Settings of centrifuge to separate blood samples

[eric1980]

In my lab, we are currently using 3000rpm for 10mins to spin down specimens to separate serum from the cells.

I have been trying to shorten the length of centrifugation by increasing the speed but was immediately dismissed and rebuffed by my seniors.

When I pursue this by questioning them why we must insist on sticking to this setting, they claimed that this setting is stated in the AABB Technical Manual. I did not search the TM to find out if this is true, as I strongly believe that "rpm" is not a standard, and that we are simply separating the specimen and it will take an ultracentrifuge to cause haemolysis due to too high a G-force.

My new section leader then asked me to find out the standard setting to separate the specimens, which I chose not to do so.

My question isn't related to any BB technical knowledge, but I would like to ask you fellas here, what else could I do to persuade them to shorten the separation time?

Please advice...

(Whenever I'm doing night shifts, I changed the settings to 2.5rcf for 2mins. It worked fine as it is, and sped things up instead.)

[Likewine99]

We are gel users so our goal is "platelet poor plasma". Our old centrifuge died about 6 months ago, we have 2 StatSpins that spin 3000rpm for 3 min, they are wonderful. WIth the old one we did 3000 rpm for only 5 min.

We uses these samples at the manual bench and on the ProVue, not a problem.

You could spin some specs at different times and see at what point you get to plt poor, i.e. <10,000 plts when run on the Hematology analyzers.

You could track turn around times for T&S from receipt in lab to final answer, tie it to a delay in getting blood out the door.

You could pray that that centrifuge dies and you have to replace it. Good luck, 10 minutes seems like an eternity to me now.

[Lcsmrz]

Spin times is a major factor in TAT. Ask anyone working in a Stat Lab!

Sample centrifugation is a function of the centrifuge model and the tube manufacturer. The former's manufacturer rarely specifies how to use their device, but the tubes come with a product insert that usually specifies the recommended settings ("at least" xxx times G at xx Mins) for separation. G has to be converted into your model's RPM for the installed rotor. I always verify the manufacturer's recommendation, and re-verify them preriodically if assay critical (like coag).

There are a few centrifuges that are specifically marketed for spinning clinical samples, and their manual talks about recommended settings by tube type (Gel tubes, plasma tubes, clot tubes, etc). You still should verify the settings for your brand of tubes.

I've found the greatest determinates in reducing spin times are using a swing-bucket rotor instead of a fixed angle one, and a high-speed motor (>5000 RPM).

[RR1]

All staff need to maintain the standard parameters set in their labs. If you go against these- you are in contravention of your SOPS. Your tests and processing have been validated against these settings.

As your seniors asked you to find out the standard setting- you need to do this.

A small project to compare the results of various times and speeds also needs to be performed, with an assessment of the advantages of making the changes you described.

Just remember this would need to go through a change control process through your BBM first. I know this all sounds like a load of nonsense, but unfortunately when folk start using different speeds, incubation times etc...it can be a nightmare for the bllod bank team to keep a control on all the processes in the department.

[Malcolm Needs ☆]

Hi eric 1980,

I agree with everything Rashmi says. It may well be that your modification of centrifuge speed and time is fine, but if you were working for me, and I found that you were altering the speed and time of centrifugation during the night shift without a) performing a fully documented Change Control and getting my permission (as Manager) you would be in grave danger of meeting with Human resources so fast that your feet wouldn't touch the floor.

If you are a scientist, you have got to be prepared to prove that any changes you wish to make will be at least as good, or better than what you want to change. If you are not prepared to do this before you choose to use your change on live patient samples, then you would thoroughly deserve the meeting with HR.

:mad:

[RR1]

eric1980, I know sometimes it's frustrating that seemingly simple changes can't just be made without going through a lot of paper-shuffling. There is logic to it all, and it all revolves around standardising the way we all work to maximise patient safety.

If you decide to change speeds, times for centrifugation .....somebody else will one day decide to change this for test incubation times and temperatures- resulting, ultimately in sub-optimal testing/ missed antibodies.

The best thing you could do is to understand the concepts of your Quality system- and champion this. Help your senior staff by obtaining the data they requested, and as part of the team, plan with them the changes you would like to introduce.

Prevents so much hassle if you do things properly....

[pluto]

Have to agree with Rashmi and Malcolm you can't just do your own thing in the miiddle of the night unseen , if everyone did their own tweaks to procedures we would have chaos and errors

I would suggest

1: reassess why you are separating the serum anyway , there is a risk transferring to a secondary sample container with ID misidentifcation

2. 10 mins does seem excessive for just separting serum but you will have to go through the change process !

I know chemistry spin for 10 mins but that is for "Gel " clotted samples to ensure gel forms correctly between cells and serum

3. I seem to recall Ortho Biovue giving recommendtions on spin speeds for samples as they were seeing weak reactions on RhD typing as cells were stuck together due to excessive centrifugation

[Malcolm Needs ☆]

Thanks for your comment pluto, which is much appreciated, but to be fair to eric 1980, I'm not sure that he is saying he actually takes the serum/plasma off the red cells, but only separates them by centrifugation; in other words, ensures that the serum/plasma is free of white cells and/or platelets prior to testing, but I am prepared to be rebutted.

[eric1980]

Thanks all for the replies! Now I've felt that I've been listened to. I've also learnt some important information from this thread. I should have posted here much sooner.

Lcsmrz: I didn't know I could find the recommended settings from the manufacturer of the blood tubes. I understand that centrifuge manufacturers could not state recommendations due to the possiblilities their centrifuges are used for. I will try to check out the recommended settings when I can!

Rashmi, Malcom Needs and Pluto: I really do understand the importance of standardisation and the reasons why there are SOPs in place. But in my personal (which, in Malcom Needs' words, I am prepared to be rebutted) opinion, using my lab's settings will only cause more stress to me when work is becoming overwhelming, increasing the chances of me making mistakes by clouding my judgement, which is critical in organisation of work and priortisation of processes. This is why I chose to use my own judgement to to change the setting to make sure that I could work my best.

Anyway, what frustrates me is that the SOP (centrifugation settings in this case) do not have any basis, as my seniors could only refer generally to the AABB TM but could not produce the information to me. What further proves to me that this setting is seriously flawed and have no basis is the fact that we changed both of our centrifuges a few months ago, we used exactly the same settings (3000rpm x 10mins) over to the new centrifuges which have a much shorter rotor!

As I said above, I did bring it up to my seniors but I ended up slamming myself against the wall. 10mins is really over the line. Therefore, I feel that the most important thing I should think about is how I should nail into my seniors the reasons why I think this setting is wrong, get them to listen to me, after which the process to find out what is the most suitable setting will come in place very easily. This is the reason of my first post, to seek advice on how to get my seniors to listen to me.

I think I will just send an email to my supervisor again.

I hope I will soon be asking for guidance on how to go about doing the small project to get the correct setting suitable for my lab.

[RR1]

eric1980, your lab must run a complaints/ incident sysytem, in which case you need to submit a form stating all the relevent points about time delays and the stressful conditions related to the sample processing, mention that this could be improved by performing a, b, c, etc...as corrective actions. This should be the official route for this sort of thing.

[eric1980]

Rashmi: We do have somewhat this system, which we must activate when an error has happened. It's a corrective system which after an error has happened, we must report how it happened, and how we make sure it will not happen again.

But for a work-improvement system like you said, we do not have exactly such. But if I need months of persuasion to get my supervisor to stop taking the temperature of a freezer, which contains nothing but ice packs, thrice daily, I think it will not be possible for me to ask to set up this system to my supervisor.

I have sent out the email 2 days ago. No replies yet. I will see my supervisor later at work. Wish me luck.

[RR1]

I do wish you luck eric. All blood bank managers have a responsibility to their staff, which includes listening to their concerns and having the coutesy to respond to them.

There must also be a system set within the lab where all staff should be able to formally input ideas- to help us continually improve our processes. May be one day eric, you could help develop this.

Best wishes

[LisaM]

Yes, I remembered my password, Malcolm--LOL

I'm bumping this thread because I have a question: we spin our BB samples at 3500rpm for 10 minutes. On occasion, we get a weakly positive antibody screens here and there, and I sign them out as such, along with any antibody ID, be it non-specific, negative panel--which has happened also. My thought is that you spin them once run your tests and it is what it is. Now here's the clincher: the day shift has taken to re-spinning samples showing weak positive antibody screens, either in the original tube or taking off the plasma and respinning that separately, rerun, and lo and behold, the screen is negative. They change the results in the computer to reflect their findings, then send out love notes in the computer, saying that we should be doing that too on the off shifts--respin, rerun.

So what does everyone think of that? I emailed AABB with that, and am waiting to hear back from them, but it seems to me like they're forcing it to come out negative in the name of conserving supplies/cost, which is their reasoning for doing that, to not waste antibody panel "needlessly". I don't know if you can "spin away" the antibodies, or if double/triple centrifugation even matters on a blood bank tube--I know it can affect chemistry analytes. Thoughts??

[LisaM]

Edit to my above post: I pulled the samples in question, and ran DAT's on them, because they'd sat in the refrigerator all night before the day shift respun/reran, and lo and behold, they had very weak microscopic positive DAT's. . . .could be something there that adsorbed out overnight, and that's why the day shift got negative screens on repeat. Sooo..... a topic for next week's BB meeting and we'll see what they say about that.

[Mabel Adams]

If you are using MTS gel, Ortho taught us to respin the specimens to prevent topline and other weak reactivity that is caused by bits of fibrin getting caught in the gel and trapping some red cells so it looks positive. I don't think you can centrifuge out antibodies at the G's we use to separate specimens. They are in solution, not suspension.

[Malcolm Needs ☆]

Agree with Mabel.

[tbostock]

We use Stat Spin centrifuges that spin in 3 minutes. We validated it and made sure there were no problems in gel testing. Also, Stat Spin will provide you with a validation study that was published about the 3 minute spin time at higher RPMs for Blood Bank specimens.

[webersl]

I agree with all the posters here who ask you to return to SOP until you have convinced your superiors and they have changed the SOP. Here is how I switched from a 10 minute spin to a 2 minute spin (I am a supervisor):

For each of 20 specimens (10 w a pos antibody screen, 10 with a negative antibody screen) I spun according to the SOP (10 min) and on a worksheet I commented as to the visual appearance, including clarity, hemolysis, and the sharpness of the interface between cells and plasma. Then I tested the specimens according to SOP and reported. Then, I completely resuspended the specimens on a tube rocker and respun them at the new setting (StatSpin3) for 2 min. After the spin I again recorded the visual apearance and then repeated all the testing and recorded the results on a worksheet (did not report). I then compared the apearance and results. There was no difference in any of the visuals or results, so I considered the new process to be valid. I wrote up the mini-study and sent it to my Medical Director for approval to change the SOP accordingly. Once approved, I began making the SOP changes. Then, staff read the new SOP, were trained on the new centrifuge settings, demonstrated competency. Then I announced to all staff that we would 'go live' with the new settings on a certain date. I realize your lab did not perform a comparison of any kind when they got their new centrifuge, but they should have. If you cannot find a way to convince them, I am sorry for you, but you MUST continue to follow SOP as written, or speak with your Medical Director (physician in charge of the lab) about your scientific concerns so that a proper change may occur. Best of luck.

[webersl]

I agree with all the posters here who ask you to return to SOP until you have convinced your superiors and they have changed the SOP. Here is how I switched from a 10 minute spin to a 2 minute spin (I am a supervisor):.

Darn. I always respond without realizing there is another page of comments to read. Sorry if this seemed out of place.

[Barbarakym]

If you are using MTS gel, Ortho taught us to respin the specimens to prevent topline and other weak reactivity that is caused by bits of fibrin getting caught in the gel and trapping some red cells so it looks positive. I don't think you can centrifuge out antibodies at the G's we use to separate specimens. They are in solution, not suspension.

We spin at 3600 for 15 minutes. We use gel. We have nearly elimnated garbage reactions. It is not just platelts that make a mess of gel but high protein and other serous stuff. We and one other local hospital made this change several yrs ago. A huge difference in artificial mf and junky gel reactions which some people over-read and others ignored (bad).

I am sure method has something to do with acceptability of specimen. We used stat spinners for tube only. But for gel this is what we went to. I DO spin superstat specimens less time but if there is a problem on ABID I go back, mix again and respin. At least I can give type specific blood Emergency Release if needed.

[LisaM]

Thanks for all the tips, everyone--I'll see what comes of this whole mess; our supervisor has threatened corrective action if anyone signs out a weak positive antibody screen without respinning and retesting. .. . .and I'm going to keep my opinion of that/her to myself.

[DFields]

I did not see it also mentioned to follow the tube manufacturer's instructions for use (IFU) for the centrifugation times/speeds--depending on which type of tube you are using.

[LisaM]

^^Thanks! I'll check the tube package insert tonight when I get to work, to see if it says anything.

[Brenda K Hutson]

Your seniors will likely be much more willing to listen to you if:

1. You treat them with the respect due to their position (which hopefully comes with the

knowledge and experience); and refusing to do what they have requested of you does not

fall into that category in my book (I would not be happy if I asked one of my staff to do

something and they simply refused on the grounds that I am wrong and they are going to

keep doing things their way)..... I can assure you that insubordination is not the way to a

Manager's heart. You may very well be correct that 10 mins. is inaccurate....but it doesn't

sound like you "know" the right answer either......and

2. You back up your disclaimer with evidence (i.e. look at the Manufacturer's Insert; do a

study; state your make and model of centrifuge and perhaps others could product the

evidence you are seeking; etc. etc.). You are upset that they are not proving their

case....but neither are you.

Just some suggestions...

Brenda Hutson, CLS(ASCP)SBB

Thanks all for the replies! Now I've felt that I've been listened to. I've also learnt some important information from this thread. I should have posted here much sooner.

Lcsmrz: I didn't know I could find the recommended settings from the manufacturer of the blood tubes. I understand that centrifuge manufacturers could not state recommendations due to the possiblilities their centrifuges are used for. I will try to check out the recommended settings when I can!

Rashmi, Malcom Needs and Pluto: I really do understand the importance of standardisation and the reasons why there are SOPs in place. But in my personal (which, in Malcom Needs' words, I am prepared to be rebutted) opinion, using my lab's settings will only cause more stress to me when work is becoming overwhelming, increasing the chances of me making mistakes by clouding my judgement, which is critical in organisation of work and priortisation of processes. This is why I chose to use my own judgement to to change the setting to make sure that I could work my best.

Anyway, what frustrates me is that the SOP (centrifugation settings in this case) do not have any basis, as my seniors could only refer generally to the AABB TM but could not produce the information to me. What further proves to me that this setting is seriously flawed and have no basis is the fact that we changed both of our centrifuges a few months ago, we used exactly the same settings (3000rpm x 10mins) over to the new centrifuges which have a much shorter rotor!

As I said above, I did bring it up to my seniors but I ended up slamming myself against the wall. 10mins is really over the line. Therefore, I feel that the most important thing I should think about is how I should nail into my seniors the reasons why I think this setting is wrong, get them to listen to me, after which the process to find out what is the most suitable setting will come in place very easily. This is the reason of my first post, to seek advice on how to get my seniors to listen to me.

I think I will just send an email to my supervisor again.

I hope I will soon be asking for guidance on how to go about doing the small project to get the correct setting suitable for my lab.

[eric1980]

Hi, Brenda.

Thanks for the suggestions. You are right in what you, and the people here, said.

But I've since moved on to haematology, and things are rather smooth here. I still like the science of blood banking and requested for my lab manager to assign me blood banking CAP competency assessments to do on top of my haematology's. It's still as interesting to me as when I first found my interest in it. =)

The main thing I brought back is that, when the time comes I have to lead a team, I will constantly ask for feedbacks from my subordinates and make sure my decisions are correct. I'll make sure communications will go both ways.

Thanks again. =)