Failed water results

[Ian Wilde]

You know what I always find a bit puzzling, that a water sample result (usually a home patient) may just fall outside of limits and the patient is dragged back into hospital for dialysis.

Yet, they were dialysing on that water for up to 2 weeks while the sample was processed with no adverse or pyrogenic reactions.  And sometimes, you can almost be certain it is a sampling/handling error.

With machines fitted with endotoxin retentive filters, I feel there almost has to be some kind of compromise in triaging what to do following a 'failure'.

I say that, having put raw water through a machine and then sampled the quality at the hansen connectors and measured zero TVC and zero Endotoxin.

[Gareth Murcutt]

Hi Ian,

I wholeheartedly agree. When we started our HDF program back in early 2000's we did lots and lots of testing of HDF fluid. We took 100ml samples so to get <0.1 cfu/ml allowed below 10 cfu in total. However, the idea that 9 is a pass and 11 is fail is to misunderstand microbiology. Thus we used a Pass/Conditional Fail (Retest)/Fail system. There are also risks to withdrawing a machine from the program and affecting someone's treatment.

I've said it before and will repeat again. We cannot eliminate risks... we have to balance them. If the result indicates pre-biotic soup running through dialyser then fair enough but a marginal fail (Conditional Fail) shouldn't always mean the patient has to revert to unit dialysis. The serious inconvenience and risks of non-attendance need to be balanced against a program of enhanced disinfection of RO, connecting tubing and machine followed by retest. Our units are running at 98% capacity so there are also knock on effects and risks to the service. In the end we are attempting to take sterile samples in someone's bedroom!

The above comments are about micro failures. Chemical failures are, in my view, much more serious and pose a genuine risk to patient health.
G