We are doing our annual competencies and this month's competency is on DATs. The question that has come up is whether or not a cell washer's finals wash and spin constitutes a dry cell button or if you still have to blot the tube. Most of the techs (and I am one) just take the tubes out and use them as is. What do any of you do?

I am a blotter now. I used to take that final spin decantation as good enough until I missed a weakly positive DAT (C3d) on a CAP survey a few years ago ;-)

BC

We don't blot and haven't failed any surveys.

I'm with Mabel. Our cell washer produces a dry enough button.

I find the amount of saline remaining in my Sorvalls after the last wash rather disturbing. I tried calibrating a harder and longer spin, but that didn't make any noticeable difference. This isn't a big issue since we do most of our testing (DAT's included) in gel. Whenever a cell washer goes in for maintenance it isn't even missed.

BC

Non-blotter, no prob. on CAP or in-house comp.

On our Dade DAC II the saline residual can actually be set. Otherwise I am not overly fond of the instrument.

The first automated cell washer I ever used was the Dac II. The one thing I don't like about the Sorvalls is the pinch valve to adjust the saline.

BC

We do not blot our DAT's. We have not had any issues. I preferred the DAC II to the Sorvall's we have now. Just a personal preference. I agree - the pinch valves are a pain.

We have Sorval Cell Washers, do not blot and have not had any problems with CAP proficiencies or internal proficiencies.

I am wishing I had kept the nifty device from our old Sorval tubing that I used instead of the pinch valve. It was a barrel shaped thing that you twisted to increase or decrease saline volume. It was standard on Sorval cellwashers 25+ years ago, I think. I should go dig around in storage for it now that I know it is valuable.

That's what we use, Mabel, but it is still basically a pinch valve- just a rotary pinch valve. I have never figured it out. One time I can twist the valve 4 or 5 rotations and only change the amount of saline dispensed by 1 or 2 mL, the next time all I have to do is thump it and it increases the output 10 mL. One time rotating it clockwise might increase the output, the next time clockwise decreases the output. Makes you want to go back to handwashing with a rubber band to hold the tubes in the rotor.

BC