Mixing study for EDTA samples on hematology analyzer?

[silverblood]

Our laboratory has purchased a new Coulter hematology analyzer-I've been told that we need to do a 'mixing study' to evaluate how long the EDTA samples shopuld be mixed before placing on the instrument. Does anyone know of a procadure for this or where to find this?

[SMILLER]

I have never heard anything about a requirement to do a "mixing study" for an automated hematology analyzer.

All but the smallest analyzers have a built-in mixer if I am not mistaken. I would think that Coulter could vouch for it's effectiveness.

Even when we use the open mode (on our LH780 or LH500) we only spend a few seconds mixing by inversion and rolling. Specimens waiting to be put on the analyzer we keep on a rocker.

[Bill]

The instrument manual should contain all this information for closed mode and open mode sampling. It should be in section about specimen requirement and preperation. Who told you that "mixing studies" are necessary?

[cthherbal ☆]

The instrument manual should contain all this information for closed mode and open mode sampling. It should be in section about specimen requirement and preperation. Who told you that "mixing studies" are necessary?

There is a section in the manual that comes with the instrument. I believe it's a CAP requirement. You are essentially showing that whether the specimen is auto mixed by instrument, rocker mixed, or hand-mixed, the results are the same (statistically).

[daviem]

in Coulter literature it does state samples/controls should be mixed at least 20 times before analysis. As far as i am aware the LH750 belt mixes 12-16 times. If you have to do a mixing study approach it using time as a guide, e.g. mixed for 1 min, 2min up to 10 mins to see if there is any difference in the results. Can i ask what analyser it is?

[Gnapplec]

This is interesting these "mixing studies". I have always wondered about this when we switched to Sysmex and we were required to get RID of our mechanical tube rocker.

[Lah66]

We have Coulters as well at our facility. Ask your rep for their mixing study procedure...it is nicely written on Beckman Coulter letterhead. Annually, we let a sample sit for 24 hours, load it into a rack without mixing the tube. It mixes only on the belt before being sampled. Next, rock the tube for 15 minutes and run it again. Compare results...we use the same criteria as our correlation studies to decide if the mixing study has passed....i thin wbc must be within 0.5, rbc within 0.10, hgb within 0.3 etc. This mixing study is required annually by CAP. Hope that helps...

[cryan]

he device that i am familiar of has a built in mixer so i am not quite ure of what you are using here. i used an automated mixer and this has always worked for our lab although i think that this kind of details should be asked to the manufacturer of your machine just to be sure you will be following the prescribed procedure

[Lah66]

It is a CAP requirement that you prove your method of mixing tubes is capable of completely mixing the tubes before testing. In our case, the only rocker we use is the built in belt of the Coulter. If you use an automated mixer, you need to test that as well. I know the instrument manufacturer must prove that their instrument is capable of complete mixing before the instrument is FDA approved, but you must prove this annually, if you are CAP licensed...not sure about JCAHO.

[Andie Tech50]

Please download the Hematology Performance Verification Manual from the Beckman Coulter Website for the instructions.