Hospital wanting to make switch from glass tubes to plastic for serologic testing

[bhwlab]

Our hospital is wanting our blood bank to switch to plastic 12 x 75 tubes for our serologic testing. Our blood bank supervisor does not want us to. We know the AABB technical manual states the fluid has to cut across the cell button and that reaction has to be observed. The plastic tubes we have are cloudy in appearance, and we know they can't be used. What we are looking for is how do we prove to the hospital committee we can NOT use those plastic tubes? Where in the technical manual/standards/any other source can we show them this is not possible? Also, what could be an alternative to the glass? Thank you all for your help!

[RR1]

You would need to formally validate the plastic tubes against your current glass ones. Write a matrix with all the tests you currently perform together with the criteria you are looking for in each test ( ease of dislodging cell button, ease of visually reading the reaction, differences in titres of weak antibodies, etc) and compare this same criteria for the different tubes.

If the plastic tubes show reduced performance then you also possibly need to write a risk assessment of what could happen if you are made to switch these tubes. Though I suspect the validation may be quite clear in showing these risks.

[Malcolm Needs ☆]

This is getting a bit worrying, but I agree with Rashmi again.

It is well known, by the way, that protein adheres to plastic, and what are antibodies??????????? Oh, protein.

I presume this move is on the grounds of health and safety. I have seen far worse cuts from broken jagged plastic tubes than I ever have from sharp broken glass tubes.

Should we also replace paper? Paper cuts are very painful.

[Mabel Adams]

Static electricity with plastic tubes can alter how drops are dispensed. I used to try to wear some of the early vinyl gloves and the drop would jump half-formed (and thus not a full drop) from the pipet tip to the tube even using glass tubes. I would hate to try that with plastic tubes--especially in a dry climate. Validate in the dryness of winter with the most "staticy" person in your lab and these tubes will probably fail. And of course, you must be able to see even very weak reactions so the the tubes must be clear!

If any staff wear glasses, claim that ADA accomodations requires the glass tubes so they can see reactions. With an aging workforce and the prevalence of cataracts this might not even be too crazy.

Best yet, switch to gel or some other technology or put your safety person to worrying about how sloppy patient ID on the wards is risking killing patients. I don't think the big report to congress (To Err is Human) in '99 mentioned anything about the dangers of glass cuts, but it surely warned about patient ID errors.

[John C. Staley]

About a 1,000,000 years ago we used a typing sysem called MLA which utilized clear plastic tubes, special cetrifuges etc. Our biggest problem with the systen was, as Mable explained, static electricty. It was virtually impossible to control the drop size or the direction of the fall of the drop. We went as far as to ground the work stations and the mats our chairs were on. That helped a little but the best thing was when the company quit producing the system and we had to move to something els.

[Malcolm Needs ☆]

About a 1,000,000 years ago we used a typing sysem called MLA which utilized clear plastic tubes, special cetrifuges etc. Our biggest problem with the systen was, as Mable explained, static electricty. It was virtually impossible to control the drop size or the direction of the fall of the drop. We went as far as to ground the work stations and the mats our chairs were on. That helped a little but the best thing was when the company quit producing the system and we had to move to something els.

If we don't learn from history, we are doomed to repeat it.

[kate murphy]

I also have experience with the MLA system...ages ago. (I guess I am becoming a dinosaur!)

Static electricity can be controlled by wiping the tube tops with a saline moistened gauze. I live in Boston, and the winters are very dry and static-y. Sometimes the drops would jump right out of the tubes! But wiping your tubes in the rack just before you dispense drops adds enough humidity that we had no problems.

As for validating, yes go through the process. The MLA tubes were clear plastic and all tests ran fine. So you may be surprised to find no difference.

I suspect this may be a cost containmant issue. Plastic tubes may be cheaper to buy and dispose of.

[Malcolm Needs ☆]

Blow me Kate. If you're beginning to fell like a dinosaur, spare a thought for us blue/green algae!!!!!!!!!!!

[MARINA]

We switched to plastic a few years ago. It was a decision made by administration to cut cost on sharps disposal. We were resistant, but it worked out ok, since we primarily use a Galileo now and just use tubes for more specific testing, etc. We have had no significant issues with panels, etc. However, ee do keep glass tubes in stck for fetal screens checks under the microscope, plastic tubes do not work at all for this.

[tbostock]

If they insist that you try them, try to get the newer type of plastic that is made of polystyrene, that is much clearer than the old type of plastic tubes. Westcott Labs sells them:

http://www.wescottlabs.com/genlab/consumables/glc-ptt.php

Disclaimer...don't work for Westcott, etc, etc, just happen to know that they sell them.

[Eoin]

Are they trying to save a few cents?

I agree with Malcolm, protein adheres to plastic, harder to see through, static electricity - stick to your soda-glass tubes.

Tell them to sack a few executives if they want to save money, not endanger testing that impacts directly on patient safety.

Cheers

[Malcolm Needs ☆]

Now that idea I could live with!

[adiescast]

Amen!

[Joanne P. Scannell]

Please stop listening to 'hearsay' and 'old adage' and learn about the different types of plastic tubes and method of manufacturing (extruded vs molded) ... yes, Wescott Labs will explain it all to you. We've been using the polystyrene 12x75mm plastic tubes very successfully for a few years now ... for EVERYTHING done in tubes.

[Malcolm Needs ☆]

Please stop listening to 'hearsay' and 'old adage' and learn about the different types of plastic tubes and method of manufacturing (extruded vs molded) ... yes, Wescott Labs will explain it all to you. We've been using the polystyrene 12x75mm plastic tubes very successfully for a few years now ... for EVERYTHING done in tubes.

But does this mean that protein no longer adsorbs to the surface of these newer plastics?

Don't know; just asking.

:confused:

[RR1]

I think the best test is to compare agglutination strengths of weak antibodies. I am sure the various suppliers would give you free samples to try out.

Look forward to your validation results.

I must admit that I don't take that much notice these days of what manufacturers say about their products, just need evidence from my own testing.

Edited December 8, 2009 by RR1

[TimOz]

Hi,

I am a bit old fashioned and would not convert to glass, especially for IAT testing. It is important that the tube used allows the cell button to stick - but not too much. If I had to change, I suggest you be aware of the following issues:

1. Static. This can vary from manufacturers, plastic type, places (humidity, temperature and wind). It can also vary between batches of tubes, so be aware of this. The main issue with static in my experience is volumes. The static charge on the plastic attractes drops and gives very significant variation in drop size. I did an experiment on a dry windy day (when I was very bored) and found that the drop size varied by around 40% depending on the shoes I wore. Leather shoes were fine but rubber soled shoes made the static worse due to the insulation. You simply do not see this effect with glass.

2. Safety. Some types of clear plastic can break with very sharp shards and can cut worse than borosilicate glass. Teh tubes mentioned above from Wescott seem not to have this problem.

3. Optics. Tubes must be clear in my opinion to be able to be read. Translucent is not usable. It is also important that the plastic moulding leaves the inner surface of the tube smooth and concave. I have seen plastic tubes with plastic "flashing" that makes it very hard to get a proper button. I have also seen glass tubes with glass blods that look like the bottom of a cola bottle. You spin the tubes and get a cell donut instead of a button. Hopeless.

So if you need to change you should validate the change but look carefully at the issues above and check a few batches of plastic tubes on a few days with varied weather (maybe with different shoes on (only joking)). Check for "stiction" of the cell button with both grouping, high protein phenotyping reagents and most impostantly IAT testing. I strongly recommend making a panel of weak and varying DAT positive cells and comparing the DAT scores and ease of reading and "tip and rolling" between the glass and plastic tubes.

I hope that is helpful.

Finally - here is a question. Why do borosilicate glass tubes always bounce once and only once? Drop them on a hard floor and they will bounce up and then shatter when they hit the second time.

I think it is the pyrex heat treatment.

[BB1956]

I was very interested in the use of plastic tubes. It has been an issue in our hospital for years. We have held out and are the only ones currently using glass tubes. I would be interested in exploring the possiblilities of plastic. We are currently using manual gel but still perform all difficult testing in tubes. Did you have a validation plan to share?

[TimOz]

In short - NO. We have not changed and will not. I think plastic is far inferior to glass for tube IAT. My post above is just relating my experiences in looking into the issues to generate an informed opinion.

At the risk of being controversal, I think converting to glass is Health and Safety trying to fix a problem that does not exist and lowering the quality of the test in the process.

[Malcolm Needs ☆]

In short - NO. We have not changed and will not. I think plastic is far inferior to glass for tube IAT. My post above is just relating my experiences in looking into the issues to generate an informed opinion.

At the risk of being controversal, I think converting to glass is Health and Safety trying to fix a problem that does not exist and lowering the quality of the test in the process.

Hear, hear!

I've seen much worse (jagged and straight) cuts caused by plastic and I agree entirely that the sensitivity of the tests performed in plastic is far inferior.

:mad::mad::mad::mad::mad:

[rravkin@aol.com]

There's nothing better than working with glass tubes hands down! Plastic tubes should never be used. Let the hospital administrators and the BB management look at other ways of cutting cost. Going to plastic just invites the posibility of mistakes and law suites!

[Eagle Eye]

I think the best test is to compare agglutination strengths of weak antibodies. I am sure the various suppliers would give you free samples to try out.

Look forward to your validation results.

I must admit that I don't take that much notice these days of what manufacturers say about their products, just need evidence from my own testing.

I am on the same boat. Anytime we have new euipment/reagent we do our own validation to see if mauf. claims are supported. If they are not supported we revise our policy accordingly. eg. if mauf. says 200 mL plasma will thaw in 10 mins but our validation shows, 15 mins we use 15 mins.(these are not accurate #s just example).

[TimOz]

Not that I want to disagree with Rashmi but to add to her comments about validation.

Please make sure that you do not go into this with the thought that a validation process is just testing and documenting the test performance. You should (especially in this case) make sure that you are testing the actual performance and ensuring that it is acceptable!!! You need to establish what is acceptable performance before testing and make sure you test appropriately - see my comments on plastic tube variability as an example of what should be covered.

If I tried to validate plasrtic tubes for IAT testing in my lab they would simply fail and not be usable.

[RR1]

Thanks Tim, I should have explained that in a better way. As you have said it is crucial that you pre-define your acceptance criteria ( and possibly rejection criteria?) before the testing begins, this also helps you to focus the testing and not deviate from the plan (unless you really need to- but this would also be documented).