Interpretation of sampling standards

[Ian Wilde]

Just wondering how people interpret the following:

4. Operation and maintenance of water treatment systems for haemodialysis 

Guideline 4.1 – Routine maintenance and monitoring
 
Guideline 4.3.2 – Frequency of monitoring
The frequency of monitoring is generally recommended by the equipment manufacturer or by local operating procedures. We recommend that the minimum frequency of monitoring of water for dialysis should be as follows (1D): Contaminant Frequency of testing
Total chlorine At least weekly
Total viable counts At least monthly
Endotoxin At least monthly
Chemical contaminants other than chlorine At least every 3 months

Frequency of monitoring of microbial contaminants and endotoxin
Total viable counts and endotoxin levels should be monitored at least monthly. A monitoring scheme should be drawn up which defines the points at which the sampling is performed. The sampling plan is dependent on whether a dead space free secondary loop is used to connect the dialysis machines to the ring main. If such a connection is used, then only one sample needs to be taken at the end of the loop.


Now, noted in BS EN ISO 23500:2015 it states there is no requirement to test for bacterial growth or endotoxins when the haemodialysis system is fitted with endotoxin retentive filters that are operated according to the manufacturer’s instructions, unless the manufacturer requires such tests to be performed.

So if you are using Diasafes or Ultrafilters, ultrasafes etc... does that contradict the need for the sampling as per guideline 4.3.2?

If not does it still need to be monthly?  Are we spending more than we need to on sampling?

[Garry]

Possibly me looking in the wrong paragraph but I notice the statement you refer to in BS EN ISO 23500 is within the section for requirements for dialysis fluid.  I interpreted this as sampling of the dialysis machine that we do annually for those not fitted with clean dialysate/HDF filters.

I interpret the recommended monthly sampling for microbiology to apply to the water treatment plant and ring main.  In our instance if the water treatment plant does not have an ultrafilter we test RO units and ring monthly.  For those with an ultrafilter we check the ring monthly but have reduced RO checking to 3 monthly to save a bit on costs

[Ian Wilde]

I would be inclined to agree with you there Garry.  
If your feed water to your machines is <100cfu/<0.25endo then with endotoxin filters fitted there is no need to further test any fluids from the machines.
In a nutshell, we can't escape sampling the ROs and rings no matter what we have in place.