What is considered allowable error in electrode placement?

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Postby labman2 » Wed Apr 11, 2012 9:28 pm

somnonaut wrote: I once gave a workshop on electrode application at annual APT meeting.



Yes he did.... and the photo he uses on binary for his sign on is actually a powerpoint frame of what his red headed patient looked like when he removed the hair soaked gauze from their head in the morning! :lol: :lol:
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Postby PSGpupil » Wed Apr 11, 2012 9:31 pm

somnonaut wrote:I like very small pieces of gauze, in face they are 1.5cm X 2 cm


I find your comments extremely helpful and confirm what I have read (but not seen). I read that it is important to not use too much Ten20 paste as the spreading out of the paste forms the true electrode site. So I try to use the minimum while being sure to fill the cup as I've heard any air spaces could produce artifact.

What I have wondered about is how to minimize the Nuprep area. The manufacturer says on the directions to leave it on while applying the electrode. So I don't wipe the Nuprep off, but it always seems to create a significantly larger area than the Ten20 and I'm assuming any residual Nuprep is also increasing the pickup area (as Nuprep says it is conductive and contains salt).

I have seen the hair covering method before but hadn't connected it as a way to reduce the tape size (which makes great sense). The last place I was at used large pieces of Hypafix (1.5" X 1.5"). It holds great, but is kind of hard to get off on tender areas like the neck and eyes.
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Postby RPSGT88athome » Thu Apr 12, 2012 12:53 am

PSGpupil,

The two most helpful texts in terms of learning proper headmarking and electrode placement as well as critically important instrumentation, neuroanatomy, neurobiology, neuropathology and on and on are:

Fundamentals of EEG Technology Volumes 1 and 2. They can be found on all of the major book seller sites on the internet.

These books also provide explanations of why things should be done a certain way unlike many of the preschool level resources available to sleep techs studying ASTEP today. A-STEP is dumbed down to about an 7th or 8th grade comprehension level. (just my opinion)

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Postby somnonaut » Thu Apr 12, 2012 1:50 am

Please pay no attention to the green little man.

To reduce the site prep area, first and foremost DO NOT use those stupid huge cotton swabs such as on the cover of the MVAP catalog. Those make HUGE areas.
Secondly,(remember childrens' skin is very soft and supple and well vascularized which allows for no or truly minimal prep of the site prior to electrode application.
Thirdly, if you must prep, use a standard cotton swap of the wooden stick variety. I typically put a very small amount (maybe 1cm diameter circle "one little squish of the tube") on a piece of gauze to do the whole hookup. I dab the cotton swab (I only use 2 maximum during a whole hookup) and I point the cotton swab perpendicular to the surface of the skin, and rolling the stick between my thumb and index finger I turn the stick 3 times (Yes like Dorothy Labman2) and when I teach it I always give my little audible to this twirling motion "Doot, doot, doot. (Ask 42.) With only enough pressure on the skin to keep the swab in place provides a very satisfactory prep, with impedances into the single digits at application time, and well below 5K at bedtime. I feel many techs are taught poor prep habits (again one of the areas of Bduce's error creep.) This twirling also provides a spot of prep exactly the same size as a typical gold cup electrode...
Oh don't get me started asking you what electrodes you are instructed to use? I feel the styrofoam electrodes are the worst thing in the world for the patients and for this field. They are terribl, in terms of the profile they make on the surface of the skin once the snap on is applied. Techs should be made to wear them in sleep to see what they feel like compared to cold cups.
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Postby RPSGT88athome » Thu Apr 12, 2012 7:34 am

Exactly.

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Postby Rattlehead » Thu Apr 12, 2012 8:18 am

bduce wrote:PSG Pupil
I have tried to be as respectful as possible with you and have tried to give you some honest and forthright responses. You are however starting to cross a line with me now.
1. You have made some sweeping statements about sleep medicine and how it is practiced in your last couple of posts. You have not been to my lab nor have you worked in the labs of a number of colleagues on here - so DO NOT try to make sweeping statements based on your experiences in a couple of labs.
2. How long have you worked in healthcare? I can tell you now that whatever field you are in there is a binomial distribution in terms of the quality and dedication of those in the profession. Physicians, nurses, X-ray, nuclear med etc etc - meaning that there will be some really bad ones, lots of average to good ones and some high flyers who know their sh!t. That is reality - I have worked in multidisciplinary teams and have seen all types.
3. You speak as if nursing, X-ray and other parts of medicine are somehow precise. Man you are so wrong. Medicine is by nature imprecise and is actually when it all boils down, statistical.
When patient A comes in to see a physician with a certain constellation of symptoms the statistics associated with those symptoms will be 60% of the time it will be disease X, 15% disease Y and 15% disease Z. So why do we do tests? The tests are performed so that we can alter the probabilities. So if a certain test is positive the probabilities may then become disease X 90%, disease Y 2% and disease Z 8%. That is the reality. Don't believe me? Well look at the DSM IV which is like the bible for psychiatric medicine. What does it stand for? DIAGNOSTIC AND STATISTICAL MANUAL - 4TH ED.
4. As for somehow implying that other health professions are more precise, well they are and they are not. Take a look at pathology tests. They give you quite a precise number don't they for whatever test. Hang on....then why do they do duplicate runs to determine precision and bias and calculate the uncertainty of measurement in each quality lab? DING DING DING because they know that whatever value is produced from the test may not necessarily be the true value. And why is that? Because they know there is a certain amount of imprecision in what they do.
5. There are a number of factors which further impact upon the precision in what we do in sleep medicine. For example, unlike path tests we are not testing for just one thing to determine presence or absence of a single disorder. We are making multiple measurements which are then incorporated together to determine presence/absence of a number of sleep disorders which may contribute to the constellation of symptoms the patients presents with.
Furthermore we do not easily have a standard with which we can all test with. Oh how I wish we had a standard person who in whatever sleep lab he/she sleeps in will have exactly 15.6/hr AHI. We could send him around to each and every lab and the lab managers could then use it as a basis to improve their procedures and techniques. Unfortunately we do not have that person.
6. Research to improve our testing methodologies is quite sparse (sad to say) but that is due to the fact that the studies take a lot of time and resources to complete. Compare that to a lung function test which takes at most 1 hour if you are measuring lung volumes as well as flow-volume loops. That is one of the reasons why this area has so much research behind their methodologies (although there are still a few consensus rules in the ATS statements) compared to ours.

Look it seems to me you could be working in a crappy lab but I will reserve that judgement as I have only heard one side of the story. It is up to you decide with how you are going to proceed with your career. If it is bothering you that much, pack up your cojones and move to another lab.

Please you need to do some learning before you start going off again on some of this stuff. Not the polysomnography stuff but about medicine in general. You need to pull your head in a bit, get some experience and then re-evaluate some of your opinions.

I know my staff think I am anally retentive about the way we do things and I can probably guess that the staff of some of my colleagues on here would think the same of them. I am happy for them to think that too - as long as they follow my policies and procedures in the lab. I am even happier when some of my staff move interstate to another lab and say to me later "I now get why you do things that way and I wish these guys would". That is why I am pretty p!ssed that you are making some of these statements about lab in general.

Honestly if the whole issue of imprecision is driving you nuts, seek another career.


Go easy on him, he's just pointing out the frustration of discovering that the rules are inconsistently applied from location to location. He's trying to learn the right way, but is seeing instructors doing things the wrong way.

PSGPupil has every right to be frustrated. He's the one investing time and money for training that is supposed to be a standardized in our field.

I'm impressed that he found the weaknesses in our field in such a short time, and that he was dedicated enough to go through multiple ASTEP programs to try to get it right. That type of observational-skill and dedication will take him far.

I'm glad to see some posters offering him mentoring and advice. That is what he truly needs at this stage.
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Postby Rattlehead » Thu Apr 12, 2012 9:09 am

To add to the previous tips given:

I use GreenPrep at work; the label indicated it should be removed prior to electrode application. I always wipe the prep off, and then rub the skin with alcohol pads to remove any chloride/body-oil residue, and then prep the site with a product like Prep 'N Stay to help with tape adhesion. I avoid using tape in the hair, and use small 1" gauze squares as mentioned previously. Tape + hair = pain + poor adhesion in my experience.

A little trick for electrode placement accuracy is that most gold-cup electrodes are 10mm/1 cm in diameter. You can use the width of a gold-cup to assess your EEG placements and locate 1 cm up/down EOG placements.

Measuring heads is vital, because you'll quickly find that heads are rarely symmetrical in shape. The finger methods can't take that in to account, and I have yet to see a pair of graduated fingers. Most heads you'll find will measure to within a certain range of say 4-6 cm as far as overall circumferences, etc.

Never be afraid to ask reasonable questions of anyone, if you can't find a good answer in a book. Also, beware people who won't give you a reasonable explanation to those questions. Always try to frame questions as clarifications to what you have already read up on.

Find a mentor, even if it's just an online contact. A person willing to share experience is worth their weight in gold-cups. Techniques will vary from person-to-person; use their examples to develop your own personal standards.

Be observant at all time, and document everything you see in or hear from a patient. Patients will often tell techs things that they won't tell a physician.
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Postby LadyCandy » Fri Apr 13, 2012 6:52 am

I literally could not wait to see the responses after the original poster mentioned fingers and knuckles, or what have you.

I thought it would be funny to share other weird placements -

I took the original photo, and the red spots are where I found someone's C3/C4 recently...I went to check it was in tact due to poor impedances, and I looked in where you would approximately expect to find the Cs, and they weren't there. They were so far away that I was initially convinced they hadn't been put on!

Image
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Postby LadyCandy » Fri Apr 13, 2012 7:28 am

RPSGT88athome wrote:
Sleep tech staff members are required to measure and mark according to the guidelines (and with a real tape measure) or they are let go.

RPSGT88


88...what does a fake tape measure look like? :?
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Postby somnonaut » Fri Apr 13, 2012 12:03 pm

For my EOG placement I put the electrodes closer to the eye, and more on the orbit of the skull. I do this by making smaller pieces of tape. That is ridiculously large pieces of tape in that picture. I make my EOG tape about 1-1.25 cm wide.

NB: I will give much props and kudos to my staff at Winthrop who fought with me on changing my hookup mandate from micropore to hypafix. That hypafix is extremely soft and pliable and makes for a serious comfortable hookup.

Side story: The lab I am presently working in perdiem had a patient come back for CPAP. I happened to do her PSG the first night, and now she was assigned to another, more fresh tech for CPAP. They were in the next room from me, as I was hooking my pt up and she hooking this woman. The tech literally came out and asked me to step into the room to talk to the patient. The patient was complaining that she did not remember all the electrodes this newer tech was putting on her face and all over. I looked at the tech, and tried my damn-est not to blurt out "WHAT THE HELL ARE YOU DOING" but this tech was using what the lab offered/suggested which was styrofoam patches and snap on leads, and here they were like boils all over this woman, and obviously the patient was much more irritated by this hookup than my original one. I assured her that it was just technique and style, and yes I did put the same electrodes on but just differently. Pt was not happy.
We have allowed error creep way too much in the field, and this is what we have now gotten to. Yes I realize that my staff pushed the envelope for me, but just like the rest of the field, once we are shown we then become disciples for that cause. Comparing notes as in here is definitely a great way to proselytize your chosen topic and learn from others.
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Postby RPSGT88athome » Fri Apr 13, 2012 12:37 pm

Gold grass handcrafted leads. A mite better than styrofoam I must say :wink:
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Postby Rocklandish » Fri Apr 13, 2012 2:18 pm

Tape measure, gauze, salt bridge, what the hell are you people talking about?
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Postby PSGpupil » Fri Apr 13, 2012 4:18 pm

somnonaut wrote:Thirdly, if you must prep, use a standard cotton swap of the wooden stick variety. I typically put a very small amount (maybe 1cm diameter circle "one little squish of the tube") on a piece of gauze to do the whole hookup. I dab the cotton swab (I only use 2 maximum during a whole hookup) and I point the cotton swab perpendicular to the surface of the skin, and rolling the stick between my thumb and index finger I turn the stick 3 times (Yes like Dorothy Labman2) and when I teach it I always give my little audible to this twirling motion "Doot, doot, doot. (Ask 42.) With only enough pressure on the skin to keep the swab in place provides a very satisfactory prep, with impedances into the single digits at application time, and well below 5K at bedtime.


I cannot thank you enough. This is the exact type of detailed information I was seeking. I have not found it in the A-STEP class, A-STEP videos, nor from my clinical associates. Instead I have found the most detailed, most accurate, and most practical answers in this forum. Thank you :D
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Postby PSGpupil » Fri Apr 13, 2012 4:25 pm

Rattlehead wrote:A little trick for electrode placement accuracy is that most gold-cup electrodes are 10mm/1 cm in diameter. You can use the width of a gold-cup to assess your EEG placements and locate 1 cm up/down EOG placements.


Excellent tip. Much appreciated!
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Postby munkyBeatz » Sat Apr 14, 2012 9:03 am

somnonaut wrote:Please pay no attention to the green little man.

To reduce the site prep area, first and foremost DO NOT use those stupid huge cotton swabs such as on the cover of the MVAP catalog. Those make HUGE areas.
Secondly,(remember childrens' skin is very soft and supple and well vascularized which allows for no or truly minimal prep of the site prior to electrode application.
Thirdly, if you must prep, use a standard cotton swap of the wooden stick variety. I typically put a very small amount (maybe 1cm diameter circle "one little squish of the tube") on a piece of gauze to do the whole hookup. I dab the cotton swab (I only use 2 maximum during a whole hookup) and I point the cotton swab perpendicular to the surface of the skin, and rolling the stick between my thumb and index finger I turn the stick 3 times (Yes like Dorothy Labman2) and when I teach it I always give my little audible to this twirling motion "Doot, doot, doot. (Ask 42.) With only enough pressure on the skin to keep the swab in place provides a very satisfactory prep, with impedances into the single digits at application time, and well below 5K at bedtime. I feel many techs are taught poor prep habits (again one of the areas of Bduce's error creep.) This twirling also provides a spot of prep exactly the same size as a typical gold cup electrode...
Oh don't get me started asking you what electrodes you are instructed to use? I feel the styrofoam electrodes are the worst thing in the world for the patients and for this field. They are terribl, in terms of the profile they make on the surface of the skin once the snap on is applied. Techs should be made to wear them in sleep to see what they feel like compared to cold cups.


Very good tips Somno. I'm always telling my techs to use as little paste and Nuprep as possible to retain better signals, to keep from creating a larger surface area, and well cost us less money.
As for your earlier post on the saturated gauze, and using the hair overlapping. I've heard of people doing this but have never actually done it myself. We buy 1x1 squares of gauze, and they're 3 layers to it; and yes, my techs currently use the entire 1x1 on a single electrode. What size of gauze do you cut yours to? Without layering the hair as you suggest, I find techs using more paste to keep the gauze in place. And they feel the need to keep the outer layers dry, to keep the gauze from sticking to the pillow while patient is down/moving. Is the layering of hair sufficient to keep the electrodes from sticking to the pillow? Also, as for Paste use, I've always used just the amount that comes up, plus a very little addition to pack on top with the gauze, since I've not layered the hair before. So, with your method, are you only needing to utilize the amount of paste that comes out of the hole at application, or is a small additional amount required?

As for the nuprep, very interesting instructional method to keep techs from over doing it with the prep! Are you place the electrode immediately, or do you wait for the prepped area to dry slightly before application? Does the 'doot, doot, doot' method remove the majority of the china markings?

Thanks in advance, I'm only asking to better understand your method, and in turn teach my techs a better method to utilize less product, and get better signals. Many of my own methods learned over the years, which work very well for me and a few of my techs, don't translate all that well to some others. It seems subjective to some of them when I say things like 'Keep the prep area small", when they see me swap horizontally to the skin. I find your methods will prove easier though.
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