When disinfecting a machine with bleach, at what level (ppm) is it considered positive for bleach, 100 ppm, 200 ppm etc.?

I think this is addressed in the AAMI guidelines but I can't seem to find it.

Chuck

Chuck, I believe 5ppm is sufficient. Our test strips don't even go higher than that level. If memory serves me right (which it often doesn't) 5ppm of aqueous bleach is approximately a 5% solution and anything over a 1% solution is usually adequate for killing microorganisms.

I'm sorry, but I couldn't find any written on this subject either.

1% is the minimum requirement..it is about 500 ppm

Laundry bleach used to be a 5.25% solution of sodium hypochlorite. Now it is usually what was first called “ultra” and is 6%. 6% is the same as 60,000 ppm. So if you dilute the bleach 100 to 1 with water you will get a 600 ppm strength. Super, hyper or shock chlorination is usually considered to be above 100 ppm. A little bleach goes a long way.

Chuck, the only thing AAMI is going to say is follow the manufacturer's guidelines. Disinfection is based on concentration and time. 600 ppm bleach for 10 minutes will disinfect a system. Also, 2400 ppm for 2 minutes. The higher the concentration, the shorter the contact time.

I recommend verifying a positive chlorine level in the machine. You need to use a test strip that can verify >500 ppm chlorine. Using a test strip that only measures a few ppm is not adequate.

I agree with florian regarding testing the strength of the bleach concentration. The only strips I am aware of test for residual bleach, and 5 ppm is that upper limit for residual bleach. I've checked with test sstrip manufacturers and no one has a test strip that is certified for medical applications. The aalternative is to use a test strip certified for "industrial" applications. I don't know where this leaves you in regard to AAMI regs, etc.

If disinfecting the external components of the dialysis machines including clamps and chairs, 1:100 (300-600mg/dl) is noted in the CDC recommendation page 15 [Centers for Disease Control and Prevention. Recommendations for preventing transmission of infections among chronic hemodialysis patients. MMWR 2001;50(No. RR-5):[inclusive page numbers]]

For the internal pathway of the dialysis machines, 5.25% to 6% bleach diluted by the machines proportioning system (44:1, 34:1 etc.) produces the concentration required to disinfect the proportioning and monitoring system of the machines. Do not forget to rinse after disinfecting with bleach!

jomoya
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