Free Chlorine and Total Chlorine, but does not detect chloramine. The chloramine level is determined by subtracting
the Free Chlorine value from the Total Chlorine value.
Chloramine = Total Chlorine - Free Chlorine
Samples for testing should be taken from a sample port located between the first and second carbon bed. If the result is greater than the standard than samples should be taken from a port located after the second tank to determine if chlorine / chloramine is breaking thorugh that tank. If levels found after the second tank exceed the standard dialysis should not occur.
If this is a routine problem it indicates more likely that the carbon beds are insufficient.
Without knowing the specific design of your water system and the chlorine / chloramine levels in the water it is difficult to pinpoint the exact cause of your problem.
[This message has been edited by Dennis Todaro (edited 10-12-2000).]
Thank you for your correction to my post, and for your more thorough explanation to the questions raised.
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